Remove damned ancient DOS line endings from Irrlicht. Hopefully I did not go overboard.

1 files changed, 4158 insertions, 4158 deletions

diff --git a/libraries/irrlicht-1.8/source/Irrlicht/libpng/pngrutil.c b/libraries/irrlicht-1.8/source/Irrlicht/libpng/pngrutil.c
index 7b4557f..d6c0e03 100644
--- a/libraries/irrlicht-1.8/source/Irrlicht/libpng/pngrutil.c
+++ b/libraries/irrlicht-1.8/source/Irrlicht/libpng/pngrutil.c
@@ -1,4158 +1,4158 @@
-

-/* pngrutil.c - utilities to read a PNG file

- *

- * Last changed in libpng 1.5.9 [February 18, 2012]

- * Copyright (c) 1998-2012 Glenn Randers-Pehrson

- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)

- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)

- *

- * This code is released under the libpng license.

- * For conditions of distribution and use, see the disclaimer

- * and license in png.h

- *

- * This file contains routines that are only called from within

- * libpng itself during the course of reading an image.

- */

-

-#include "pngpriv.h"

-

-#ifdef PNG_READ_SUPPORTED

-

-#define png_strtod(p,a,b) strtod(a,b)

-

-png_uint_32 PNGAPI

-png_get_uint_31(png_structp png_ptr, png_const_bytep buf)

-{

-   png_uint_32 uval = png_get_uint_32(buf);

-

-   if (uval > PNG_UINT_31_MAX)

-      png_error(png_ptr, "PNG unsigned integer out of range");

-

-   return (uval);

-}

-

-#if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_READ_cHRM_SUPPORTED)

-/* The following is a variation on the above for use with the fixed

- * point values used for gAMA and cHRM.  Instead of png_error it

- * issues a warning and returns (-1) - an invalid value because both

- * gAMA and cHRM use *unsigned* integers for fixed point values.

- */

-#define PNG_FIXED_ERROR (-1)

-

-static png_fixed_point /* PRIVATE */

-png_get_fixed_point(png_structp png_ptr, png_const_bytep buf)

-{

-   png_uint_32 uval = png_get_uint_32(buf);

-

-   if (uval <= PNG_UINT_31_MAX)

-      return (png_fixed_point)uval; /* known to be in range */

-

-   /* The caller can turn off the warning by passing NULL. */

-   if (png_ptr != NULL)

-      png_warning(png_ptr, "PNG fixed point integer out of range");

-

-   return PNG_FIXED_ERROR;

-}

-#endif

-

-#ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED

-/* NOTE: the read macros will obscure these definitions, so that if

- * PNG_USE_READ_MACROS is set the library will not use them internally,

- * but the APIs will still be available externally.

- *

- * The parentheses around "PNGAPI function_name" in the following three

- * functions are necessary because they allow the macros to co-exist with

- * these (unused but exported) functions.

- */

-

-/* Grab an unsigned 32-bit integer from a buffer in big-endian format. */

-png_uint_32 (PNGAPI

-png_get_uint_32)(png_const_bytep buf)

-{

-   png_uint_32 uval =

-       ((png_uint_32)(*(buf    )) << 24) +

-       ((png_uint_32)(*(buf + 1)) << 16) +

-       ((png_uint_32)(*(buf + 2)) <<  8) +

-       ((png_uint_32)(*(buf + 3))      ) ;

-

-   return uval;

-}

-

-/* Grab a signed 32-bit integer from a buffer in big-endian format.  The

- * data is stored in the PNG file in two's complement format and there

- * is no guarantee that a 'png_int_32' is exactly 32 bits, therefore

- * the following code does a two's complement to native conversion.

- */

-png_int_32 (PNGAPI

-png_get_int_32)(png_const_bytep buf)

-{

-   png_uint_32 uval = png_get_uint_32(buf);

-   if ((uval & 0x80000000) == 0) /* non-negative */

-      return uval;

-

-   uval = (uval ^ 0xffffffff) + 1;  /* 2's complement: -x = ~x+1 */

-   return -(png_int_32)uval;

-}

-

-/* Grab an unsigned 16-bit integer from a buffer in big-endian format. */

-png_uint_16 (PNGAPI

-png_get_uint_16)(png_const_bytep buf)

-{

-   /* ANSI-C requires an int value to accomodate at least 16 bits so this

-    * works and allows the compiler not to worry about possible narrowing

-    * on 32 bit systems.  (Pre-ANSI systems did not make integers smaller

-    * than 16 bits either.)

-    */

-   unsigned int val =

-       ((unsigned int)(*buf) << 8) +

-       ((unsigned int)(*(buf + 1)));

-

-   return (png_uint_16)val;

-}

-

-#endif /* PNG_READ_INT_FUNCTIONS_SUPPORTED */

-

-/* Read and check the PNG file signature */

-void /* PRIVATE */

-png_read_sig(png_structp png_ptr, png_infop info_ptr)

-{

-   png_size_t num_checked, num_to_check;

-

-   /* Exit if the user application does not expect a signature. */

-   if (png_ptr->sig_bytes >= 8)

-      return;

-

-   num_checked = png_ptr->sig_bytes;

-   num_to_check = 8 - num_checked;

-

-#ifdef PNG_IO_STATE_SUPPORTED

-   png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE;

-#endif

-

-   /* The signature must be serialized in a single I/O call. */

-   png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);

-   png_ptr->sig_bytes = 8;

-

-   if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))

-   {

-      if (num_checked < 4 &&

-          png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))

-         png_error(png_ptr, "Not a PNG file");

-      else

-         png_error(png_ptr, "PNG file corrupted by ASCII conversion");

-   }

-   if (num_checked < 3)

-      png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;

-}

-

-/* Read the chunk header (length + type name).

- * Put the type name into png_ptr->chunk_name, and return the length.

- */

-png_uint_32 /* PRIVATE */

-png_read_chunk_header(png_structp png_ptr)

-{

-   png_byte buf[8];

-   png_uint_32 length;

-

-#ifdef PNG_IO_STATE_SUPPORTED

-   png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR;

-#endif

-

-   /* Read the length and the chunk name.

-    * This must be performed in a single I/O call.

-    */

-   png_read_data(png_ptr, buf, 8);

-   length = png_get_uint_31(png_ptr, buf);

-

-   /* Put the chunk name into png_ptr->chunk_name. */

-   png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(buf+4);

-

-   png_debug2(0, "Reading %lx chunk, length = %lu",

-       (unsigned long)png_ptr->chunk_name, (unsigned long)length);

-

-   /* Reset the crc and run it over the chunk name. */

-   png_reset_crc(png_ptr);

-   png_calculate_crc(png_ptr, buf + 4, 4);

-

-   /* Check to see if chunk name is valid. */

-   png_check_chunk_name(png_ptr, png_ptr->chunk_name);

-

-#ifdef PNG_IO_STATE_SUPPORTED

-   png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;

-#endif

-

-   return length;

-}

-

-/* Read data, and (optionally) run it through the CRC. */

-void /* PRIVATE */

-png_crc_read(png_structp png_ptr, png_bytep buf, png_size_t length)

-{

-   if (png_ptr == NULL)

-      return;

-

-   png_read_data(png_ptr, buf, length);

-   png_calculate_crc(png_ptr, buf, length);

-}

-

-/* Optionally skip data and then check the CRC.  Depending on whether we

- * are reading a ancillary or critical chunk, and how the program has set

- * things up, we may calculate the CRC on the data and print a message.

- * Returns '1' if there was a CRC error, '0' otherwise.

- */

-int /* PRIVATE */

-png_crc_finish(png_structp png_ptr, png_uint_32 skip)

-{

-   png_size_t i;

-   png_size_t istop = png_ptr->zbuf_size;

-

-   for (i = (png_size_t)skip; i > istop; i -= istop)

-   {

-      png_crc_read(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);

-   }

-

-   if (i)

-   {

-      png_crc_read(png_ptr, png_ptr->zbuf, i);

-   }

-

-   if (png_crc_error(png_ptr))

-   {

-      if (PNG_CHUNK_ANCILLIARY(png_ptr->chunk_name) ?

-          !(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) :

-          (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE))

-      {

-         png_chunk_warning(png_ptr, "CRC error");

-      }

-

-      else

-      {

-         png_chunk_benign_error(png_ptr, "CRC error");

-         return (0);

-      }

-

-      return (1);

-   }

-

-   return (0);

-}

-

-/* Compare the CRC stored in the PNG file with that calculated by libpng from

- * the data it has read thus far.

- */

-int /* PRIVATE */

-png_crc_error(png_structp png_ptr)

-{

-   png_byte crc_bytes[4];

-   png_uint_32 crc;

-   int need_crc = 1;

-

-   if (PNG_CHUNK_ANCILLIARY(png_ptr->chunk_name))

-   {

-      if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==

-          (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))

-         need_crc = 0;

-   }

-

-   else /* critical */

-   {

-      if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)

-         need_crc = 0;

-   }

-

-#ifdef PNG_IO_STATE_SUPPORTED

-   png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_CRC;

-#endif

-

-   /* The chunk CRC must be serialized in a single I/O call. */

-   png_read_data(png_ptr, crc_bytes, 4);

-

-   if (need_crc)

-   {

-      crc = png_get_uint_32(crc_bytes);

-      return ((int)(crc != png_ptr->crc));

-   }

-

-   else

-      return (0);

-}

-

-#ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED

-static png_size_t

-png_inflate(png_structp png_ptr, png_bytep data, png_size_t size,

-    png_bytep output, png_size_t output_size)

-{

-   png_size_t count = 0;

-

-   /* zlib can't necessarily handle more than 65535 bytes at once (i.e. it can't

-    * even necessarily handle 65536 bytes) because the type uInt is "16 bits or

-    * more".  Consequently it is necessary to chunk the input to zlib.  This

-    * code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the maximum value

-    * that can be stored in a uInt.)  It is possible to set ZLIB_IO_MAX to a

-    * lower value in pngpriv.h and this may sometimes have a performance

-    * advantage, because it forces access of the input data to be separated from

-    * at least some of the use by some period of time.

-    */

-   png_ptr->zstream.next_in = data;

-   /* avail_in is set below from 'size' */

-   png_ptr->zstream.avail_in = 0;

-

-   while (1)

-   {

-      int ret, avail;

-

-      /* The setting of 'avail_in' used to be outside the loop; by setting it

-       * inside it is possible to chunk the input to zlib and simply rely on

-       * zlib to advance the 'next_in' pointer.  This allows arbitrary amounts o

-       * data to be passed through zlib at the unavoidable cost of requiring a

-       * window save (memcpy of up to 32768 output bytes) every ZLIB_IO_MAX

-       * input bytes.

-       */

-      if (png_ptr->zstream.avail_in == 0 && size > 0)

-      {

-         if (size <= ZLIB_IO_MAX)

-         {

-            /* The value is less than ZLIB_IO_MAX so the cast is safe: */

-            png_ptr->zstream.avail_in = (uInt)size;

-            size = 0;

-         }

-

-         else

-         {

-            png_ptr->zstream.avail_in = ZLIB_IO_MAX;

-            size -= ZLIB_IO_MAX;

-         }

-      }

-

-      /* Reset the output buffer each time round - we empty it

-       * after every inflate call.

-       */

-      png_ptr->zstream.next_out = png_ptr->zbuf;

-      png_ptr->zstream.avail_out = png_ptr->zbuf_size;

-

-      ret = inflate(&png_ptr->zstream, Z_NO_FLUSH);

-      avail = png_ptr->zbuf_size - png_ptr->zstream.avail_out;

-

-      /* First copy/count any new output - but only if we didn't

-       * get an error code.

-       */

-      if ((ret == Z_OK || ret == Z_STREAM_END) && avail > 0)

-      {

-         png_size_t space = avail; /* > 0, see above */

-

-         if (output != 0 && output_size > count)

-         {

-            png_size_t copy = output_size - count;

-

-            if (space < copy)

-               copy = space;

-

-            png_memcpy(output + count, png_ptr->zbuf, copy);

-         }

-         count += space;

-      }

-

-      if (ret == Z_OK)

-         continue;

-

-      /* Termination conditions - always reset the zstream, it

-       * must be left in inflateInit state.

-       */

-      png_ptr->zstream.avail_in = 0;

-      inflateReset(&png_ptr->zstream);

-

-      if (ret == Z_STREAM_END)

-         return count; /* NOTE: may be zero. */

-

-      /* Now handle the error codes - the API always returns 0

-       * and the error message is dumped into the uncompressed

-       * buffer if available.

-       */

-#     ifdef PNG_WARNINGS_SUPPORTED

-      {

-         png_const_charp msg;

-

-         if (png_ptr->zstream.msg != 0)

-            msg = png_ptr->zstream.msg;

-

-         else switch (ret)

-         {

-            case Z_BUF_ERROR:

-               msg = "Buffer error in compressed datastream";

-               break;

-

-            case Z_DATA_ERROR:

-               msg = "Data error in compressed datastream";

-               break;

-

-            default:

-               msg = "Incomplete compressed datastream";

-               break;

-         }

-

-         png_chunk_warning(png_ptr, msg);

-      }

-#     endif

-

-      /* 0 means an error - notice that this code simply ignores

-       * zero length compressed chunks as a result.

-       */

-      return 0;

-   }

-}

-

-/*

- * Decompress trailing data in a chunk.  The assumption is that chunkdata

- * points at an allocated area holding the contents of a chunk with a

- * trailing compressed part.  What we get back is an allocated area

- * holding the original prefix part and an uncompressed version of the

- * trailing part (the malloc area passed in is freed).

- */

-void /* PRIVATE */

-png_decompress_chunk(png_structp png_ptr, int comp_type,

-    png_size_t chunklength,

-    png_size_t prefix_size, png_size_t *newlength)

-{

-   /* The caller should guarantee this */

-   if (prefix_size > chunklength)

-   {

-      /* The recovery is to delete the chunk. */

-      png_warning(png_ptr, "invalid chunklength");

-      prefix_size = 0; /* To delete everything */

-   }

-

-   else if (comp_type == PNG_COMPRESSION_TYPE_BASE)

-   {

-      png_size_t expanded_size = png_inflate(png_ptr,

-          (png_bytep)(png_ptr->chunkdata + prefix_size),

-          chunklength - prefix_size,

-          0,            /* output */

-          0);           /* output size */

-

-      /* Now check the limits on this chunk - if the limit fails the

-       * compressed data will be removed, the prefix will remain.

-       */

-      if (prefix_size >= (~(png_size_t)0) - 1 ||

-         expanded_size >= (~(png_size_t)0) - 1 - prefix_size

-#ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED

-         || (png_ptr->user_chunk_malloc_max &&

-          (prefix_size + expanded_size >= png_ptr->user_chunk_malloc_max - 1))

-#else

-#  ifdef PNG_USER_CHUNK_MALLOC_MAX

-         || ((PNG_USER_CHUNK_MALLOC_MAX > 0) &&

-          prefix_size + expanded_size >= PNG_USER_CHUNK_MALLOC_MAX - 1)

-#  endif

-#endif

-         )

-         png_warning(png_ptr, "Exceeded size limit while expanding chunk");

-

-      /* If the size is zero either there was an error and a message

-       * has already been output (warning) or the size really is zero

-       * and we have nothing to do - the code will exit through the

-       * error case below.

-       */

-      else if (expanded_size > 0)

-      {

-         /* Success (maybe) - really uncompress the chunk. */

-         png_size_t new_size = 0;

-         png_charp text = (png_charp)png_malloc_warn(png_ptr,

-             prefix_size + expanded_size + 1);

-

-         if (text != NULL)

-         {

-            png_memcpy(text, png_ptr->chunkdata, prefix_size);

-            new_size = png_inflate(png_ptr,

-                (png_bytep)(png_ptr->chunkdata + prefix_size),

-                chunklength - prefix_size,

-                (png_bytep)(text + prefix_size), expanded_size);

-            text[prefix_size + expanded_size] = 0; /* just in case */

-

-            if (new_size == expanded_size)

-            {

-               png_free(png_ptr, png_ptr->chunkdata);

-               png_ptr->chunkdata = text;

-               *newlength = prefix_size + expanded_size;

-               return; /* The success return! */

-            }

-

-            png_warning(png_ptr, "png_inflate logic error");

-            png_free(png_ptr, text);

-         }

-

-         else

-            png_warning(png_ptr, "Not enough memory to decompress chunk");

-      }

-   }

-

-   else /* if (comp_type != PNG_COMPRESSION_TYPE_BASE) */

-   {

-      PNG_WARNING_PARAMETERS(p)

-      png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_d, comp_type);

-      png_formatted_warning(png_ptr, p, "Unknown compression type @1");

-

-      /* The recovery is to simply drop the data. */

-   }

-

-   /* Generic error return - leave the prefix, delete the compressed

-    * data, reallocate the chunkdata to remove the potentially large

-    * amount of compressed data.

-    */

-   {

-      png_charp text = (png_charp)png_malloc_warn(png_ptr, prefix_size + 1);

-

-      if (text != NULL)

-      {

-         if (prefix_size > 0)

-            png_memcpy(text, png_ptr->chunkdata, prefix_size);

-

-         png_free(png_ptr, png_ptr->chunkdata);

-         png_ptr->chunkdata = text;

-

-         /* This is an extra zero in the 'uncompressed' part. */

-         *(png_ptr->chunkdata + prefix_size) = 0x00;

-      }

-      /* Ignore a malloc error here - it is safe. */

-   }

-

-   *newlength = prefix_size;

-}

-#endif /* PNG_READ_COMPRESSED_TEXT_SUPPORTED */

-

-/* Read and check the IDHR chunk */

-void /* PRIVATE */

-png_handle_IHDR(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   png_byte buf[13];

-   png_uint_32 width, height;

-   int bit_depth, color_type, compression_type, filter_type;

-   int interlace_type;

-

-   png_debug(1, "in png_handle_IHDR");

-

-   if (png_ptr->mode & PNG_HAVE_IHDR)

-      png_error(png_ptr, "Out of place IHDR");

-

-   /* Check the length */

-   if (length != 13)

-      png_error(png_ptr, "Invalid IHDR chunk");

-

-   png_ptr->mode |= PNG_HAVE_IHDR;

-

-   png_crc_read(png_ptr, buf, 13);

-   png_crc_finish(png_ptr, 0);

-

-   width = png_get_uint_31(png_ptr, buf);

-   height = png_get_uint_31(png_ptr, buf + 4);

-   bit_depth = buf[8];

-   color_type = buf[9];

-   compression_type = buf[10];

-   filter_type = buf[11];

-   interlace_type = buf[12];

-

-   /* Set internal variables */

-   png_ptr->width = width;

-   png_ptr->height = height;

-   png_ptr->bit_depth = (png_byte)bit_depth;

-   png_ptr->interlaced = (png_byte)interlace_type;

-   png_ptr->color_type = (png_byte)color_type;

-#ifdef PNG_MNG_FEATURES_SUPPORTED

-   png_ptr->filter_type = (png_byte)filter_type;

-#endif

-   png_ptr->compression_type = (png_byte)compression_type;

-

-   /* Find number of channels */

-   switch (png_ptr->color_type)

-   {

-      default: /* invalid, png_set_IHDR calls png_error */

-      case PNG_COLOR_TYPE_GRAY:

-      case PNG_COLOR_TYPE_PALETTE:

-         png_ptr->channels = 1;

-         break;

-

-      case PNG_COLOR_TYPE_RGB:

-         png_ptr->channels = 3;

-         break;

-

-      case PNG_COLOR_TYPE_GRAY_ALPHA:

-         png_ptr->channels = 2;

-         break;

-

-      case PNG_COLOR_TYPE_RGB_ALPHA:

-         png_ptr->channels = 4;

-         break;

-   }

-

-   /* Set up other useful info */

-   png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth *

-   png_ptr->channels);

-   png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);

-   png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);

-   png_debug1(3, "channels = %d", png_ptr->channels);

-   png_debug1(3, "rowbytes = %lu", (unsigned long)png_ptr->rowbytes);

-   png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,

-       color_type, interlace_type, compression_type, filter_type);

-}

-

-/* Read and check the palette */

-void /* PRIVATE */

-png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   png_color palette[PNG_MAX_PALETTE_LENGTH];

-   int num, i;

-#ifdef PNG_POINTER_INDEXING_SUPPORTED

-   png_colorp pal_ptr;

-#endif

-

-   png_debug(1, "in png_handle_PLTE");

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))

-      png_error(png_ptr, "Missing IHDR before PLTE");

-

-   else if (png_ptr->mode & PNG_HAVE_IDAT)

-   {

-      png_warning(png_ptr, "Invalid PLTE after IDAT");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   else if (png_ptr->mode & PNG_HAVE_PLTE)

-      png_error(png_ptr, "Duplicate PLTE chunk");

-

-   png_ptr->mode |= PNG_HAVE_PLTE;

-

-   if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))

-   {

-      png_warning(png_ptr,

-          "Ignoring PLTE chunk in grayscale PNG");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-#ifndef PNG_READ_OPT_PLTE_SUPPORTED

-   if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)

-   {

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-#endif

-

-   if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)

-   {

-      if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)

-      {

-         png_warning(png_ptr, "Invalid palette chunk");

-         png_crc_finish(png_ptr, length);

-         return;

-      }

-

-      else

-      {

-         png_error(png_ptr, "Invalid palette chunk");

-      }

-   }

-

-   num = (int)length / 3;

-

-#ifdef PNG_POINTER_INDEXING_SUPPORTED

-   for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)

-   {

-      png_byte buf[3];

-

-      png_crc_read(png_ptr, buf, 3);

-      pal_ptr->red = buf[0];

-      pal_ptr->green = buf[1];

-      pal_ptr->blue = buf[2];

-   }

-#else

-   for (i = 0; i < num; i++)

-   {

-      png_byte buf[3];

-

-      png_crc_read(png_ptr, buf, 3);

-      /* Don't depend upon png_color being any order */

-      palette[i].red = buf[0];

-      palette[i].green = buf[1];

-      palette[i].blue = buf[2];

-   }

-#endif

-

-   /* If we actually need the PLTE chunk (ie for a paletted image), we do

-    * whatever the normal CRC configuration tells us.  However, if we

-    * have an RGB image, the PLTE can be considered ancillary, so

-    * we will act as though it is.

-    */

-#ifndef PNG_READ_OPT_PLTE_SUPPORTED

-   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)

-#endif

-   {

-      png_crc_finish(png_ptr, 0);

-   }

-

-#ifndef PNG_READ_OPT_PLTE_SUPPORTED

-   else if (png_crc_error(png_ptr))  /* Only if we have a CRC error */

-   {

-      /* If we don't want to use the data from an ancillary chunk,

-       * we have two options: an error abort, or a warning and we

-       * ignore the data in this chunk (which should be OK, since

-       * it's considered ancillary for a RGB or RGBA image).

-       */

-      if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE))

-      {

-         if (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)

-         {

-            png_chunk_benign_error(png_ptr, "CRC error");

-         }

-

-         else

-         {

-            png_chunk_warning(png_ptr, "CRC error");

-            return;

-         }

-      }

-

-      /* Otherwise, we (optionally) emit a warning and use the chunk. */

-      else if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN))

-      {

-         png_chunk_warning(png_ptr, "CRC error");

-      }

-   }

-#endif

-

-   png_set_PLTE(png_ptr, info_ptr, palette, num);

-

-#ifdef PNG_READ_tRNS_SUPPORTED

-   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)

-   {

-      if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))

-      {

-         if (png_ptr->num_trans > (png_uint_16)num)

-         {

-            png_warning(png_ptr, "Truncating incorrect tRNS chunk length");

-            png_ptr->num_trans = (png_uint_16)num;

-         }

-

-         if (info_ptr->num_trans > (png_uint_16)num)

-         {

-            png_warning(png_ptr, "Truncating incorrect info tRNS chunk length");

-            info_ptr->num_trans = (png_uint_16)num;

-         }

-      }

-   }

-#endif

-

-}

-

-void /* PRIVATE */

-png_handle_IEND(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   png_debug(1, "in png_handle_IEND");

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR) || !(png_ptr->mode & PNG_HAVE_IDAT))

-   {

-      png_error(png_ptr, "No image in file");

-   }

-

-   png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND);

-

-   if (length != 0)

-   {

-      png_warning(png_ptr, "Incorrect IEND chunk length");

-   }

-

-   png_crc_finish(png_ptr, length);

-

-   PNG_UNUSED(info_ptr) /* Quiet compiler warnings about unused info_ptr */

-}

-

-#ifdef PNG_READ_gAMA_SUPPORTED

-void /* PRIVATE */

-png_handle_gAMA(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   png_fixed_point igamma;

-   png_byte buf[4];

-

-   png_debug(1, "in png_handle_gAMA");

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))

-      png_error(png_ptr, "Missing IHDR before gAMA");

-

-   else if (png_ptr->mode & PNG_HAVE_IDAT)

-   {

-      png_warning(png_ptr, "Invalid gAMA after IDAT");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   else if (png_ptr->mode & PNG_HAVE_PLTE)

-      /* Should be an error, but we can cope with it */

-      png_warning(png_ptr, "Out of place gAMA chunk");

-

-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA)

-#ifdef PNG_READ_sRGB_SUPPORTED

-       && !(info_ptr->valid & PNG_INFO_sRGB)

-#endif

-       )

-   {

-      png_warning(png_ptr, "Duplicate gAMA chunk");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   if (length != 4)

-   {

-      png_warning(png_ptr, "Incorrect gAMA chunk length");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   png_crc_read(png_ptr, buf, 4);

-

-   if (png_crc_finish(png_ptr, 0))

-      return;

-

-   igamma = png_get_fixed_point(NULL, buf);

-

-   /* Check for zero gamma or an error. */

-   if (igamma <= 0)

-   {

-      png_warning(png_ptr,

-          "Ignoring gAMA chunk with out of range gamma");

-

-      return;

-   }

-

-#  ifdef PNG_READ_sRGB_SUPPORTED

-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB))

-   {

-      if (PNG_OUT_OF_RANGE(igamma, 45500, 500))

-      {

-         PNG_WARNING_PARAMETERS(p)

-         png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_fixed, igamma);

-         png_formatted_warning(png_ptr, p,

-             "Ignoring incorrect gAMA value @1 when sRGB is also present");

-         return;

-      }

-   }

-#  endif /* PNG_READ_sRGB_SUPPORTED */

-

-#  ifdef PNG_READ_GAMMA_SUPPORTED

-   /* Gamma correction on read is supported. */

-   png_ptr->gamma = igamma;

-#  endif

-   /* And set the 'info' structure members. */

-   png_set_gAMA_fixed(png_ptr, info_ptr, igamma);

-}

-#endif

-

-#ifdef PNG_READ_sBIT_SUPPORTED

-void /* PRIVATE */

-png_handle_sBIT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   png_size_t truelen;

-   png_byte buf[4];

-

-   png_debug(1, "in png_handle_sBIT");

-

-   buf[0] = buf[1] = buf[2] = buf[3] = 0;

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))

-      png_error(png_ptr, "Missing IHDR before sBIT");

-

-   else if (png_ptr->mode & PNG_HAVE_IDAT)

-   {

-      png_warning(png_ptr, "Invalid sBIT after IDAT");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   else if (png_ptr->mode & PNG_HAVE_PLTE)

-   {

-      /* Should be an error, but we can cope with it */

-      png_warning(png_ptr, "Out of place sBIT chunk");

-   }

-

-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT))

-   {

-      png_warning(png_ptr, "Duplicate sBIT chunk");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)

-      truelen = 3;

-

-   else

-      truelen = (png_size_t)png_ptr->channels;

-

-   if (length != truelen || length > 4)

-   {

-      png_warning(png_ptr, "Incorrect sBIT chunk length");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   png_crc_read(png_ptr, buf, truelen);

-

-   if (png_crc_finish(png_ptr, 0))

-      return;

-

-   if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)

-   {

-      png_ptr->sig_bit.red = buf[0];

-      png_ptr->sig_bit.green = buf[1];

-      png_ptr->sig_bit.blue = buf[2];

-      png_ptr->sig_bit.alpha = buf[3];

-   }

-

-   else

-   {

-      png_ptr->sig_bit.gray = buf[0];

-      png_ptr->sig_bit.red = buf[0];

-      png_ptr->sig_bit.green = buf[0];

-      png_ptr->sig_bit.blue = buf[0];

-      png_ptr->sig_bit.alpha = buf[1];

-   }

-

-   png_set_sBIT(png_ptr, info_ptr, &(png_ptr->sig_bit));

-}

-#endif

-

-#ifdef PNG_READ_cHRM_SUPPORTED

-void /* PRIVATE */

-png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   png_byte buf[32];

-   png_fixed_point x_white, y_white, x_red, y_red, x_green, y_green, x_blue,

-      y_blue;

-

-   png_debug(1, "in png_handle_cHRM");

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))

-      png_error(png_ptr, "Missing IHDR before cHRM");

-

-   else if (png_ptr->mode & PNG_HAVE_IDAT)

-   {

-      png_warning(png_ptr, "Invalid cHRM after IDAT");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   else if (png_ptr->mode & PNG_HAVE_PLTE)

-      /* Should be an error, but we can cope with it */

-      png_warning(png_ptr, "Out of place cHRM chunk");

-

-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM)

-#  ifdef PNG_READ_sRGB_SUPPORTED

-       && !(info_ptr->valid & PNG_INFO_sRGB)

-#  endif

-      )

-   {

-      png_warning(png_ptr, "Duplicate cHRM chunk");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   if (length != 32)

-   {

-      png_warning(png_ptr, "Incorrect cHRM chunk length");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   png_crc_read(png_ptr, buf, 32);

-

-   if (png_crc_finish(png_ptr, 0))

-      return;

-

-   x_white = png_get_fixed_point(NULL, buf);

-   y_white = png_get_fixed_point(NULL, buf + 4);

-   x_red   = png_get_fixed_point(NULL, buf + 8);

-   y_red   = png_get_fixed_point(NULL, buf + 12);

-   x_green = png_get_fixed_point(NULL, buf + 16);

-   y_green = png_get_fixed_point(NULL, buf + 20);

-   x_blue  = png_get_fixed_point(NULL, buf + 24);

-   y_blue  = png_get_fixed_point(NULL, buf + 28);

-

-   if (x_white == PNG_FIXED_ERROR ||

-       y_white == PNG_FIXED_ERROR ||

-       x_red   == PNG_FIXED_ERROR ||

-       y_red   == PNG_FIXED_ERROR ||

-       x_green == PNG_FIXED_ERROR ||

-       y_green == PNG_FIXED_ERROR ||

-       x_blue  == PNG_FIXED_ERROR ||

-       y_blue  == PNG_FIXED_ERROR)

-   {

-      png_warning(png_ptr, "Ignoring cHRM chunk with negative chromaticities");

-      return;

-   }

-

-#ifdef PNG_READ_sRGB_SUPPORTED

-   if ((info_ptr != NULL) && (info_ptr->valid & PNG_INFO_sRGB))

-   {

-      if (PNG_OUT_OF_RANGE(x_white, 31270,  1000) ||

-          PNG_OUT_OF_RANGE(y_white, 32900,  1000) ||

-          PNG_OUT_OF_RANGE(x_red,   64000,  1000) ||

-          PNG_OUT_OF_RANGE(y_red,   33000,  1000) ||

-          PNG_OUT_OF_RANGE(x_green, 30000,  1000) ||

-          PNG_OUT_OF_RANGE(y_green, 60000,  1000) ||

-          PNG_OUT_OF_RANGE(x_blue,  15000,  1000) ||

-          PNG_OUT_OF_RANGE(y_blue,   6000,  1000))

-      {

-         PNG_WARNING_PARAMETERS(p)

-

-         png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_fixed, x_white);

-         png_warning_parameter_signed(p, 2, PNG_NUMBER_FORMAT_fixed, y_white);

-         png_warning_parameter_signed(p, 3, PNG_NUMBER_FORMAT_fixed, x_red);

-         png_warning_parameter_signed(p, 4, PNG_NUMBER_FORMAT_fixed, y_red);

-         png_warning_parameter_signed(p, 5, PNG_NUMBER_FORMAT_fixed, x_green);

-         png_warning_parameter_signed(p, 6, PNG_NUMBER_FORMAT_fixed, y_green);

-         png_warning_parameter_signed(p, 7, PNG_NUMBER_FORMAT_fixed, x_blue);

-         png_warning_parameter_signed(p, 8, PNG_NUMBER_FORMAT_fixed, y_blue);

-

-         png_formatted_warning(png_ptr, p,

-             "Ignoring incorrect cHRM white(@1,@2) r(@3,@4)g(@5,@6)b(@7,@8) "

-             "when sRGB is also present");

-      }

-      return;

-   }

-#endif /* PNG_READ_sRGB_SUPPORTED */

-

-#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED

-   /* Store the _white values as default coefficients for the rgb to gray

-    * operation if it is supported.  Check if the transform is already set to

-    * avoid destroying the transform values.

