# Check prerequisites for compiling lib/c-stack.c.
-# Copyright (C) 2002-2004, 2008-2011 Free Software Foundation, Inc.
+# Copyright (C) 2002-2004, 2008-2021 Free Software Foundation, Inc.
# This file is free software; the Free Software Foundation
# gives unlimited permission to copy and/or distribute it,
# with or without modifications, as long as this notice is preserved.
# Written by Paul Eggert.
-# serial 12
-
-AC_DEFUN([AC_SYS_XSI_STACK_OVERFLOW_HEURISTIC],
- [# for STACK_DIRECTION
- AC_REQUIRE([AC_FUNC_ALLOCA])
- AC_REQUIRE([AC_CANONICAL_HOST])
- AC_CHECK_FUNCS_ONCE([setrlimit])
- AC_CHECK_HEADERS_ONCE([ucontext.h])
-
- dnl List of signals that are sent when an invalid virtual memory address
- dnl is accessed, or when the stack overflows.
- dnl Either { SIGSEGV } or { SIGSEGV, SIGBUS }.
- case "$host_os" in
- sunos4* | freebsd* | dragonfly* | openbsd* | mirbsd* | netbsd* | kfreebsd* | knetbsd*) # BSD systems
- FAULT_YIELDS_SIGBUS=1 ;;
- hpux*) # HP-UX
- FAULT_YIELDS_SIGBUS=1 ;;
- macos* | darwin*) # MacOS X
- FAULT_YIELDS_SIGBUS=1 ;;
- gnu*) # Hurd
- FAULT_YIELDS_SIGBUS=1 ;;
- *)
- FAULT_YIELDS_SIGBUS=0 ;;
- esac
- AC_DEFINE_UNQUOTED([FAULT_YIELDS_SIGBUS], [$FAULT_YIELDS_SIGBUS],
- [Define to 1 if an invalid memory address access may yield a SIGBUS.])
-
- AC_CACHE_CHECK([for working C stack overflow detection],
- [ac_cv_sys_stack_overflow_works],
- [AC_RUN_IFELSE([AC_LANG_SOURCE(
- [[
- #include <unistd.h>
- #include <signal.h>
- #if HAVE_SETRLIMIT
- # include <sys/types.h>
- # include <sys/time.h>
- # include <sys/resource.h>
- #endif
- #ifndef SIGSTKSZ
- # define SIGSTKSZ 16384
- #endif
-
- static union
- {
- char buffer[2 * SIGSTKSZ];
- long double ld;
- long u;
- void *p;
- } alternate_signal_stack;
-
- static void
- segv_handler (int signo)
- {
- _exit (0);
- }
-
- static int
- c_stack_action ()
- {
- stack_t st;
- struct sigaction act;
- int r;
-
- st.ss_flags = 0;
- /* Use the midpoint to avoid Irix sigaltstack bug. */
- st.ss_sp = alternate_signal_stack.buffer + SIGSTKSZ;
- st.ss_size = SIGSTKSZ;
- r = sigaltstack (&st, 0);
- if (r != 0)
- return 1;
-
- sigemptyset (&act.sa_mask);
- act.sa_flags = SA_NODEFER | SA_ONSTACK | SA_RESETHAND;
- act.sa_handler = segv_handler;
- #if FAULT_YIELDS_SIGBUS
- if (sigaction (SIGBUS, &act, 0) < 0)
- return 2;
- #endif
- if (sigaction (SIGSEGV, &act, 0) < 0)
- return 3;
- return 0;
- }
- static volatile int *
- recurse_1 (volatile int n, volatile int *p)
- {
- if (n >= 0)
- *recurse_1 (n + 1, p) += n;
- return p;
- }
- static int
- recurse (volatile int n)
- {
- int sum = 0;
- return *recurse_1 (n, &sum);
- }
- int
- main ()
- {
- int result;
- #if HAVE_SETRLIMIT && defined RLIMIT_STACK
- /* Before starting the endless recursion, try to be friendly
- to the user's machine. On some Linux 2.2.x systems, there
- is no stack limit for user processes at all. We don't want
- to kill such systems. */
- struct rlimit rl;
- rl.rlim_cur = rl.rlim_max = 0x100000; /* 1 MB */
- setrlimit (RLIMIT_STACK, &rl);
- #endif
-
- result = c_stack_action ();
- if (result != 0)
- return result;
- return recurse (0);
- }
- ]])],
- [ac_cv_sys_stack_overflow_works=yes],
- [ac_cv_sys_stack_overflow_works=no],
- [ac_cv_sys_stack_overflow_works=cross-compiling])])
-
- if test $ac_cv_sys_stack_overflow_works = yes; then
- AC_DEFINE([HAVE_STACK_OVERFLOW_HANDLING], [1],
- [Define to 1 if extending the stack slightly past the limit causes
- a SIGSEGV which can be handled on an alternate stack established
- with sigaltstack.])
