+++ /dev/null
-/* Stack overflow handling.
-
- Copyright (C) 2002 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 2, 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, write to the Free Software Foundation,
- Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
-
-/* 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.
-
- If ! HAVE_XSI_STACK_OVERFLOW_HEURISTIC, the current implementation
- assumes that, if the RLIMIT_STACK limit changes during execution,
- then c_stack_action is invoked immediately afterwards. */
-
-#if HAVE_CONFIG_H
-# include <config.h>
-#endif
-
-#ifndef __attribute__
-# if __GNUC__ < 3 || __STRICT_ANSI__
-# define __attribute__(x)
-# endif
-#endif
-
-#include "gettext.h"
-#define _(msgid) gettext (msgid)
-
-#include <errno.h>
-#ifndef ENOTSUP
-# define ENOTSUP EINVAL
-#endif
-#ifndef EOVERFLOW
-# define EOVERFLOW EINVAL
-#endif
-
-#include <signal.h>
-#if ! HAVE_STACK_T && ! defined stack_t
-typedef struct sigaltstack stack_t;
-#endif
-
-#include <stdlib.h>
-#include <string.h>
-
-#if HAVE_SYS_RESOURCE_H
-/* Include sys/time.h here, because...
- SunOS-4.1.x <sys/resource.h> fails to include <sys/time.h>.
- This gives "incomplete type" errors for ru_utime and tu_stime. */
-# if HAVE_SYS_TIME_H
-# include <sys/time.h>
-# endif
-# include <sys/resource.h>
-#endif
-
-#if HAVE_UCONTEXT_H
-# include <ucontext.h>
-#endif
-
-#if HAVE_UNISTD_H
-# include <unistd.h>
-#endif
-#ifndef STDERR_FILENO
-# define STDERR_FILENO 2
-#endif
-
-#if DEBUG
-# include <stdio.h>
-#endif
-
-#include "c-stack.h"
-#include "exitfail.h"
-
-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 =
- signo ? program_error_message : stack_overflow_message;
- segv_action (signo);
- 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);
- kill (getpid (), 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
-
-# if HAVE_XSI_STACK_OVERFLOW_HEURISTIC
-# define get_stack_location(argv) 0
-# else
-
-# if defined RLIMIT_STACK && defined _SC_PAGESIZE
-
-/* Return the minimum machine address deducible from ARGV. This
- includes the addresses of all the strings that ARGV points at, as
- well as the address of ARGV itself. */
-
-static char const *
-min_address_from_argv (char * const *argv)
-{
- char const *min = (char const *) argv;
- char const *p;
- while ((p = *argv++))
- if (p < min)
- min = p;
- return min;
-}
-
-/* Return the maximum machine address deducible from ARGV. */
-
-static char const *
-max_address_from_argv (char * const *argv)
-{
- char const *max = *argv;
- char const *max1;
- char const *p;
- while ((p = *argv++))
- if (max < p)
- max = p;
- max1 = (char const *) (argv + 1);
- return max && max1 < max ? max + strlen (max) + 1 : max1;
-}
-# endif
-
-/* The base and size of the stack, determined at startup. */
-static char const * volatile stack_base;
-static size_t volatile stack_size;
-
-/* Store the base and size of the stack into the static variables
- STACK_BASE and STACK_SIZE. The base is the numerically lowest
- address in the stack. Return -1 (setting errno) if this cannot be
- done. */
-
-static int
-get_stack_location (char * const *argv)
-{
-# if ! (defined RLIMIT_STACK && defined _SC_PAGESIZE)
-
- errno = ENOTSUP;
- return -1;
-
-# else
-
- struct rlimit rlimit;
- int r = getrlimit (RLIMIT_STACK, &rlimit);
- if (r == 0)
- {
- char const *base;
- size_t size = rlimit.rlim_cur;
- extern char **environ;
- size_t page_size = sysconf (_SC_PAGESIZE);
- int stack_direction = find_stack_direction (0);
-
-# if HAVE_GETCONTEXT && HAVE_DECL_GETCONTEXT
- ucontext_t context;