-    */

-   if (!png_ptr->rgb_to_gray_coefficients_set)

-   {

-      /* png_set_background has not been called and we haven't seen an sRGB

-       * chunk yet.  Find the XYZ of the three end points.

-       */

-      png_XYZ XYZ;

-      png_xy xy;

-

-      xy.redx = x_red;

-      xy.redy = y_red;

-      xy.greenx = x_green;

-      xy.greeny = y_green;

-      xy.bluex = x_blue;

-      xy.bluey = y_blue;

-      xy.whitex = x_white;

-      xy.whitey = y_white;

-

-      if (png_XYZ_from_xy_checked(png_ptr, &XYZ, xy))

-      {

-         /* The success case, because XYZ_from_xy normalises to a reference

-          * white Y of 1.0 we just need to scale the numbers.  This should

-          * always work just fine. It is an internal error if this overflows.

-          */

-         {

-            png_fixed_point r, g, b;

-            if (png_muldiv(&r, XYZ.redY, 32768, PNG_FP_1) &&

-               r >= 0 && r <= 32768 &&

-               png_muldiv(&g, XYZ.greenY, 32768, PNG_FP_1) &&

-               g >= 0 && g <= 32768 &&

-               png_muldiv(&b, XYZ.blueY, 32768, PNG_FP_1) &&

-               b >= 0 && b <= 32768 &&

-               r+g+b <= 32769)

-            {

-               /* We allow 0 coefficients here.  r+g+b may be 32769 if two or

-                * all of the coefficients were rounded up.  Handle this by

-                * reducing the *largest* coefficient by 1; this matches the

-                * approach used for the default coefficients in pngrtran.c

-                */

-               int add = 0;

-

-               if (r+g+b > 32768)

-                  add = -1;

-               else if (r+g+b < 32768)

-                  add = 1;

-

-               if (add != 0)

-               {

-                  if (g >= r && g >= b)

-                     g += add;

-                  else if (r >= g && r >= b)

-                     r += add;

-                  else

-                     b += add;

-               }

-

-               /* Check for an internal error. */

-               if (r+g+b != 32768)

-                  png_error(png_ptr,

-                     "internal error handling cHRM coefficients");

-

-               png_ptr->rgb_to_gray_red_coeff   = (png_uint_16)r;

-               png_ptr->rgb_to_gray_green_coeff = (png_uint_16)g;

-            }

-

-            /* This is a png_error at present even though it could be ignored -

-             * it should never happen, but it is important that if it does, the

-             * bug is fixed.

-             */

-            else

-               png_error(png_ptr, "internal error handling cHRM->XYZ");

-         }

-      }

-   }

-#endif

-

-   png_set_cHRM_fixed(png_ptr, info_ptr, x_white, y_white, x_red, y_red,

-      x_green, y_green, x_blue, y_blue);

-}

-#endif

-

-#ifdef PNG_READ_sRGB_SUPPORTED

-void /* PRIVATE */

-png_handle_sRGB(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   int intent;

-   png_byte buf[1];

-

-   png_debug(1, "in png_handle_sRGB");

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))

-      png_error(png_ptr, "Missing IHDR before sRGB");

-

-   else if (png_ptr->mode & PNG_HAVE_IDAT)

-   {

-      png_warning(png_ptr, "Invalid sRGB after IDAT");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   else if (png_ptr->mode & PNG_HAVE_PLTE)

-      /* Should be an error, but we can cope with it */

-      png_warning(png_ptr, "Out of place sRGB chunk");

-

-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB))

-   {

-      png_warning(png_ptr, "Duplicate sRGB chunk");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   if (length != 1)

-   {

-      png_warning(png_ptr, "Incorrect sRGB chunk length");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   png_crc_read(png_ptr, buf, 1);

-

-   if (png_crc_finish(png_ptr, 0))

-      return;

-

-   intent = buf[0];

-

-   /* Check for bad intent */

-   if (intent >= PNG_sRGB_INTENT_LAST)

-   {

-      png_warning(png_ptr, "Unknown sRGB intent");

-      return;

-   }

-

-#if defined(PNG_READ_gAMA_SUPPORTED) && defined(PNG_READ_GAMMA_SUPPORTED)

-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA))

-   {

-      if (PNG_OUT_OF_RANGE(info_ptr->gamma, 45500, 500))

-      {

-         PNG_WARNING_PARAMETERS(p)

-

-         png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_fixed,

-            info_ptr->gamma);

-

-         png_formatted_warning(png_ptr, p,

-             "Ignoring incorrect gAMA value @1 when sRGB is also present");

-      }

-   }

-#endif /* PNG_READ_gAMA_SUPPORTED */

-

-#ifdef PNG_READ_cHRM_SUPPORTED

-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM))

-      if (PNG_OUT_OF_RANGE(info_ptr->x_white, 31270,  1000) ||

-          PNG_OUT_OF_RANGE(info_ptr->y_white, 32900,  1000) ||

-          PNG_OUT_OF_RANGE(info_ptr->x_red,   64000,  1000) ||

-          PNG_OUT_OF_RANGE(info_ptr->y_red,   33000,  1000) ||

-          PNG_OUT_OF_RANGE(info_ptr->x_green, 30000,  1000) ||

-          PNG_OUT_OF_RANGE(info_ptr->y_green, 60000,  1000) ||

-          PNG_OUT_OF_RANGE(info_ptr->x_blue,  15000,  1000) ||

-          PNG_OUT_OF_RANGE(info_ptr->y_blue,   6000,  1000))

-      {

-         png_warning(png_ptr,

-             "Ignoring incorrect cHRM value when sRGB is also present");

-      }

-#endif /* PNG_READ_cHRM_SUPPORTED */

-

-   /* This is recorded for use when handling the cHRM chunk above.  An sRGB

-    * chunk unconditionally overwrites the coefficients for grayscale conversion

-    * too.

-    */

-   png_ptr->is_sRGB = 1;

-

-#  ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED

-      /* Don't overwrite user supplied values: */

-      if (!png_ptr->rgb_to_gray_coefficients_set)

-      {

-         /* These numbers come from the sRGB specification (or, since one has to

-          * pay much money to get a copy, the wikipedia sRGB page) the

-          * chromaticity values quoted have been inverted to get the reverse

-          * transformation from RGB to XYZ and the 'Y' coefficients scaled by

-          * 32768 (then rounded).

-          *

-          * sRGB and ITU Rec-709 both truncate the values for the D65 white

-          * point to four digits and, even though it actually stores five

-          * digits, the PNG spec gives the truncated value.

-          *

-          * This means that when the chromaticities are converted back to XYZ

-          * end points we end up with (6968,23435,2366), which, as described in

-          * pngrtran.c, would overflow.  If the five digit precision and up is

-          * used we get, instead:

-          *

-          *    6968*R + 23435*G + 2365*B

-          *

-          * (Notice that this rounds the blue coefficient down, rather than the

-          * choice used in pngrtran.c which is to round the green one down.)

-          */

-         png_ptr->rgb_to_gray_red_coeff   =  6968; /* 0.212639005871510 */

-         png_ptr->rgb_to_gray_green_coeff = 23434; /* 0.715168678767756 */

-         /* png_ptr->rgb_to_gray_blue_coeff  =  2366; 0.072192315360734 */

-

-         /* The following keeps the cHRM chunk from destroying the

-          * coefficients again in the event that it follows the sRGB chunk.

-          */

-         png_ptr->rgb_to_gray_coefficients_set = 1;

-      }

-#  endif

-

-   png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr, intent);

-}

-#endif /* PNG_READ_sRGB_SUPPORTED */

-

-#ifdef PNG_READ_iCCP_SUPPORTED

-void /* PRIVATE */

-png_handle_iCCP(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-/* Note: this does not properly handle chunks that are > 64K under DOS */

-{

-   png_byte compression_type;

-   png_bytep pC;

-   png_charp profile;

-   png_uint_32 skip = 0;

-   png_uint_32 profile_size;

-   png_alloc_size_t profile_length;

-   png_size_t slength, prefix_length, data_length;

-

-   png_debug(1, "in png_handle_iCCP");

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))

-      png_error(png_ptr, "Missing IHDR before iCCP");

-

-   else if (png_ptr->mode & PNG_HAVE_IDAT)

-   {

-      png_warning(png_ptr, "Invalid iCCP after IDAT");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   else if (png_ptr->mode & PNG_HAVE_PLTE)

-      /* Should be an error, but we can cope with it */

-      png_warning(png_ptr, "Out of place iCCP chunk");

-

-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_iCCP))

-   {

-      png_warning(png_ptr, "Duplicate iCCP chunk");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-#ifdef PNG_MAX_MALLOC_64K

-   if (length > (png_uint_32)65535L)

-   {

-      png_warning(png_ptr, "iCCP chunk too large to fit in memory");

-      skip = length - (png_uint_32)65535L;

-      length = (png_uint_32)65535L;

-   }

-#endif

-

-   png_free(png_ptr, png_ptr->chunkdata);

-   png_ptr->chunkdata = (png_charp)png_malloc(png_ptr, length + 1);

-   slength = length;

-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);

-

-   if (png_crc_finish(png_ptr, skip))

-   {

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      return;

-   }

-

-   png_ptr->chunkdata[slength] = 0x00;

-

-   for (profile = png_ptr->chunkdata; *profile; profile++)

-      /* Empty loop to find end of name */ ;

-

-   ++profile;

-

-   /* There should be at least one zero (the compression type byte)

-    * following the separator, and we should be on it

-    */

-   if (profile >= png_ptr->chunkdata + slength - 1)

-   {

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      png_warning(png_ptr, "Malformed iCCP chunk");

-      return;

-   }

-

-   /* Compression_type should always be zero */

-   compression_type = *profile++;

-

-   if (compression_type)

-   {

-      png_warning(png_ptr, "Ignoring nonzero compression type in iCCP chunk");

-      compression_type = 0x00;  /* Reset it to zero (libpng-1.0.6 through 1.0.8

-                                 wrote nonzero) */

-   }

-

-   prefix_length = profile - png_ptr->chunkdata;

-   png_decompress_chunk(png_ptr, compression_type,

-       slength, prefix_length, &data_length);

-

-   profile_length = data_length - prefix_length;

-

-   if (prefix_length > data_length || profile_length < 4)

-   {

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      png_warning(png_ptr, "Profile size field missing from iCCP chunk");

-      return;

-   }

-

-   /* Check the profile_size recorded in the first 32 bits of the ICC profile */

-   pC = (png_bytep)(png_ptr->chunkdata + prefix_length);

-   profile_size = ((*(pC    )) << 24) |

-                  ((*(pC + 1)) << 16) |

-                  ((*(pC + 2)) <<  8) |

-                  ((*(pC + 3))      );

-

-   /* NOTE: the following guarantees that 'profile_length' fits into 32 bits,

-    * because profile_size is a 32 bit value.

-    */

-   if (profile_size < profile_length)

-      profile_length = profile_size;

-

-   /* And the following guarantees that profile_size == profile_length. */

-   if (profile_size > profile_length)

-   {

-      PNG_WARNING_PARAMETERS(p)

-

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-

-      png_warning_parameter_unsigned(p, 1, PNG_NUMBER_FORMAT_u, profile_size);

-      png_warning_parameter_unsigned(p, 2, PNG_NUMBER_FORMAT_u, profile_length);

-      png_formatted_warning(png_ptr, p,

-         "Ignoring iCCP chunk with declared size = @1 and actual length = @2");

-      return;

-   }

-

-   png_set_iCCP(png_ptr, info_ptr, png_ptr->chunkdata,

-       compression_type, (png_bytep)png_ptr->chunkdata + prefix_length,

-       profile_size);

-   png_free(png_ptr, png_ptr->chunkdata);

-   png_ptr->chunkdata = NULL;

-}

-#endif /* PNG_READ_iCCP_SUPPORTED */

-

-#ifdef PNG_READ_sPLT_SUPPORTED

-void /* PRIVATE */

-png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-/* Note: this does not properly handle chunks that are > 64K under DOS */

-{

-   png_bytep entry_start;

-   png_sPLT_t new_palette;

-   png_sPLT_entryp pp;

-   png_uint_32 data_length;

-   int entry_size, i;

-   png_uint_32 skip = 0;

-   png_size_t slength;

-   png_uint_32 dl;

-   png_size_t max_dl;

-

-   png_debug(1, "in png_handle_sPLT");

-

-#ifdef PNG_USER_LIMITS_SUPPORTED

-

-   if (png_ptr->user_chunk_cache_max != 0)

-   {

-      if (png_ptr->user_chunk_cache_max == 1)

-      {

-         png_crc_finish(png_ptr, length);

-         return;

-      }

-

-      if (--png_ptr->user_chunk_cache_max == 1)

-      {

-         png_warning(png_ptr, "No space in chunk cache for sPLT");

-         png_crc_finish(png_ptr, length);

-         return;

-      }

-   }

-#endif

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))

-      png_error(png_ptr, "Missing IHDR before sPLT");

-

-   else if (png_ptr->mode & PNG_HAVE_IDAT)

-   {

-      png_warning(png_ptr, "Invalid sPLT after IDAT");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-#ifdef PNG_MAX_MALLOC_64K

-   if (length > (png_uint_32)65535L)

-   {

-      png_warning(png_ptr, "sPLT chunk too large to fit in memory");

-      skip = length - (png_uint_32)65535L;

-      length = (png_uint_32)65535L;

-   }

-#endif

-

-   png_free(png_ptr, png_ptr->chunkdata);

-   png_ptr->chunkdata = (png_charp)png_malloc(png_ptr, length + 1);

-

-   /* WARNING: this may break if size_t is less than 32 bits; it is assumed

-    * that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a

-    * potential breakage point if the types in pngconf.h aren't exactly right.

-    */

-   slength = length;

-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);

-

-   if (png_crc_finish(png_ptr, skip))

-   {

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      return;

-   }

-

-   png_ptr->chunkdata[slength] = 0x00;

-

-   for (entry_start = (png_bytep)png_ptr->chunkdata; *entry_start;

-       entry_start++)

-      /* Empty loop to find end of name */ ;

-

-   ++entry_start;

-

-   /* A sample depth should follow the separator, and we should be on it  */

-   if (entry_start > (png_bytep)png_ptr->chunkdata + slength - 2)

-   {

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      png_warning(png_ptr, "malformed sPLT chunk");

-      return;

-   }

-

-   new_palette.depth = *entry_start++;

-   entry_size = (new_palette.depth == 8 ? 6 : 10);

-   /* This must fit in a png_uint_32 because it is derived from the original

-    * chunk data length (and use 'length', not 'slength' here for clarity -

-    * they are guaranteed to be the same, see the tests above.)

-    */

-   data_length = length - (png_uint_32)(entry_start -

-      (png_bytep)png_ptr->chunkdata);

-

-   /* Integrity-check the data length */

-   if (data_length % entry_size)

-   {

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      png_warning(png_ptr, "sPLT chunk has bad length");

-      return;

-   }

-

-   dl = (png_int_32)(data_length / entry_size);

-   max_dl = PNG_SIZE_MAX / png_sizeof(png_sPLT_entry);

-

-   if (dl > max_dl)

-   {

-       png_warning(png_ptr, "sPLT chunk too long");

-       return;

-   }

-

-   new_palette.nentries = (png_int_32)(data_length / entry_size);

-

-   new_palette.entries = (png_sPLT_entryp)png_malloc_warn(

-       png_ptr, new_palette.nentries * png_sizeof(png_sPLT_entry));

-

-   if (new_palette.entries == NULL)

-   {

-       png_warning(png_ptr, "sPLT chunk requires too much memory");

-       return;

-   }

-

-#ifdef PNG_POINTER_INDEXING_SUPPORTED

-   for (i = 0; i < new_palette.nentries; i++)

-   {

-      pp = new_palette.entries + i;

-

-      if (new_palette.depth == 8)

-      {

-         pp->red = *entry_start++;

-         pp->green = *entry_start++;

-         pp->blue = *entry_start++;

-         pp->alpha = *entry_start++;

-      }

-

-      else

-      {

-         pp->red   = png_get_uint_16(entry_start); entry_start += 2;

-         pp->green = png_get_uint_16(entry_start); entry_start += 2;

-         pp->blue  = png_get_uint_16(entry_start); entry_start += 2;

-         pp->alpha = png_get_uint_16(entry_start); entry_start += 2;

-      }

-

-      pp->frequency = png_get_uint_16(entry_start); entry_start += 2;

-   }

-#else

-   pp = new_palette.entries;

-

-   for (i = 0; i < new_palette.nentries; i++)

-   {

-

-      if (new_palette.depth == 8)

-      {

-         pp[i].red   = *entry_start++;

-         pp[i].green = *entry_start++;

-         pp[i].blue  = *entry_start++;

-         pp[i].alpha = *entry_start++;

-      }

-

-      else

-      {

-         pp[i].red   = png_get_uint_16(entry_start); entry_start += 2;

-         pp[i].green = png_get_uint_16(entry_start); entry_start += 2;

-         pp[i].blue  = png_get_uint_16(entry_start); entry_start += 2;

-         pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2;

-      }

-

-      pp[i].frequency = png_get_uint_16(entry_start); entry_start += 2;

-   }

-#endif

-

-   /* Discard all chunk data except the name and stash that */

-   new_palette.name = png_ptr->chunkdata;

-

-   png_set_sPLT(png_ptr, info_ptr, &new_palette, 1);

-

-   png_free(png_ptr, png_ptr->chunkdata);

-   png_ptr->chunkdata = NULL;

-   png_free(png_ptr, new_palette.entries);

-}

-#endif /* PNG_READ_sPLT_SUPPORTED */

-

-#ifdef PNG_READ_tRNS_SUPPORTED

-void /* PRIVATE */

-png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   png_byte readbuf[PNG_MAX_PALETTE_LENGTH];

-

-   png_debug(1, "in png_handle_tRNS");

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))

-      png_error(png_ptr, "Missing IHDR before tRNS");

-

-   else if (png_ptr->mode & PNG_HAVE_IDAT)

-   {

-      png_warning(png_ptr, "Invalid tRNS after IDAT");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))

-   {

-      png_warning(png_ptr, "Duplicate tRNS chunk");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)

-   {

-      png_byte buf[2];

-

-      if (length != 2)

-      {

-         png_warning(png_ptr, "Incorrect tRNS chunk length");

-         png_crc_finish(png_ptr, length);

-         return;

-      }

-

-      png_crc_read(png_ptr, buf, 2);

-      png_ptr->num_trans = 1;

-      png_ptr->trans_color.gray = png_get_uint_16(buf);

-   }

-

-   else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)

-   {

-      png_byte buf[6];

-

-      if (length != 6)

-      {

-         png_warning(png_ptr, "Incorrect tRNS chunk length");

-         png_crc_finish(png_ptr, length);

-         return;

-      }

-

-      png_crc_read(png_ptr, buf, (png_size_t)length);

-      png_ptr->num_trans = 1;

-      png_ptr->trans_color.red = png_get_uint_16(buf);

-      png_ptr->trans_color.green = png_get_uint_16(buf + 2);

-      png_ptr->trans_color.blue = png_get_uint_16(buf + 4);

-   }

-

-   else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)

-   {

-      if (!(png_ptr->mode & PNG_HAVE_PLTE))

-      {

-         /* Should be an error, but we can cope with it. */

-         png_warning(png_ptr, "Missing PLTE before tRNS");

-      }

-

-      if (length > (png_uint_32)png_ptr->num_palette ||

-          length > PNG_MAX_PALETTE_LENGTH)

-      {

-         png_warning(png_ptr, "Incorrect tRNS chunk length");

-         png_crc_finish(png_ptr, length);

-         return;

-      }

-

-      if (length == 0)

-      {

-         png_warning(png_ptr, "Zero length tRNS chunk");

-         png_crc_finish(png_ptr, length);

-         return;

-      }

-

-      png_crc_read(png_ptr, readbuf, (png_size_t)length);

-      png_ptr->num_trans = (png_uint_16)length;

-   }

-

-   else

-   {

-      png_warning(png_ptr, "tRNS chunk not allowed with alpha channel");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   if (png_crc_finish(png_ptr, 0))

-   {

-      png_ptr->num_trans = 0;

-      return;

-   }

-

-   png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans,

-       &(png_ptr->trans_color));

-}

-#endif

-

-#ifdef PNG_READ_bKGD_SUPPORTED

-void /* PRIVATE */

-png_handle_bKGD(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   png_size_t truelen;

-   png_byte buf[6];

-   png_color_16 background;

-

-   png_debug(1, "in png_handle_bKGD");

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))

-      png_error(png_ptr, "Missing IHDR before bKGD");

-

-   else if (png_ptr->mode & PNG_HAVE_IDAT)

-   {

-      png_warning(png_ptr, "Invalid bKGD after IDAT");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&

-       !(png_ptr->mode & PNG_HAVE_PLTE))

-   {

-      png_warning(png_ptr, "Missing PLTE before bKGD");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD))

-   {

-      png_warning(png_ptr, "Duplicate bKGD chunk");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)

-      truelen = 1;

-

-   else if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)

-      truelen = 6;

-

-   else

-      truelen = 2;

-

-   if (length != truelen)

-   {

-      png_warning(png_ptr, "Incorrect bKGD chunk length");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   png_crc_read(png_ptr, buf, truelen);

-

-   if (png_crc_finish(png_ptr, 0))

-      return;

-

-   /* We convert the index value into RGB components so that we can allow

-    * arbitrary RGB values for background when we have transparency, and

-    * so it is easy to determine the RGB values of the background color

-    * from the info_ptr struct.

-    */

-   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)

-   {

-      background.index = buf[0];

-

-      if (info_ptr && info_ptr->num_palette)

-      {

-         if (buf[0] >= info_ptr->num_palette)

-         {

-            png_warning(png_ptr, "Incorrect bKGD chunk index value");

-            return;

-         }

-

-         background.red = (png_uint_16)png_ptr->palette[buf[0]].red;

-         background.green = (png_uint_16)png_ptr->palette[buf[0]].green;

-         background.blue = (png_uint_16)png_ptr->palette[buf[0]].blue;

-      }

-

-      else

-         background.red = background.green = background.blue = 0;

-

-      background.gray = 0;

-   }

-

-   else if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) /* GRAY */

-   {

-      background.index = 0;

-      background.red =

-      background.green =

-      background.blue =

-      background.gray = png_get_uint_16(buf);

-   }

-

-   else

-   {

-      background.index = 0;

-      background.red = png_get_uint_16(buf);

-      background.green = png_get_uint_16(buf + 2);

-      background.blue = png_get_uint_16(buf + 4);

-      background.gray = 0;

-   }

-

-   png_set_bKGD(png_ptr, info_ptr, &background);

-}

-#endif

-

-#ifdef PNG_READ_hIST_SUPPORTED

-void /* PRIVATE */

-png_handle_hIST(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   unsigned int num, i;

-   png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH];

-

-   png_debug(1, "in png_handle_hIST");

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))

-      png_error(png_ptr, "Missing IHDR before hIST");

-

-   else if (png_ptr->mode & PNG_HAVE_IDAT)

-   {

-      png_warning(png_ptr, "Invalid hIST after IDAT");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   else if (!(png_ptr->mode & PNG_HAVE_PLTE))

-   {

-      png_warning(png_ptr, "Missing PLTE before hIST");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST))

-   {

-      png_warning(png_ptr, "Duplicate hIST chunk");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   num = length / 2 ;

-

-   if (num != (unsigned int)png_ptr->num_palette || num >

-       (unsigned int)PNG_MAX_PALETTE_LENGTH)

-   {

-      png_warning(png_ptr, "Incorrect hIST chunk length");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   for (i = 0; i < num; i++)

-   {

-      png_byte buf[2];

-

-      png_crc_read(png_ptr, buf, 2);

-      readbuf[i] = png_get_uint_16(buf);

-   }

-

-   if (png_crc_finish(png_ptr, 0))

-      return;

-

-   png_set_hIST(png_ptr, info_ptr, readbuf);

-}

-#endif

-

-#ifdef PNG_READ_pHYs_SUPPORTED

-void /* PRIVATE */

-png_handle_pHYs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   png_byte buf[9];

-   png_uint_32 res_x, res_y;

-   int unit_type;

-

-   png_debug(1, "in png_handle_pHYs");

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))

-      png_error(png_ptr, "Missing IHDR before pHYs");

-

-   else if (png_ptr->mode & PNG_HAVE_IDAT)

-   {

-      png_warning(png_ptr, "Invalid pHYs after IDAT");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))

-   {

-      png_warning(png_ptr, "Duplicate pHYs chunk");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   if (length != 9)

-   {

-      png_warning(png_ptr, "Incorrect pHYs chunk length");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   png_crc_read(png_ptr, buf, 9);

-

-   if (png_crc_finish(png_ptr, 0))

-      return;

-

-   res_x = png_get_uint_32(buf);

-   res_y = png_get_uint_32(buf + 4);

-   unit_type = buf[8];

-   png_set_pHYs(png_ptr, info_ptr, res_x, res_y, unit_type);

-}

-#endif

-

-#ifdef PNG_READ_oFFs_SUPPORTED

-void /* PRIVATE */

-png_handle_oFFs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   png_byte buf[9];

-   png_int_32 offset_x, offset_y;

-   int unit_type;

-

-   png_debug(1, "in png_handle_oFFs");

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))

-      png_error(png_ptr, "Missing IHDR before oFFs");

-

-   else if (png_ptr->mode & PNG_HAVE_IDAT)

-   {

-      png_warning(png_ptr, "Invalid oFFs after IDAT");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))

-   {

-      png_warning(png_ptr, "Duplicate oFFs chunk");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   if (length != 9)

-   {

-      png_warning(png_ptr, "Incorrect oFFs chunk length");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   png_crc_read(png_ptr, buf, 9);

-

-   if (png_crc_finish(png_ptr, 0))

-      return;

-

-   offset_x = png_get_int_32(buf);

-   offset_y = png_get_int_32(buf + 4);

-   unit_type = buf[8];

-   png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y, unit_type);

-}

-#endif

-

-#ifdef PNG_READ_pCAL_SUPPORTED

-/* Read the pCAL chunk (described in the PNG Extensions document) */

-void /* PRIVATE */

-png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   png_int_32 X0, X1;

-   png_byte type, nparams;

-   png_charp buf, units, endptr;

-   png_charpp params;

-   png_size_t slength;

-   int i;

-

-   png_debug(1, "in png_handle_pCAL");

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))

-      png_error(png_ptr, "Missing IHDR before pCAL");

-

-   else if (png_ptr->mode & PNG_HAVE_IDAT)

-   {

-      png_warning(png_ptr, "Invalid pCAL after IDAT");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL))

-   {

-      png_warning(png_ptr, "Duplicate pCAL chunk");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)",

-       length + 1);

-   png_free(png_ptr, png_ptr->chunkdata);

-   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);

-

-   if (png_ptr->chunkdata == NULL)

-   {

-      png_warning(png_ptr, "No memory for pCAL purpose");

-      return;

-   }

-

-   slength = length;

-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);

-

-   if (png_crc_finish(png_ptr, 0))

-   {

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      return;

-   }

-

-   png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */

-

-   png_debug(3, "Finding end of pCAL purpose string");

-   for (buf = png_ptr->chunkdata; *buf; buf++)

-      /* Empty loop */ ;

-

-   endptr = png_ptr->chunkdata + slength;

-

-   /* We need to have at least 12 bytes after the purpose string

-    * in order to get the parameter information.

-    */

-   if (endptr <= buf + 12)

-   {

-      png_warning(png_ptr, "Invalid pCAL data");

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      return;

-   }

-

-   png_debug(3, "Reading pCAL X0, X1, type, nparams, and units");

-   X0 = png_get_int_32((png_bytep)buf+1);

-   X1 = png_get_int_32((png_bytep)buf+5);

-   type = buf[9];

-   nparams = buf[10];

-   units = buf + 11;

-

-   png_debug(3, "Checking pCAL equation type and number of parameters");

-   /* Check that we have the right number of parameters for known

-    * equation types.

