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authorJakub Jelinek <jakub@redhat.com>2007-07-12 18:26:36 +0000
committerJakub Jelinek <jakub@redhat.com>2007-07-12 18:26:36 +0000
commit0ecb606cb6cf65de1d9fc8a919bceb4be476c602 (patch)
tree2ea1f8305970753e4a657acb2ccc15ca3eec8e2c /debug/segfault.c
parent7d58530341304d403a6626d7f7a1913165fe2f32 (diff)
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2.5-18.1
Diffstat (limited to 'debug/segfault.c')
-rw-r--r--debug/segfault.c214
1 files changed, 214 insertions, 0 deletions
diff --git a/debug/segfault.c b/debug/segfault.c
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+++ b/debug/segfault.c
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+/* Catch segmentation faults and print backtrace.
+ Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004
+ Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
+
+ The GNU C 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.
+
+ The GNU C 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 the GNU C Library; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <alloca.h>
+#include <ctype.h>
+#include <errno.h>
+#include <execinfo.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdio-common/_itoa.h>
+#include <ldsodefs.h>
+
+#include <bp-checks.h>
+
+/* This file defines macros to access the content of the sigcontext element
+ passed up by the signal handler. */
+#include <sigcontextinfo.h>
+
+/* Get code to possibly dump the content of all registers. */
+#include <register-dump.h>
+
+/* We'll use tis a lot. */
+#define WRITE_STRING(s) write (fd, s, strlen (s))
+
+/* Name of the output file. */
+static const char *fname;
+
+
+/* We better should not use `strerror' since it can call far too many
+ other functions which might fail. Do it here ourselves. */
+static void
+write_strsignal (int fd, int signal)
+{
+ if (signal < 0 || signal >= _NSIG || _sys_siglist[signal] == NULL)
+ {
+ char buf[30];
+ char *ptr = _itoa_word (signal, &buf[sizeof (buf)], 10, 0);
+ WRITE_STRING ("signal ");
+ write (fd, buf, &buf[sizeof (buf)] - ptr);
+ }
+ else
+ WRITE_STRING (_sys_siglist[signal]);
+}
+
+
+/* This function is called when a segmentation fault is caught. The system
+ is in an instable state now. This means especially that malloc() might
+ not work anymore. */
+static void
+catch_segfault (int signal, SIGCONTEXT ctx)
+{
+ int fd, cnt, i;
+ void **arr;
+ struct sigaction sa;
+ uintptr_t pc;
+
+ /* This is the name of the file we are writing to. If none is given
+ or we cannot write to this file write to stderr. */
+ fd = 2;
+ if (fname != NULL)
+ {
+ fd = open (fname, O_TRUNC | O_WRONLY | O_CREAT, 0666);
+ if (fd == -1)
+ fd = 2;
+ }
+
+ WRITE_STRING ("*** ");
+ write_strsignal (fd, signal);
+ WRITE_STRING ("\n");
+
+#ifdef REGISTER_DUMP
+ REGISTER_DUMP;
+#endif
+
+ WRITE_STRING ("\nBacktrace:\n");
+
+ /* Get the backtrace. */
+ arr = alloca (256 * sizeof (void *));
+ cnt = backtrace (arr, 256);
+
+ /* Now try to locate the PC from signal context in the backtrace.
+ Normally it will be found at arr[2], but it might appear later
+ if there were some signal handler wrappers. Allow a few bytes
+ difference to cope with as many arches as possible. */
+ pc = (uintptr_t) GET_PC (ctx);
+ for (i = 0; i < cnt; ++i)
+ if ((uintptr_t) arr[i] >= pc - 16 && (uintptr_t) arr[i] <= pc + 16)
+ break;
+
+ /* If we haven't found it, better dump full backtrace even including
+ the signal handler frames instead of not dumping anything. */
+ if (i == cnt)
+ i = 0;
+
+ /* Now generate nicely formatted output. */
+ __backtrace_symbols_fd (arr + i, cnt - i, fd);
+
+#ifdef HAVE_PROC_SELF
+ /* Now the link map. */
+ int mapfd = open ("/proc/self/maps", O_RDONLY);
+ if (mapfd != -1)
+ {
+ write (fd, "\nMemory map:\n\n", 14);
+
+ char buf[256];
+ ssize_t n;
+
+ while ((n = TEMP_FAILURE_RETRY (read (mapfd, buf, sizeof (buf)))) > 0)
+ TEMP_FAILURE_RETRY (write (fd, buf, n));
+
+ close (mapfd);
+ }
+#endif
+
+ /* Pass on the signal (so that a core file is produced). */
+ sa.sa_handler = SIG_DFL;
+ sigemptyset (&sa.sa_mask);
+ sa.sa_flags = 0;
+ sigaction (signal, &sa, NULL);
+ raise (signal);
+}
+
+
+static void
+__attribute__ ((constructor))
+install_handler (void)
+{
+ struct sigaction sa;
+ const char *sigs = getenv ("SEGFAULT_SIGNALS");
+ const char *name;
+
+ sa.sa_handler = (void *) catch_segfault;
+ sigemptyset (&sa.sa_mask);
+ sa.sa_flags = SA_RESTART;
+
+ /* Maybe we are expected to use an alternative stack. */
+ if (getenv ("SEGFAULT_USE_ALTSTACK") != 0)
+ {
+ void *stack_mem = malloc (2 * SIGSTKSZ);
+ struct sigaltstack ss;
+
+ if (stack_mem != NULL)
+ {
+ ss.ss_sp = stack_mem;
+ ss.ss_flags = 0;
+ ss.ss_size = 2 * SIGSTKSZ;
+
+ if (sigaltstack (&ss, NULL) == 0)
+ sa.sa_flags |= SA_ONSTACK;
+ }
+ }
+
+ if (sigs == NULL)
+ sigaction (SIGSEGV, &sa, NULL);
+ else if (sigs[0] == '\0')
+ /* Do not do anything. */
+ return;
+ else
+ {
+ const char *where;
+ int all = __strcasecmp (sigs, "all") == 0;
+
+#define INSTALL_FOR_SIG(sig, name) \
+ where = __strcasestr (sigs, name); \
+ if (all || (where != NULL \
+ && (where == sigs || !isalnum (where[-1])) \
+ && !isalnum (where[sizeof (name) - 1]))) \
+ sigaction (sig, &sa, NULL);
+
+ INSTALL_FOR_SIG (SIGSEGV, "segv");
+ INSTALL_FOR_SIG (SIGILL, "ill");
+#ifdef SIGBUS
+ INSTALL_FOR_SIG (SIGBUS, "bus");
+#endif
+#ifdef SIGSTKFLT
+ INSTALL_FOR_SIG (SIGSTKFLT, "stkflt");
+#endif
+ INSTALL_FOR_SIG (SIGABRT, "abrt");
+ INSTALL_FOR_SIG (SIGFPE, "fpe");
+ }
+
+ /* Preserve the output file name if there is any given. */
+ name = getenv ("SEGFAULT_OUTPUT_NAME");
+ if (name != NULL && name[0] != '\0')
+ {
+ int ret = access (name, R_OK | W_OK);
+
+ if (ret == 0 || (ret == -1 && errno == ENOENT))
+ fname = __strdup (name);
+ }
+}