Mercurial > gnulib
view lib/c-stack.c @ 10230:54813304edd2
Use sigaction module rather than signal().
* modules/c-stack (Depends-on): Add sigaction.
* modules/fatal-signal (Depends-on): Likewise.
* modules/nanosleep (Depends-on): Likewise.
* modules/sigprocmask (Files): Add sig-handler.h.
* modules/sigaction (Files): Likewise.
* lib/sig-handler.h (get_handler): New file, suggested by Paul
Eggert.
* lib/c-stack.c (SIGACTION_WORKS): Simplify conditions.
(c_stack_action) [!SIGACTION_WORKS]: Use sigaction, not signal.
* lib/fatal-signal.c (uninstall_handlers, install_handlers)
(init_fatal_signals): Likewise.
* lib/nanosleep.c (rpl_nanosleep): Likewise.
(siginterrupt): Delete fallback.
* lib/sigprocmask.c (handler_t): Delete.
(old_handlers): Use sa_handler_t instead.
* m4/nanosleep.m4 (gl_PREREQ_NANOSLEEP): Drop check for
siginterrupt.
Signed-off-by: Eric Blake <ebb9@byu.net>
author | Eric Blake <ebb9@byu.net> |
---|---|
date | Sat, 21 Jun 2008 07:08:49 -0600 |
parents | 6fcac230dda4 |
children | adfc5a204195 |
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/* Stack overflow handling. Copyright (C) 2002, 2004, 2006, 2008 Free Software Foundation, Inc. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program 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 General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ /* Written by Paul Eggert. */ /* NOTES: A program that uses alloca, dynamic arrays, or large local variables may extend the stack by more than a page at a time. If so, when the stack overflows the operating system may not detect the overflow until the program uses the array, and this module may incorrectly report a program error instead of a stack overflow. To avoid this problem, allocate only small objects on the stack; a program should be OK if it limits single allocations to a page or less. Allocate larger arrays in static storage, or on the heap (e.g., with malloc). Yes, this is a pain, but we don't know of any better solution that is portable. No attempt has been made to deal with multithreaded applications. */ #include <config.h> #ifndef __attribute__ # if __GNUC__ < 3 # define __attribute__(x) # endif #endif #include "gettext.h" #define _(msgid) gettext (msgid) #include <errno.h> #ifndef ENOTSUP # define ENOTSUP EINVAL #endif #include <signal.h> #if ! HAVE_STACK_T && ! defined stack_t typedef struct sigaltstack stack_t; #endif #include <stdlib.h> #include <string.h> /* Posix 2001 declares ucontext_t in <ucontext.h>, Posix 200x in <signal.h>. */ #if HAVE_UCONTEXT_H # include <ucontext.h> #endif #include <unistd.h> #ifndef STDERR_FILENO # define STDERR_FILENO 2 #endif #include "c-stack.h" #include "exitfail.h" #if defined SA_ONSTACK && defined SA_SIGINFO # define SIGACTION_WORKS 1 #else # define SIGACTION_WORKS 0 #endif extern char *program_name; /* The user-specified action to take when a SEGV-related program error or stack overflow occurs. */ static void (* volatile segv_action) (int); /* Translated messages for program errors and stack overflow. Do not translate them in the signal handler, since gettext is not async-signal-safe. */ static char const * volatile program_error_message; static char const * volatile stack_overflow_message; /* Output an error message, then exit with status EXIT_FAILURE if it appears to have been a stack overflow, or with a core dump otherwise. This function is async-signal-safe. */ static void die (int) __attribute__ ((noreturn)); static void die (int signo) { char const *message; segv_action (signo); message = signo ? program_error_message : stack_overflow_message; write (STDERR_FILENO, program_name, strlen (program_name)); write (STDERR_FILENO, ": ", 2); write (STDERR_FILENO, message, strlen (message)); write (STDERR_FILENO, "\n", 1); if (! signo) _exit (exit_failure); raise (signo); abort (); } #if HAVE_SIGALTSTACK && HAVE_DECL_SIGALTSTACK /* Direction of the C runtime stack. This function is async-signal-safe. */ # if STACK_DIRECTION # define find_stack_direction(ptr) STACK_DIRECTION # else static int find_stack_direction (char const *addr) { char dummy; return ! addr ? find_stack_direction (&dummy) : addr < &dummy ? 