-    */

-   if ((type == PNG_EQUATION_LINEAR && nparams != 2) ||

-       (type == PNG_EQUATION_BASE_E && nparams != 3) ||

-       (type == PNG_EQUATION_ARBITRARY && nparams != 3) ||

-       (type == PNG_EQUATION_HYPERBOLIC && nparams != 4))

-   {

-      png_warning(png_ptr, "Invalid pCAL parameters for equation type");

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      return;

-   }

-

-   else if (type >= PNG_EQUATION_LAST)

-   {

-      png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");

-   }

-

-   for (buf = units; *buf; buf++)

-      /* Empty loop to move past the units string. */ ;

-

-   png_debug(3, "Allocating pCAL parameters array");

-

-   params = (png_charpp)png_malloc_warn(png_ptr,

-       (png_size_t)(nparams * png_sizeof(png_charp)));

-

-   if (params == NULL)

-   {

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      png_warning(png_ptr, "No memory for pCAL params");

-      return;

-   }

-

-   /* Get pointers to the start of each parameter string. */

-   for (i = 0; i < (int)nparams; i++)

-   {

-      buf++; /* Skip the null string terminator from previous parameter. */

-

-      png_debug1(3, "Reading pCAL parameter %d", i);

-

-      for (params[i] = buf; buf <= endptr && *buf != 0x00; buf++)

-         /* Empty loop to move past each parameter string */ ;

-

-      /* Make sure we haven't run out of data yet */

-      if (buf > endptr)

-      {

-         png_warning(png_ptr, "Invalid pCAL data");

-         png_free(png_ptr, png_ptr->chunkdata);

-         png_ptr->chunkdata = NULL;

-         png_free(png_ptr, params);

-         return;

-      }

-   }

-

-   png_set_pCAL(png_ptr, info_ptr, png_ptr->chunkdata, X0, X1, type, nparams,

-      units, params);

-

-   png_free(png_ptr, png_ptr->chunkdata);

-   png_ptr->chunkdata = NULL;

-   png_free(png_ptr, params);

-}

-#endif

-

-#ifdef PNG_READ_sCAL_SUPPORTED

-/* Read the sCAL chunk */

-void /* PRIVATE */

-png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   png_size_t slength, i;

-   int state;

-

-   png_debug(1, "in png_handle_sCAL");

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))

-      png_error(png_ptr, "Missing IHDR before sCAL");

-

-   else if (png_ptr->mode & PNG_HAVE_IDAT)

-   {

-      png_warning(png_ptr, "Invalid sCAL after IDAT");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL))

-   {

-      png_warning(png_ptr, "Duplicate sCAL chunk");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   /* Need unit type, width, \0, height: minimum 4 bytes */

-   else if (length < 4)

-   {

-      png_warning(png_ptr, "sCAL chunk too short");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)",

-      length + 1);

-

-   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);

-

-   if (png_ptr->chunkdata == NULL)

-   {

-      png_warning(png_ptr, "Out of memory while processing sCAL chunk");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   slength = length;

-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);

-   png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */

-

-   if (png_crc_finish(png_ptr, 0))

-   {

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      return;

-   }

-

-   /* Validate the unit. */

-   if (png_ptr->chunkdata[0] != 1 && png_ptr->chunkdata[0] != 2)

-   {

-      png_warning(png_ptr, "Invalid sCAL ignored: invalid unit");

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      return;

-   }

-

-   /* Validate the ASCII numbers, need two ASCII numbers separated by

-    * a '\0' and they need to fit exactly in the chunk data.

-    */

-   i = 1;

-   state = 0;

-

-   if (!png_check_fp_number(png_ptr->chunkdata, slength, &state, &i) ||

-       i >= slength || png_ptr->chunkdata[i++] != 0)

-      png_warning(png_ptr, "Invalid sCAL chunk ignored: bad width format");

-

-   else if (!PNG_FP_IS_POSITIVE(state))

-      png_warning(png_ptr, "Invalid sCAL chunk ignored: non-positive width");

-

-   else

-   {

-      png_size_t heighti = i;

-

-      state = 0;

-      if (!png_check_fp_number(png_ptr->chunkdata, slength, &state, &i) ||

-          i != slength)

-         png_warning(png_ptr, "Invalid sCAL chunk ignored: bad height format");

-

-      else if (!PNG_FP_IS_POSITIVE(state))

-         png_warning(png_ptr,

-            "Invalid sCAL chunk ignored: non-positive height");

-

-      else

-         /* This is the (only) success case. */

-         png_set_sCAL_s(png_ptr, info_ptr, png_ptr->chunkdata[0],

-            png_ptr->chunkdata+1, png_ptr->chunkdata+heighti);

-   }

-

-   /* Clean up - just free the temporarily allocated buffer. */

-   png_free(png_ptr, png_ptr->chunkdata);

-   png_ptr->chunkdata = NULL;

-}

-#endif

-

-#ifdef PNG_READ_tIME_SUPPORTED

-void /* PRIVATE */

-png_handle_tIME(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   png_byte buf[7];

-   png_time mod_time;

-

-   png_debug(1, "in png_handle_tIME");

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))

-      png_error(png_ptr, "Out of place tIME chunk");

-

-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME))

-   {

-      png_warning(png_ptr, "Duplicate tIME chunk");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   if (png_ptr->mode & PNG_HAVE_IDAT)

-      png_ptr->mode |= PNG_AFTER_IDAT;

-

-   if (length != 7)

-   {

-      png_warning(png_ptr, "Incorrect tIME chunk length");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-

-   png_crc_read(png_ptr, buf, 7);

-

-   if (png_crc_finish(png_ptr, 0))

-      return;

-

-   mod_time.second = buf[6];

-   mod_time.minute = buf[5];

-   mod_time.hour = buf[4];

-   mod_time.day = buf[3];

-   mod_time.month = buf[2];

-   mod_time.year = png_get_uint_16(buf);

-

-   png_set_tIME(png_ptr, info_ptr, &mod_time);

-}

-#endif

-

-#ifdef PNG_READ_tEXt_SUPPORTED

-/* Note: this does not properly handle chunks that are > 64K under DOS */

-void /* PRIVATE */

-png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   png_textp text_ptr;

-   png_charp key;

-   png_charp text;

-   png_uint_32 skip = 0;

-   png_size_t slength;

-   int ret;

-

-   png_debug(1, "in png_handle_tEXt");

-

-#ifdef PNG_USER_LIMITS_SUPPORTED

-   if (png_ptr->user_chunk_cache_max != 0)

-   {

-      if (png_ptr->user_chunk_cache_max == 1)

-      {

-         png_crc_finish(png_ptr, length);

-         return;

-      }

-

-      if (--png_ptr->user_chunk_cache_max == 1)

-      {

-         png_warning(png_ptr, "No space in chunk cache for tEXt");

-         png_crc_finish(png_ptr, length);

-         return;

-      }

-   }

-#endif

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))

-      png_error(png_ptr, "Missing IHDR before tEXt");

-

-   if (png_ptr->mode & PNG_HAVE_IDAT)

-      png_ptr->mode |= PNG_AFTER_IDAT;

-

-#ifdef PNG_MAX_MALLOC_64K

-   if (length > (png_uint_32)65535L)

-   {

-      png_warning(png_ptr, "tEXt chunk too large to fit in memory");

-      skip = length - (png_uint_32)65535L;

-      length = (png_uint_32)65535L;

-   }

-#endif

-

-   png_free(png_ptr, png_ptr->chunkdata);

-

-   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);

-

-   if (png_ptr->chunkdata == NULL)

-   {

-     png_warning(png_ptr, "No memory to process text chunk");

-     return;

-   }

-

-   slength = length;

-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);

-

-   if (png_crc_finish(png_ptr, skip))

-   {

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      return;

-   }

-

-   key = png_ptr->chunkdata;

-

-   key[slength] = 0x00;

-

-   for (text = key; *text; text++)

-      /* Empty loop to find end of key */ ;

-

-   if (text != key + slength)

-      text++;

-

-   text_ptr = (png_textp)png_malloc_warn(png_ptr,

-       png_sizeof(png_text));

-

-   if (text_ptr == NULL)

-   {

-      png_warning(png_ptr, "Not enough memory to process text chunk");

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      return;

-   }

-

-   text_ptr->compression = PNG_TEXT_COMPRESSION_NONE;

-   text_ptr->key = key;

-   text_ptr->lang = NULL;

-   text_ptr->lang_key = NULL;

-   text_ptr->itxt_length = 0;

-   text_ptr->text = text;

-   text_ptr->text_length = png_strlen(text);

-

-   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);

-

-   png_free(png_ptr, png_ptr->chunkdata);

-   png_ptr->chunkdata = NULL;

-   png_free(png_ptr, text_ptr);

-

-   if (ret)

-      png_warning(png_ptr, "Insufficient memory to process text chunk");

-}

-#endif

-

-#ifdef PNG_READ_zTXt_SUPPORTED

-/* Note: this does not correctly handle chunks that are > 64K under DOS */

-void /* PRIVATE */

-png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   png_textp text_ptr;

-   png_charp text;

-   int comp_type;

-   int ret;

-   png_size_t slength, prefix_len, data_len;

-

-   png_debug(1, "in png_handle_zTXt");

-

-#ifdef PNG_USER_LIMITS_SUPPORTED

-   if (png_ptr->user_chunk_cache_max != 0)

-   {

-      if (png_ptr->user_chunk_cache_max == 1)

-      {

-         png_crc_finish(png_ptr, length);

-         return;

-      }

-

-      if (--png_ptr->user_chunk_cache_max == 1)

-      {

-         png_warning(png_ptr, "No space in chunk cache for zTXt");

-         png_crc_finish(png_ptr, length);

-         return;

-      }

-   }

-#endif

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))

-      png_error(png_ptr, "Missing IHDR before zTXt");

-

-   if (png_ptr->mode & PNG_HAVE_IDAT)

-      png_ptr->mode |= PNG_AFTER_IDAT;

-

-#ifdef PNG_MAX_MALLOC_64K

-   /* We will no doubt have problems with chunks even half this size, but

-    * there is no hard and fast rule to tell us where to stop.

-    */

-   if (length > (png_uint_32)65535L)

-   {

-      png_warning(png_ptr, "zTXt chunk too large to fit in memory");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-#endif

-

-   png_free(png_ptr, png_ptr->chunkdata);

-   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);

-

-   if (png_ptr->chunkdata == NULL)

-   {

-      png_warning(png_ptr, "Out of memory processing zTXt chunk");

-      return;

-   }

-

-   slength = length;

-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);

-

-   if (png_crc_finish(png_ptr, 0))

-   {

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      return;

-   }

-

-   png_ptr->chunkdata[slength] = 0x00;

-

-   for (text = png_ptr->chunkdata; *text; text++)

-      /* Empty loop */ ;

-

-   /* zTXt must have some text after the chunkdataword */

-   if (text >= png_ptr->chunkdata + slength - 2)

-   {

-      png_warning(png_ptr, "Truncated zTXt chunk");

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      return;

-   }

-

-   else

-   {

-       comp_type = *(++text);

-

-       if (comp_type != PNG_TEXT_COMPRESSION_zTXt)

-       {

-          png_warning(png_ptr, "Unknown compression type in zTXt chunk");

-          comp_type = PNG_TEXT_COMPRESSION_zTXt;

-       }

-

-       text++;        /* Skip the compression_method byte */

-   }

-

-   prefix_len = text - png_ptr->chunkdata;

-

-   png_decompress_chunk(png_ptr, comp_type,

-       (png_size_t)length, prefix_len, &data_len);

-

-   text_ptr = (png_textp)png_malloc_warn(png_ptr,

-       png_sizeof(png_text));

-

-   if (text_ptr == NULL)

-   {

-      png_warning(png_ptr, "Not enough memory to process zTXt chunk");

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      return;

-   }

-

-   text_ptr->compression = comp_type;

-   text_ptr->key = png_ptr->chunkdata;

-   text_ptr->lang = NULL;

-   text_ptr->lang_key = NULL;

-   text_ptr->itxt_length = 0;

-   text_ptr->text = png_ptr->chunkdata + prefix_len;

-   text_ptr->text_length = data_len;

-

-   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);

-

-   png_free(png_ptr, text_ptr);

-   png_free(png_ptr, png_ptr->chunkdata);

-   png_ptr->chunkdata = NULL;

-

-   if (ret)

-      png_error(png_ptr, "Insufficient memory to store zTXt chunk");

-}

-#endif

-

-#ifdef PNG_READ_iTXt_SUPPORTED

-/* Note: this does not correctly handle chunks that are > 64K under DOS */

-void /* PRIVATE */

-png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   png_textp text_ptr;

-   png_charp key, lang, text, lang_key;

-   int comp_flag;

-   int comp_type = 0;

-   int ret;

-   png_size_t slength, prefix_len, data_len;

-

-   png_debug(1, "in png_handle_iTXt");

-

-#ifdef PNG_USER_LIMITS_SUPPORTED

-   if (png_ptr->user_chunk_cache_max != 0)

-   {

-      if (png_ptr->user_chunk_cache_max == 1)

-      {

-         png_crc_finish(png_ptr, length);

-         return;

-      }

-

-      if (--png_ptr->user_chunk_cache_max == 1)

-      {

-         png_warning(png_ptr, "No space in chunk cache for iTXt");

-         png_crc_finish(png_ptr, length);

-         return;

-      }

-   }

-#endif

-

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))

-      png_error(png_ptr, "Missing IHDR before iTXt");

-

-   if (png_ptr->mode & PNG_HAVE_IDAT)

-      png_ptr->mode |= PNG_AFTER_IDAT;

-

-#ifdef PNG_MAX_MALLOC_64K

-   /* We will no doubt have problems with chunks even half this size, but

-    * there is no hard and fast rule to tell us where to stop.

-    */

-   if (length > (png_uint_32)65535L)

-   {

-      png_warning(png_ptr, "iTXt chunk too large to fit in memory");

-      png_crc_finish(png_ptr, length);

-      return;

-   }

-#endif

-

-   png_free(png_ptr, png_ptr->chunkdata);

-   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);

-

-   if (png_ptr->chunkdata == NULL)

-   {

-      png_warning(png_ptr, "No memory to process iTXt chunk");

-      return;

-   }

-

-   slength = length;

-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);

-

-   if (png_crc_finish(png_ptr, 0))

-   {

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      return;

-   }

-

-   png_ptr->chunkdata[slength] = 0x00;

-

-   for (lang = png_ptr->chunkdata; *lang; lang++)

-      /* Empty loop */ ;

-

-   lang++;        /* Skip NUL separator */

-

-   /* iTXt must have a language tag (possibly empty), two compression bytes,

-    * translated keyword (possibly empty), and possibly some text after the

-    * keyword

-    */

-

-   if (lang >= png_ptr->chunkdata + slength - 3)

-   {

-      png_warning(png_ptr, "Truncated iTXt chunk");

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      return;

-   }

-

-   else

-   {

-      comp_flag = *lang++;

-      comp_type = *lang++;

-   }

-

-   if (comp_type || (comp_flag && comp_flag != PNG_TEXT_COMPRESSION_zTXt))

-   {

-      png_warning(png_ptr, "Unknown iTXt compression type or method");

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      return;

-   }

-

-   for (lang_key = lang; *lang_key; lang_key++)

-      /* Empty loop */ ;

-

-   lang_key++;        /* Skip NUL separator */

-

-   if (lang_key >= png_ptr->chunkdata + slength)

-   {

-      png_warning(png_ptr, "Truncated iTXt chunk");

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      return;

-   }

-

-   for (text = lang_key; *text; text++)

-      /* Empty loop */ ;

-

-   text++;        /* Skip NUL separator */

-

-   if (text >= png_ptr->chunkdata + slength)

-   {

-      png_warning(png_ptr, "Malformed iTXt chunk");

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      return;

-   }

-

-   prefix_len = text - png_ptr->chunkdata;

-

-   key=png_ptr->chunkdata;

-

-   if (comp_flag)

-      png_decompress_chunk(png_ptr, comp_type,

-          (size_t)length, prefix_len, &data_len);

-

-   else

-      data_len = png_strlen(png_ptr->chunkdata + prefix_len);

-

-   text_ptr = (png_textp)png_malloc_warn(png_ptr,

-       png_sizeof(png_text));

-

-   if (text_ptr == NULL)

-   {

-      png_warning(png_ptr, "Not enough memory to process iTXt chunk");

-      png_free(png_ptr, png_ptr->chunkdata);

-      png_ptr->chunkdata = NULL;

-      return;

-   }

-

-   text_ptr->compression = (int)comp_flag + 1;

-   text_ptr->lang_key = png_ptr->chunkdata + (lang_key - key);

-   text_ptr->lang = png_ptr->chunkdata + (lang - key);

-   text_ptr->itxt_length = data_len;

-   text_ptr->text_length = 0;

-   text_ptr->key = png_ptr->chunkdata;

-   text_ptr->text = png_ptr->chunkdata + prefix_len;

-

-   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);

-

-   png_free(png_ptr, text_ptr);

-   png_free(png_ptr, png_ptr->chunkdata);

-   png_ptr->chunkdata = NULL;

-

-   if (ret)

-      png_error(png_ptr, "Insufficient memory to store iTXt chunk");

-}

-#endif

-

-/* This function is called when we haven't found a handler for a

- * chunk.  If there isn't a problem with the chunk itself (ie bad

- * chunk name, CRC, or a critical chunk), the chunk is silently ignored

- * -- unless the PNG_FLAG_UNKNOWN_CHUNKS_SUPPORTED flag is on in which

- * case it will be saved away to be written out later.

- */

-void /* PRIVATE */

-png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)

-{

-   png_uint_32 skip = 0;

-

-   png_debug(1, "in png_handle_unknown");

-

-#ifdef PNG_USER_LIMITS_SUPPORTED

-   if (png_ptr->user_chunk_cache_max != 0)

-   {

-      if (png_ptr->user_chunk_cache_max == 1)

-      {

-         png_crc_finish(png_ptr, length);

-         return;

-      }

-

-      if (--png_ptr->user_chunk_cache_max == 1)

-      {

-         png_warning(png_ptr, "No space in chunk cache for unknown chunk");

-         png_crc_finish(png_ptr, length);

-         return;

-      }

-   }

-#endif

-

-   if (png_ptr->mode & PNG_HAVE_IDAT)

-   {

-      if (png_ptr->chunk_name != png_IDAT)

-         png_ptr->mode |= PNG_AFTER_IDAT;

-   }

-

-   if (PNG_CHUNK_CRITICAL(png_ptr->chunk_name))

-   {

-#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED

-      if (png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name) !=

-          PNG_HANDLE_CHUNK_ALWAYS

-#ifdef PNG_READ_USER_CHUNKS_SUPPORTED

-          && png_ptr->read_user_chunk_fn == NULL

-#endif

-          )

-#endif

-         png_chunk_error(png_ptr, "unknown critical chunk");

-   }

-

-#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED

-   if ((png_ptr->flags & PNG_FLAG_KEEP_UNKNOWN_CHUNKS)

-#ifdef PNG_READ_USER_CHUNKS_SUPPORTED

-       || (png_ptr->read_user_chunk_fn != NULL)

-#endif

-       )

-   {

-#ifdef PNG_MAX_MALLOC_64K

-      if (length > 65535)

-      {

-         png_warning(png_ptr, "unknown chunk too large to fit in memory");

-         skip = length - 65535;

-         length = 65535;

-      }

-#endif

-

-      /* TODO: this code is very close to the unknown handling in pngpread.c,

-       * maybe it can be put into a common utility routine?

-       * png_struct::unknown_chunk is just used as a temporary variable, along

-       * with the data into which the chunk is read.  These can be eliminated.

-       */

-      PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name);

-      png_ptr->unknown_chunk.size = (png_size_t)length;

-

-      if (length == 0)

-         png_ptr->unknown_chunk.data = NULL;

-

-      else

-      {

-         png_ptr->unknown_chunk.data = (png_bytep)png_malloc(png_ptr, length);

-         png_crc_read(png_ptr, png_ptr->unknown_chunk.data, length);

-      }

-

-#ifdef PNG_READ_USER_CHUNKS_SUPPORTED

-      if (png_ptr->read_user_chunk_fn != NULL)

-      {

-         /* Callback to user unknown chunk handler */

-         int ret;

-

-         ret = (*(png_ptr->read_user_chunk_fn))

-             (png_ptr, &png_ptr->unknown_chunk);

-

-         if (ret < 0)

-            png_chunk_error(png_ptr, "error in user chunk");

-

-         if (ret == 0)

-         {

-            if (PNG_CHUNK_CRITICAL(png_ptr->chunk_name))

-            {

-#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED

-               if (png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name) !=

-                   PNG_HANDLE_CHUNK_ALWAYS)

-#endif

-                  png_chunk_error(png_ptr, "unknown critical chunk");

-            }

-

-            png_set_unknown_chunks(png_ptr, info_ptr,

-                &png_ptr->unknown_chunk, 1);

-         }

-      }

-

-      else

-#endif

-         png_set_unknown_chunks(png_ptr, info_ptr, &png_ptr->unknown_chunk, 1);

-

-      png_free(png_ptr, png_ptr->unknown_chunk.data);

-      png_ptr->unknown_chunk.data = NULL;

-   }

-

-   else

-#endif

-      skip = length;

-

-   png_crc_finish(png_ptr, skip);

-

-#ifndef PNG_READ_USER_CHUNKS_SUPPORTED

-   PNG_UNUSED(info_ptr) /* Quiet compiler warnings about unused info_ptr */

-#endif

-}

-

-/* This function is called to verify that a chunk name is valid.

- * This function can't have the "critical chunk check" incorporated

- * into it, since in the future we will need to be able to call user

- * functions to handle unknown critical chunks after we check that

- * the chunk name itself is valid.

- */

-

-/* Bit hacking: the test for an invalid byte in the 4 byte chunk name is:

- *

- * ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))

- */

-

-void /* PRIVATE */

-png_check_chunk_name(png_structp png_ptr, png_uint_32 chunk_name)

-{

-   int i;

-

-   png_debug(1, "in png_check_chunk_name");

-

-   for (i=1; i<=4; ++i)

-   {

-      int c = chunk_name & 0xff;

-

-      if (c < 65 || c > 122 || (c > 90 && c < 97))

-         png_chunk_error(png_ptr, "invalid chunk type");

-

-      chunk_name >>= 8;

-   }

-}

-

-/* Combines the row recently read in with the existing pixels in the row.  This

- * routine takes care of alpha and transparency if requested.  This routine also

- * handles the two methods of progressive display of interlaced images,

- * depending on the 'display' value; if 'display' is true then the whole row

- * (dp) is filled from the start by replicating the available pixels.  If

- * 'display' is false only those pixels present in the pass are filled in.

- */

-void /* PRIVATE */

-png_combine_row(png_structp png_ptr, png_bytep dp, int display)

-{

-   unsigned int pixel_depth = png_ptr->transformed_pixel_depth;

-   png_const_bytep sp = png_ptr->row_buf + 1;

-   png_uint_32 row_width = png_ptr->width;

-   unsigned int pass = png_ptr->pass;

-   png_bytep end_ptr = 0;

-   png_byte end_byte = 0;

-   unsigned int end_mask;

-

-   png_debug(1, "in png_combine_row");

-

-   /* Added in 1.5.6: it should not be possible to enter this routine until at

-    * least one row has been read from the PNG data and transformed.

-    */

-   if (pixel_depth == 0)

-      png_error(png_ptr, "internal row logic error");

-

-   /* Added in 1.5.4: the pixel depth should match the information returned by

-    * any call to png_read_update_info at this point.  Do not continue if we got

-    * this wrong.

-    */

-   if (png_ptr->info_rowbytes != 0 && png_ptr->info_rowbytes !=

-          PNG_ROWBYTES(pixel_depth, row_width))

-      png_error(png_ptr, "internal row size calculation error");

-

-   /* Don't expect this to ever happen: */

-   if (row_width == 0)

-      png_error(png_ptr, "internal row width error");

-

-   /* Preserve the last byte in cases where only part of it will be overwritten,

-    * the multiply below may overflow, we don't care because ANSI-C guarantees

-    * we get the low bits.

-    */

-   end_mask = (pixel_depth * row_width) & 7;

-   if (end_mask != 0)

-   {

-      /* end_ptr == NULL is a flag to say do nothing */

-      end_ptr = dp + PNG_ROWBYTES(pixel_depth, row_width) - 1;

-      end_byte = *end_ptr;

-#     ifdef PNG_READ_PACKSWAP_SUPPORTED

-         if (png_ptr->transformations & PNG_PACKSWAP) /* little-endian byte */

-            end_mask = 0xff << end_mask;

-

-         else /* big-endian byte */

-#     endif

-         end_mask = 0xff >> end_mask;

-      /* end_mask is now the bits to *keep* from the destination row */

-   }

-

-   /* For non-interlaced images this reduces to a png_memcpy(). A png_memcpy()

-    * will also happen if interlacing isn't supported or if the application

-    * does not call png_set_interlace_handling().  In the latter cases the

-    * caller just gets a sequence of the unexpanded rows from each interlace

-    * pass.

-    */

-#ifdef PNG_READ_INTERLACING_SUPPORTED

-   if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE) &&

-      pass < 6 && (display == 0 ||

-      /* The following copies everything for 'display' on passes 0, 2 and 4. */

-      (display == 1 && (pass & 1) != 0)))

-   {

-      /* Narrow images may have no bits in a pass; the caller should handle

-       * this, but this test is cheap:

-       */

-      if (row_width <= PNG_PASS_START_COL(pass))

-         return;

-

-      if (pixel_depth < 8)

-      {

-         /* For pixel depths up to 4 bpp the 8-pixel mask can be expanded to fit

-          * into 32 bits, then a single loop over the bytes using the four byte

-          * values in the 32-bit mask can be used.  For the 'display' option the

-          * expanded mask may also not require any masking within a byte.  To

-          * make this work the PACKSWAP option must be taken into account - it

-          * simply requires the pixels to be reversed in each byte.

-          *

-          * The 'regular' case requires a mask for each of the first 6 passes,

-          * the 'display' case does a copy for the even passes in the range

-          * 0..6.  This has already been handled in the test above.

-          *

-          * The masks are arranged as four bytes with the first byte to use in

-          * the lowest bits (little-endian) regardless of the order (PACKSWAP or

-          * not) of the pixels in each byte.

-          *

-          * NOTE: the whole of this logic depends on the caller of this function

-          * only calling it on rows appropriate to the pass.  This function only

-          * understands the 'x' logic; the 'y' logic is handled by the caller.

-          *

-          * The following defines allow generation of compile time constant bit

-          * masks for each pixel depth and each possibility of swapped or not

-          * swapped bytes.  Pass 'p' is in the range 0..6; 'x', a pixel index,

-          * is in the range 0..7; and the result is 1 if the pixel is to be

-          * copied in the pass, 0 if not.  'S' is for the sparkle method, 'B'

-          * for the block method.

-          *

-          * With some compilers a compile time expression of the general form:

-          *

-          *    (shift >= 32) ? (a >> (shift-32)) : (b >> shift)

-          *

-          * Produces warnings with values of 'shift' in the range 33 to 63

-          * because the right hand side of the ?: expression is evaluated by

-          * the compiler even though it isn't used.  Microsoft Visual C (various

-          * versions) and the Intel C compiler are known to do this.  To avoid

-          * this the following macros are used in 1.5.6.  This is a temporary

-          * solution to avoid destabilizing the code during the release process.

-          */

-#        if PNG_USE_COMPILE_TIME_MASKS

-#           define PNG_LSR(x,s) ((x)>>((s) & 0x1f))

-#           define PNG_LSL(x,s) ((x)<<((s) & 0x1f))

-#        else

-#           define PNG_LSR(x,s) ((x)>>(s))

-#           define PNG_LSL(x,s) ((x)<<(s))

-#        endif

-#        define S_COPY(p,x) (((p)<4 ? PNG_LSR(0x80088822,(3-(p))*8+(7-(x))) :\

-           PNG_LSR(0xaa55ff00,(7-(p))*8+(7-(x)))) & 1)

-#        define B_COPY(p,x) (((p)<4 ? PNG_LSR(0xff0fff33,(3-(p))*8+(7-(x))) :\

-           PNG_LSR(0xff55ff00,(7-(p))*8+(7-(x)))) & 1)

-

-         /* Return a mask for pass 'p' pixel 'x' at depth 'd'.  The mask is

-          * little endian - the first pixel is at bit 0 - however the extra

-          * parameter 's' can be set to cause the mask position to be swapped

-          * within each byte, to match the PNG format.  This is done by XOR of

-          * the shift with 7, 6 or 4 for bit depths 1, 2 and 4.

-          */

-#        define PIXEL_MASK(p,x,d,s) \

-            (PNG_LSL(((PNG_LSL(1U,(d)))-1),(((x)*(d))^((s)?8-(d):0))))

-

-         /* Hence generate the appropriate 'block' or 'sparkle' pixel copy mask.

-          */

-#        define S_MASKx(p,x,d,s) (S_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)

-#        define B_MASKx(p,x,d,s) (B_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)

-

-         /* Combine 8 of these to get the full mask.  For the 1-bpp and 2-bpp

-          * cases the result needs replicating, for the 4-bpp case the above

-          * generates a full 32 bits.

-          */

-#        define MASK_EXPAND(m,d) ((m)*((d)==1?0x01010101:((d)==2?0x00010001:1)))

-

-#        define S_MASK(p,d,s) MASK_EXPAND(S_MASKx(p,0,d,s) + S_MASKx(p,1,d,s) +\

-            S_MASKx(p,2,d,s) + S_MASKx(p,3,d,s) + S_MASKx(p,4,d,s) +\

-            S_MASKx(p,5,d,s) + S_MASKx(p,6,d,s) + S_MASKx(p,7,d,s), d)

-

-#        define B_MASK(p,d,s) MASK_EXPAND(B_MASKx(p,0,d,s) + B_MASKx(p,1,d,s) +\

-            B_MASKx(p,2,d,s) + B_MASKx(p,3,d,s) + B_MASKx(p,4,d,s) +\

-            B_MASKx(p,5,d,s) + B_MASKx(p,6,d,s) + B_MASKx(p,7,d,s), d)

-

-#if PNG_USE_COMPILE_TIME_MASKS

-         /* Utility macros to construct all the masks for a depth/swap

-          * combination.  The 's' parameter says whether the format is PNG

-          * (big endian bytes) or not.  Only the three odd-numbered passes are

-          * required for the display/block algorithm.

-          */

-#        define S_MASKS(d,s) { S_MASK(0,d,s), S_MASK(1,d,s), S_MASK(2,d,s),\

-            S_MASK(3,d,s), S_MASK(4,d,s), S_MASK(5,d,s) }

-

-#        define B_MASKS(d,s) { B_MASK(1,d,s), S_MASK(3,d,s), S_MASK(5,d,s) }

-

-#        define DEPTH_INDEX(d) ((d)==1?0:((d)==2?1:2))

-

-         /* Hence the pre-compiled masks indexed by PACKSWAP (or not), depth and

-          * then pass:

-          */

-         static PNG_CONST png_uint_32 row_mask[2/*PACKSWAP*/][3/*depth*/][6] =

-         {

-            /* Little-endian byte masks for PACKSWAP */

-            { S_MASKS(1,0), S_MASKS(2,0), S_MASKS(4,0) },

-            /* Normal (big-endian byte) masks - PNG format */

-            { S_MASKS(1,1), S_MASKS(2,1), S_MASKS(4,1) }

-         };

-

-         /* display_mask has only three entries for the odd passes, so index by

-          * pass>>1.

-          */

-         static PNG_CONST png_uint_32 display_mask[2][3][3] =

-         {

-            /* Little-endian byte masks for PACKSWAP */

-            { B_MASKS(1,0), B_MASKS(2,0), B_MASKS(4,0) },

-            /* Normal (big-endian byte) masks - PNG format */

-            { B_MASKS(1,1), B_MASKS(2,1), B_MASKS(4,1) }

-         };

-

-#        define MASK(pass,depth,display,png)\

-            ((display)?display_mask[png][DEPTH_INDEX(depth)][pass>>1]:\

-               row_mask[png][DEPTH_INDEX(depth)][pass])

-

-#else /* !PNG_USE_COMPILE_TIME_MASKS */

-         /* This is the runtime alternative: it seems unlikely that this will

-          * ever be either smaller or faster than the compile time approach.

