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/*
* Copyright (c) Contributors, http://opensimulator.org/
* See CONTRIBUTORS.TXT for a full list of copyright holders.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the OpenSim Project nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
using System;
using System.IO;
using System.Reflection;
using System.Text;
using log4net;
namespace OpenSim.Region.Environment.Modules.World.Archiver
{
/// <summary>
/// Temporary code to do the bare minimum required to read a tar archive for our purposes
/// </summary>
public class TarArchiveReader
{
private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
protected static ASCIIEncoding m_asciiEncoding = new ASCIIEncoding();
/// <summary>
/// Binary reader for the underlying stream
/// </summary>
protected BinaryReader m_br;
/// <summary>
/// Used to trim off null chars
/// </summary>
protected char[] m_nullCharArray = new char[] { '\0' };
public TarArchiveReader(string archivePath)
{
m_br = new BinaryReader(new FileStream(archivePath, FileMode.Open));
}
/// <summary>
/// Are we at the end of the archive?
/// </summary>
/// <returns></returns>
public bool AtEof()
{
// If we've reached the end of the archive we'll be in null block territory, which means
// the next byte will be 0
if (m_br.PeekChar() == 0)
return true;
return false;
}
/// <summary>
/// Read the next entry in the tar file.
/// </summary>
/// <param name="filePath"></param>
/// <returns>the data for the entry. Returns null if there are no more entries</returns>
public byte[] ReadEntry(out string filePath)
{
filePath = String.Empty;
if (AtEof())
return null;
TarHeader header = ReadHeader();
filePath = header.FilePath;
byte[] data = m_br.ReadBytes(header.FileSize);
m_log.DebugFormat("[TAR ARCHIVE READER]: filePath {0}, fileSize {1}", filePath, header.FileSize);
// Read the rest of the empty padding in the 512 byte block
if (header.FileSize % 512 != 0)
{
int paddingLeft = 512 - (header.FileSize % 512);
m_log.DebugFormat("[TAR ARCHIVE READER]: Reading {0} padding bytes", paddingLeft);
m_br.ReadBytes(paddingLeft);
}
return data;
}
/// <summary>
/// Read the next 512 byte chunk of data as a tar header.
/// This method assumes we are not at the end of the archive
/// </summary>
/// <returns>A tar header struct.</returns>
protected TarHeader ReadHeader()
{
TarHeader tarHeader = new TarHeader();
byte[] header = m_br.ReadBytes(512);
tarHeader.FilePath = m_asciiEncoding.GetString(header, 0, 100);
tarHeader.FilePath = tarHeader.FilePath.Trim(m_nullCharArray);
tarHeader.FileSize = ConvertOctalBytesToDecimal(header, 124, 11);
return tarHeader;
}
public void Close()
{
m_br.Close();
}
/// <summary>
/// Convert octal bytes to a decimal representation
/// </summary>
/// <param name="bytes"></param>
/// <returns></returns>
public static int ConvertOctalBytesToDecimal(byte[] bytes, int startIndex, int count)
{
string oString = m_asciiEncoding.GetString(bytes, startIndex, count);
int d = 0;
foreach (char c in oString)
{
d <<= 3;
d |= c - '0';
}
return d;
}
}
public struct TarHeader
{
public string FilePath;
public int FileSize;
}
}
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