-
- dnl The ss_sp field of a stack_t is, according to POSIX, the lowest address
- dnl of the memory block designated as an alternate stack. But IRIX 5.3
- dnl interprets it as the highest address!
- AC_CACHE_CHECK([for correct stack_t interpretation],
- [gl_cv_sigaltstack_low_base], [
- AC_RUN_IFELSE([
- AC_LANG_SOURCE([[
-#include <stdlib.h>
-#include <signal.h>
-#if HAVE_SYS_SIGNAL_H
-# include <sys/signal.h>
-#endif
-#ifndef SIGSTKSZ
-# define SIGSTKSZ 16384
-#endif
-volatile char *stack_lower_bound;
-volatile char *stack_upper_bound;
-static void check_stack_location (volatile char *addr)
-{
- if (addr >= stack_lower_bound && addr <= stack_upper_bound)
- exit (0);
- else
- exit (1);
-}
-static void stackoverflow_handler (int sig)
-{
- char dummy;
- check_stack_location (&dummy);
-}
-int main ()
-{
- char mystack[2 * SIGSTKSZ];
- stack_t altstack;
- struct sigaction action;
- /* Install the alternate stack. */
- altstack.ss_sp = mystack + SIGSTKSZ;
- altstack.ss_size = SIGSTKSZ;
- stack_lower_bound = (char *) altstack.ss_sp;
- stack_upper_bound = (char *) altstack.ss_sp + altstack.ss_size - 1;
- altstack.ss_flags = 0; /* no SS_DISABLE */
- if (sigaltstack (&altstack, NULL) < 0)
- exit (2);
- /* Install the SIGSEGV handler. */
- sigemptyset (&action.sa_mask);
- action.sa_handler = &stackoverflow_handler;
- action.sa_flags = SA_ONSTACK;
- if (sigaction (SIGSEGV, &action, (struct sigaction *) NULL) < 0)
- exit(3);
- /* Provoke a SIGSEGV. */
- raise (SIGSEGV);
- exit (4);
-}]])],
- [gl_cv_sigaltstack_low_base=yes],
- [gl_cv_sigaltstack_low_base=no],
- [gl_cv_sigaltstack_low_base=cross-compiling])])
- if test "$gl_cv_sigaltstack_low_base" = no; then
- AC_DEFINE([SIGALTSTACK_SS_REVERSED], [1],
- [Define if sigaltstack() interprets the stack_t.ss_sp field
- incorrectly, as the highest address of the alternate stack range
- rather than as the lowest address.])
- fi
-
- AC_CACHE_CHECK([for precise C stack overflow detection],
- ac_cv_sys_xsi_stack_overflow_heuristic,
- [AC_RUN_IFELSE([AC_LANG_SOURCE(
- [[
- #include <unistd.h>
- #include <signal.h>
- #if HAVE_UCONTEXT_H
- # include <ucontext.h>
- #endif
- #if HAVE_SETRLIMIT
- # include <sys/types.h>
- # include <sys/time.h>
- # include <sys/resource.h>
- #endif
- #ifndef SIGSTKSZ
- # define SIGSTKSZ 16384
- #endif
-
- static union
- {
- char buffer[2 * SIGSTKSZ];
- long double ld;
- long u;
- void *p;
- } alternate_signal_stack;
-
- #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
-
- static void
- segv_handler (int signo, siginfo_t *info, void *context)
- {
- if (0 < info->si_code)
- {
- /* For XSI heuristics to work, we need uc_stack to describe
- the interrupted stack (as on Solaris), and not the
- currently executing stack (as on Linux). */
- ucontext_t const *user_context = context;
- char const *stack_min = 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_min;
- size_t page_size = sysconf (_SC_PAGESIZE);
- if (find_stack_direction (0) < 0)
- s += page_size;
- if (s < stack_size + page_size)
- _exit (0);
- _exit (4);
- }
- _exit (5);
- }
-
- static int