-          */

-#        define MASK(pass,depth,display,png)\

-            ((display)?B_MASK(pass,depth,png):S_MASK(pass,depth,png))

-#endif /* !PNG_USE_COMPILE_TIME_MASKS */

-

-         /* Use the appropriate mask to copy the required bits.  In some cases

-          * the byte mask will be 0 or 0xff, optimize these cases.  row_width is

-          * the number of pixels, but the code copies bytes, so it is necessary

-          * to special case the end.

-          */

-         png_uint_32 pixels_per_byte = 8 / pixel_depth;

-         png_uint_32 mask;

-

-#        ifdef PNG_READ_PACKSWAP_SUPPORTED

-            if (png_ptr->transformations & PNG_PACKSWAP)

-               mask = MASK(pass, pixel_depth, display, 0);

-

-            else

-#        endif

-            mask = MASK(pass, pixel_depth, display, 1);

-

-         for (;;)

-         {

-            png_uint_32 m;

-

-            /* It doesn't matter in the following if png_uint_32 has more than

-             * 32 bits because the high bits always match those in m<<24; it is,

-             * however, essential to use OR here, not +, because of this.

-             */

-            m = mask;

-            mask = (m >> 8) | (m << 24); /* rotate right to good compilers */

-            m &= 0xff;

-

-            if (m != 0) /* something to copy */

-            {

-               if (m != 0xff)

-                  *dp = (png_byte)((*dp & ~m) | (*sp & m));

-               else

-                  *dp = *sp;

-            }

-

-            /* NOTE: this may overwrite the last byte with garbage if the image

-             * is not an exact number of bytes wide; libpng has always done

-             * this.

-             */

-            if (row_width <= pixels_per_byte)

-               break; /* May need to restore part of the last byte */

-

-            row_width -= pixels_per_byte;

-            ++dp;

-            ++sp;

-         }

-      }

-

-      else /* pixel_depth >= 8 */

-      {

-         unsigned int bytes_to_copy, bytes_to_jump;

-

-         /* Validate the depth - it must be a multiple of 8 */

-         if (pixel_depth & 7)

-            png_error(png_ptr, "invalid user transform pixel depth");

-

-         pixel_depth >>= 3; /* now in bytes */

-         row_width *= pixel_depth;

-

-         /* Regardless of pass number the Adam 7 interlace always results in a

-          * fixed number of pixels to copy then to skip.  There may be a

-          * different number of pixels to skip at the start though.

-          */

-         {

-            unsigned int offset = PNG_PASS_START_COL(pass) * pixel_depth;

-

-            row_width -= offset;

-            dp += offset;

-            sp += offset;

-         }

-

-         /* Work out the bytes to copy. */

-         if (display)

-         {

-            /* When doing the 'block' algorithm the pixel in the pass gets

-             * replicated to adjacent pixels.  This is why the even (0,2,4,6)

-             * passes are skipped above - the entire expanded row is copied.

-             */

-            bytes_to_copy = (1<<((6-pass)>>1)) * pixel_depth;

-

-            /* But don't allow this number to exceed the actual row width. */

-            if (bytes_to_copy > row_width)

-               bytes_to_copy = row_width;

-         }

-

-         else /* normal row; Adam7 only ever gives us one pixel to copy. */

-            bytes_to_copy = pixel_depth;

-

-         /* In Adam7 there is a constant offset between where the pixels go. */

-         bytes_to_jump = PNG_PASS_COL_OFFSET(pass) * pixel_depth;

-

-         /* And simply copy these bytes.  Some optimization is possible here,

-          * depending on the value of 'bytes_to_copy'.  Special case the low

-          * byte counts, which we know to be frequent.

-          *

-          * Notice that these cases all 'return' rather than 'break' - this

-          * avoids an unnecessary test on whether to restore the last byte

-          * below.

-          */

-         switch (bytes_to_copy)

-         {

-            case 1:

-               for (;;)

-               {

-                  *dp = *sp;

-

-                  if (row_width <= bytes_to_jump)

-                     return;

-

-                  dp += bytes_to_jump;

-                  sp += bytes_to_jump;

-                  row_width -= bytes_to_jump;

-               }

-

-            case 2:

-               /* There is a possibility of a partial copy at the end here; this

-                * slows the code down somewhat.

-                */

-               do

-               {

-                  dp[0] = sp[0], dp[1] = sp[1];

-

-                  if (row_width <= bytes_to_jump)

-                     return;

-

-                  sp += bytes_to_jump;

-                  dp += bytes_to_jump;

-                  row_width -= bytes_to_jump;

-               }

-               while (row_width > 1);

-

-               /* And there can only be one byte left at this point: */

-               *dp = *sp;

-               return;

-

-            case 3:

-               /* This can only be the RGB case, so each copy is exactly one

-                * pixel and it is not necessary to check for a partial copy.

-                */

-               for(;;)

-               {

-                  dp[0] = sp[0], dp[1] = sp[1], dp[2] = sp[2];

-

-                  if (row_width <= bytes_to_jump)

-                     return;

-

-                  sp += bytes_to_jump;

-                  dp += bytes_to_jump;

-                  row_width -= bytes_to_jump;

-               }

-

-            default:

-#if PNG_ALIGN_TYPE != PNG_ALIGN_NONE

-               /* Check for double byte alignment and, if possible, use a

-                * 16-bit copy.  Don't attempt this for narrow images - ones that

-                * are less than an interlace panel wide.  Don't attempt it for

-                * wide bytes_to_copy either - use the png_memcpy there.

-                */

-               if (bytes_to_copy < 16 /*else use png_memcpy*/ &&

-                  png_isaligned(dp, png_uint_16) &&

-                  png_isaligned(sp, png_uint_16) &&

-                  bytes_to_copy % sizeof (png_uint_16) == 0 &&

-                  bytes_to_jump % sizeof (png_uint_16) == 0)

-               {

-                  /* Everything is aligned for png_uint_16 copies, but try for

-                   * png_uint_32 first.

-                   */

-                  if (png_isaligned(dp, png_uint_32) &&

-                     png_isaligned(sp, png_uint_32) &&

-                     bytes_to_copy % sizeof (png_uint_32) == 0 &&

-                     bytes_to_jump % sizeof (png_uint_32) == 0)

-                  {

-                     png_uint_32p dp32 = (png_uint_32p)dp;

-                     png_const_uint_32p sp32 = (png_const_uint_32p)sp;

-                     unsigned int skip = (bytes_to_jump-bytes_to_copy) /

-                        sizeof (png_uint_32);

-

-                     do

-                     {

-                        size_t c = bytes_to_copy;

-                        do

-                        {

-                           *dp32++ = *sp32++;

-                           c -= sizeof (png_uint_32);

-                        }

-                        while (c > 0);

-

-                        if (row_width <= bytes_to_jump)

-                           return;

-

-                        dp32 += skip;

-                        sp32 += skip;

-                        row_width -= bytes_to_jump;

-                     }

-                     while (bytes_to_copy <= row_width);

-

-                     /* Get to here when the row_width truncates the final copy.

-                      * There will be 1-3 bytes left to copy, so don't try the

-                      * 16-bit loop below.

-                      */

-                     dp = (png_bytep)dp32;

-                     sp = (png_const_bytep)sp32;

-                     do

-                        *dp++ = *sp++;

-                     while (--row_width > 0);

-                     return;

-                  }

-

-                  /* Else do it in 16-bit quantities, but only if the size is

-                   * not too large.

-                   */

-                  else

-                  {

-                     png_uint_16p dp16 = (png_uint_16p)dp;

-                     png_const_uint_16p sp16 = (png_const_uint_16p)sp;

-                     unsigned int skip = (bytes_to_jump-bytes_to_copy) /

-                        sizeof (png_uint_16);

-

-                     do

-                     {

-                        size_t c = bytes_to_copy;

-                        do

-                        {

-                           *dp16++ = *sp16++;

-                           c -= sizeof (png_uint_16);

-                        }

-                        while (c > 0);

-

-                        if (row_width <= bytes_to_jump)

-                           return;

-

-                        dp16 += skip;

-                        sp16 += skip;

-                        row_width -= bytes_to_jump;

-                     }

-                     while (bytes_to_copy <= row_width);

-

-                     /* End of row - 1 byte left, bytes_to_copy > row_width: */

-                     dp = (png_bytep)dp16;

-                     sp = (png_const_bytep)sp16;

-                     do

-                        *dp++ = *sp++;

-                     while (--row_width > 0);

-                     return;

-                  }

-               }

-#endif /* PNG_ALIGN_ code */

-

-               /* The true default - use a png_memcpy: */

-               for (;;)

-               {

-                  png_memcpy(dp, sp, bytes_to_copy);

-

-                  if (row_width <= bytes_to_jump)

-                     return;

-

-                  sp += bytes_to_jump;

-                  dp += bytes_to_jump;

-                  row_width -= bytes_to_jump;

-                  if (bytes_to_copy > row_width)

-                     bytes_to_copy = row_width;

-               }

-         }

-

-         /* NOT REACHED*/

-      } /* pixel_depth >= 8 */

-

-      /* Here if pixel_depth < 8 to check 'end_ptr' below. */

-   }

-   else

-#endif

-

-   /* If here then the switch above wasn't used so just png_memcpy the whole row

-    * from the temporary row buffer (notice that this overwrites the end of the

-    * destination row if it is a partial byte.)

-    */

-   png_memcpy(dp, sp, PNG_ROWBYTES(pixel_depth, row_width));

-

-   /* Restore the overwritten bits from the last byte if necessary. */

-   if (end_ptr != NULL)

-      *end_ptr = (png_byte)((end_byte & end_mask) | (*end_ptr & ~end_mask));

-}

-

-#ifdef PNG_READ_INTERLACING_SUPPORTED

-void /* PRIVATE */

-png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,

-   png_uint_32 transformations /* Because these may affect the byte layout */)

-{

-   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */

-   /* Offset to next interlace block */

-   static PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};

-

-   png_debug(1, "in png_do_read_interlace");

-   if (row != NULL && row_info != NULL)

-   {

-      png_uint_32 final_width;

-

-      final_width = row_info->width * png_pass_inc[pass];

-

-      switch (row_info->pixel_depth)

-      {

-         case 1:

-         {

-            png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 3);

-            png_bytep dp = row + (png_size_t)((final_width - 1) >> 3);

-            int sshift, dshift;

-            int s_start, s_end, s_inc;

-            int jstop = png_pass_inc[pass];

-            png_byte v;

-            png_uint_32 i;

-            int j;

-

-#ifdef PNG_READ_PACKSWAP_SUPPORTED

-            if (transformations & PNG_PACKSWAP)

-            {

-                sshift = (int)((row_info->width + 7) & 0x07);

-                dshift = (int)((final_width + 7) & 0x07);

-                s_start = 7;

-                s_end = 0;

-                s_inc = -1;

-            }

-

-            else

-#endif

-            {

-                sshift = 7 - (int)((row_info->width + 7) & 0x07);

-                dshift = 7 - (int)((final_width + 7) & 0x07);

-                s_start = 0;

-                s_end = 7;

-                s_inc = 1;

-            }

-

-            for (i = 0; i < row_info->width; i++)

-            {

-               v = (png_byte)((*sp >> sshift) & 0x01);

-               for (j = 0; j < jstop; j++)

-               {

-                  *dp &= (png_byte)((0x7f7f >> (7 - dshift)) & 0xff);

-                  *dp |= (png_byte)(v << dshift);

-

-                  if (dshift == s_end)

-                  {

-                     dshift = s_start;

-                     dp--;

-                  }

-

-                  else

-                     dshift += s_inc;

-               }

-

-               if (sshift == s_end)

-               {

-                  sshift = s_start;

-                  sp--;

-               }

-

-               else

-                  sshift += s_inc;

-            }

-            break;

-         }

-

-         case 2:

-         {

-            png_bytep sp = row + (png_uint_32)((row_info->width - 1) >> 2);

-            png_bytep dp = row + (png_uint_32)((final_width - 1) >> 2);

-            int sshift, dshift;

-            int s_start, s_end, s_inc;

-            int jstop = png_pass_inc[pass];

-            png_uint_32 i;

-

-#ifdef PNG_READ_PACKSWAP_SUPPORTED

-            if (transformations & PNG_PACKSWAP)

-            {

-               sshift = (int)(((row_info->width + 3) & 0x03) << 1);

-               dshift = (int)(((final_width + 3) & 0x03) << 1);

-               s_start = 6;

-               s_end = 0;

-               s_inc = -2;

-            }

-

-            else

-#endif

-            {

-               sshift = (int)((3 - ((row_info->width + 3) & 0x03)) << 1);

-               dshift = (int)((3 - ((final_width + 3) & 0x03)) << 1);

-               s_start = 0;

-               s_end = 6;

-               s_inc = 2;

-            }

-

-            for (i = 0; i < row_info->width; i++)

-            {

-               png_byte v;

-               int j;

-

-               v = (png_byte)((*sp >> sshift) & 0x03);

-               for (j = 0; j < jstop; j++)

-               {

-                  *dp &= (png_byte)((0x3f3f >> (6 - dshift)) & 0xff);

-                  *dp |= (png_byte)(v << dshift);

-

-                  if (dshift == s_end)

-                  {

-                     dshift = s_start;

-                     dp--;

-                  }

-

-                  else

-                     dshift += s_inc;

-               }

-

-               if (sshift == s_end)

-               {

-                  sshift = s_start;

-                  sp--;

-               }

-

-               else

-                  sshift += s_inc;

-            }

-            break;

-         }

-

-         case 4:

-         {

-            png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 1);

-            png_bytep dp = row + (png_size_t)((final_width - 1) >> 1);

-            int sshift, dshift;

-            int s_start, s_end, s_inc;

-            png_uint_32 i;

-            int jstop = png_pass_inc[pass];

-

-#ifdef PNG_READ_PACKSWAP_SUPPORTED

-            if (transformations & PNG_PACKSWAP)

-            {

-               sshift = (int)(((row_info->width + 1) & 0x01) << 2);

-               dshift = (int)(((final_width + 1) & 0x01) << 2);

-               s_start = 4;

-               s_end = 0;

-               s_inc = -4;

-            }

-

-            else

-#endif

-            {

-               sshift = (int)((1 - ((row_info->width + 1) & 0x01)) << 2);

-               dshift = (int)((1 - ((final_width + 1) & 0x01)) << 2);

-               s_start = 0;

-               s_end = 4;

-               s_inc = 4;

-            }

-

-            for (i = 0; i < row_info->width; i++)

-            {

-               png_byte v = (png_byte)((*sp >> sshift) & 0x0f);

-               int j;

-

-               for (j = 0; j < jstop; j++)

-               {

-                  *dp &= (png_byte)((0xf0f >> (4 - dshift)) & 0xff);

-                  *dp |= (png_byte)(v << dshift);

-

-                  if (dshift == s_end)

-                  {

-                     dshift = s_start;

-                     dp--;

-                  }

-

-                  else

-                     dshift += s_inc;

-               }

-

-               if (sshift == s_end)

-               {

-                  sshift = s_start;

-                  sp--;

-               }

-

-               else

-                  sshift += s_inc;

-            }

-            break;

-         }

-

-         default:

-         {

-            png_size_t pixel_bytes = (row_info->pixel_depth >> 3);

-

-            png_bytep sp = row + (png_size_t)(row_info->width - 1)

-                * pixel_bytes;

-

-            png_bytep dp = row + (png_size_t)(final_width - 1) * pixel_bytes;

-

-            int jstop = png_pass_inc[pass];

-            png_uint_32 i;

-

-            for (i = 0; i < row_info->width; i++)

-            {

-               png_byte v[8];

-               int j;

-

-               png_memcpy(v, sp, pixel_bytes);

-

-               for (j = 0; j < jstop; j++)

-               {

-                  png_memcpy(dp, v, pixel_bytes);

-                  dp -= pixel_bytes;

-               }

-

-               sp -= pixel_bytes;

-            }

-            break;

-         }

-      }

-

-      row_info->width = final_width;

-      row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width);

-   }

-#ifndef PNG_READ_PACKSWAP_SUPPORTED

-   PNG_UNUSED(transformations)  /* Silence compiler warning */

-#endif

-}

-#endif /* PNG_READ_INTERLACING_SUPPORTED */

-

-static void

-png_read_filter_row_sub(png_row_infop row_info, png_bytep row,

-   png_const_bytep prev_row)

-{

-   png_size_t i;

-   png_size_t istop = row_info->rowbytes;

-   unsigned int bpp = (row_info->pixel_depth + 7) >> 3;

-   png_bytep rp = row + bpp;

-

-   PNG_UNUSED(prev_row)

-

-   for (i = bpp; i < istop; i++)

-   {

-      *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);

-      rp++;

-   }

-}

-

-static void

-png_read_filter_row_up(png_row_infop row_info, png_bytep row,

-   png_const_bytep prev_row)

-{

-   png_size_t i;

-   png_size_t istop = row_info->rowbytes;

-   png_bytep rp = row;

-   png_const_bytep pp = prev_row;

-

-   for (i = 0; i < istop; i++)

-   {

-      *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);

-      rp++;

-   }

-}

-

-static void

-png_read_filter_row_avg(png_row_infop row_info, png_bytep row,

-   png_const_bytep prev_row)

-{

-   png_size_t i;

-   png_bytep rp = row;

-   png_const_bytep pp = prev_row;

-   unsigned int bpp = (row_info->pixel_depth + 7) >> 3;

-   png_size_t istop = row_info->rowbytes - bpp;

-

-   for (i = 0; i < bpp; i++)

-   {

-      *rp = (png_byte)(((int)(*rp) +

-         ((int)(*pp++) / 2 )) & 0xff);

-

-      rp++;

-   }

-

-   for (i = 0; i < istop; i++)

-   {

-      *rp = (png_byte)(((int)(*rp) +

-         (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);

-

-      rp++;

-   }

-}

-

-static void

-png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row,

-   png_const_bytep prev_row)

-{

-   png_bytep rp_end = row + row_info->rowbytes;

-   int a, c;

-

-   /* First pixel/byte */

-   c = *prev_row++;

-   a = *row + c;

-   *row++ = (png_byte)a;

-

-   /* Remainder */

-   while (row < rp_end)

-   {

-      int b, pa, pb, pc, p;

-

-      a &= 0xff; /* From previous iteration or start */

-      b = *prev_row++;

-

-      p = b - c;

-      pc = a - c;

-

-#     ifdef PNG_USE_ABS

-         pa = abs(p);

-         pb = abs(pc);

-         pc = abs(p + pc);

-#     else

-         pa = p < 0 ? -p : p;

-         pb = pc < 0 ? -pc : pc;

-         pc = (p + pc) < 0 ? -(p + pc) : p + pc;

-#     endif

-

-      /* Find the best predictor, the least of pa, pb, pc favoring the earlier

-       * ones in the case of a tie.

-       */

-      if (pb < pa) pa = pb, a = b;

-      if (pc < pa) a = c;

-

-      /* Calculate the current pixel in a, and move the previous row pixel to c

-       * for the next time round the loop

-       */

-      c = b;

-      a += *row;

-      *row++ = (png_byte)a;

-   }

-}

-

-static void

-png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,

-   png_const_bytep prev_row)

-{

-   int bpp = (row_info->pixel_depth + 7) >> 3;

-   png_bytep rp_end = row + bpp;

-

-   /* Process the first pixel in the row completely (this is the same as 'up'

-    * because there is only one candidate predictor for the first row).

-    */

-   while (row < rp_end)

-   {

-      int a = *row + *prev_row++;

-      *row++ = (png_byte)a;

-   }

-

-   /* Remainder */

-   rp_end += row_info->rowbytes - bpp;

-

-   while (row < rp_end)

-   {

-      int a, b, c, pa, pb, pc, p;

-

-      c = *(prev_row - bpp);

-      a = *(row - bpp);

-      b = *prev_row++;

-

-      p = b - c;

-      pc = a - c;

-

-#     ifdef PNG_USE_ABS

-         pa = abs(p);

-         pb = abs(pc);

-         pc = abs(p + pc);

-#     else

-         pa = p < 0 ? -p : p;

-         pb = pc < 0 ? -pc : pc;

-         pc = (p + pc) < 0 ? -(p + pc) : p + pc;

-#     endif

-

-      if (pb < pa) pa = pb, a = b;

-      if (pc < pa) a = c;

-

-      c = b;

-      a += *row;

-      *row++ = (png_byte)a;

-   }

-}

-

-#ifdef PNG_ARM_NEON

-

-#ifdef __linux__

-#include <stdio.h>

-#include <elf.h>

-#include <asm/hwcap.h>

-

-static int png_have_hwcap(unsigned cap)

-{

-   FILE *f = fopen("/proc/self/auxv", "r");

-   Elf32_auxv_t aux;

-   int have_cap = 0;

-

-   if (!f)

-      return 0;

-

-   while (fread(&aux, sizeof(aux), 1, f) > 0)

-   {

-      if (aux.a_type == AT_HWCAP &&

-          aux.a_un.a_val & cap)

-      {

-         have_cap = 1;

-         break;

-      }

-   }

-

-   fclose(f);

-

-   return have_cap;

-}

-#endif /* __linux__ */

-

-static void

-png_init_filter_functions_neon(png_structp pp, unsigned int bpp)

-{

-#ifdef __linux__

-   if (!png_have_hwcap(HWCAP_NEON))

-      return;

-#endif

-

-   pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up_neon;

-

-   if (bpp == 3)

-   {

-      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_neon;

-      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_neon;

-      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] = 

-         png_read_filter_row_paeth3_neon;

-   }

-

-   else if (bpp == 4)

-   {

-      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_neon;

-      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_neon;

-      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =

-          png_read_filter_row_paeth4_neon;

-   }

-}

-#endif /* PNG_ARM_NEON */

-

-static void

-png_init_filter_functions(png_structp pp)

-{

-   unsigned int bpp = (pp->pixel_depth + 7) >> 3;

-

-   pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub;

-   pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up;

-   pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg;

-   if (bpp == 1)

-      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =

-         png_read_filter_row_paeth_1byte_pixel;

-   else

-      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =

-         png_read_filter_row_paeth_multibyte_pixel;

-

-#ifdef PNG_ARM_NEON

-   png_init_filter_functions_neon(pp, bpp);

-#endif

-}

-

-void /* PRIVATE */

-png_read_filter_row(png_structp pp, png_row_infop row_info, png_bytep row,

-   png_const_bytep prev_row, int filter)

-{

-   if (pp->read_filter[0] == NULL)

-      png_init_filter_functions(pp);

-   if (filter > PNG_FILTER_VALUE_NONE && filter < PNG_FILTER_VALUE_LAST)

-      pp->read_filter[filter-1](row_info, row, prev_row);

-}

-

-#ifdef PNG_SEQUENTIAL_READ_SUPPORTED

-void /* PRIVATE */

-png_read_finish_row(png_structp png_ptr)

-{

-#ifdef PNG_READ_INTERLACING_SUPPORTED

-   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */

-

-   /* Start of interlace block */

-   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};

-

-   /* Offset to next interlace block */

-   static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};

-

-   /* Start of interlace block in the y direction */

-   static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};

-

-   /* Offset to next interlace block in the y direction */

-   static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};

-#endif /* PNG_READ_INTERLACING_SUPPORTED */

-

-   png_debug(1, "in png_read_finish_row");

-   png_ptr->row_number++;

-   if (png_ptr->row_number < png_ptr->num_rows)

-      return;

-

-#ifdef PNG_READ_INTERLACING_SUPPORTED

-   if (png_ptr->interlaced)

-   {

-      png_ptr->row_number = 0;

-

-      /* TO DO: don't do this if prev_row isn't needed (requires

-       * read-ahead of the next row's filter byte.

-       */

-      png_memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);

-

-      do

-      {

-         png_ptr->pass++;

-

-         if (png_ptr->pass >= 7)

-            break;

-

-         png_ptr->iwidth = (png_ptr->width +

-            png_pass_inc[png_ptr->pass] - 1 -

-            png_pass_start[png_ptr->pass]) /

-            png_pass_inc[png_ptr->pass];

-

-         if (!(png_ptr->transformations & PNG_INTERLACE))

-         {

-            png_ptr->num_rows = (png_ptr->height +

-                png_pass_yinc[png_ptr->pass] - 1 -

-                png_pass_ystart[png_ptr->pass]) /

-                png_pass_yinc[png_ptr->pass];

-         }

-

-         else  /* if (png_ptr->transformations & PNG_INTERLACE) */

-            break; /* libpng deinterlacing sees every row */

-

-      } while (png_ptr->num_rows == 0 || png_ptr->iwidth == 0);

-

-      if (png_ptr->pass < 7)

-         return;

-   }

-#endif /* PNG_READ_INTERLACING_SUPPORTED */

-

-   if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))

-   {

-      char extra;

-      int ret;

-

-      png_ptr->zstream.next_out = (Byte *)&extra;

-      png_ptr->zstream.avail_out = (uInt)1;

-

-      for (;;)

-      {

-         if (!(png_ptr->zstream.avail_in))

-         {

-            while (!png_ptr->idat_size)

-            {

-               png_crc_finish(png_ptr, 0);

-               png_ptr->idat_size = png_read_chunk_header(png_ptr);

-               if (png_ptr->chunk_name != png_IDAT)

-                  png_error(png_ptr, "Not enough image data");

-            }

-

-            png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size;

-            png_ptr->zstream.next_in = png_ptr->zbuf;

-

-            if (png_ptr->zbuf_size > png_ptr->idat_size)

-               png_ptr->zstream.avail_in = (uInt)png_ptr->idat_size;

-

-            png_crc_read(png_ptr, png_ptr->zbuf, png_ptr->zstream.avail_in);

-            png_ptr->idat_size -= png_ptr->zstream.avail_in;

-         }

-

-         ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);

-

-         if (ret == Z_STREAM_END)

-         {

-            if (!(png_ptr->zstream.avail_out) || png_ptr->zstream.avail_in ||

-                png_ptr->idat_size)

-               png_warning(png_ptr, "Extra compressed data");

-

-            png_ptr->mode |= PNG_AFTER_IDAT;

-            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;

-            break;

-         }

-

-         if (ret != Z_OK)

-            png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg :

-                "Decompression Error");

-

-         if (!(png_ptr->zstream.avail_out))

-         {

-            png_warning(png_ptr, "Extra compressed data");

-            png_ptr->mode |= PNG_AFTER_IDAT;

-            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;

-            break;

-         }

-

-      }

-      png_ptr->zstream.avail_out = 0;

-   }

-

-   if (png_ptr->idat_size || png_ptr->zstream.avail_in)

-      png_warning(png_ptr, "Extra compression data");

-

-   inflateReset(&png_ptr->zstream);

-

-   png_ptr->mode |= PNG_AFTER_IDAT;

-}

-#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */

-

-void /* PRIVATE */

-png_read_start_row(png_structp png_ptr)

-{

-#ifdef PNG_READ_INTERLACING_SUPPORTED

-   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */

-

-   /* Start of interlace block */

-   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};

-

-   /* Offset to next interlace block */

-   static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};

-

-   /* Start of interlace block in the y direction */

-   static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};

-

-   /* Offset to next interlace block in the y direction */

-   static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};

-#endif

-

-   int max_pixel_depth;

-   png_size_t row_bytes;

-

-   png_debug(1, "in png_read_start_row");

-   png_ptr->zstream.avail_in = 0;

-#ifdef PNG_READ_TRANSFORMS_SUPPORTED

-   png_init_read_transformations(png_ptr);

-#endif

-#ifdef PNG_READ_INTERLACING_SUPPORTED

-   if (png_ptr->interlaced)

-   {

-      if (!(png_ptr->transformations & PNG_INTERLACE))

-         png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -

-             png_pass_ystart[0]) / png_pass_yinc[0];

-

-      else

-         png_ptr->num_rows = png_ptr->height;

-

-      png_ptr->iwidth = (png_ptr->width +

-          png_pass_inc[png_ptr->pass] - 1 -

-          png_pass_start[png_ptr->pass]) /

-          png_pass_inc[png_ptr->pass];

-   }

-

-   else

-#endif /* PNG_READ_INTERLACING_SUPPORTED */

-   {

-      png_ptr->num_rows = png_ptr->height;

-      png_ptr->iwidth = png_ptr->width;

-   }

-

-   max_pixel_depth = png_ptr->pixel_depth;

-

-   /* WARNING: * png_read_transform_info (pngrtran.c) performs a simpliar set of

-    * calculations to calculate the final pixel depth, then

-    * png_do_read_transforms actually does the transforms.  This means that the

-    * code which effectively calculates this value is actually repeated in three

-    * separate places.  They must all match.  Innocent changes to the order of

-    * transformations can and will break libpng in a way that causes memory

-    * overwrites.

-    *

-    * TODO: fix this.

-    */

-#ifdef PNG_READ_PACK_SUPPORTED

-   if ((png_ptr->transformations & PNG_PACK) && png_ptr->bit_depth < 8)

-      max_pixel_depth = 8;

-#endif

-

-#ifdef PNG_READ_EXPAND_SUPPORTED

-   if (png_ptr->transformations & PNG_EXPAND)

-   {

-      if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)

-      {

-         if (png_ptr->num_trans)

-            max_pixel_depth = 32;

-

-         else

-            max_pixel_depth = 24;

-      }

-

-      else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)

-      {

-         if (max_pixel_depth < 8)

-            max_pixel_depth = 8;

-

-         if (png_ptr->num_trans)

-            max_pixel_depth *= 2;

-      }

-

-      else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)

-      {

-         if (png_ptr->num_trans)

-         {

-            max_pixel_depth *= 4;

-            max_pixel_depth /= 3;

-         }

-      }

-   }

-#endif

-

-#ifdef PNG_READ_EXPAND_16_SUPPORTED

-   if (png_ptr->transformations & PNG_EXPAND_16)

-   {

-#     ifdef PNG_READ_EXPAND_SUPPORTED

-         /* In fact it is an error if it isn't supported, but checking is

-          * the safe way.

-          */

-         if (png_ptr->transformations & PNG_EXPAND)

-         {

-            if (png_ptr->bit_depth < 16)

-               max_pixel_depth *= 2;

-         }

-         else

-#     endif

-         png_ptr->transformations &= ~PNG_EXPAND_16;

-   }

-#endif

-

-#ifdef PNG_READ_FILLER_SUPPORTED

-   if (png_ptr->transformations & (PNG_FILLER))

-   {

-      if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)

-      {

-         if (max_pixel_depth <= 8)

-            max_pixel_depth = 16;

-

-         else

-            max_pixel_depth = 32;

-      }

-

-      else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB ||

-         png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)

-      {

-         if (max_pixel_depth <= 32)

-            max_pixel_depth = 32;

-

-         else

-            max_pixel_depth = 64;

-      }

-   }

-#endif

-

-#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED

-   if (png_ptr->transformations & PNG_GRAY_TO_RGB)

-   {

-      if (

-#ifdef PNG_READ_EXPAND_SUPPORTED

-          (png_ptr->num_trans && (png_ptr->transformations & PNG_EXPAND)) ||

-#endif

-#ifdef PNG_READ_FILLER_SUPPORTED

-          (png_ptr->transformations & (PNG_FILLER)) ||

-#endif

-          png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)

-      {

-         if (max_pixel_depth <= 16)

-            max_pixel_depth = 32;

-

-         else

-            max_pixel_depth = 64;

-      }

-

-      else

-      {

-         if (max_pixel_depth <= 8)

-         {

-            if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)

-               max_pixel_depth = 32;

-

-            else

-               max_pixel_depth = 24;

-         }

-

-         else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)

-            max_pixel_depth = 64;

-

-         else

-            max_pixel_depth = 48;

-      }

-   }

-#endif

-

-#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \

-defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)

-   if (png_ptr->transformations & PNG_USER_TRANSFORM)

-   {

-      int user_pixel_depth = png_ptr->user_transform_depth *

-         png_ptr->user_transform_channels;

-

-      if (user_pixel_depth > max_pixel_depth)

-         max_pixel_depth = user_pixel_depth;

-   }

-#endif

-

-   /* This value is stored in png_struct and double checked in the row read

-    * code.

