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Diffstat (limited to 'REORG.TODO/debug/segfault.c')
| -rw-r--r-- | REORG.TODO/debug/segfault.c | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/REORG.TODO/debug/segfault.c b/REORG.TODO/debug/segfault.c new file mode 100644 index 0000000000..78c1cf5d1d --- /dev/null +++ b/REORG.TODO/debug/segfault.c @@ -0,0 +1,210 @@ +/* Catch segmentation faults and print backtrace. + Copyright (C) 1998-2017 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, see + <http://www.gnu.org/licenses/>. */ + +#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 <_itoa.h> +#include <ldsodefs.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 this 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 unstable 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); + stack_t 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); + } +} |