--- /dev/null
+#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
--- /dev/null
+/* 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;
+}
projects / framework / uifw / eina.git / commitdiff