-    */

-   png_ptr->maximum_pixel_depth = (png_byte)max_pixel_depth;

-   png_ptr->transformed_pixel_depth = 0; /* calculated on demand */

-

-   /* Align the width on the next larger 8 pixels.  Mainly used

-    * for interlacing

-    */

-   row_bytes = ((png_ptr->width + 7) & ~((png_uint_32)7));

-   /* Calculate the maximum bytes needed, adding a byte and a pixel

-    * for safety's sake

-    */

-   row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) +

-       1 + ((max_pixel_depth + 7) >> 3);

-

-#ifdef PNG_MAX_MALLOC_64K

-   if (row_bytes > (png_uint_32)65536L)

-      png_error(png_ptr, "This image requires a row greater than 64KB");

-#endif

-

-   if (row_bytes + 48 > png_ptr->old_big_row_buf_size)

-   {

-     png_free(png_ptr, png_ptr->big_row_buf);

-     png_free(png_ptr, png_ptr->big_prev_row);

-

-     if (png_ptr->interlaced)

-        png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,

-            row_bytes + 48);

-

-     else

-        png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 48);

-

-     png_ptr->big_prev_row = (png_bytep)png_malloc(png_ptr, row_bytes + 48);

-

-#ifdef PNG_ALIGNED_MEMORY_SUPPORTED

-     /* Use 16-byte aligned memory for row_buf with at least 16 bytes

-      * of padding before and after row_buf; treat prev_row similarly.

-      * NOTE: the alignment is to the start of the pixels, one beyond the start

-      * of the buffer, because of the filter byte.  Prior to libpng 1.5.6 this

-      * was incorrect; the filter byte was aligned, which had the exact

-      * opposite effect of that intended.

-      */

-     {

-        png_bytep temp = png_ptr->big_row_buf + 32;

-        int extra = (int)((temp - (png_bytep)0) & 0x0f);

-        png_ptr->row_buf = temp - extra - 1/*filter byte*/;

-

-        temp = png_ptr->big_prev_row + 32;

-        extra = (int)((temp - (png_bytep)0) & 0x0f);

-        png_ptr->prev_row = temp - extra - 1/*filter byte*/;

-     }

-

-#else

-     /* Use 31 bytes of padding before and 17 bytes after row_buf. */

-     png_ptr->row_buf = png_ptr->big_row_buf + 31;

-     png_ptr->prev_row = png_ptr->big_prev_row + 31;

-#endif

-     png_ptr->old_big_row_buf_size = row_bytes + 48;

-   }

-

-#ifdef PNG_MAX_MALLOC_64K

-   if (png_ptr->rowbytes > 65535)

-      png_error(png_ptr, "This image requires a row greater than 64KB");

-

-#endif

-   if (png_ptr->rowbytes > (PNG_SIZE_MAX - 1))

-      png_error(png_ptr, "Row has too many bytes to allocate in memory");

-

-   png_memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);

-

-   png_debug1(3, "width = %u,", png_ptr->width);

-   png_debug1(3, "height = %u,", png_ptr->height);

-   png_debug1(3, "iwidth = %u,", png_ptr->iwidth);

-   png_debug1(3, "num_rows = %u,", png_ptr->num_rows);

-   png_debug1(3, "rowbytes = %lu,", (unsigned long)png_ptr->rowbytes);

-   png_debug1(3, "irowbytes = %lu",

-       (unsigned long)PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);

-

-   png_ptr->flags |= PNG_FLAG_ROW_INIT;