1 : -1; } # endif /* Storage for the alternate signal stack. */ static union { char buffer[SIGSTKSZ]; /* These other members are for proper alignment. There's no standard way to guarantee stack alignment, but this seems enough in practice. */ long double ld; long l; void *p; } alternate_signal_stack; # if SIGACTION_WORKS /* Handle a segmentation violation and exit. This function is async-signal-safe. */ static void segv_handler (int, siginfo_t *, void *) __attribute__((noreturn)); static void segv_handler (int signo, siginfo_t *info, void *context __attribute__ ((unused))) { /* Clear SIGNO if it seems to have been a stack overflow. */ if (0 < info->si_code) { # if ! HAVE_XSI_STACK_OVERFLOW_HEURISTIC /* We can't easily determine whether it is a stack overflow; so assume that the rest of our program is perfect (!) and that this segmentation violation is a stack overflow. */ signo = 0; # else /* If the faulting address is within the stack, or within one page of the stack end, assume that it is a stack overflow. */ ucontext_t const *user_context = context; char const *stack_base = user_context->uc_stack.ss_sp; size_t stack_size = user_context->uc_stack.ss_size; char const *faulting_address = info->si_addr; size_t s = faulting_address - stack_base; size_t page_size = sysconf (_SC_PAGESIZE); if (find_stack_direction (NULL) < 0) s += page_size; if (s < stack_size + page_size) signo = 0; # if DEBUG { char buf[1024]; sprintf (buf, "segv_handler fault=%p base=%p size=%lx page=%lx signo=%d\n", faulting_address, stack_base, (unsigned long) stack_size, (unsigned long) page_size, signo); write (STDERR_FILENO, buf, strlen (buf)); } # endif # endif } die (signo); } # endif static void null_action (int signo __attribute__ ((unused))) { } /* Set up ACTION so that it is invoked on C stack overflow. Return -1 (setting errno) if this cannot be done. When ACTION is called, it is passed an argument equal to SIGSEGV for a segmentation violation that does not appear related to stack overflow, and is passed zero otherwise. On many platforms it is hard to tell; when in doubt, zero is passed. A null ACTION acts like an action that does nothing. ACTION must be async-signal-safe. ACTION together with its callees must not require more than SIGSTKSZ bytes of stack space. */ int c_stack_action (void (*action) (int)) { int r; stack_t st; struct sigaction act; st.ss_flags = 0; st.ss_sp = alternate_signal_stack.buffer; st.ss_size = sizeof alternate_signal_stack.buffer; r = sigaltstack (&st, NULL); if (r != 0) return r; segv_action = action ? action : null_action; program_error_message = _("program error"); stack_overflow_message = _("stack overflow"); sigemptyset (&act.sa_mask); # if SIGACTION_WORKS /* POSIX 1003.1-2001 says SA_RESETHAND implies SA_NODEFER, but this is not true on Solaris 8 at least. It doesn't hurt to use SA_NODEFER here, so leave it in. */ act.sa_flags = SA_NODEFER | SA_ONSTACK | SA_RESETHAND | SA_SIGINFO; act.sa_sigaction = segv_handler; # else act.sa_flags = SA_NODEFER | SA_RESETHAND; act.sa_handler = die; # endif return sigaction (SIGSEGV, &act, NULL); } #else /* ! (HAVE_SIGALTSTACK && HAVE_DECL_SIGALTSTACK) */ int c_stack_action (void (*action) (int) __attribute__ ((unused))) { errno = ENOTSUP; return -1; } #endif