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/* EINA - EFL data type library
* Copyright (C) 2011 Carsten Haitzler
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library;
* if not, see <http://www.gnu.org/licenses/>.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#ifdef HAVE_SIGINFO_T
#ifdef STDC_HEADERS
# include <stdlib.h>
# include <stddef.h>
#else
# ifdef HAVE_STDLIB_H
# include <stdlib.h>
# endif
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <limits.h>
#include <signal.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#if HAVE_SIGINFO_H
# include <siginfo.h>
#endif
#endif
#include "eina_config.h"
#include "eina_private.h"
#include "eina_log.h"
#include "eina_mmap.h"
/*============================================================================*
* Local *
*============================================================================*/
static Eina_Bool mmap_safe = EINA_FALSE;
#ifdef HAVE_SIGINFO_T
static int _eina_mmap_log_dom = -1;
static int _eina_mmap_zero_fd = -1;
static long _eina_mmap_pagesize = -1;
#ifdef ERR
#undef ERR
#endif
#define ERR(...) EINA_LOG_DOM_ERR(_eina_mmap_log_dom, __VA_ARGS__)
#ifdef DBG
#undef DBG
#endif
#define DBG(...) EINA_LOG_DOM_DBG(_eina_mmap_log_dom, __VA_ARGS__)
static void
_eina_mmap_safe_sigbus(int sig __UNUSED__,
siginfo_t *siginfo,
void *ptr __UNUSED__)
{
unsigned char *addr = (unsigned char *)(siginfo->si_addr);
int perrno;
/* save previous errno */
perrno = errno;
/* if problems was an unaligned access - complain accordingly and abort */
if (siginfo->si_code == BUS_ADRALN)
{
ERR("Unaligned memory access. SIGBUS!!!");
errno = perrno;
abort();
}
/* send this to stderr - not eina_log. Specifically want this on stderr */
fprintf(stderr,
"EINA: Data at address 0x%lx is invalid. Replacing with zero page.\n",
(unsigned long)addr);
/* align address to the lower page boundary */
addr = (unsigned char *)((long)addr & (~(_eina_mmap_pagesize - 1)));
/* mmap a pzge of zero's from /dev/zero in there */
if (mmap(addr, _eina_mmap_pagesize,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_PRIVATE | MAP_FIXED,
_eina_mmap_zero_fd, 0) == MAP_FAILED)
{
/* mmap of /dev/zero failed :( */
perror("mmap");
ERR("Failed to mmap() /dev/zero in place of page. SIGBUS!!!");
errno = perrno;
abort();
}
/* restore previous errno */
errno = perrno;
}
#endif
/*============================================================================*
* API *
*============================================================================*/
EAPI Eina_Bool
eina_mmap_safety_enabled_set(Eina_Bool enabled)
{
#ifndef HAVE_SIGINFO_T
(void) enabled;
return EINA_FALSE;
#else
if (_eina_mmap_log_dom < 0)
{
_eina_mmap_log_dom = eina_log_domain_register("eina_mmap",
EINA_LOG_COLOR_DEFAULT);
if (_eina_mmap_log_dom < 0)
{
EINA_LOG_ERR("Could not register log domain: eina_mmap");
return EINA_FALSE;
}
}
enabled = !!enabled;
if (mmap_safe == enabled) return mmap_safe;
if (enabled)
{
struct sigaction sa;
/* find out system page size the cleanest way we can */
#ifdef _SC_PAGESIZE
_eina_mmap_pagesize = sysconf(_SC_PAGESIZE);
if (_eina_mmap_pagesize <= 0) return EINA_FALSE;
#else
_eina_mmap_pagesize = 4096;
#endif
/* no zero page device - open it */
if (_eina_mmap_zero_fd < 0)
{
_eina_mmap_zero_fd = open("/dev/zero", O_RDWR);
/* if we don;'t have one - fail to set up mmap safety */
if (_eina_mmap_zero_fd < 0) return EINA_FALSE;
}
/* set up signal handler for SIGBUS */
sa.sa_sigaction = _eina_mmap_safe_sigbus;
sa.sa_flags = SA_RESTART | SA_SIGINFO;
sigemptyset(&sa.sa_mask);
if (sigaction(SIGBUS, &sa, NULL) == 0) return EINA_FALSE;
/* setup of SIGBUS handler failed, lets close zero page dev and fail */
close(_eina_mmap_zero_fd);
_eina_mmap_zero_fd = -1;
return EINA_FALSE;
}
else
{
/* reset signal handler to default for SIGBUS */
signal(SIGBUS, SIG_DFL);
}
mmap_safe = enabled;
return mmap_safe;
#endif
}
EAPI Eina_Bool
eina_mmap_safety_enabled_get(void)
{
return mmap_safe;
}
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