-}

-#endif /* PNG_READ_SUPPORTED */

+
+/* pngrutil.c - utilities to read a PNG file
+ *
+ * Last changed in libpng 1.5.9 [February 18, 2012]
+ * Copyright (c) 1998-2012 Glenn Randers-Pehrson
+ * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * This file contains routines that are only called from within
+ * libpng itself during the course of reading an image.
+ */
+
+#include "pngpriv.h"
+
+#ifdef PNG_READ_SUPPORTED
+
+#define png_strtod(p,a,b) strtod(a,b)
+
+png_uint_32 PNGAPI
+png_get_uint_31(png_structp png_ptr, png_const_bytep buf)
+{
+   png_uint_32 uval = png_get_uint_32(buf);
+
+   if (uval > PNG_UINT_31_MAX)
+      png_error(png_ptr, "PNG unsigned integer out of range");
+
+   return (uval);
+}
+
+#if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_READ_cHRM_SUPPORTED)
+/* The following is a variation on the above for use with the fixed
+ * point values used for gAMA and cHRM.  Instead of png_error it
+ * issues a warning and returns (-1) - an invalid value because both
+ * gAMA and cHRM use *unsigned* integers for fixed point values.
+ */
+#define PNG_FIXED_ERROR (-1)
+
+static png_fixed_point /* PRIVATE */
+png_get_fixed_point(png_structp png_ptr, png_const_bytep buf)
+{
+   png_uint_32 uval = png_get_uint_32(buf);
+
+   if (uval <= PNG_UINT_31_MAX)
+      return (png_fixed_point)uval; /* known to be in range */
+
+   /* The caller can turn off the warning by passing NULL. */
+   if (png_ptr != NULL)
+      png_warning(png_ptr, "PNG fixed point integer out of range");
+
+   return PNG_FIXED_ERROR;
+}
+#endif
+
+#ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
+/* NOTE: the read macros will obscure these definitions, so that if
+ * PNG_USE_READ_MACROS is set the library will not use them internally,
+ * but the APIs will still be available externally.
+ *
+ * The parentheses around "PNGAPI function_name" in the following three
+ * functions are necessary because they allow the macros to co-exist with
+ * these (unused but exported) functions.
+ */
+
+/* Grab an unsigned 32-bit integer from a buffer in big-endian format. */
+png_uint_32 (PNGAPI
+png_get_uint_32)(png_const_bytep buf)
+{
+   png_uint_32 uval =
+       ((png_uint_32)(*(buf    )) << 24) +
+       ((png_uint_32)(*(buf + 1)) << 16) +
+       ((png_uint_32)(*(buf + 2)) <<  8) +
+       ((png_uint_32)(*(buf + 3))      ) ;
+
+   return uval;
+}
+
+/* Grab a signed 32-bit integer from a buffer in big-endian format.  The
+ * data is stored in the PNG file in two's complement format and there
+ * is no guarantee that a 'png_int_32' is exactly 32 bits, therefore
+ * the following code does a two's complement to native conversion.
+ */
+png_int_32 (PNGAPI
+png_get_int_32)(png_const_bytep buf)
+{
+   png_uint_32 uval = png_get_uint_32(buf);
+   if ((uval & 0x80000000) == 0) /* non-negative */
+      return uval;
+
+   uval = (uval ^ 0xffffffff) + 1;  /* 2's complement: -x = ~x+1 */
+   return -(png_int_32)uval;
+}
+
+/* Grab an unsigned 16-bit integer from a buffer in big-endian format. */
+png_uint_16 (PNGAPI
+png_get_uint_16)(png_const_bytep buf)
+{
+   /* ANSI-C requires an int value to accomodate at least 16 bits so this
+    * works and allows the compiler not to worry about possible narrowing
+    * on 32 bit systems.  (Pre-ANSI systems did not make integers smaller
+    * than 16 bits either.)
+    */
+   unsigned int val =
+       ((unsigned int)(*buf) << 8) +
+       ((unsigned int)(*(buf + 1)));
+
+   return (png_uint_16)val;
+}
+
+#endif /* PNG_READ_INT_FUNCTIONS_SUPPORTED */
+
+/* Read and check the PNG file signature */
+void /* PRIVATE */
+png_read_sig(png_structp png_ptr, png_infop info_ptr)
+{
+   png_size_t num_checked, num_to_check;
+
+   /* Exit if the user application does not expect a signature. */
+   if (png_ptr->sig_bytes >= 8)
+      return;
+
+   num_checked = png_ptr->sig_bytes;
+   num_to_check = 8 - num_checked;
+
+#ifdef PNG_IO_STATE_SUPPORTED
+   png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE;
+#endif
+
+   /* The signature must be serialized in a single I/O call. */
+   png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
+   png_ptr->sig_bytes = 8;
+
+   if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
+   {
+      if (num_checked < 4 &&
+          png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
+         png_error(png_ptr, "Not a PNG file");
+      else
+         png_error(png_ptr, "PNG file corrupted by ASCII conversion");
+   }
+   if (num_checked < 3)
+      png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
+}
+
+/* Read the chunk header (length + type name).
+ * Put the type name into png_ptr->chunk_name, and return the length.
+ */
+png_uint_32 /* PRIVATE */
+png_read_chunk_header(png_structp png_ptr)
+{
+   png_byte buf[8];
+   png_uint_32 length;
+
+#ifdef PNG_IO_STATE_SUPPORTED
+   png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR;
+#endif
+
+   /* Read the length and the chunk name.
+    * This must be performed in a single I/O call.
+    */
+   png_read_data(png_ptr, buf, 8);
+   length = png_get_uint_31(png_ptr, buf);
+
+   /* Put the chunk name into png_ptr->chunk_name. */
+   png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(buf+4);
+
+   png_debug2(0, "Reading %lx chunk, length = %lu",
+       (unsigned long)png_ptr->chunk_name, (unsigned long)length);
+
+   /* Reset the crc and run it over the chunk name. */
+   png_reset_crc(png_ptr);
+   png_calculate_crc(png_ptr, buf + 4, 4);
+
+   /* Check to see if chunk name is valid. */
+   png_check_chunk_name(png_ptr, png_ptr->chunk_name);
+
+#ifdef PNG_IO_STATE_SUPPORTED
+   png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
+#endif
+
+   return length;
+}
+
+/* Read data, and (optionally) run it through the CRC. */
+void /* PRIVATE */
+png_crc_read(png_structp png_ptr, png_bytep buf, png_size_t length)
+{
+   if (png_ptr == NULL)
+      return;
+
+   png_read_data(png_ptr, buf, length);
+   png_calculate_crc(png_ptr, buf, length);
+}
+
+/* Optionally skip data and then check the CRC.  Depending on whether we
+ * are reading a ancillary or critical chunk, and how the program has set
+ * things up, we may calculate the CRC on the data and print a message.
+ * Returns '1' if there was a CRC error, '0' otherwise.
+ */
+int /* PRIVATE */
+png_crc_finish(png_structp png_ptr, png_uint_32 skip)
+{
+   png_size_t i;
+   png_size_t istop = png_ptr->zbuf_size;
+
+   for (i = (png_size_t)skip; i > istop; i -= istop)
+   {
+      png_crc_read(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
+   }
+
+   if (i)
+   {
+      png_crc_read(png_ptr, png_ptr->zbuf, i);
+   }
+
+   if (png_crc_error(png_ptr))
+   {
+      if (PNG_CHUNK_ANCILLIARY(png_ptr->chunk_name) ?
+          !(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) :
+          (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE))
+      {
+         png_chunk_warning(png_ptr, "CRC error");
+      }
+
+      else
+      {
+         png_chunk_benign_error(png_ptr, "CRC error");
+         return (0);
+      }
+
+      return (1);
+   }
+
+   return (0);
+}
+
+/* Compare the CRC stored in the PNG file with that calculated by libpng from
+ * the data it has read thus far.
+ */
+int /* PRIVATE */
+png_crc_error(png_structp png_ptr)
+{
+   png_byte crc_bytes[4];
+   png_uint_32 crc;
+   int need_crc = 1;
+
+   if (PNG_CHUNK_ANCILLIARY(png_ptr->chunk_name))
+   {
+      if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
+          (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
+         need_crc = 0;
+   }
+
+   else /* critical */
+   {
+      if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
+         need_crc = 0;
+   }
+
+#ifdef PNG_IO_STATE_SUPPORTED
+   png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_CRC;
+#endif
+
+   /* The chunk CRC must be serialized in a single I/O call. */
+   png_read_data(png_ptr, crc_bytes, 4);
+
+   if (need_crc)
+   {
+      crc = png_get_uint_32(crc_bytes);
+      return ((int)(crc != png_ptr->crc));
+   }
+
+   else
+      return (0);
+}
+
+#ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED
+static png_size_t
+png_inflate(png_structp png_ptr, png_bytep data, png_size_t size,
+    png_bytep output, png_size_t output_size)
+{
+   png_size_t count = 0;
+
+   /* zlib can't necessarily handle more than 65535 bytes at once (i.e. it can't
+    * even necessarily handle 65536 bytes) because the type uInt is "16 bits or
+    * more".  Consequently it is necessary to chunk the input to zlib.  This
+    * code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the maximum value
+    * that can be stored in a uInt.)  It is possible to set ZLIB_IO_MAX to a
+    * lower value in pngpriv.h and this may sometimes have a performance
+    * advantage, because it forces access of the input data to be separated from
+    * at least some of the use by some period of time.
+    */
+   png_ptr->zstream.next_in = data;
+   /* avail_in is set below from 'size' */
+   png_ptr->zstream.avail_in = 0;
+
+   while (1)
+   {
+      int ret, avail;
+
+      /* The setting of 'avail_in' used to be outside the loop; by setting it
+       * inside it is possible to chunk the input to zlib and simply rely on
+       * zlib to advance the 'next_in' pointer.  This allows arbitrary amounts o
+       * data to be passed through zlib at the unavoidable cost of requiring a
+       * window save (memcpy of up to 32768 output bytes) every ZLIB_IO_MAX
+       * input bytes.
+       */
+      if (png_ptr->zstream.avail_in == 0 && size > 0)
+      {
+         if (size <= ZLIB_IO_MAX)
+         {
+            /* The value is less than ZLIB_IO_MAX so the cast is safe: */
+            png_ptr->zstream.avail_in = (uInt)size;
+            size = 0;
+         }
+
+         else
+         {
+            png_ptr->zstream.avail_in = ZLIB_IO_MAX;
+            size -= ZLIB_IO_MAX;
+         }
+      }
+
+      /* Reset the output buffer each time round - we empty it
+       * after every inflate call.
+       */
+      png_ptr->zstream.next_out = png_ptr->zbuf;
+      png_ptr->zstream.avail_out = png_ptr->zbuf_size;
+
+      ret = inflate(&png_ptr->zstream, Z_NO_FLUSH);
+      avail = png_ptr->zbuf_size - png_ptr->zstream.avail_out;
+
+      /* First copy/count any new output - but only if we didn't
+       * get an error code.
+       */
+      if ((ret == Z_OK || ret == Z_STREAM_END) && avail > 0)
+      {
+         png_size_t space = avail; /* > 0, see above */
+
+         if (output != 0 && output_size > count)
+         {
+            png_size_t copy = output_size - count;
+
+            if (space < copy)
+               copy = space;
+
+            png_memcpy(output + count, png_ptr->zbuf, copy);
+         }
+         count += space;
+      }
+
+      if (ret == Z_OK)
+         continue;
+
+      /* Termination conditions - always reset the zstream, it
+       * must be left in inflateInit state.
+       */
+      png_ptr->zstream.avail_in = 0;
+      inflateReset(&png_ptr->zstream);
+
+      if (ret == Z_STREAM_END)
+         return count; /* NOTE: may be zero. */
+
+      /* Now handle the error codes - the API always returns 0
+       * and the error message is dumped into the uncompressed
+       * buffer if available.
+       */
+#     ifdef PNG_WARNINGS_SUPPORTED
+      {
+         png_const_charp msg;
+
+         if (png_ptr->zstream.msg != 0)
+            msg = png_ptr->zstream.msg;
+
+         else switch (ret)
+         {
+            case Z_BUF_ERROR:
+               msg = "Buffer error in compressed datastream";
+               break;
+
+            case Z_DATA_ERROR:
+               msg = "Data error in compressed datastream";
+               break;
+
+            default:
+               msg = "Incomplete compressed datastream";
+               break;
+         }
+
+         png_chunk_warning(png_ptr, msg);
+      }
+#     endif
+
+      /* 0 means an error - notice that this code simply ignores
+       * zero length compressed chunks as a result.
+       */
+      return 0;
+   }
+}
+
+/*
+ * Decompress trailing data in a chunk.  The assumption is that chunkdata
+ * points at an allocated area holding the contents of a chunk with a
+ * trailing compressed part.  What we get back is an allocated area
+ * holding the original prefix part and an uncompressed version of the
+ * trailing part (the malloc area passed in is freed).
+ */
+void /* PRIVATE */
+png_decompress_chunk(png_structp png_ptr, int comp_type,
+    png_size_t chunklength,
+    png_size_t prefix_size, png_size_t *newlength)
+{
+   /* The caller should guarantee this */
+   if (prefix_size > chunklength)
+   {
+      /* The recovery is to delete the chunk. */
+      png_warning(png_ptr, "invalid chunklength");
+      prefix_size = 0; /* To delete everything */
+   }
+
+   else if (comp_type == PNG_COMPRESSION_TYPE_BASE)
+   {
+      png_size_t expanded_size = png_inflate(png_ptr,
+          (png_bytep)(png_ptr->chunkdata + prefix_size),
+          chunklength - prefix_size,
+          0,            /* output */
+          0);           /* output size */
+
+      /* Now check the limits on this chunk - if the limit fails the
+       * compressed data will be removed, the prefix will remain.
+       */
+      if (prefix_size >= (~(png_size_t)0) - 1 ||
+         expanded_size >= (~(png_size_t)0) - 1 - prefix_size
+#ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
+         || (png_ptr->user_chunk_malloc_max &&
+          (prefix_size + expanded_size >= png_ptr->user_chunk_malloc_max - 1))
+#else
+#  ifdef PNG_USER_CHUNK_MALLOC_MAX
+         || ((PNG_USER_CHUNK_MALLOC_MAX > 0) &&
+          prefix_size + expanded_size >= PNG_USER_CHUNK_MALLOC_MAX - 1)
+#  endif
+#endif
+         )
+         png_warning(png_ptr, "Exceeded size limit while expanding chunk");
+
+      /* If the size is zero either there was an error and a message
+       * has already been output (warning) or the size really is zero
+       * and we have nothing to do - the code will exit through the
+       * error case below.
+       */
+      else if (expanded_size > 0)
+      {
+         /* Success (maybe) - really uncompress the chunk. */
+         png_size_t new_size = 0;
+         png_charp text = (png_charp)png_malloc_warn(png_ptr,
+             prefix_size + expanded_size + 1);
+
+         if (text != NULL)
+         {
+            png_memcpy(text, png_ptr->chunkdata, prefix_size);
+            new_size = png_inflate(png_ptr,
+                (png_bytep)(png_ptr->chunkdata + prefix_size),
+                chunklength - prefix_size,
+                (png_bytep)(text + prefix_size), expanded_size);
+            text[prefix_size + expanded_size] = 0; /* just in case */
+
+            if (new_size == expanded_size)
+            {
+               png_free(png_ptr, png_ptr->chunkdata);
+               png_ptr->chunkdata = text;
+               *newlength = prefix_size + expanded_size;
+               return; /* The success return! */
+            }
+
+            png_warning(png_ptr, "png_inflate logic error");
+            png_free(png_ptr, text);
+         }
+
+         else
+            png_warning(png_ptr, "Not enough memory to decompress chunk");
+      }
+   }
+
+   else /* if (comp_type != PNG_COMPRESSION_TYPE_BASE) */
+   {
+      PNG_WARNING_PARAMETERS(p)
+      png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_d, comp_type);
+      png_formatted_warning(png_ptr, p, "Unknown compression type @1");
+
+      /* The recovery is to simply drop the data. */
+   }
+
+   /* Generic error return - leave the prefix, delete the compressed
+    * data, reallocate the chunkdata to remove the potentially large
+    * amount of compressed data.
+    */
+   {
+      png_charp text = (png_charp)png_malloc_warn(png_ptr, prefix_size + 1);
+
+      if (text != NULL)
+      {
+         if (prefix_size > 0)
+            png_memcpy(text, png_ptr->chunkdata, prefix_size);
+
+         png_free(png_ptr, png_ptr->chunkdata);
+         png_ptr->chunkdata = text;
+
+         /* This is an extra zero in the 'uncompressed' part. */
+         *(png_ptr->chunkdata + prefix_size) = 0x00;
+      }
+      /* Ignore a malloc error here - it is safe. */
+   }
+
+   *newlength = prefix_size;
+}
+#endif /* PNG_READ_COMPRESSED_TEXT_SUPPORTED */
+
+/* Read and check the IDHR chunk */
+void /* PRIVATE */
+png_handle_IHDR(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   png_byte buf[13];
+   png_uint_32 width, height;
+   int bit_depth, color_type, compression_type, filter_type;
+   int interlace_type;
+
+   png_debug(1, "in png_handle_IHDR");
+
+   if (png_ptr->mode & PNG_HAVE_IHDR)
+      png_error(png_ptr, "Out of place IHDR");
+
+   /* Check the length */
+   if (length != 13)
+      png_error(png_ptr, "Invalid IHDR chunk");
+
+   png_ptr->mode |= PNG_HAVE_IHDR;
+
+   png_crc_read(png_ptr, buf, 13);
+   png_crc_finish(png_ptr, 0);
+
+   width = png_get_uint_31(png_ptr, buf);
+   height = png_get_uint_31(png_ptr, buf + 4);
+   bit_depth = buf[8];
+   color_type = buf[9];
+   compression_type = buf[10];
+   filter_type = buf[11];
+   interlace_type = buf[12];
+
+   /* Set internal variables */
+   png_ptr->width = width;
+   png_ptr->height = height;
+   png_ptr->bit_depth = (png_byte)bit_depth;
+   png_ptr->interlaced = (png_byte)interlace_type;
+   png_ptr->color_type = (png_byte)color_type;
+#ifdef PNG_MNG_FEATURES_SUPPORTED
+   png_ptr->filter_type = (png_byte)filter_type;
+#endif
+   png_ptr->compression_type = (png_byte)compression_type;
+
+   /* Find number of channels */
+   switch (png_ptr->color_type)
+   {
+      default: /* invalid, png_set_IHDR calls png_error */
+      case PNG_COLOR_TYPE_GRAY:
+      case PNG_COLOR_TYPE_PALETTE:
+         png_ptr->channels = 1;
+         break;
+
+      case PNG_COLOR_TYPE_RGB:
+         png_ptr->channels = 3;
+         break;
+
+      case PNG_COLOR_TYPE_GRAY_ALPHA:
+         png_ptr->channels = 2;
+         break;
+
+      case PNG_COLOR_TYPE_RGB_ALPHA:
+         png_ptr->channels = 4;
+         break;
+   }
+
+   /* Set up other useful info */
+   png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth *
+   png_ptr->channels);
+   png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);
+   png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);
+   png_debug1(3, "channels = %d", png_ptr->channels);
+   png_debug1(3, "rowbytes = %lu", (unsigned long)png_ptr->rowbytes);
+   png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
+       color_type, interlace_type, compression_type, filter_type);
+}
+
+/* Read and check the palette */
+void /* PRIVATE */
+png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   png_color palette[PNG_MAX_PALETTE_LENGTH];
+   int num, i;
+#ifdef PNG_POINTER_INDEXING_SUPPORTED
+   png_colorp pal_ptr;
+#endif
+
+   png_debug(1, "in png_handle_PLTE");
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Missing IHDR before PLTE");
+
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid PLTE after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   else if (png_ptr->mode & PNG_HAVE_PLTE)
+      png_error(png_ptr, "Duplicate PLTE chunk");
+
+   png_ptr->mode |= PNG_HAVE_PLTE;
+
+   if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
+   {
+      png_warning(png_ptr,
+          "Ignoring PLTE chunk in grayscale PNG");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+#ifndef PNG_READ_OPT_PLTE_SUPPORTED
+   if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
+   {
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+#endif
+
+   if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)
+   {
+      if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
+      {
+         png_warning(png_ptr, "Invalid palette chunk");
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+
+      else
+      {
+         png_error(png_ptr, "Invalid palette chunk");
+      }
+   }
+
+   num = (int)length / 3;
+
+#ifdef PNG_POINTER_INDEXING_SUPPORTED
+   for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
+   {
+      png_byte buf[3];
+
+      png_crc_read(png_ptr, buf, 3);
+      pal_ptr->red = buf[0];
+      pal_ptr->green = buf[1];
+      pal_ptr->blue = buf[2];
+   }
+#else
+   for (i = 0; i < num; i++)
+   {
+      png_byte buf[3];
+
+      png_crc_read(png_ptr, buf, 3);
+      /* Don't depend upon png_color being any order */
+      palette[i].red = buf[0];
+      palette[i].green = buf[1];
+      palette[i].blue = buf[2];
+   }
+#endif
+
+   /* If we actually need the PLTE chunk (ie for a paletted image), we do
+    * whatever the normal CRC configuration tells us.  However, if we
+    * have an RGB image, the PLTE can be considered ancillary, so
+    * we will act as though it is.
+    */
+#ifndef PNG_READ_OPT_PLTE_SUPPORTED
+   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+#endif
+   {
+      png_crc_finish(png_ptr, 0);
+   }
+
+#ifndef PNG_READ_OPT_PLTE_SUPPORTED
+   else if (png_crc_error(png_ptr))  /* Only if we have a CRC error */
+   {
+      /* If we don't want to use the data from an ancillary chunk,
+       * we have two options: an error abort, or a warning and we
+       * ignore the data in this chunk (which should be OK, since
+       * it's considered ancillary for a RGB or RGBA image).
+       */
+      if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE))
+      {
+         if (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)
+         {
+            png_chunk_benign_error(png_ptr, "CRC error");
+         }
+
+         else
+         {
+            png_chunk_warning(png_ptr, "CRC error");
+            return;
+         }
+      }
+
+      /* Otherwise, we (optionally) emit a warning and use the chunk. */
+      else if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN))
+      {
+         png_chunk_warning(png_ptr, "CRC error");
+      }
+   }
+#endif
+
+   png_set_PLTE(png_ptr, info_ptr, palette, num);
+
+#ifdef PNG_READ_tRNS_SUPPORTED
+   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+   {
+      if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
+      {
+         if (png_ptr->num_trans > (png_uint_16)num)
+         {
+            png_warning(png_ptr, "Truncating incorrect tRNS chunk length");
+            png_ptr->num_trans = (png_uint_16)num;
+         }
+
+         if (info_ptr->num_trans > (png_uint_16)num)
+         {
+            png_warning(png_ptr, "Truncating incorrect info tRNS chunk length");
+            info_ptr->num_trans = (png_uint_16)num;
+         }
+      }
+   }
+#endif
+
+}
+
+void /* PRIVATE */
+png_handle_IEND(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   png_debug(1, "in png_handle_IEND");
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR) || !(png_ptr->mode & PNG_HAVE_IDAT))
+   {
+      png_error(png_ptr, "No image in file");
+   }
+
+   png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND);
+
+   if (length != 0)
+   {
+      png_warning(png_ptr, "Incorrect IEND chunk length");
+   }
+
+   png_crc_finish(png_ptr, length);
+
+   PNG_UNUSED(info_ptr) /* Quiet compiler warnings about unused info_ptr */
+}
+
+#ifdef PNG_READ_gAMA_SUPPORTED
+void /* PRIVATE */
+png_handle_gAMA(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   png_fixed_point igamma;
+   png_byte buf[4];
+
+   png_debug(1, "in png_handle_gAMA");
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Missing IHDR before gAMA");
+
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid gAMA after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   else if (png_ptr->mode & PNG_HAVE_PLTE)
+      /* Should be an error, but we can cope with it */
+      png_warning(png_ptr, "Out of place gAMA chunk");
+
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA)
+#ifdef PNG_READ_sRGB_SUPPORTED
+       && !(info_ptr->valid & PNG_INFO_sRGB)
+#endif
+       )
+   {
+      png_warning(png_ptr, "Duplicate gAMA chunk");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   if (length != 4)
+   {
+      png_warning(png_ptr, "Incorrect gAMA chunk length");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   png_crc_read(png_ptr, buf, 4);
+
+   if (png_crc_finish(png_ptr, 0))
+      return;
+
+   igamma = png_get_fixed_point(NULL, buf);
+
+   /* Check for zero gamma or an error. */
+   if (igamma <= 0)
+   {
+      png_warning(png_ptr,
+          "Ignoring gAMA chunk with out of range gamma");
+
+      return;
+   }
+
+#  ifdef PNG_READ_sRGB_SUPPORTED
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB))
+   {
+      if (PNG_OUT_OF_RANGE(igamma, 45500, 500))
+      {
+         PNG_WARNING_PARAMETERS(p)
+         png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_fixed, igamma);
+         png_formatted_warning(png_ptr, p,
+             "Ignoring incorrect gAMA value @1 when sRGB is also present");
+         return;
+      }
+   }
+#  endif /* PNG_READ_sRGB_SUPPORTED */
+
+#  ifdef PNG_READ_GAMMA_SUPPORTED
+   /* Gamma correction on read is supported. */
+   png_ptr->gamma = igamma;
+#  endif
+   /* And set the 'info' structure members. */
+   png_set_gAMA_fixed(png_ptr, info_ptr, igamma);
+}
+#endif
+
+#ifdef PNG_READ_sBIT_SUPPORTED
+void /* PRIVATE */
+png_handle_sBIT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   png_size_t truelen;
+   png_byte buf[4];
+
+   png_debug(1, "in png_handle_sBIT");
+
+   buf[0] = buf[1] = buf[2] = buf[3] = 0;
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Missing IHDR before sBIT");
+
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid sBIT after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   else if (png_ptr->mode & PNG_HAVE_PLTE)
+   {
+      /* Should be an error, but we can cope with it */
+      png_warning(png_ptr, "Out of place sBIT chunk");
+   }
+
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT))
+   {
+      png_warning(png_ptr, "Duplicate sBIT chunk");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+      truelen = 3;
+
+   else
+      truelen = (png_size_t)png_ptr->channels;
+
+   if (length != truelen || length > 4)
+   {
+      png_warning(png_ptr, "Incorrect sBIT chunk length");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   png_crc_read(png_ptr, buf, truelen);
+
+   if (png_crc_finish(png_ptr, 0))
+      return;
+
+   if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
+   {
+      png_ptr->sig_bit.red = buf[0];
+      png_ptr->sig_bit.green = buf[1];
+      png_ptr->sig_bit.blue = buf[2];
+      png_ptr->sig_bit.alpha = buf[3];
+   }
+
+   else
+   {
+      png_ptr->sig_bit.gray = buf[0];
+      png_ptr->sig_bit.red = buf[0];
+      png_ptr->sig_bit.green = buf[0];
+      png_ptr->sig_bit.blue = buf[0];
+      png_ptr->sig_bit.alpha = buf[1];
+   }
+
+   png_set_sBIT(png_ptr, info_ptr, &(png_ptr->sig_bit));
+}
+#endif
+
+#ifdef PNG_READ_cHRM_SUPPORTED
+void /* PRIVATE */
+png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   png_byte buf[32];
+   png_fixed_point x_white, y_white, x_red, y_red, x_green, y_green, x_blue,
+      y_blue;
+
+   png_debug(1, "in png_handle_cHRM");
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Missing IHDR before cHRM");
+
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid cHRM after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   else if (png_ptr->mode & PNG_HAVE_PLTE)
+      /* Should be an error, but we can cope with it */
+      png_warning(png_ptr, "Out of place cHRM chunk");
+
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM)
+#  ifdef PNG_READ_sRGB_SUPPORTED
+       && !(info_ptr->valid & PNG_INFO_sRGB)
+#  endif
+      )
+   {
+      png_warning(png_ptr, "Duplicate cHRM chunk");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   if (length != 32)
+   {
+      png_warning(png_ptr, "Incorrect cHRM chunk length");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   png_crc_read(png_ptr, buf, 32);
+
+   if (png_crc_finish(png_ptr, 0))
+      return;
+
+   x_white = png_get_fixed_point(NULL, buf);
+   y_white = png_get_fixed_point(NULL, buf + 4);
+   x_red   = png_get_fixed_point(NULL, buf + 8);
+   y_red   = png_get_fixed_point(NULL, buf + 12);
+   x_green = png_get_fixed_point(NULL, buf + 16);
+   y_green = png_get_fixed_point(NULL, buf + 20);
+   x_blue  = png_get_fixed_point(NULL, buf + 24);
+   y_blue  = png_get_fixed_point(NULL, buf + 28);
+
+   if (x_white == PNG_FIXED_ERROR ||
+       y_white == PNG_FIXED_ERROR ||
+       x_red   == PNG_FIXED_ERROR ||
+       y_red   == PNG_FIXED_ERROR ||
+       x_green == PNG_FIXED_ERROR ||
+       y_green == PNG_FIXED_ERROR ||
+       x_blue  == PNG_FIXED_ERROR ||
+       y_blue  == PNG_FIXED_ERROR)
+   {
+      png_warning(png_ptr, "Ignoring cHRM chunk with negative chromaticities");
+      return;
+   }
+
+#ifdef PNG_READ_sRGB_SUPPORTED
+   if ((info_ptr != NULL) && (info_ptr->valid & PNG_INFO_sRGB))
+   {
+      if (PNG_OUT_OF_RANGE(x_white, 31270,  1000) ||
+          PNG_OUT_OF_RANGE(y_white, 32900,  1000) ||
+          PNG_OUT_OF_RANGE(x_red,   64000,  1000) ||
+          PNG_OUT_OF_RANGE(y_red,   33000,  1000) ||
+          PNG_OUT_OF_RANGE(x_green, 30000,  1000) ||
+          PNG_OUT_OF_RANGE(y_green, 60000,  1000) ||
+          PNG_OUT_OF_RANGE(x_blue,  15000,  1000) ||
+          PNG_OUT_OF_RANGE(y_blue,   6000,  1000))
+      {
+         PNG_WARNING_PARAMETERS(p)
+
+         png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_fixed, x_white);
+         png_warning_parameter_signed(p, 2, PNG_NUMBER_FORMAT_fixed, y_white);
+         png_warning_parameter_signed(p, 3, PNG_NUMBER_FORMAT_fixed, x_red);
+         png_warning_parameter_signed(p, 4, PNG_NUMBER_FORMAT_fixed, y_red);
+         png_warning_parameter_signed(p, 5, PNG_NUMBER_FORMAT_fixed, x_green);
+         png_warning_parameter_signed(p, 6, PNG_NUMBER_FORMAT_fixed, y_green);
+         png_warning_parameter_signed(p, 7, PNG_NUMBER_FORMAT_fixed, x_blue);
+         png_warning_parameter_signed(p, 8, PNG_NUMBER_FORMAT_fixed, y_blue);
+
+         png_formatted_warning(png_ptr, p,
+             "Ignoring incorrect cHRM white(@1,@2) r(@3,@4)g(@5,@6)b(@7,@8) "
+             "when sRGB is also present");
+      }
+      return;
+   }
+#endif /* PNG_READ_sRGB_SUPPORTED */
+
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+   /* Store the _white values as default coefficients for the rgb to gray
+    * operation if it is supported.  Check if the transform is already set to
+    * avoid destroying the transform values.
+    */
+   if (!png_ptr->rgb_to_gray_coefficients_set)
+   {
+      /* png_set_background has not been called and we haven't seen an sRGB
+       * chunk yet.  Find the XYZ of the three end points.
+       */
+      png_XYZ XYZ;
+      png_xy xy;
+
+      xy.redx = x_red;
+      xy.redy = y_red;
+      xy.greenx = x_green;
+      xy.greeny = y_green;
+      xy.bluex = x_blue;
+      xy.bluey = y_blue;
+      xy.whitex = x_white;
+      xy.whitey = y_white;
+
+      if (png_XYZ_from_xy_checked(png_ptr, &XYZ, xy))
+      {
+         /* The success case, because XYZ_from_xy normalises to a reference
+          * white Y of 1.0 we just need to scale the numbers.  This should
+          * always work just fine. It is an internal error if this overflows.
+          */
+         {
+            png_fixed_point r, g, b;
+            if (png_muldiv(&r, XYZ.redY, 32768, PNG_FP_1) &&
+               r >= 0 && r <= 32768 &&
+               png_muldiv(&g, XYZ.greenY, 32768, PNG_FP_1) &&
+               g >= 0 && g <= 32768 &&
+               png_muldiv(&b, XYZ.blueY, 32768, PNG_FP_1) &&
+               b >= 0 && b <= 32768 &&
+               r+g+b <= 32769)
+            {
+               /* We allow 0 coefficients here.  r+g+b may be 32769 if two or
+                * all of the coefficients were rounded up.  Handle this by
+                * reducing the *largest* coefficient by 1; this matches the
+                * approach used for the default coefficients in pngrtran.c
+                */
+               int add = 0;
+
+               if (r+g+b > 32768)
+                  add = -1;
+               else if (r+g+b < 32768)
+                  add = 1;
+
+               if (add != 0)
+               {
+                  if (g >= r && g >= b)
+                     g += add;
+                  else if (r >= g && r >= b)
+                     r += add;
+                  else
+                     b += add;
+               }
+
+               /* Check for an internal error. */
+               if (r+g+b != 32768)
+                  png_error(png_ptr,
+                     "internal error handling cHRM coefficients");
+
+               png_ptr->rgb_to_gray_red_coeff   = (png_uint_16)r;
+               png_ptr->rgb_to_gray_green_coeff = (png_uint_16)g;
+            }
+
+            /* This is a png_error at present even though it could be ignored -
+             * it should never happen, but it is important that if it does, the
+             * bug is fixed.
+             */
+            else
+               png_error(png_ptr, "internal error handling cHRM->XYZ");
+         }
+      }
+   }
+#endif
+
+   png_set_cHRM_fixed(png_ptr, info_ptr, x_white, y_white, x_red, y_red,
+      x_green, y_green, x_blue, y_blue);
+}
+#endif
+
+#ifdef PNG_READ_sRGB_SUPPORTED
+void /* PRIVATE */
+png_handle_sRGB(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   int intent;
+   png_byte buf[1];
+
+   png_debug(1, "in png_handle_sRGB");
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Missing IHDR before sRGB");
+
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid sRGB after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   else if (png_ptr->mode & PNG_HAVE_PLTE)
+      /* Should be an error, but we can cope with it */
+      png_warning(png_ptr, "Out of place sRGB chunk");
+
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB))
+   {
+      png_warning(png_ptr, "Duplicate sRGB chunk");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   if (length != 1)
+   {
+      png_warning(png_ptr, "Incorrect sRGB chunk length");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   png_crc_read(png_ptr, buf, 1);
+
+   if (png_crc_finish(png_ptr, 0))
+      return;
+
+   intent = buf[0];
+
+   /* Check for bad intent */
+   if (intent >= PNG_sRGB_INTENT_LAST)
+   {
+      png_warning(png_ptr, "Unknown sRGB intent");
+      return;
+   }
+
+#if defined(PNG_READ_gAMA_SUPPORTED) && defined(PNG_READ_GAMMA_SUPPORTED)
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA))
+   {
+      if (PNG_OUT_OF_RANGE(info_ptr->gamma, 45500, 500))
+      {
+         PNG_WARNING_PARAMETERS(p)
+
+         png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_fixed,
+            info_ptr->gamma);
+
+         png_formatted_warning(png_ptr, p,
+             "Ignoring incorrect gAMA value @1 when sRGB is also present");
+      }
+   }
+#endif /* PNG_READ_gAMA_SUPPORTED */
+
+#ifdef PNG_READ_cHRM_SUPPORTED
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM))
+      if (PNG_OUT_OF_RANGE(info_ptr->x_white, 31270,  1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->y_white, 32900,  1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->x_red,   64000,  1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->y_red,   33000,  1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->x_green, 30000,  1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->y_green, 60000,  1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->x_blue,  15000,  1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->y_blue,   6000,  1000))
+      {
+         png_warning(png_ptr,
+             "Ignoring incorrect cHRM value when sRGB is also present");
+      }
+#endif /* PNG_READ_cHRM_SUPPORTED */
+
+   /* This is recorded for use when handling the cHRM chunk above.  An sRGB
+    * chunk unconditionally overwrites the coefficients for grayscale conversion
+    * too.
+    */
+   png_ptr->is_sRGB = 1;
+
+#  ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+      /* Don't overwrite user supplied values: */
+      if (!png_ptr->rgb_to_gray_coefficients_set)
+      {
+         /* These numbers come from the sRGB specification (or, since one has to
+          * pay much money to get a copy, the wikipedia sRGB page) the
+          * chromaticity values quoted have been inverted to get the reverse
+          * transformation from RGB to XYZ and the 'Y' coefficients scaled by
+          * 32768 (then rounded).
+          *
+          * sRGB and ITU Rec-709 both truncate the values for the D65 white
+          * point to four digits and, even though it actually stores five
+          * digits, the PNG spec gives the truncated value.
+          *
+          * This means that when the chromaticities are converted back to XYZ
+          * end points we end up with (6968,23435,2366), which, as described in
+          * pngrtran.c, would overflow.  If the five digit precision and up is
+          * used we get, instead:
+          *
+          *    6968*R + 23435*G + 2365*B
+          *
+          * (Notice that this rounds the blue coefficient down, rather than the
+          * choice used in pngrtran.c which is to round the green one down.)
+          */
+         png_ptr->rgb_to_gray_red_coeff   =  6968; /* 0.212639005871510 */
+         png_ptr->rgb_to_gray_green_coeff = 23434; /* 0.715168678767756 */
+         /* png_ptr->rgb_to_gray_blue_coeff  =  2366; 0.072192315360734 */
+
+         /* The following keeps the cHRM chunk from destroying the
+          * coefficients again in the event that it follows the sRGB chunk.
+          */
+         png_ptr->rgb_to_gray_coefficients_set = 1;
+      }
+#  endif
+
+   png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr, intent);
+}
+#endif /* PNG_READ_sRGB_SUPPORTED */
+
+#ifdef PNG_READ_iCCP_SUPPORTED
+void /* PRIVATE */
+png_handle_iCCP(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+/* Note: this does not properly handle chunks that are > 64K under DOS */
+{
+   png_byte compression_type;
+   png_bytep pC;
+   png_charp profile;
+   png_uint_32 skip = 0;
+   png_uint_32 profile_size;
+   png_alloc_size_t profile_length;
+   png_size_t slength, prefix_length, data_length;
+
+   png_debug(1, "in png_handle_iCCP");
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Missing IHDR before iCCP");
+
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid iCCP after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   else if (png_ptr->mode & PNG_HAVE_PLTE)
+      /* Should be an error, but we can cope with it */
+      png_warning(png_ptr, "Out of place iCCP chunk");
+
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_iCCP))
+   {
+      png_warning(png_ptr, "Duplicate iCCP chunk");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+#ifdef PNG_MAX_MALLOC_64K
+   if (length > (png_uint_32)65535L)
+   {
+      png_warning(png_ptr, "iCCP chunk too large to fit in memory");
+      skip = length - (png_uint_32)65535L;
+      length = (png_uint_32)65535L;
+   }
+#endif
+
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = (png_charp)png_malloc(png_ptr, length + 1);
+   slength = length;
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+
+   if (png_crc_finish(png_ptr, skip))
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   png_ptr->chunkdata[slength] = 0x00;
+
+   for (profile = png_ptr->chunkdata; *profile; profile++)
+      /* Empty loop to find end of name */ ;
+
+   ++profile;
+
+   /* There should be at least one zero (the compression type byte)
+    * following the separator, and we should be on it
+    */
+   if (profile >= png_ptr->chunkdata + slength - 1)
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      png_warning(png_ptr, "Malformed iCCP chunk");
+      return;
+   }
+
+   /* Compression_type should always be zero */
+   compression_type = *profile++;
+
+   if (compression_type)
+   {
+      png_warning(png_ptr, "Ignoring nonzero compression type in iCCP chunk");
+      compression_type = 0x00;  /* Reset it to zero (libpng-1.0.6 through 1.0.8
+                                 wrote nonzero) */
+   }
+
+   prefix_length = profile - png_ptr->chunkdata;
+   png_decompress_chunk(png_ptr, compression_type,
+       slength, prefix_length, &data_length);
+
+   profile_length = data_length - prefix_length;
+
+   if (prefix_length > data_length || profile_length < 4)
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      png_warning(png_ptr, "Profile size field missing from iCCP chunk");
+      return;
+   }
+
+   /* Check the profile_size recorded in the first 32 bits of the ICC profile */
+   pC = (png_bytep)(png_ptr->chunkdata + prefix_length);
+   profile_size = ((*(pC    )) << 24) |
+                  ((*(pC + 1)) << 16) |
+                  ((*(pC + 2)) <<  8) |
+                  ((*(pC + 3))      );
+
+   /* NOTE: the following guarantees that 'profile_length' fits into 32 bits,