- c_stack_action ()
- {
- stack_t st;
- struct sigaction act;
- int r;
-
- st.ss_flags = 0;
- /* Use the midpoint to avoid Irix sigaltstack bug. */
- st.ss_sp = alternate_signal_stack.buffer + SIGSTKSZ;
- st.ss_size = SIGSTKSZ;
- r = sigaltstack (&st, 0);
- if (r != 0)
- return 1;
-
- sigemptyset (&act.sa_mask);
- act.sa_flags = SA_NODEFER | SA_ONSTACK | SA_RESETHAND | SA_SIGINFO;
- act.sa_sigaction = segv_handler;
- #if FAULT_YIELDS_SIGBUS
- if (sigaction (SIGBUS, &act, 0) < 0)
- return 2;
- #endif
- if (sigaction (SIGSEGV, &act, 0) < 0)
- return 3;
- return 0;
- }
- static volatile int *
- recurse_1 (volatile int n, volatile int *p)
- {
- if (n >= 0)
- *recurse_1 (n + 1, p) += n;
- return p;
- }
- static int
- recurse (volatile int n)
- {
- int sum = 0;
- return *recurse_1 (n, &sum);
- }
- int
- main ()
- {
- int result;
- #if HAVE_SETRLIMIT && defined RLIMIT_STACK
- /* Before starting the endless recursion, try to be friendly
- to the user's machine. On some Linux 2.2.x systems, there
- is no stack limit for user processes at all. We don't want
- to kill such systems. */
- struct rlimit rl;
- rl.rlim_cur = rl.rlim_max = 0x100000; /* 1 MB */
- setrlimit (RLIMIT_STACK, &rl);
- #endif
-
- result = c_stack_action ();
- if (result != 0)
- return result;
- return recurse (0);
- }
- ]])],
- [ac_cv_sys_xsi_stack_overflow_heuristic=yes],
- [ac_cv_sys_xsi_stack_overflow_heuristic=no],
- [ac_cv_sys_xsi_stack_overflow_heuristic=cross-compiling])])
-
- if test $ac_cv_sys_xsi_stack_overflow_heuristic = yes; then
- AC_DEFINE([HAVE_XSI_STACK_OVERFLOW_HEURISTIC], [1],
- [Define to 1 if extending the stack slightly past the limit causes
- a SIGSEGV, and an alternate stack can be established with sigaltstack,
- and the signal handler is passed a context that specifies the
- run time stack. This behavior is defined by POSIX 1003.1-2001
- with the X/Open System Interface (XSI) option
- and is a standardized way to implement a SEGV-based stack
- overflow detection heuristic.])
- fi
- fi])
-
-
-AC_DEFUN([gl_PREREQ_C_STACK],
- [AC_REQUIRE([AC_SYS_XSI_STACK_OVERFLOW_HEURISTIC])
- AC_REQUIRE([gl_LIBSIGSEGV])
-
- # for STACK_DIRECTION
- AC_REQUIRE([AC_FUNC_ALLOCA])
-
- AC_CHECK_FUNCS_ONCE([sigaltstack])
- AC_CHECK_DECLS([sigaltstack], , , [#include <signal.h>])
-
- AC_CHECK_HEADERS_ONCE([unistd.h ucontext.h])
-
- AC_CHECK_TYPES([stack_t], , , [#include <signal.h>])
-
- dnl c-stack does not need -lsigsegv if the system has XSI heuristics.
- if test "$gl_cv_lib_sigsegv" = yes \
- && test $"ac_cv_sys_xsi_stack_overflow_heuristic" != yes ; then
- AC_SUBST([LIBCSTACK], [$LIBSIGSEGV])
- AC_SUBST([LTLIBCSTACK], [$LTLIBSIGSEGV])
- fi
-])
+# serial 23
AC_DEFUN([gl_C_STACK],
[
- dnl Prerequisites of lib/c-stack.c.
- gl_PREREQ_C_STACK
+ dnl 'c-stack' needs -lsigsegv if and only if the 'sigsegv' module needs it.
+ if test "$with_libsigsegv" = yes; then
+ if test "$gl_cv_lib_sigsegv" = yes; then
+ AC_SUBST([LIBCSTACK], [$LIBSIGSEGV])
+ AC_SUBST([LTLIBCSTACK], [$LTLIBSIGSEGV])
+ fi
+ fi
])
projects / platform / upstream / m4.git / blobdiff