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add eina mmap safety handling. 

SVN revision: 60976
This commit is contained in:
Carsten Haitzler 2011-07-04 09:29:59 +00:00
parent 015a2ca208
commit d926889559
6 changed files with 267 additions and 1 deletions
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4
legacy/eina/ChangeLog
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@ -114,3 +114,7 @@
2011-06-23 Cedric Bail
* Add Eina_LockRW.
2011-07-04 Carsten Haitzler (The Rasterman)
* Add eina_mmap safety handling.

3
legacy/eina/src/include/Makefile.am
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@ -57,7 +57,8 @@ eina_quadtree.h \
eina_simple_xml_parser.h \
eina_lock.h \
eina_prefix.h \
eina_refcount.h
eina_refcount.h \
eina_mmap.h
# Will be back for developper after 1.1.
# eina_object.h

59
legacy/eina/src/include/eina_mmap.h Normal file
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@ -0,0 +1,59 @@
#ifndef EINA_MMAP_H_
#define EINA_MMAP_H_
/**
* @addtogroup Eina_Mmap_Group Group
*
* @brief These functions provide helpers for safe mmap handling
*
* @{
*
* @since 1.1.0
*/
/**
* @brief Enable or disable safe mmaped IO handling
*
* @param enabled The enabled state (to enable, pass EINA_TRUE)
*
* This enables (if possible on your platform) a signal handler for
* SIGBUS, that replaces the "bad page" with a pzge of 0's (from /dev/zero)
* if a SIGBUS occurs. This allows for safe mmap() of files that may truncate
* or from files on devices with IO errors. Normally these cases will result
* in a SIGBUS being delivered (and termination of yyour process), but
* when "mmap safety" is enabled, this will not occur. Instead a page of
* bytes of the value 0 will replace the "bad page", allowing the process
* to continue and allow its own parsing error detection to safely abort
* the operation without the process falling apart.
*
* If you disable mmap safety, the SIGBUS handler will be restored to its
* default handler. Note that eina_file_map_all() and eina_file_map_new()
* will automatically enable mmap safety as they provide an mmaped file IO
* layer, and rely on mmap to not fail for any part of the file.
*
* If you set up your own SIGBUS handler, then this will effectively disable
* the safe mmap handling and make you liable to crashes on IO to or from
* such "damaged files" that would take down your process.
*
* @since 1.1.0
*/
EAPI Eina_Bool
eina_mmap_safety_enabled_set(Eina_Bool enabled);
/**
* @brief Get the enabled state of mmap safety.
*
* @return The safety state (EINA_TRUE if enabled)
*
* This returns the mmap safety state set by eina_mmap_safety_enabled_set().
* See eina_mmap_safety_enabled_set() for more information.
*
* @since 1.1.0
*/
EAPI Eina_Bool
eina_mmap_safety_enabled_get(void);
/**
* @}
*/
#endif

1
legacy/eina/src/lib/Makefile.am
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@ -31,6 +31,7 @@ eina_magic.c \
eina_main.c \
eina_matrixsparse.c \
eina_mempool.c \
eina_mmap.c \
eina_module.c \
eina_prefix.c \
eina_quadtree.c \

3
legacy/eina/src/lib/eina_file.c
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@ -65,6 +65,7 @@ void *alloca (size_t);
#include "eina_hash.h"
#include "eina_list.h"
#include "eina_lock.h"
#include "eina_mmap.h"
/*============================================================================*
* Local *
@ -867,6 +868,7 @@ eina_file_map_all(Eina_File *file, Eina_File_Populate rule)
if (file->length > EINA_HUGE_PAGE) flags |= MAP_HUGETLB;
#endif
eina_mmap_safety_enabled_set(EINA_TRUE);
eina_lock_take(&file->lock);
if (file->global_map == MAP_FAILED)
file->global_map = mmap(NULL, file->length, PROT_READ, flags, file->fd, 0);
@ -900,6 +902,7 @@ eina_file_map_new(Eina_File *file, Eina_File_Populate rule,
key[0] = offset;
key[1] = length;
eina_mmap_safety_enabled_set(EINA_TRUE);
eina_lock_take(&file->lock);
map = eina_hash_find(file->map, &key);

198
legacy/eina/src/lib/eina_mmap.c Normal file
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@ -0,0 +1,198 @@
/* 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 STDC_HEADERS
# include <stdlib.h>
# include <stddef.h>
#else
# ifdef HAVE_STDLIB_H
# include <stdlib.h>
# endif
#endif
#ifdef HAVE_ALLOCA_H
# include <alloca.h>
#elif defined __GNUC__
# define alloca __builtin_alloca
#elif defined _AIX
# define alloca __alloca
#elif defined _MSC_VER
# include <malloc.h>
# define alloca _alloca
#else
# ifndef HAVE_ALLOCA
# ifdef __cplusplus
extern "C"
# endif
void *alloca (size_t);
# 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>
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#ifdef HAVE_EVIL
# include <Evil.h>
#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;
#ifndef _WIN32
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)
{
#ifdef _WIN32
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;
}