+    * because profile_size is a 32 bit value.
+    */
+   if (profile_size < profile_length)
+      profile_length = profile_size;
+
+   /* And the following guarantees that profile_size == profile_length. */
+   if (profile_size > profile_length)
+   {
+      PNG_WARNING_PARAMETERS(p)
+
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+
+      png_warning_parameter_unsigned(p, 1, PNG_NUMBER_FORMAT_u, profile_size);
+      png_warning_parameter_unsigned(p, 2, PNG_NUMBER_FORMAT_u, profile_length);
+      png_formatted_warning(png_ptr, p,
+         "Ignoring iCCP chunk with declared size = @1 and actual length = @2");
+      return;
+   }
+
+   png_set_iCCP(png_ptr, info_ptr, png_ptr->chunkdata,
+       compression_type, (png_bytep)png_ptr->chunkdata + prefix_length,
+       profile_size);
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
+}
+#endif /* PNG_READ_iCCP_SUPPORTED */
+
+#ifdef PNG_READ_sPLT_SUPPORTED
+void /* PRIVATE */
+png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+/* Note: this does not properly handle chunks that are > 64K under DOS */
+{
+   png_bytep entry_start;
+   png_sPLT_t new_palette;
+   png_sPLT_entryp pp;
+   png_uint_32 data_length;
+   int entry_size, i;
+   png_uint_32 skip = 0;
+   png_size_t slength;
+   png_uint_32 dl;
+   png_size_t max_dl;
+
+   png_debug(1, "in png_handle_sPLT");
+
+#ifdef PNG_USER_LIMITS_SUPPORTED
+
+   if (png_ptr->user_chunk_cache_max != 0)
+   {
+      if (png_ptr->user_chunk_cache_max == 1)
+      {
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+
+      if (--png_ptr->user_chunk_cache_max == 1)
+      {
+         png_warning(png_ptr, "No space in chunk cache for sPLT");
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+   }
+#endif
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Missing IHDR before sPLT");
+
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid sPLT after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+#ifdef PNG_MAX_MALLOC_64K
+   if (length > (png_uint_32)65535L)
+   {
+      png_warning(png_ptr, "sPLT chunk too large to fit in memory");
+      skip = length - (png_uint_32)65535L;
+      length = (png_uint_32)65535L;
+   }
+#endif
+
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = (png_charp)png_malloc(png_ptr, length + 1);
+
+   /* WARNING: this may break if size_t is less than 32 bits; it is assumed
+    * that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a
+    * potential breakage point if the types in pngconf.h aren't exactly right.
+    */
+   slength = length;
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+
+   if (png_crc_finish(png_ptr, skip))
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   png_ptr->chunkdata[slength] = 0x00;
+
+   for (entry_start = (png_bytep)png_ptr->chunkdata; *entry_start;
+       entry_start++)
+      /* Empty loop to find end of name */ ;
+
+   ++entry_start;
+
+   /* A sample depth should follow the separator, and we should be on it  */
+   if (entry_start > (png_bytep)png_ptr->chunkdata + slength - 2)
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      png_warning(png_ptr, "malformed sPLT chunk");
+      return;
+   }
+
+   new_palette.depth = *entry_start++;
+   entry_size = (new_palette.depth == 8 ? 6 : 10);
+   /* This must fit in a png_uint_32 because it is derived from the original
+    * chunk data length (and use 'length', not 'slength' here for clarity -
+    * they are guaranteed to be the same, see the tests above.)
+    */
+   data_length = length - (png_uint_32)(entry_start -
+      (png_bytep)png_ptr->chunkdata);
+
+   /* Integrity-check the data length */
+   if (data_length % entry_size)
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      png_warning(png_ptr, "sPLT chunk has bad length");
+      return;
+   }
+
+   dl = (png_int_32)(data_length / entry_size);
+   max_dl = PNG_SIZE_MAX / png_sizeof(png_sPLT_entry);
+
+   if (dl > max_dl)
+   {
+       png_warning(png_ptr, "sPLT chunk too long");
+       return;
+   }
+
+   new_palette.nentries = (png_int_32)(data_length / entry_size);
+
+   new_palette.entries = (png_sPLT_entryp)png_malloc_warn(
+       png_ptr, new_palette.nentries * png_sizeof(png_sPLT_entry));
+
+   if (new_palette.entries == NULL)
+   {
+       png_warning(png_ptr, "sPLT chunk requires too much memory");
+       return;
+   }
+
+#ifdef PNG_POINTER_INDEXING_SUPPORTED
+   for (i = 0; i < new_palette.nentries; i++)
+   {
+      pp = new_palette.entries + i;
+
+      if (new_palette.depth == 8)
+      {
+         pp->red = *entry_start++;
+         pp->green = *entry_start++;
+         pp->blue = *entry_start++;
+         pp->alpha = *entry_start++;
+      }
+
+      else
+      {
+         pp->red   = png_get_uint_16(entry_start); entry_start += 2;
+         pp->green = png_get_uint_16(entry_start); entry_start += 2;
+         pp->blue  = png_get_uint_16(entry_start); entry_start += 2;
+         pp->alpha = png_get_uint_16(entry_start); entry_start += 2;
+      }
+
+      pp->frequency = png_get_uint_16(entry_start); entry_start += 2;
+   }
+#else
+   pp = new_palette.entries;
+
+   for (i = 0; i < new_palette.nentries; i++)
+   {
+
+      if (new_palette.depth == 8)
+      {
+         pp[i].red   = *entry_start++;
+         pp[i].green = *entry_start++;
+         pp[i].blue  = *entry_start++;
+         pp[i].alpha = *entry_start++;
+      }
+
+      else
+      {
+         pp[i].red   = png_get_uint_16(entry_start); entry_start += 2;
+         pp[i].green = png_get_uint_16(entry_start); entry_start += 2;
+         pp[i].blue  = png_get_uint_16(entry_start); entry_start += 2;
+         pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2;
+      }
+
+      pp[i].frequency = png_get_uint_16(entry_start); entry_start += 2;
+   }
+#endif
+
+   /* Discard all chunk data except the name and stash that */
+   new_palette.name = png_ptr->chunkdata;
+
+   png_set_sPLT(png_ptr, info_ptr, &new_palette, 1);
+
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
+   png_free(png_ptr, new_palette.entries);
+}
+#endif /* PNG_READ_sPLT_SUPPORTED */
+
+#ifdef PNG_READ_tRNS_SUPPORTED
+void /* PRIVATE */
+png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   png_byte readbuf[PNG_MAX_PALETTE_LENGTH];
+
+   png_debug(1, "in png_handle_tRNS");
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Missing IHDR before tRNS");
+
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid tRNS after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
+   {
+      png_warning(png_ptr, "Duplicate tRNS chunk");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
+   {
+      png_byte buf[2];
+
+      if (length != 2)
+      {
+         png_warning(png_ptr, "Incorrect tRNS chunk length");
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+
+      png_crc_read(png_ptr, buf, 2);
+      png_ptr->num_trans = 1;
+      png_ptr->trans_color.gray = png_get_uint_16(buf);
+   }
+
+   else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
+   {
+      png_byte buf[6];
+
+      if (length != 6)
+      {
+         png_warning(png_ptr, "Incorrect tRNS chunk length");
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+
+      png_crc_read(png_ptr, buf, (png_size_t)length);
+      png_ptr->num_trans = 1;
+      png_ptr->trans_color.red = png_get_uint_16(buf);
+      png_ptr->trans_color.green = png_get_uint_16(buf + 2);
+      png_ptr->trans_color.blue = png_get_uint_16(buf + 4);
+   }
+
+   else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+   {
+      if (!(png_ptr->mode & PNG_HAVE_PLTE))
+      {
+         /* Should be an error, but we can cope with it. */
+         png_warning(png_ptr, "Missing PLTE before tRNS");
+      }
+
+      if (length > (png_uint_32)png_ptr->num_palette ||
+          length > PNG_MAX_PALETTE_LENGTH)
+      {
+         png_warning(png_ptr, "Incorrect tRNS chunk length");
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+
+      if (length == 0)
+      {
+         png_warning(png_ptr, "Zero length tRNS chunk");
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+
+      png_crc_read(png_ptr, readbuf, (png_size_t)length);
+      png_ptr->num_trans = (png_uint_16)length;
+   }
+
+   else
+   {
+      png_warning(png_ptr, "tRNS chunk not allowed with alpha channel");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   if (png_crc_finish(png_ptr, 0))
+   {
+      png_ptr->num_trans = 0;
+      return;
+   }
+
+   png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans,
+       &(png_ptr->trans_color));
+}
+#endif
+
+#ifdef PNG_READ_bKGD_SUPPORTED
+void /* PRIVATE */
+png_handle_bKGD(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   png_size_t truelen;
+   png_byte buf[6];
+   png_color_16 background;
+
+   png_debug(1, "in png_handle_bKGD");
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Missing IHDR before bKGD");
+
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid bKGD after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
+       !(png_ptr->mode & PNG_HAVE_PLTE))
+   {
+      png_warning(png_ptr, "Missing PLTE before bKGD");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD))
+   {
+      png_warning(png_ptr, "Duplicate bKGD chunk");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+      truelen = 1;
+
+   else if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
+      truelen = 6;
+
+   else
+      truelen = 2;
+
+   if (length != truelen)
+   {
+      png_warning(png_ptr, "Incorrect bKGD chunk length");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   png_crc_read(png_ptr, buf, truelen);
+
+   if (png_crc_finish(png_ptr, 0))
+      return;
+
+   /* We convert the index value into RGB components so that we can allow
+    * arbitrary RGB values for background when we have transparency, and
+    * so it is easy to determine the RGB values of the background color
+    * from the info_ptr struct.
+    */
+   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+   {
+      background.index = buf[0];
+
+      if (info_ptr && info_ptr->num_palette)
+      {
+         if (buf[0] >= info_ptr->num_palette)
+         {
+            png_warning(png_ptr, "Incorrect bKGD chunk index value");
+            return;
+         }
+
+         background.red = (png_uint_16)png_ptr->palette[buf[0]].red;
+         background.green = (png_uint_16)png_ptr->palette[buf[0]].green;
+         background.blue = (png_uint_16)png_ptr->palette[buf[0]].blue;
+      }
+
+      else
+         background.red = background.green = background.blue = 0;
+
+      background.gray = 0;
+   }
+
+   else if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) /* GRAY */
+   {
+      background.index = 0;
+      background.red =
+      background.green =
+      background.blue =
+      background.gray = png_get_uint_16(buf);
+   }
+
+   else
+   {
+      background.index = 0;
+      background.red = png_get_uint_16(buf);
+      background.green = png_get_uint_16(buf + 2);
+      background.blue = png_get_uint_16(buf + 4);
+      background.gray = 0;
+   }
+
+   png_set_bKGD(png_ptr, info_ptr, &background);
+}
+#endif
+
+#ifdef PNG_READ_hIST_SUPPORTED
+void /* PRIVATE */
+png_handle_hIST(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   unsigned int num, i;
+   png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH];
+
+   png_debug(1, "in png_handle_hIST");
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Missing IHDR before hIST");
+
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid hIST after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   else if (!(png_ptr->mode & PNG_HAVE_PLTE))
+   {
+      png_warning(png_ptr, "Missing PLTE before hIST");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST))
+   {
+      png_warning(png_ptr, "Duplicate hIST chunk");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   num = length / 2 ;
+
+   if (num != (unsigned int)png_ptr->num_palette || num >
+       (unsigned int)PNG_MAX_PALETTE_LENGTH)
+   {
+      png_warning(png_ptr, "Incorrect hIST chunk length");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   for (i = 0; i < num; i++)
+   {
+      png_byte buf[2];
+
+      png_crc_read(png_ptr, buf, 2);
+      readbuf[i] = png_get_uint_16(buf);
+   }
+
+   if (png_crc_finish(png_ptr, 0))
+      return;
+
+   png_set_hIST(png_ptr, info_ptr, readbuf);
+}
+#endif
+
+#ifdef PNG_READ_pHYs_SUPPORTED
+void /* PRIVATE */
+png_handle_pHYs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   png_byte buf[9];
+   png_uint_32 res_x, res_y;
+   int unit_type;
+
+   png_debug(1, "in png_handle_pHYs");
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Missing IHDR before pHYs");
+
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid pHYs after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
+   {
+      png_warning(png_ptr, "Duplicate pHYs chunk");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   if (length != 9)
+   {
+      png_warning(png_ptr, "Incorrect pHYs chunk length");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   png_crc_read(png_ptr, buf, 9);
+
+   if (png_crc_finish(png_ptr, 0))
+      return;
+
+   res_x = png_get_uint_32(buf);
+   res_y = png_get_uint_32(buf + 4);
+   unit_type = buf[8];
+   png_set_pHYs(png_ptr, info_ptr, res_x, res_y, unit_type);
+}
+#endif
+
+#ifdef PNG_READ_oFFs_SUPPORTED
+void /* PRIVATE */
+png_handle_oFFs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   png_byte buf[9];
+   png_int_32 offset_x, offset_y;
+   int unit_type;
+
+   png_debug(1, "in png_handle_oFFs");
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Missing IHDR before oFFs");
+
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid oFFs after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
+   {
+      png_warning(png_ptr, "Duplicate oFFs chunk");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   if (length != 9)
+   {
+      png_warning(png_ptr, "Incorrect oFFs chunk length");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   png_crc_read(png_ptr, buf, 9);
+
+   if (png_crc_finish(png_ptr, 0))
+      return;
+
+   offset_x = png_get_int_32(buf);
+   offset_y = png_get_int_32(buf + 4);
+   unit_type = buf[8];
+   png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y, unit_type);
+}
+#endif
+
+#ifdef PNG_READ_pCAL_SUPPORTED
+/* Read the pCAL chunk (described in the PNG Extensions document) */
+void /* PRIVATE */
+png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   png_int_32 X0, X1;
+   png_byte type, nparams;
+   png_charp buf, units, endptr;
+   png_charpp params;
+   png_size_t slength;
+   int i;
+
+   png_debug(1, "in png_handle_pCAL");
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Missing IHDR before pCAL");
+
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid pCAL after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL))
+   {
+      png_warning(png_ptr, "Duplicate pCAL chunk");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)",
+       length + 1);
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+
+   if (png_ptr->chunkdata == NULL)
+   {
+      png_warning(png_ptr, "No memory for pCAL purpose");
+      return;
+   }
+
+   slength = length;
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+
+   if (png_crc_finish(png_ptr, 0))
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */
+
+   png_debug(3, "Finding end of pCAL purpose string");
+   for (buf = png_ptr->chunkdata; *buf; buf++)
+      /* Empty loop */ ;
+
+   endptr = png_ptr->chunkdata + slength;
+
+   /* We need to have at least 12 bytes after the purpose string
+    * in order to get the parameter information.
+    */
+   if (endptr <= buf + 12)
+   {
+      png_warning(png_ptr, "Invalid pCAL data");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   png_debug(3, "Reading pCAL X0, X1, type, nparams, and units");
+   X0 = png_get_int_32((png_bytep)buf+1);
+   X1 = png_get_int_32((png_bytep)buf+5);
+   type = buf[9];
+   nparams = buf[10];
+   units = buf + 11;
+
+   png_debug(3, "Checking pCAL equation type and number of parameters");
+   /* Check that we have the right number of parameters for known
+    * equation types.
+    */
+   if ((type == PNG_EQUATION_LINEAR && nparams != 2) ||
+       (type == PNG_EQUATION_BASE_E && nparams != 3) ||
+       (type == PNG_EQUATION_ARBITRARY && nparams != 3) ||
+       (type == PNG_EQUATION_HYPERBOLIC && nparams != 4))
+   {
+      png_warning(png_ptr, "Invalid pCAL parameters for equation type");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   else if (type >= PNG_EQUATION_LAST)
+   {
+      png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
+   }
+
+   for (buf = units; *buf; buf++)
+      /* Empty loop to move past the units string. */ ;
+
+   png_debug(3, "Allocating pCAL parameters array");
+
+   params = (png_charpp)png_malloc_warn(png_ptr,
+       (png_size_t)(nparams * png_sizeof(png_charp)));
+
+   if (params == NULL)
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      png_warning(png_ptr, "No memory for pCAL params");
+      return;
+   }
+
+   /* Get pointers to the start of each parameter string. */
+   for (i = 0; i < (int)nparams; i++)
+   {
+      buf++; /* Skip the null string terminator from previous parameter. */
+
+      png_debug1(3, "Reading pCAL parameter %d", i);
+
+      for (params[i] = buf; buf <= endptr && *buf != 0x00; buf++)
+         /* Empty loop to move past each parameter string */ ;
+
+      /* Make sure we haven't run out of data yet */
+      if (buf > endptr)
+      {
+         png_warning(png_ptr, "Invalid pCAL data");
+         png_free(png_ptr, png_ptr->chunkdata);
+         png_ptr->chunkdata = NULL;
+         png_free(png_ptr, params);
+         return;
+      }
+   }
+
+   png_set_pCAL(png_ptr, info_ptr, png_ptr->chunkdata, X0, X1, type, nparams,
+      units, params);
+
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
+   png_free(png_ptr, params);
+}
+#endif
+
+#ifdef PNG_READ_sCAL_SUPPORTED
+/* Read the sCAL chunk */
+void /* PRIVATE */
+png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   png_size_t slength, i;
+   int state;
+
+   png_debug(1, "in png_handle_sCAL");
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Missing IHDR before sCAL");
+
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid sCAL after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL))
+   {
+      png_warning(png_ptr, "Duplicate sCAL chunk");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   /* Need unit type, width, \0, height: minimum 4 bytes */
+   else if (length < 4)
+   {
+      png_warning(png_ptr, "sCAL chunk too short");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)",
+      length + 1);
+
+   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+
+   if (png_ptr->chunkdata == NULL)
+   {
+      png_warning(png_ptr, "Out of memory while processing sCAL chunk");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   slength = length;
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+   png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */
+
+   if (png_crc_finish(png_ptr, 0))
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   /* Validate the unit. */
+   if (png_ptr->chunkdata[0] != 1 && png_ptr->chunkdata[0] != 2)
+   {
+      png_warning(png_ptr, "Invalid sCAL ignored: invalid unit");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   /* Validate the ASCII numbers, need two ASCII numbers separated by
+    * a '\0' and they need to fit exactly in the chunk data.
+    */
+   i = 1;
+   state = 0;
+
+   if (!png_check_fp_number(png_ptr->chunkdata, slength, &state, &i) ||
+       i >= slength || png_ptr->chunkdata[i++] != 0)
+      png_warning(png_ptr, "Invalid sCAL chunk ignored: bad width format");
+
+   else if (!PNG_FP_IS_POSITIVE(state))
+      png_warning(png_ptr, "Invalid sCAL chunk ignored: non-positive width");
+
+   else
+   {
+      png_size_t heighti = i;
+
+      state = 0;
+      if (!png_check_fp_number(png_ptr->chunkdata, slength, &state, &i) ||
+          i != slength)
+         png_warning(png_ptr, "Invalid sCAL chunk ignored: bad height format");
+
+      else if (!PNG_FP_IS_POSITIVE(state))
+         png_warning(png_ptr,
+            "Invalid sCAL chunk ignored: non-positive height");
+
+      else
+         /* This is the (only) success case. */
+         png_set_sCAL_s(png_ptr, info_ptr, png_ptr->chunkdata[0],
+            png_ptr->chunkdata+1, png_ptr->chunkdata+heighti);
+   }
+
+   /* Clean up - just free the temporarily allocated buffer. */
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
+}
+#endif
+
+#ifdef PNG_READ_tIME_SUPPORTED
+void /* PRIVATE */
+png_handle_tIME(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   png_byte buf[7];
+   png_time mod_time;
+
+   png_debug(1, "in png_handle_tIME");
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Out of place tIME chunk");
+
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME))
+   {
+      png_warning(png_ptr, "Duplicate tIME chunk");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   if (png_ptr->mode & PNG_HAVE_IDAT)
+      png_ptr->mode |= PNG_AFTER_IDAT;
+
+   if (length != 7)
+   {
+      png_warning(png_ptr, "Incorrect tIME chunk length");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   png_crc_read(png_ptr, buf, 7);
+
+   if (png_crc_finish(png_ptr, 0))
+      return;
+
+   mod_time.second = buf[6];
+   mod_time.minute = buf[5];
+   mod_time.hour = buf[4];
+   mod_time.day = buf[3];
+   mod_time.month = buf[2];
+   mod_time.year = png_get_uint_16(buf);
+
+   png_set_tIME(png_ptr, info_ptr, &mod_time);
+}
+#endif
+
+#ifdef PNG_READ_tEXt_SUPPORTED
+/* Note: this does not properly handle chunks that are > 64K under DOS */
+void /* PRIVATE */
+png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   png_textp text_ptr;
+   png_charp key;
+   png_charp text;
+   png_uint_32 skip = 0;
+   png_size_t slength;
+   int ret;
+
+   png_debug(1, "in png_handle_tEXt");
+
+#ifdef PNG_USER_LIMITS_SUPPORTED
+   if (png_ptr->user_chunk_cache_max != 0)
+   {
+      if (png_ptr->user_chunk_cache_max == 1)
+      {
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+
+      if (--png_ptr->user_chunk_cache_max == 1)
+      {
+         png_warning(png_ptr, "No space in chunk cache for tEXt");
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+   }
+#endif
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Missing IHDR before tEXt");
+
+   if (png_ptr->mode & PNG_HAVE_IDAT)
+      png_ptr->mode |= PNG_AFTER_IDAT;
+
+#ifdef PNG_MAX_MALLOC_64K
+   if (length > (png_uint_32)65535L)
+   {
+      png_warning(png_ptr, "tEXt chunk too large to fit in memory");
+      skip = length - (png_uint_32)65535L;
+      length = (png_uint_32)65535L;
+   }
+#endif
+
+   png_free(png_ptr, png_ptr->chunkdata);
+
+   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+
+   if (png_ptr->chunkdata == NULL)
+   {
+     png_warning(png_ptr, "No memory to process text chunk");
+     return;
+   }
+
+   slength = length;
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+
+   if (png_crc_finish(png_ptr, skip))
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   key = png_ptr->chunkdata;
+
+   key[slength] = 0x00;
+
+   for (text = key; *text; text++)
+      /* Empty loop to find end of key */ ;
+
+   if (text != key + slength)
+      text++;
+
+   text_ptr = (png_textp)png_malloc_warn(png_ptr,
+       png_sizeof(png_text));
+
+   if (text_ptr == NULL)
+   {
+      png_warning(png_ptr, "Not enough memory to process text chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   text_ptr->compression = PNG_TEXT_COMPRESSION_NONE;
+   text_ptr->key = key;
+   text_ptr->lang = NULL;
+   text_ptr->lang_key = NULL;
+   text_ptr->itxt_length = 0;
+   text_ptr->text = text;
+   text_ptr->text_length = png_strlen(text);
+
+   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
+
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
+   png_free(png_ptr, text_ptr);
+
+   if (ret)
+      png_warning(png_ptr, "Insufficient memory to process text chunk");
+}
+#endif
+
+#ifdef PNG_READ_zTXt_SUPPORTED
+/* Note: this does not correctly handle chunks that are > 64K under DOS */
+void /* PRIVATE */
+png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   png_textp text_ptr;
+   png_charp text;
+   int comp_type;
+   int ret;
+   png_size_t slength, prefix_len, data_len;
+
+   png_debug(1, "in png_handle_zTXt");
+
+#ifdef PNG_USER_LIMITS_SUPPORTED
+   if (png_ptr->user_chunk_cache_max != 0)
+   {
+      if (png_ptr->user_chunk_cache_max == 1)
+      {
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+
+      if (--png_ptr->user_chunk_cache_max == 1)
+      {
+         png_warning(png_ptr, "No space in chunk cache for zTXt");
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+   }
+#endif
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Missing IHDR before zTXt");
+
+   if (png_ptr->mode & PNG_HAVE_IDAT)
+      png_ptr->mode |= PNG_AFTER_IDAT;
+
+#ifdef PNG_MAX_MALLOC_64K
+   /* We will no doubt have problems with chunks even half this size, but
+    * there is no hard and fast rule to tell us where to stop.
+    */
+   if (length > (png_uint_32)65535L)
+   {
+      png_warning(png_ptr, "zTXt chunk too large to fit in memory");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+#endif
+
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+
+   if (png_ptr->chunkdata == NULL)
+   {
+      png_warning(png_ptr, "Out of memory processing zTXt chunk");
+      return;
+   }
+
+   slength = length;
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+
+   if (png_crc_finish(png_ptr, 0))
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   png_ptr->chunkdata[slength] = 0x00;
+
+   for (text = png_ptr->chunkdata; *text; text++)
+      /* Empty loop */ ;
+
+   /* zTXt must have some text after the chunkdataword */
+   if (text >= png_ptr->chunkdata + slength - 2)
+   {
+      png_warning(png_ptr, "Truncated zTXt chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   else
+   {
+       comp_type = *(++text);
+
+       if (comp_type != PNG_TEXT_COMPRESSION_zTXt)
+       {
+          png_warning(png_ptr, "Unknown compression type in zTXt chunk");
+          comp_type = PNG_TEXT_COMPRESSION_zTXt;
+       }
+
+       text++;        /* Skip the compression_method byte */
+   }
+
+   prefix_len = text - png_ptr->chunkdata;
+
+   png_decompress_chunk(png_ptr, comp_type,
+       (png_size_t)length, prefix_len, &data_len);
+
+   text_ptr = (png_textp)png_malloc_warn(png_ptr,
+       png_sizeof(png_text));
+
+   if (text_ptr == NULL)
+   {
+      png_warning(png_ptr, "Not enough memory to process zTXt chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   text_ptr->compression = comp_type;
+   text_ptr->key = png_ptr->chunkdata;
+   text_ptr->lang = NULL;
+   text_ptr->lang_key = NULL;
+   text_ptr->itxt_length = 0;
+   text_ptr->text = png_ptr->chunkdata + prefix_len;
+   text_ptr->text_length = data_len;
+
+   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
+
+   png_free(png_ptr, text_ptr);
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
+
+   if (ret)
+      png_error(png_ptr, "Insufficient memory to store zTXt chunk");
+}
+#endif
+
+#ifdef PNG_READ_iTXt_SUPPORTED
+/* Note: this does not correctly handle chunks that are > 64K under DOS */
+void /* PRIVATE */
+png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   png_textp text_ptr;
+   png_charp key, lang, text, lang_key;
+   int comp_flag;
+   int comp_type = 0;
+   int ret;
+   png_size_t slength, prefix_len, data_len;
+
+   png_debug(1, "in png_handle_iTXt");
+
+#ifdef PNG_USER_LIMITS_SUPPORTED
+   if (png_ptr->user_chunk_cache_max != 0)
+   {
+      if (png_ptr->user_chunk_cache_max == 1)
+      {
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+
+      if (--png_ptr->user_chunk_cache_max == 1)
+      {
+         png_warning(png_ptr, "No space in chunk cache for iTXt");
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+   }
+#endif
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Missing IHDR before iTXt");
+
+   if (png_ptr->mode & PNG_HAVE_IDAT)
+      png_ptr->mode |= PNG_AFTER_IDAT;
+
+#ifdef PNG_MAX_MALLOC_64K
+   /* We will no doubt have problems with chunks even half this size, but
+    * there is no hard and fast rule to tell us where to stop.
+    */
+   if (length > (png_uint_32)65535L)
+   {
+      png_warning(png_ptr, "iTXt chunk too large to fit in memory");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+#endif
+
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+
+   if (png_ptr->chunkdata == NULL)
+   {
+      png_warning(png_ptr, "No memory to process iTXt chunk");
+      return;
+   }
+
+   slength = length;
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+
+   if (png_crc_finish(png_ptr, 0))
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   png_ptr->chunkdata[slength] = 0x00;
+
+   for (lang = png_ptr->chunkdata; *lang; lang++)
+      /* Empty loop */ ;
+
+   lang++;        /* Skip NUL separator */
+
+   /* iTXt must have a language tag (possibly empty), two compression bytes,
+    * translated keyword (possibly empty), and possibly some text after the
+    * keyword
+    */
+
+   if (lang >= png_ptr->chunkdata + slength - 3)
+   {
+      png_warning(png_ptr, "Truncated iTXt chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   else
+   {
+      comp_flag = *lang++;
+      comp_type = *lang++;
+   }
+
+   if (comp_type || (comp_flag && comp_flag != PNG_TEXT_COMPRESSION_zTXt))
+   {
+      png_warning(png_ptr, "Unknown iTXt compression type or method");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   for (lang_key = lang; *lang_key; lang_key++)
+      /* Empty loop */ ;
+
+   lang_key++;        /* Skip NUL separator */
+
+   if (lang_key >= png_ptr->chunkdata + slength)
+   {
+      png_warning(png_ptr, "Truncated iTXt chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   for (text = lang_key; *text; text++)
+      /* Empty loop */ ;
+
+   text++;        /* Skip NUL separator */
+
+   if (text >= png_ptr->chunkdata + slength)
+   {
+      png_warning(png_ptr, "Malformed iTXt chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   prefix_len = text - png_ptr->chunkdata;
+
+   key=png_ptr->chunkdata;
+
+   if (comp_flag)
+      png_decompress_chunk(png_ptr, comp_type,
+          (size_t)length, prefix_len, &data_len);
+
+   else
+      data_len = png_strlen(png_ptr->chunkdata + prefix_len);
+
+   text_ptr = (png_textp)png_malloc_warn(png_ptr,
+       png_sizeof(png_text));
+
+   if (text_ptr == NULL)
+   {
+      png_warning(png_ptr, "Not enough memory to process iTXt chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   text_ptr->compression = (int)comp_flag + 1;
+   text_ptr->lang_key = png_ptr->chunkdata + (lang_key - key);
+   text_ptr->lang = png_ptr->chunkdata + (lang - key);
+   text_ptr->itxt_length = data_len;
+   text_ptr->text_length = 0;
+   text_ptr->key = png_ptr->chunkdata;
+   text_ptr->text = png_ptr->chunkdata + prefix_len;
+
+   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
+
+   png_free(png_ptr, text_ptr);
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
+
+   if (ret)
+      png_error(png_ptr, "Insufficient memory to store iTXt chunk");
+}
+#endif
+
+/* This function is called when we haven't found a handler for a
+ * chunk.  If there isn't a problem with the chunk itself (ie bad
+ * chunk name, CRC, or a critical chunk), the chunk is silently ignored
+ * -- unless the PNG_FLAG_UNKNOWN_CHUNKS_SUPPORTED flag is on in which
+ * case it will be saved away to be written out later.
+ */
+void /* PRIVATE */
+png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   png_uint_32 skip = 0;
+
+   png_debug(1, "in png_handle_unknown");
+
+#ifdef PNG_USER_LIMITS_SUPPORTED
+   if (png_ptr->user_chunk_cache_max != 0)
+   {
+      if (png_ptr->user_chunk_cache_max == 1)
+      {
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+
+      if (--png_ptr->user_chunk_cache_max == 1)
+      {
+         png_warning(png_ptr, "No space in chunk cache for unknown chunk");
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+   }
+#endif
+
+   if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      if (png_ptr->chunk_name != png_IDAT)
+         png_ptr->mode |= PNG_AFTER_IDAT;
+   }
+
+   if (PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
+   {
+#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+      if (png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name) !=
+          PNG_HANDLE_CHUNK_ALWAYS
+#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
+          && png_ptr->read_user_chunk_fn == NULL
+#endif
+          )
+#endif
+         png_chunk_error(png_ptr, "unknown critical chunk");
+   }
+
+#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
+   if ((png_ptr->flags & PNG_FLAG_KEEP_UNKNOWN_CHUNKS)
+#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
+       || (png_ptr->read_user_chunk_fn != NULL)
+#endif
+       )
+   {
+#ifdef PNG_MAX_MALLOC_64K
+      if (length > 65535)
+      {
+         png_warning(png_ptr, "unknown chunk too large to fit in memory");
+         skip = length - 65535;
+         length = 65535;
+      }
+#endif
+
+      /* TODO: this code is very close to the unknown handling in pngpread.c,
+       * maybe it can be put into a common utility routine?
+       * png_struct::unknown_chunk is just used as a temporary variable, along
+       * with the data into which the chunk is read.  These can be eliminated.
+       */
+      PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name);
+      png_ptr->unknown_chunk.size = (png_size_t)length;
+
+      if (length == 0)
+         png_ptr->unknown_chunk.data = NULL;
+
+      else
+      {
+         png_ptr->unknown_chunk.data = (png_bytep)png_malloc(png_ptr, length);
+         png_crc_read(png_ptr, png_ptr->unknown_chunk.data, length);
+      }
+
+#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
+      if (png_ptr->read_user_chunk_fn != NULL)
+      {
+         /* Callback to user unknown chunk handler */
+         int ret;
+
+         ret = (*(png_ptr->read_user_chunk_fn))
+             (png_ptr, &png_ptr->unknown_chunk);
+
+         if (ret < 0)
+            png_chunk_error(png_ptr, "error in user chunk");
+
+         if (ret == 0)
+         {
+            if (PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
+            {
+#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+               if (png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name) !=
+                   PNG_HANDLE_CHUNK_ALWAYS)
+#endif
+                  png_chunk_error(png_ptr, "unknown critical chunk");
+            }
+
+            png_set_unknown_chunks(png_ptr, info_ptr,
+                &png_ptr->unknown_chunk, 1);
+         }
+      }
+
+      else
+#endif
+         png_set_unknown_chunks(png_ptr, info_ptr, &png_ptr->unknown_chunk, 1);
+
+      png_free(png_ptr, png_ptr->unknown_chunk.data);
+      png_ptr->unknown_chunk.data = NULL;
+   }
+
+   else
+#endif
+      skip = length;
+
+   png_crc_finish(png_ptr, skip);
+
+#ifndef PNG_READ_USER_CHUNKS_SUPPORTED
+   PNG_UNUSED(info_ptr) /* Quiet compiler warnings about unused info_ptr */
+#endif
+}
+
+/* This function is called to verify that a chunk name is valid.
+ * This function can't have the "critical chunk check" incorporated
+ * into it, since in the future we will need to be able to call user
+ * functions to handle unknown critical chunks after we check that
+ * the chunk name itself is valid.
+ */
+
+/* Bit hacking: the test for an invalid byte in the 4 byte chunk name is:
+ *
+ * ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
+ */
+
+void /* PRIVATE */
+png_check_chunk_name(png_structp png_ptr, png_uint_32 chunk_name)
+{
+   int i;
+
+   png_debug(1, "in png_check_chunk_name");
+
+   for (i=1; i<=4; ++i)
+   {
+      int c = chunk_name & 0xff;
+
+      if (c < 65 || c > 122 || (c > 90 && c < 97))
+         png_chunk_error(png_ptr, "invalid chunk type");
+
+      chunk_name >>= 8;
+   }
+}
+
+/* Combines the row recently read in with the existing pixels in the row.  This
+ * routine takes care of alpha and transparency if requested.  This routine also
+ * handles the two methods of progressive display of interlaced images,
+ * depending on the 'display' value; if 'display' is true then the whole row
+ * (dp) is filled from the start by replicating the available pixels.  If
+ * 'display' is false only those pixels present in the pass are filled in.
+ */
+void /* PRIVATE */
+png_combine_row(png_structp png_ptr, png_bytep dp, int display)
+{
+   unsigned int pixel_depth = png_ptr->transformed_pixel_depth;
+   png_const_bytep sp = png_ptr->row_buf + 1;
+   png_uint_32 row_width = png_ptr->width;
+   unsigned int pass = png_ptr->pass;
+   png_bytep end_ptr = 0;
+   png_byte end_byte = 0;
+   unsigned int end_mask;
+
+   png_debug(1, "in png_combine_row");
+
+   /* Added in 1.5.6: it should not be possible to enter this routine until at
+    * least one row has been read from the PNG data and transformed.
+    */
+   if (pixel_depth == 0)
+      png_error(png_ptr, "internal row logic error");
+
+   /* Added in 1.5.4: the pixel depth should match the information returned by
+    * any call to png_read_update_info at this point.  Do not continue if we got
+    * this wrong.
+    */
+   if (png_ptr->info_rowbytes != 0 && png_ptr->info_rowbytes !=
+          PNG_ROWBYTES(pixel_depth, row_width))
+      png_error(png_ptr, "internal row size calculation error");
+
+   /* Don't expect this to ever happen: */
+   if (row_width == 0)
+      png_error(png_ptr, "internal row width error");
+
+   /* Preserve the last byte in cases where only part of it will be overwritten,
+    * the multiply below may overflow, we don't care because ANSI-C guarantees
+    * we get the low bits.
+    */
+   end_mask = (pixel_depth * row_width) & 7;
+   if (end_mask != 0)
+   {
+      /* end_ptr == NULL is a flag to say do nothing */
+      end_ptr = dp + PNG_ROWBYTES(pixel_depth, row_width) - 1;
+      end_byte = *end_ptr;
+#     ifdef PNG_READ_PACKSWAP_SUPPORTED
+         if (png_ptr->transformations & PNG_PACKSWAP) /* little-endian byte */
+            end_mask = 0xff << end_mask;
+
+         else /* big-endian byte */
+#     endif
+         end_mask = 0xff >> end_mask;
+      /* end_mask is now the bits to *keep* from the destination row */
+   }
+
+   /* For non-interlaced images this reduces to a png_memcpy(). A png_memcpy()
+    * will also happen if interlacing isn't supported or if the application
+    * does not call png_set_interlace_handling().  In the latter cases the
+    * caller just gets a sequence of the unexpanded rows from each interlace
+    * pass.
+    */
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+   if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE) &&
+      pass < 6 && (display == 0 ||
+      /* The following copies everything for 'display' on passes 0, 2 and 4. */
+      (display == 1 && (pass & 1) != 0)))
+   {
+      /* Narrow images may have no bits in a pass; the caller should handle
+       * this, but this test is cheap:
+       */
+      if (row_width <= PNG_PASS_START_COL(pass))
+         return;
+
+      if (pixel_depth < 8)
+      {
+         /* For pixel depths up to 4 bpp the 8-pixel mask can be expanded to fit
+          * into 32 bits, then a single loop over the bytes using the four byte
+          * values in the 32-bit mask can be used.  For the 'display' option the
+          * expanded mask may also not require any masking within a byte.  To
+          * make this work the PACKSWAP option must be taken into account - it
+          * simply requires the pixels to be reversed in each byte.
+          *
+          * The 'regular' case requires a mask for each of the first 6 passes,
+          * the 'display' case does a copy for the even passes in the range
+          * 0..6.  This has already been handled in the test above.
+          *
+          * The masks are arranged as four bytes with the first byte to use in
+          * the lowest bits (little-endian) regardless of the order (PACKSWAP or
+          * not) of the pixels in each byte.
+          *
+          * NOTE: the whole of this logic depends on the caller of this function
+          * only calling it on rows appropriate to the pass.  This function only
+          * understands the 'x' logic; the 'y' logic is handled by the caller.
+          *
+          * The following defines allow generation of compile time constant bit
+          * masks for each pixel depth and each possibility of swapped or not
+          * swapped bytes.  Pass 'p' is in the range 0..6; 'x', a pixel index,
+          * is in the range 0..7; and the result is 1 if the pixel is to be
