diff options
Diffstat (limited to 'm4/c-stack.m4')
| -rw-r--r-- | m4/c-stack.m4 | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/m4/c-stack.m4 b/m4/c-stack.m4 new file mode 100644 index 000000000..01c9a884c --- /dev/null +++ b/m4/c-stack.m4 @@ -0,0 +1,136 @@ +# Check prerequisites for compiling lib/c-stack.c. + +# 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. + +AC_DEFUN([AC_SYS_XSI_STACK_OVERFLOW_HEURISTIC], + [# for STACK_DIRECTION + AC_REQUIRE([AC_FUNC_ALLOCA]) + + AC_CACHE_CHECK([for working C stack overflow detection], + ac_cv_sys_xsi_stack_overflow_heuristic, + [AC_TRY_RUN( + [ + #include <signal.h> + #include <ucontext.h> + + static union + { + char buffer[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) + { + 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 (1); + } + + static int + c_stack_action (void) + { + stack_t st; + struct sigaction act; + int r; + + 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; + + sigemptyset (&act.sa_mask); + act.sa_flags = SA_NODEFER | SA_ONSTACK | SA_RESETHAND | SA_SIGINFO; + act.sa_sigaction = segv_handler; + return sigaction (SIGSEGV, &act, 0); + } + + static int + recurse (char *p) + { + char array[500]; + array[0] = 1; + return *p + recurse (array); + } + + int + main (void) + { + c_stack_action (); + return recurse ("\1"); + } + ], + [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]) + + +AC_DEFUN([jm_PREREQ_C_STACK], + [AC_REQUIRE([AC_SYS_XSI_STACK_OVERFLOW_HEURISTIC]) + + # for STACK_DIRECTION + AC_REQUIRE([AC_FUNC_ALLOCA]) + + AC_CHECK_FUNCS(getcontext sigaltstack) + AC_CHECK_DECLS([getcontext], , , [#include <ucontext.h>]) + AC_CHECK_DECLS([sigaltstack], , , [#include <signal.h>]) + + AC_CHECK_HEADERS(sys/resource.h ucontext.h unistd.h) + + AC_CHECK_TYPES([stack_t], , , [#include <signal.h>])]) |