- if (getcontext (&context) == 0)
- {
- base = context.uc_stack.ss_sp;
- if (stack_direction < 0)
- base -= size - context.uc_stack.ss_size;
- }
- else
-# endif
- {
- if (stack_direction < 0)
- {
- char const *a = max_address_from_argv (argv);
- char const *b = max_address_from_argv (environ);
- base = (a < b ? b : a) - size;
- base += - (size_t) base % page_size;
- }
- else
- {
- char const *a = min_address_from_argv (argv);
- char const *b = min_address_from_argv (environ);
- base = a < b ? a : b;
- base -= (size_t) base % page_size;
- }
- }
-
- if (size != rlimit.rlim_cur
- || rlimit.rlim_cur < 0
- || base + size < base
-# ifdef RLIM_SAVED_CUR
- || rlimit.rlim_cur == RLIM_SAVED_CUR
-# endif
-# ifdef RLIM_SAVED_MAX
- || rlimit.rlim_cur == RLIM_SAVED_MAX
-# endif
-# ifdef RLIM_INFINITY
- || rlimit.rlim_cur == RLIM_INFINITY
-# endif
- )
- {
- errno = EOVERFLOW;
- return -1;
- }
-
- stack_base = base;
- stack_size = size;
-
-# if DEBUG
- fprintf (stderr, "get_stack_location base=%p size=%lx\n",
- base, (unsigned long) size);
-# endif
- }
-
- return r;
-
-# endif
-}
-# 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 defined SA_ONSTACK && defined SA_SIGINFO && defined _SC_PAGESIZE
-
-/* 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 the faulting address is within the stack, or within one
- page of the stack end, assume that it is a stack
- overflow. */
-# if HAVE_XSI_STACK_OVERFLOW_HEURISTIC
- 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;
-# endif
- 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 (0) < 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
- }
-
- die (signo);
-}
-# endif
-
-static void
-null_action (int signo __attribute__ ((unused)))
-{
-}
-
-/* Assuming ARGV is the argument vector of `main', 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.
-
- 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 (char * const *argv __attribute__ ((unused)),
- void (*action) (int))
-{
- int r = get_stack_location (argv);
- if (r != 0)
- return r;
-
- {
- stack_t st;
- st.ss_flags = 0;
- st.ss_sp = alternate_signal_stack.buffer;
- st.ss_size = sizeof alternate_signal_stack.buffer;
- r = sigaltstack (&st, 0);
- if (r != 0)
- return r;
- }
-
- segv_action = action ? action : null_action;
- program_error_message = _("program error");
- stack_overflow_message = _("stack overflow");
-
- {
-# if ! (defined SA_ONSTACK && defined SA_SIGINFO && defined _SC_PAGESIZE)
- return signal (SIGSEGV, die) == SIG_ERR ? -1 : 0;
-# else
- struct sigaction act;
- sigemptyset (&act.sa_mask);
-
- /* 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;
-
- return sigaction (SIGSEGV, &act, 0);
-# endif
- }
-}
-
-#else /* ! (HAVE_SIGALTSTACK && HAVE_DECL_SIGALTSTACK) */
-
-int
-c_stack_action (char * const *argv __attribute__ ((unused)),
- void (*action) (int) __attribute__ ((unused)))
-{
- errno = ENOTSUP;
- return -1;
-}
-
-#endif
-
-\f
-
-#if DEBUG
-
-int volatile exit_failure;
-
-static long
-recurse (char *p)
-{
- char array[500];
- array[0] = 1;
- return *p + recurse (array);
-}
-
-char *program_name;
-
-int
-main (int argc __attribute__ ((unused)), char **argv)
-{
- program_name = argv[0];
- fprintf (stderr, "The last line of output should be \"stack overflow\".\n");
- if (c_stack_action (argv, 0) == 0)
- return recurse ("\1");
- perror ("c_stack_action");
- return 1;
-}
-
-#endif /* DEBUG */
-\f
-/*
-Local Variables:
-compile-command: "gcc -DDEBUG -DHAVE_CONFIG_H -I.. -g -O -Wall -W c-stack.c"
-End:
-*/
projects / platform / upstream / coreutils.git / commitdiff