+          * copied in the pass, 0 if not.  'S' is for the sparkle method, 'B'
+          * for the block method.
+          *
+          * With some compilers a compile time expression of the general form:
+          *
+          *    (shift >= 32) ? (a >> (shift-32)) : (b >> shift)
+          *
+          * Produces warnings with values of 'shift' in the range 33 to 63
+          * because the right hand side of the ?: expression is evaluated by
+          * the compiler even though it isn't used.  Microsoft Visual C (various
+          * versions) and the Intel C compiler are known to do this.  To avoid
+          * this the following macros are used in 1.5.6.  This is a temporary
+          * solution to avoid destabilizing the code during the release process.
+          */
+#        if PNG_USE_COMPILE_TIME_MASKS
+#           define PNG_LSR(x,s) ((x)>>((s) & 0x1f))
+#           define PNG_LSL(x,s) ((x)<<((s) & 0x1f))
+#        else
+#           define PNG_LSR(x,s) ((x)>>(s))
+#           define PNG_LSL(x,s) ((x)<<(s))
+#        endif
+#        define S_COPY(p,x) (((p)<4 ? PNG_LSR(0x80088822,(3-(p))*8+(7-(x))) :\
+           PNG_LSR(0xaa55ff00,(7-(p))*8+(7-(x)))) & 1)
+#        define B_COPY(p,x) (((p)<4 ? PNG_LSR(0xff0fff33,(3-(p))*8+(7-(x))) :\
+           PNG_LSR(0xff55ff00,(7-(p))*8+(7-(x)))) & 1)
+
+         /* Return a mask for pass 'p' pixel 'x' at depth 'd'.  The mask is
+          * little endian - the first pixel is at bit 0 - however the extra
+          * parameter 's' can be set to cause the mask position to be swapped
+          * within each byte, to match the PNG format.  This is done by XOR of
+          * the shift with 7, 6 or 4 for bit depths 1, 2 and 4.
+          */
+#        define PIXEL_MASK(p,x,d,s) \
+            (PNG_LSL(((PNG_LSL(1U,(d)))-1),(((x)*(d))^((s)?8-(d):0))))
+
+         /* Hence generate the appropriate 'block' or 'sparkle' pixel copy mask.
+          */
+#        define S_MASKx(p,x,d,s) (S_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
+#        define B_MASKx(p,x,d,s) (B_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
+
+         /* Combine 8 of these to get the full mask.  For the 1-bpp and 2-bpp
+          * cases the result needs replicating, for the 4-bpp case the above
+          * generates a full 32 bits.
+          */
+#        define MASK_EXPAND(m,d) ((m)*((d)==1?0x01010101:((d)==2?0x00010001:1)))
+
+#        define S_MASK(p,d,s) MASK_EXPAND(S_MASKx(p,0,d,s) + S_MASKx(p,1,d,s) +\
+            S_MASKx(p,2,d,s) + S_MASKx(p,3,d,s) + S_MASKx(p,4,d,s) +\
+            S_MASKx(p,5,d,s) + S_MASKx(p,6,d,s) + S_MASKx(p,7,d,s), d)
+
+#        define B_MASK(p,d,s) MASK_EXPAND(B_MASKx(p,0,d,s) + B_MASKx(p,1,d,s) +\
+            B_MASKx(p,2,d,s) + B_MASKx(p,3,d,s) + B_MASKx(p,4,d,s) +\
+            B_MASKx(p,5,d,s) + B_MASKx(p,6,d,s) + B_MASKx(p,7,d,s), d)
+
+#if PNG_USE_COMPILE_TIME_MASKS
+         /* Utility macros to construct all the masks for a depth/swap
+          * combination.  The 's' parameter says whether the format is PNG
+          * (big endian bytes) or not.  Only the three odd-numbered passes are
+          * required for the display/block algorithm.
+          */
+#        define S_MASKS(d,s) { S_MASK(0,d,s), S_MASK(1,d,s), S_MASK(2,d,s),\
+            S_MASK(3,d,s), S_MASK(4,d,s), S_MASK(5,d,s) }
+
+#        define B_MASKS(d,s) { B_MASK(1,d,s), S_MASK(3,d,s), S_MASK(5,d,s) }
+
+#        define DEPTH_INDEX(d) ((d)==1?0:((d)==2?1:2))
+
+         /* Hence the pre-compiled masks indexed by PACKSWAP (or not), depth and
+          * then pass:
+          */
+         static PNG_CONST png_uint_32 row_mask[2/*PACKSWAP*/][3/*depth*/][6] =
+         {
+            /* Little-endian byte masks for PACKSWAP */
+            { S_MASKS(1,0), S_MASKS(2,0), S_MASKS(4,0) },
+            /* Normal (big-endian byte) masks - PNG format */
+            { S_MASKS(1,1), S_MASKS(2,1), S_MASKS(4,1) }
+         };
+
+         /* display_mask has only three entries for the odd passes, so index by
+          * pass>>1.
+          */
+         static PNG_CONST png_uint_32 display_mask[2][3][3] =
+         {
+            /* Little-endian byte masks for PACKSWAP */
+            { B_MASKS(1,0), B_MASKS(2,0), B_MASKS(4,0) },
+            /* Normal (big-endian byte) masks - PNG format */
+            { B_MASKS(1,1), B_MASKS(2,1), B_MASKS(4,1) }
+         };
+
+#        define MASK(pass,depth,display,png)\
+            ((display)?display_mask[png][DEPTH_INDEX(depth)][pass>>1]:\
+               row_mask[png][DEPTH_INDEX(depth)][pass])
+
+#else /* !PNG_USE_COMPILE_TIME_MASKS */
+         /* This is the runtime alternative: it seems unlikely that this will
+          * ever be either smaller or faster than the compile time approach.
+          */
+#        define MASK(pass,depth,display,png)\
+            ((display)?B_MASK(pass,depth,png):S_MASK(pass,depth,png))
+#endif /* !PNG_USE_COMPILE_TIME_MASKS */
+
+         /* Use the appropriate mask to copy the required bits.  In some cases
+          * the byte mask will be 0 or 0xff, optimize these cases.  row_width is
+          * the number of pixels, but the code copies bytes, so it is necessary
+          * to special case the end.
+          */
+         png_uint_32 pixels_per_byte = 8 / pixel_depth;
+         png_uint_32 mask;
+
+#        ifdef PNG_READ_PACKSWAP_SUPPORTED
+            if (png_ptr->transformations & PNG_PACKSWAP)
+               mask = MASK(pass, pixel_depth, display, 0);
+
+            else
+#        endif
+            mask = MASK(pass, pixel_depth, display, 1);
+
+         for (;;)
+         {
+            png_uint_32 m;
+
+            /* It doesn't matter in the following if png_uint_32 has more than
+             * 32 bits because the high bits always match those in m<<24; it is,
+             * however, essential to use OR here, not +, because of this.
+             */
+            m = mask;
+            mask = (m >> 8) | (m << 24); /* rotate right to good compilers */
+            m &= 0xff;
+
+            if (m != 0) /* something to copy */
+            {
+               if (m != 0xff)
+                  *dp = (png_byte)((*dp & ~m) | (*sp & m));
+               else
+                  *dp = *sp;
+            }
+
+            /* NOTE: this may overwrite the last byte with garbage if the image
+             * is not an exact number of bytes wide; libpng has always done
+             * this.
+             */
+            if (row_width <= pixels_per_byte)
+               break; /* May need to restore part of the last byte */
+
+            row_width -= pixels_per_byte;
+            ++dp;
+            ++sp;
+         }
+      }
+
+      else /* pixel_depth >= 8 */
+      {
+         unsigned int bytes_to_copy, bytes_to_jump;
+
+         /* Validate the depth - it must be a multiple of 8 */
+         if (pixel_depth & 7)
+            png_error(png_ptr, "invalid user transform pixel depth");
+
+         pixel_depth >>= 3; /* now in bytes */
+         row_width *= pixel_depth;
+
+         /* Regardless of pass number the Adam 7 interlace always results in a
+          * fixed number of pixels to copy then to skip.  There may be a
+          * different number of pixels to skip at the start though.
+          */
+         {
+            unsigned int offset = PNG_PASS_START_COL(pass) * pixel_depth;
+
+            row_width -= offset;
+            dp += offset;
+            sp += offset;
+         }
+
+         /* Work out the bytes to copy. */
+         if (display)
+         {
+            /* When doing the 'block' algorithm the pixel in the pass gets
+             * replicated to adjacent pixels.  This is why the even (0,2,4,6)
+             * passes are skipped above - the entire expanded row is copied.
+             */
+            bytes_to_copy = (1<<((6-pass)>>1)) * pixel_depth;
+
+            /* But don't allow this number to exceed the actual row width. */
+            if (bytes_to_copy > row_width)
+               bytes_to_copy = row_width;
+         }
+
+         else /* normal row; Adam7 only ever gives us one pixel to copy. */
+            bytes_to_copy = pixel_depth;
+
+         /* In Adam7 there is a constant offset between where the pixels go. */
+         bytes_to_jump = PNG_PASS_COL_OFFSET(pass) * pixel_depth;
+
+         /* And simply copy these bytes.  Some optimization is possible here,
+          * depending on the value of 'bytes_to_copy'.  Special case the low
+          * byte counts, which we know to be frequent.
+          *
+          * Notice that these cases all 'return' rather than 'break' - this
+          * avoids an unnecessary test on whether to restore the last byte
+          * below.
+          */
+         switch (bytes_to_copy)
+         {
+            case 1:
+               for (;;)
+               {
+                  *dp = *sp;
+
+                  if (row_width <= bytes_to_jump)
+                     return;
+
+                  dp += bytes_to_jump;
+                  sp += bytes_to_jump;
+                  row_width -= bytes_to_jump;
+               }
+
+            case 2:
+               /* There is a possibility of a partial copy at the end here; this
+                * slows the code down somewhat.
+                */
+               do
+               {
+                  dp[0] = sp[0], dp[1] = sp[1];
+
+                  if (row_width <= bytes_to_jump)
+                     return;
+
+                  sp += bytes_to_jump;
+                  dp += bytes_to_jump;
+                  row_width -= bytes_to_jump;
+               }
+               while (row_width > 1);
+
+               /* And there can only be one byte left at this point: */
+               *dp = *sp;
+               return;
+
+            case 3:
+               /* This can only be the RGB case, so each copy is exactly one
+                * pixel and it is not necessary to check for a partial copy.
+                */
+               for(;;)
+               {
+                  dp[0] = sp[0], dp[1] = sp[1], dp[2] = sp[2];
+
+                  if (row_width <= bytes_to_jump)
+                     return;
+
+                  sp += bytes_to_jump;
+                  dp += bytes_to_jump;
+                  row_width -= bytes_to_jump;
+               }
+
+            default:
+#if PNG_ALIGN_TYPE != PNG_ALIGN_NONE
+               /* Check for double byte alignment and, if possible, use a
+                * 16-bit copy.  Don't attempt this for narrow images - ones that
+                * are less than an interlace panel wide.  Don't attempt it for
+                * wide bytes_to_copy either - use the png_memcpy there.
+                */
+               if (bytes_to_copy < 16 /*else use png_memcpy*/ &&
+                  png_isaligned(dp, png_uint_16) &&
+                  png_isaligned(sp, png_uint_16) &&
+                  bytes_to_copy % sizeof (png_uint_16) == 0 &&
+                  bytes_to_jump % sizeof (png_uint_16) == 0)
+               {
+                  /* Everything is aligned for png_uint_16 copies, but try for
+                   * png_uint_32 first.
+                   */
+                  if (png_isaligned(dp, png_uint_32) &&
+                     png_isaligned(sp, png_uint_32) &&
+                     bytes_to_copy % sizeof (png_uint_32) == 0 &&
+                     bytes_to_jump % sizeof (png_uint_32) == 0)
+                  {
+                     png_uint_32p dp32 = (png_uint_32p)dp;
+                     png_const_uint_32p sp32 = (png_const_uint_32p)sp;
+                     unsigned int skip = (bytes_to_jump-bytes_to_copy) /
+                        sizeof (png_uint_32);
+
+                     do
+                     {
+                        size_t c = bytes_to_copy;
+                        do
+                        {
+                           *dp32++ = *sp32++;
+                           c -= sizeof (png_uint_32);
+                        }
+                        while (c > 0);
+
+                        if (row_width <= bytes_to_jump)
+                           return;
+
+                        dp32 += skip;
+                        sp32 += skip;
+                        row_width -= bytes_to_jump;
+                     }
+                     while (bytes_to_copy <= row_width);
+
+                     /* Get to here when the row_width truncates the final copy.
+                      * There will be 1-3 bytes left to copy, so don't try the
+                      * 16-bit loop below.
+                      */
+                     dp = (png_bytep)dp32;
+                     sp = (png_const_bytep)sp32;
+                     do
+                        *dp++ = *sp++;
+                     while (--row_width > 0);
+                     return;
+                  }
+
+                  /* Else do it in 16-bit quantities, but only if the size is
+                   * not too large.
+                   */
+                  else
+                  {
+                     png_uint_16p dp16 = (png_uint_16p)dp;
+                     png_const_uint_16p sp16 = (png_const_uint_16p)sp;
+                     unsigned int skip = (bytes_to_jump-bytes_to_copy) /
+                        sizeof (png_uint_16);
+
+                     do
+                     {
+                        size_t c = bytes_to_copy;
+                        do
+                        {
+                           *dp16++ = *sp16++;
+                           c -= sizeof (png_uint_16);
+                        }
+                        while (c > 0);
+
+                        if (row_width <= bytes_to_jump)
+                           return;
+
+                        dp16 += skip;
+                        sp16 += skip;
+                        row_width -= bytes_to_jump;
+                     }
+                     while (bytes_to_copy <= row_width);
+
+                     /* End of row - 1 byte left, bytes_to_copy > row_width: */
+                     dp = (png_bytep)dp16;
+                     sp = (png_const_bytep)sp16;
+                     do
+                        *dp++ = *sp++;
+                     while (--row_width > 0);
+                     return;
+                  }
+               }
+#endif /* PNG_ALIGN_ code */
+
+               /* The true default - use a png_memcpy: */
+               for (;;)
+               {
+                  png_memcpy(dp, sp, bytes_to_copy);
+
+                  if (row_width <= bytes_to_jump)
+                     return;
+
+                  sp += bytes_to_jump;
+                  dp += bytes_to_jump;
+                  row_width -= bytes_to_jump;
+                  if (bytes_to_copy > row_width)
+                     bytes_to_copy = row_width;
+               }
+         }
+
+         /* NOT REACHED*/
+      } /* pixel_depth >= 8 */
+
+      /* Here if pixel_depth < 8 to check 'end_ptr' below. */
+   }
+   else
+#endif
+
+   /* If here then the switch above wasn't used so just png_memcpy the whole row
+    * from the temporary row buffer (notice that this overwrites the end of the
+    * destination row if it is a partial byte.)
+    */
+   png_memcpy(dp, sp, PNG_ROWBYTES(pixel_depth, row_width));
+
+   /* Restore the overwritten bits from the last byte if necessary. */
+   if (end_ptr != NULL)
+      *end_ptr = (png_byte)((end_byte & end_mask) | (*end_ptr & ~end_mask));
+}
+
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+void /* PRIVATE */
+png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
+   png_uint_32 transformations /* Because these may affect the byte layout */)
+{
+   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+   /* Offset to next interlace block */
+   static PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+
+   png_debug(1, "in png_do_read_interlace");
+   if (row != NULL && row_info != NULL)
+   {
+      png_uint_32 final_width;
+
+      final_width = row_info->width * png_pass_inc[pass];
+
+      switch (row_info->pixel_depth)
+      {
+         case 1:
+         {
+            png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 3);
+            png_bytep dp = row + (png_size_t)((final_width - 1) >> 3);
+            int sshift, dshift;
+            int s_start, s_end, s_inc;
+            int jstop = png_pass_inc[pass];
+            png_byte v;
+            png_uint_32 i;
+            int j;
+
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
+            if (transformations & PNG_PACKSWAP)
+            {
+                sshift = (int)((row_info->width + 7) & 0x07);
+                dshift = (int)((final_width + 7) & 0x07);
+                s_start = 7;
+                s_end = 0;
+                s_inc = -1;
+            }
+
+            else
+#endif
+            {
+                sshift = 7 - (int)((row_info->width + 7) & 0x07);
+                dshift = 7 - (int)((final_width + 7) & 0x07);
+                s_start = 0;
+                s_end = 7;
+                s_inc = 1;
+            }
+
+            for (i = 0; i < row_info->width; i++)
+            {
+               v = (png_byte)((*sp >> sshift) & 0x01);
+               for (j = 0; j < jstop; j++)
+               {
+                  *dp &= (png_byte)((0x7f7f >> (7 - dshift)) & 0xff);
+                  *dp |= (png_byte)(v << dshift);
+
+                  if (dshift == s_end)
+                  {
+                     dshift = s_start;
+                     dp--;
+                  }
+
+                  else
+                     dshift += s_inc;
+               }
+
+               if (sshift == s_end)
+               {
+                  sshift = s_start;
+                  sp--;
+               }
+
+               else
+                  sshift += s_inc;
+            }
+            break;
+         }
+
+         case 2:
+         {
+            png_bytep sp = row + (png_uint_32)((row_info->width - 1) >> 2);
+            png_bytep dp = row + (png_uint_32)((final_width - 1) >> 2);
+            int sshift, dshift;
+            int s_start, s_end, s_inc;
+            int jstop = png_pass_inc[pass];
+            png_uint_32 i;
+
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
+            if (transformations & PNG_PACKSWAP)
+            {
+               sshift = (int)(((row_info->width + 3) & 0x03) << 1);
+               dshift = (int)(((final_width + 3) & 0x03) << 1);
+               s_start = 6;
+               s_end = 0;
+               s_inc = -2;
+            }
+
+            else
+#endif
+            {
+               sshift = (int)((3 - ((row_info->width + 3) & 0x03)) << 1);
+               dshift = (int)((3 - ((final_width + 3) & 0x03)) << 1);
+               s_start = 0;
+               s_end = 6;
+               s_inc = 2;
+            }
+
+            for (i = 0; i < row_info->width; i++)
+            {
+               png_byte v;
+               int j;
+
+               v = (png_byte)((*sp >> sshift) & 0x03);
+               for (j = 0; j < jstop; j++)
+               {
+                  *dp &= (png_byte)((0x3f3f >> (6 - dshift)) & 0xff);
+                  *dp |= (png_byte)(v << dshift);
+
+                  if (dshift == s_end)
+                  {
+                     dshift = s_start;
+                     dp--;
+                  }
+
+                  else
+                     dshift += s_inc;
+               }
+
+               if (sshift == s_end)
+               {
+                  sshift = s_start;
+                  sp--;
+               }
+
+               else
+                  sshift += s_inc;
+            }
+            break;
+         }
+
+         case 4:
+         {
+            png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 1);
+            png_bytep dp = row + (png_size_t)((final_width - 1) >> 1);
+            int sshift, dshift;
+            int s_start, s_end, s_inc;
+            png_uint_32 i;
+            int jstop = png_pass_inc[pass];
+
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
+            if (transformations & PNG_PACKSWAP)
+            {
+               sshift = (int)(((row_info->width + 1) & 0x01) << 2);
+               dshift = (int)(((final_width + 1) & 0x01) << 2);
+               s_start = 4;
+               s_end = 0;
+               s_inc = -4;
+            }
+
+            else
+#endif
+            {
+               sshift = (int)((1 - ((row_info->width + 1) & 0x01)) << 2);
+               dshift = (int)((1 - ((final_width + 1) & 0x01)) << 2);
+               s_start = 0;
+               s_end = 4;
+               s_inc = 4;
+            }
+
+            for (i = 0; i < row_info->width; i++)
+            {
+               png_byte v = (png_byte)((*sp >> sshift) & 0x0f);
+               int j;
+
+               for (j = 0; j < jstop; j++)
+               {
+                  *dp &= (png_byte)((0xf0f >> (4 - dshift)) & 0xff);
+                  *dp |= (png_byte)(v << dshift);
+
+                  if (dshift == s_end)
+                  {
+                     dshift = s_start;
+                     dp--;
+                  }
+
+                  else
+                     dshift += s_inc;
+               }
+
+               if (sshift == s_end)
+               {
+                  sshift = s_start;
+                  sp--;
+               }
+
+               else
+                  sshift += s_inc;
+            }
+            break;
+         }
+
+         default:
+         {
+            png_size_t pixel_bytes = (row_info->pixel_depth >> 3);
+
+            png_bytep sp = row + (png_size_t)(row_info->width - 1)
+                * pixel_bytes;
+
+            png_bytep dp = row + (png_size_t)(final_width - 1) * pixel_bytes;
+
+            int jstop = png_pass_inc[pass];
+            png_uint_32 i;
+
+            for (i = 0; i < row_info->width; i++)
+            {
+               png_byte v[8];
+               int j;
+
+               png_memcpy(v, sp, pixel_bytes);
+
+               for (j = 0; j < jstop; j++)
+               {
+                  png_memcpy(dp, v, pixel_bytes);
+                  dp -= pixel_bytes;
+               }
+
+               sp -= pixel_bytes;
+            }
+            break;
+         }
+      }
+
+      row_info->width = final_width;
+      row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width);
+   }
+#ifndef PNG_READ_PACKSWAP_SUPPORTED
+   PNG_UNUSED(transformations)  /* Silence compiler warning */
+#endif
+}
+#endif /* PNG_READ_INTERLACING_SUPPORTED */
+
+static void
+png_read_filter_row_sub(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
+{
+   png_size_t i;
+   png_size_t istop = row_info->rowbytes;
+   unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
+   png_bytep rp = row + bpp;
+
+   PNG_UNUSED(prev_row)
+
+   for (i = bpp; i < istop; i++)
+   {
+      *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
+      rp++;
+   }
+}
+
+static void
+png_read_filter_row_up(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
+{
+   png_size_t i;
+   png_size_t istop = row_info->rowbytes;
+   png_bytep rp = row;
+   png_const_bytep pp = prev_row;
+
+   for (i = 0; i < istop; i++)
+   {
+      *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
+      rp++;
+   }
+}
+
+static void
+png_read_filter_row_avg(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
+{
+   png_size_t i;
+   png_bytep rp = row;
+   png_const_bytep pp = prev_row;
+   unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
+   png_size_t istop = row_info->rowbytes - bpp;
+
+   for (i = 0; i < bpp; i++)
+   {
+      *rp = (png_byte)(((int)(*rp) +
+         ((int)(*pp++) / 2 )) & 0xff);
+
+      rp++;
+   }
+
+   for (i = 0; i < istop; i++)
+   {
+      *rp = (png_byte)(((int)(*rp) +
+         (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
+
+      rp++;
+   }
+}
+
+static void
+png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
+{
+   png_bytep rp_end = row + row_info->rowbytes;
+   int a, c;
+
+   /* First pixel/byte */
+   c = *prev_row++;
+   a = *row + c;
+   *row++ = (png_byte)a;
+
+   /* Remainder */
+   while (row < rp_end)
+   {
+      int b, pa, pb, pc, p;
+
+      a &= 0xff; /* From previous iteration or start */
+      b = *prev_row++;
+
+      p = b - c;
+      pc = a - c;
+
+#     ifdef PNG_USE_ABS
+         pa = abs(p);
+         pb = abs(pc);
+         pc = abs(p + pc);
+#     else
+         pa = p < 0 ? -p : p;
+         pb = pc < 0 ? -pc : pc;
+         pc = (p + pc) < 0 ? -(p + pc) : p + pc;
+#     endif
+
+      /* Find the best predictor, the least of pa, pb, pc favoring the earlier
+       * ones in the case of a tie.
+       */
+      if (pb < pa) pa = pb, a = b;
+      if (pc < pa) a = c;
+
+      /* Calculate the current pixel in a, and move the previous row pixel to c
+       * for the next time round the loop
+       */
+      c = b;
+      a += *row;
+      *row++ = (png_byte)a;
+   }
+}
+
+static void
+png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
+{
+   int bpp = (row_info->pixel_depth + 7) >> 3;
+   png_bytep rp_end = row + bpp;
+
+   /* Process the first pixel in the row completely (this is the same as 'up'
+    * because there is only one candidate predictor for the first row).
+    */
+   while (row < rp_end)
+   {
+      int a = *row + *prev_row++;
+      *row++ = (png_byte)a;
+   }
+
+   /* Remainder */
+   rp_end += row_info->rowbytes - bpp;
+
+   while (row < rp_end)
+   {
+      int a, b, c, pa, pb, pc, p;
+
+      c = *(prev_row - bpp);
+      a = *(row - bpp);
+      b = *prev_row++;
+
+      p = b - c;
+      pc = a - c;
+
+#     ifdef PNG_USE_ABS
+         pa = abs(p);
+         pb = abs(pc);
+         pc = abs(p + pc);
+#     else
+         pa = p < 0 ? -p : p;
+         pb = pc < 0 ? -pc : pc;
+         pc = (p + pc) < 0 ? -(p + pc) : p + pc;
+#     endif
+
+      if (pb < pa) pa = pb, a = b;
+      if (pc < pa) a = c;
+
+      c = b;
+      a += *row;
+      *row++ = (png_byte)a;
+   }
+}
+
+#ifdef PNG_ARM_NEON
+
+#ifdef __linux__
+#include <stdio.h>
+#include <elf.h>
+#include <asm/hwcap.h>
+
+static int png_have_hwcap(unsigned cap)
+{
+   FILE *f = fopen("/proc/self/auxv", "r");
+   Elf32_auxv_t aux;
+   int have_cap = 0;
+
+   if (!f)
+      return 0;
+
+   while (fread(&aux, sizeof(aux), 1, f) > 0)
+   {
+      if (aux.a_type == AT_HWCAP &&
+          aux.a_un.a_val & cap)
+      {
+         have_cap = 1;
+         break;
+      }
+   }
+
+   fclose(f);
+
+   return have_cap;
+}
+#endif /* __linux__ */
+
+static void
+png_init_filter_functions_neon(png_structp pp, unsigned int bpp)
+{
+#ifdef __linux__
+   if (!png_have_hwcap(HWCAP_NEON))
+      return;
+#endif
+
+   pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up_neon;
+
+   if (bpp == 3)
+   {
+      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_neon;
+      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_neon;
+      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] = 
+         png_read_filter_row_paeth3_neon;
+   }
+
+   else if (bpp == 4)
+   {
+      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_neon;
+      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_neon;
+      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
+          png_read_filter_row_paeth4_neon;
+   }
+}
+#endif /* PNG_ARM_NEON */
+
+static void
+png_init_filter_functions(png_structp pp)
+{
+   unsigned int bpp = (pp->pixel_depth + 7) >> 3;
+
+   pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub;
+   pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up;
+   pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg;
+   if (bpp == 1)
+      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
+         png_read_filter_row_paeth_1byte_pixel;
+   else
+      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
+         png_read_filter_row_paeth_multibyte_pixel;
+
+#ifdef PNG_ARM_NEON
+   png_init_filter_functions_neon(pp, bpp);
+#endif
+}
+
+void /* PRIVATE */
+png_read_filter_row(png_structp pp, png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row, int filter)
+{
+   if (pp->read_filter[0] == NULL)
+      png_init_filter_functions(pp);
+   if (filter > PNG_FILTER_VALUE_NONE && filter < PNG_FILTER_VALUE_LAST)
+      pp->read_filter[filter-1](row_info, row, prev_row);
+}
+
+#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
+void /* PRIVATE */
+png_read_finish_row(png_structp png_ptr)
+{
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+
+   /* Start of interlace block */
+   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+
+   /* Offset to next interlace block */
+   static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+
+   /* Start of interlace block in the y direction */
+   static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
+
+   /* Offset to next interlace block in the y direction */
+   static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
+#endif /* PNG_READ_INTERLACING_SUPPORTED */
+
+   png_debug(1, "in png_read_finish_row");
+   png_ptr->row_number++;
+   if (png_ptr->row_number < png_ptr->num_rows)
+      return;
+
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+   if (png_ptr->interlaced)
+   {
+      png_ptr->row_number = 0;
+
+      /* TO DO: don't do this if prev_row isn't needed (requires
+       * read-ahead of the next row's filter byte.
+       */
+      png_memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
+
+      do
+      {
+         png_ptr->pass++;
+
+         if (png_ptr->pass >= 7)
+            break;
+
+         png_ptr->iwidth = (png_ptr->width +
+            png_pass_inc[png_ptr->pass] - 1 -
+            png_pass_start[png_ptr->pass]) /
+            png_pass_inc[png_ptr->pass];
+
+         if (!(png_ptr->transformations & PNG_INTERLACE))
+         {
+            png_ptr->num_rows = (png_ptr->height +
+                png_pass_yinc[png_ptr->pass] - 1 -
+                png_pass_ystart[png_ptr->pass]) /
+                png_pass_yinc[png_ptr->pass];
+         }
+
+         else  /* if (png_ptr->transformations & PNG_INTERLACE) */
+            break; /* libpng deinterlacing sees every row */
+
+      } while (png_ptr->num_rows == 0 || png_ptr->iwidth == 0);
+
+      if (png_ptr->pass < 7)
+         return;
+   }
+#endif /* PNG_READ_INTERLACING_SUPPORTED */
+
+   if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
+   {
+      char extra;
+      int ret;
+
+      png_ptr->zstream.next_out = (Byte *)&extra;
+      png_ptr->zstream.avail_out = (uInt)1;
+
+      for (;;)
+      {
+         if (!(png_ptr->zstream.avail_in))
+         {
+            while (!png_ptr->idat_size)
+            {
+               png_crc_finish(png_ptr, 0);
+               png_ptr->idat_size = png_read_chunk_header(png_ptr);
+               if (png_ptr->chunk_name != png_IDAT)
+                  png_error(png_ptr, "Not enough image data");
+            }
+
+            png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size;
+            png_ptr->zstream.next_in = png_ptr->zbuf;
+
+            if (png_ptr->zbuf_size > png_ptr->idat_size)
+               png_ptr->zstream.avail_in = (uInt)png_ptr->idat_size;
+
+            png_crc_read(png_ptr, png_ptr->zbuf, png_ptr->zstream.avail_in);
+            png_ptr->idat_size -= png_ptr->zstream.avail_in;
+         }
+
+         ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
+
+         if (ret == Z_STREAM_END)
+         {
+            if (!(png_ptr->zstream.avail_out) || png_ptr->zstream.avail_in ||
+                png_ptr->idat_size)
+               png_warning(png_ptr, "Extra compressed data");
+
+            png_ptr->mode |= PNG_AFTER_IDAT;
+            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
+            break;
+         }
+
+         if (ret != Z_OK)
+            png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg :
+                "Decompression Error");
+
+         if (!(png_ptr->zstream.avail_out))
+         {
+            png_warning(png_ptr, "Extra compressed data");
+            png_ptr->mode |= PNG_AFTER_IDAT;
+            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
+            break;
+         }
+
+      }
+      png_ptr->zstream.avail_out = 0;
+   }
+
+   if (png_ptr->idat_size || png_ptr->zstream.avail_in)
+      png_warning(png_ptr, "Extra compression data");
+
+   inflateReset(&png_ptr->zstream);
+
+   png_ptr->mode |= PNG_AFTER_IDAT;
+}
+#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
+
+void /* PRIVATE */
+png_read_start_row(png_structp png_ptr)
+{
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+
+   /* Start of interlace block */
+   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+
+   /* Offset to next interlace block */
+   static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+
+   /* Start of interlace block in the y direction */
+   static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
+
+   /* Offset to next interlace block in the y direction */
+   static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
+#endif
+
+   int max_pixel_depth;
+   png_size_t row_bytes;
+
+   png_debug(1, "in png_read_start_row");
+   png_ptr->zstream.avail_in = 0;
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+   png_init_read_transformations(png_ptr);
+#endif
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+   if (png_ptr->interlaced)
+   {
+      if (!(png_ptr->transformations & PNG_INTERLACE))
+         png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
+             png_pass_ystart[0]) / png_pass_yinc[0];
+
+      else
+         png_ptr->num_rows = png_ptr->height;
+
+      png_ptr->iwidth = (png_ptr->width +
+          png_pass_inc[png_ptr->pass] - 1 -
+          png_pass_start[png_ptr->pass]) /
+          png_pass_inc[png_ptr->pass];
+   }
+
+   else
+#endif /* PNG_READ_INTERLACING_SUPPORTED */
+   {
+      png_ptr->num_rows = png_ptr->height;
+      png_ptr->iwidth = png_ptr->width;
+   }
+
+   max_pixel_depth = png_ptr->pixel_depth;
+
+   /* WARNING: * png_read_transform_info (pngrtran.c) performs a simpliar set of
+    * calculations to calculate the final pixel depth, then
+    * png_do_read_transforms actually does the transforms.  This means that the
+    * code which effectively calculates this value is actually repeated in three
+    * separate places.  They must all match.  Innocent changes to the order of
+    * transformations can and will break libpng in a way that causes memory
+    * overwrites.
+    *
+    * TODO: fix this.
+    */
+#ifdef PNG_READ_PACK_SUPPORTED
+   if ((png_ptr->transformations & PNG_PACK) && png_ptr->bit_depth < 8)
+      max_pixel_depth = 8;
+#endif
+
+#ifdef PNG_READ_EXPAND_SUPPORTED
+   if (png_ptr->transformations & PNG_EXPAND)
+   {
+      if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+      {
+         if (png_ptr->num_trans)
+            max_pixel_depth = 32;
+
+         else
+            max_pixel_depth = 24;
+      }
+
+      else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
+      {
+         if (max_pixel_depth < 8)
+            max_pixel_depth = 8;
+
+         if (png_ptr->num_trans)
+            max_pixel_depth *= 2;
+      }
+
+      else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
+      {
+         if (png_ptr->num_trans)
+         {
+            max_pixel_depth *= 4;
+            max_pixel_depth /= 3;
+         }
+      }
+   }
+#endif
+
+#ifdef PNG_READ_EXPAND_16_SUPPORTED
+   if (png_ptr->transformations & PNG_EXPAND_16)
+   {
+#     ifdef PNG_READ_EXPAND_SUPPORTED
+         /* In fact it is an error if it isn't supported, but checking is
+          * the safe way.
+          */
+         if (png_ptr->transformations & PNG_EXPAND)
+         {
+            if (png_ptr->bit_depth < 16)
+               max_pixel_depth *= 2;
+         }
+         else
+#     endif
+         png_ptr->transformations &= ~PNG_EXPAND_16;
+   }
+#endif
+
+#ifdef PNG_READ_FILLER_SUPPORTED
+   if (png_ptr->transformations & (PNG_FILLER))
+   {
+      if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
+      {
+         if (max_pixel_depth <= 8)
+            max_pixel_depth = 16;
+
+         else
+            max_pixel_depth = 32;
+      }
+
+      else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB ||
+         png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+      {
+         if (max_pixel_depth <= 32)
+            max_pixel_depth = 32;
+
+         else
+            max_pixel_depth = 64;
+      }
+   }
+#endif
+
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
+   if (png_ptr->transformations & PNG_GRAY_TO_RGB)
+   {
+      if (
+#ifdef PNG_READ_EXPAND_SUPPORTED
+          (png_ptr->num_trans && (png_ptr->transformations & PNG_EXPAND)) ||
+#endif
+#ifdef PNG_READ_FILLER_SUPPORTED
+          (png_ptr->transformations & (PNG_FILLER)) ||
+#endif
+          png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+      {
+         if (max_pixel_depth <= 16)
+            max_pixel_depth = 32;
+
+         else
+            max_pixel_depth = 64;
+      }
+
+      else
+      {
+         if (max_pixel_depth <= 8)
+         {
+            if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+               max_pixel_depth = 32;
+
+            else
+               max_pixel_depth = 24;
+         }
+
+         else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+            max_pixel_depth = 64;
+
+         else
+            max_pixel_depth = 48;
+      }
+   }
+#endif
+
+#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \
+defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
+   if (png_ptr->transformations & PNG_USER_TRANSFORM)
+   {
+      int user_pixel_depth = png_ptr->user_transform_depth *
+         png_ptr->user_transform_channels;
+
+      if (user_pixel_depth > max_pixel_depth)
+         max_pixel_depth = user_pixel_depth;
+   }
+#endif
+
+   /* This value is stored in png_struct and double checked in the row read
+    * code.
+    */
+   png_ptr->maximum_pixel_depth = (png_byte)max_pixel_depth;
+   png_ptr->transformed_pixel_depth = 0; /* calculated on demand */
+
+   /* Align the width on the next larger 8 pixels.  Mainly used
+    * for interlacing
+    */
+   row_bytes = ((png_ptr->width + 7) & ~((png_uint_32)7));
+   /* Calculate the maximum bytes needed, adding a byte and a pixel
+    * for safety's sake
+    */
+   row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) +
+       1 + ((max_pixel_depth + 7) >> 3);
+
+#ifdef PNG_MAX_MALLOC_64K
+   if (row_bytes > (png_uint_32)65536L)
+      png_error(png_ptr, "This image requires a row greater than 64KB");
+#endif
+
+   if (row_bytes + 48 > png_ptr->old_big_row_buf_size)
+   {
+     png_free(png_ptr, png_ptr->big_row_buf);
+     png_free(png_ptr, png_ptr->big_prev_row);
+
+     if (png_ptr->interlaced)
+        png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,
+            row_bytes + 48);
+
+     else
+        png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
+
+     png_ptr->big_prev_row = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
+
+#ifdef PNG_ALIGNED_MEMORY_SUPPORTED
+     /* Use 16-byte aligned memory for row_buf with at least 16 bytes
+      * of padding before and after row_buf; treat prev_row similarly.
+      * NOTE: the alignment is to the start of the pixels, one beyond the start
+      * of the buffer, because of the filter byte.  Prior to libpng 1.5.6 this
+      * was incorrect; the filter byte was aligned, which had the exact
+      * opposite effect of that intended.
+      */
+     {
+        png_bytep temp = png_ptr->big_row_buf + 32;
+        int extra = (int)((temp - (png_bytep)0) & 0x0f);
+        png_ptr->row_buf = temp - extra - 1/*filter byte*/;
+
+        temp = png_ptr->big_prev_row + 32;
+        extra = (int)((temp - (png_bytep)0) & 0x0f);
+        png_ptr->prev_row = temp - extra - 1/*filter byte*/;
+     }
+
+#else
+     /* Use 31 bytes of padding before and 17 bytes after row_buf. */
+     png_ptr->row_buf = png_ptr->big_row_buf + 31;
+     png_ptr->prev_row = png_ptr->big_prev_row + 31;
+#endif
+     png_ptr->old_big_row_buf_size = row_bytes + 48;
+   }
+
+#ifdef PNG_MAX_MALLOC_64K
+   if (png_ptr->rowbytes > 65535)
+      png_error(png_ptr, "This image requires a row greater than 64KB");
+
+#endif
+   if (png_ptr->rowbytes > (PNG_SIZE_MAX - 1))
+      png_error(png_ptr, "Row has too many bytes to allocate in memory");
+
+   png_memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
+
+   png_debug1(3, "width = %u,", png_ptr->width);
+   png_debug1(3, "height = %u,", png_ptr->height);
+   png_debug1(3, "iwidth = %u,", png_ptr->iwidth);
+   png_debug1(3, "num_rows = %u,", png_ptr->num_rows);
+   png_debug1(3, "rowbytes = %lu,", (unsigned long)png_ptr->rowbytes);
+   png_debug1(3, "irowbytes = %lu",
+       (unsigned long)PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);
+
+   png_ptr->flags |= PNG_FLAG_ROW_INIT;
+}
+#endif /* PNG_READ_SUPPORTED */