diff options
Diffstat (limited to 'sysdeps/generic/segfault.c')
| -rw-r--r-- | sysdeps/generic/segfault.c | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/sysdeps/generic/segfault.c b/sysdeps/generic/segfault.c new file mode 100644 index 0000000000..868ff1dfd7 --- /dev/null +++ b/sysdeps/generic/segfault.c @@ -0,0 +1,165 @@ +/* Catch segmentation faults and print backtrace. + Copyright (C) 1998 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 Library General Public License as + published by the Free Software Foundation; either version 2 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 + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +#include <execinfo.h> +#include <fcntl.h> +#include <signal.h> +#include <stdlib.h> +#include <unistd.h> + +/* This file defines macros to access the content of the sigcontext element + passed up by the signal handler. */ +#include <sigcontextinfo.h> + +/* This is a global variable set at program start time. It marks the + highest used stack address. */ +extern void *__libc_stack_end; + + +/* This implementation assumes a stack layout that matches the defaults + used by gcc's `__builtin_frame_address' and `__builtin_return_address' + (FP is the frame pointer register): + + +-----------------+ +-----------------+ + FP -> | previous FP --------> | previous FP ------>... + | | | | + | return address | | return address | + +-----------------+ +-----------------+ + + */ + +/* Get some notion of the current stack. Need not be exactly the top + of the stack, just something somewhere in the current frame. */ +#ifndef CURRENT_STACK_FRAME +# define CURRENT_STACK_FRAME ({ char __csf; &__csf; }) +#endif + +/* By default we assume that the stack grows downward. */ +#ifndef INNER_THAN +# define INNER_THAN < +#endif + +struct layout +{ + struct layout *next; + void *return_address; +}; + + +static void +handle (int fd, void *addr) +{ +} + + +/* 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) +{ + struct layout *current; + void *top_frame; + void *top_stack; + const char *fname; + int fd; + void **arr; + size_t cnt; + + /* 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; + fname = getenv ("SEGFAULT_OUTPUT_NAME"); + if (fname != NULL && fname[0] != '\0') + { + fd = open (fname, O_TRUNC | O_WRONLY | O_CREAT); + if (fd == -1) + fd = 2; + } + +#define WRITE_STRING(s) write (fd, s, sizeof (s) - 1) + WRITE_STRING ("*** Segmentation Fault\n"); + WRITE_STRING ("Backtrace:\n"); + + top_frame = GET_FRAME (ctx); + top_stack = GET_STACK (ctx); + + /* First count how many entries we'll have. */ + cnt = 1; + current = (struct layout *) top_frame; + while (!((void *) current INNER_THAN top_stack + || !((void *) current INNER_THAN __libc_stack_end))) + { + ++cnt; + + current = current->next; + } + + arr = alloca (cnt * sizeof (void *)); + + /* First handle the program counter from the structure. */ + arr[0] = GET_EIP (ctx); + + current = (struct layout *) top_frame; + cnt = 1; + while (!((void *) current INNER_THAN top_stack + || !((void *) current INNER_THAN __libc_stack_end))) + { + arr[cnt++] = current->return_address; + + current = current->next; + } + + /* Now generate nicely formatted output. */ + __backtrace_symbols_fd (arr, cnt, fd); + + /* Nothing else to do. */ + _exit (128 + SIGSEGV); +} + + +static void +__attribute__ ((constructor)) +install_handler (void) +{ + struct sigaction sa; + + sa.sa_handler = (void *) catch_segfault; + sigemptyset (&sa.sa_mask); + sa.sa_flags = SA_RESTART; + + sigaction (SIGSEGV, &sa, NULL); + + /* 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 = SS_ONSTACK; + ss.ss_size = 2 * SIGSTKSZ; + + sigaltstack (&ss, NULL); + } + } +} |