1 # Check prerequisites for compiling lib/c-stack.c.
3 # Copyright (C) 2002, 2003 Free Software Foundation, Inc.
5 # This program is free software; you can redistribute it and/or modify
6 # it under the terms of the GNU General Public License as published by
7 # the Free Software Foundation; either version 2, or (at your option)
10 # This program is distributed in the hope that it will be useful,
11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 # GNU General Public License for more details.
15 # You should have received a copy of the GNU General Public License
16 # along with this program; if not, write to the Free Software
17 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
20 # Written by Paul Eggert.
22 AC_DEFUN([AC_SYS_XSI_STACK_OVERFLOW_HEURISTIC],
23 [# for STACK_DIRECTION
24 AC_REQUIRE([AC_FUNC_ALLOCA])
25 AC_CHECK_FUNCS(setrlimit)
27 AC_CACHE_CHECK([for working C stack overflow detection],
28 ac_cv_sys_xsi_stack_overflow_heuristic,
35 # include <sys/types.h>
36 # include <sys/time.h>
37 # include <sys/resource.h>
42 char buffer[SIGSTKSZ];
46 } alternate_signal_stack;
49 # define find_stack_direction(ptr) STACK_DIRECTION
52 find_stack_direction (char const *addr)
55 return (! addr ? find_stack_direction (&dummy)
56 : addr < &dummy ? 1 : -1);
61 segv_handler (int signo, siginfo_t *info, void *context)
63 if (0 < info->si_code)
65 ucontext_t const *user_context = context;
66 char const *stack_min = user_context->uc_stack.ss_sp;
67 size_t stack_size = user_context->uc_stack.ss_size;
68 char const *faulting_address = info->si_addr;
69 size_t s = faulting_address - stack_min;
70 size_t page_size = sysconf (_SC_PAGESIZE);
71 if (find_stack_direction (0) < 0)
73 if (s < stack_size + page_size)
88 st.ss_sp = alternate_signal_stack.buffer;
89 st.ss_size = sizeof alternate_signal_stack.buffer;
90 r = sigaltstack (&st, 0);
94 sigemptyset (&act.sa_mask);
95 act.sa_flags = SA_NODEFER | SA_ONSTACK | SA_RESETHAND | SA_SIGINFO;
96 act.sa_sigaction = segv_handler;
97 return sigaction (SIGSEGV, &act, 0);
105 return *p + recurse (array);
111 #if HAVE_SETRLIMIT && defined RLIMIT_STACK
112 /* Before starting the endless recursion, try to be friendly
113 to the user's machine. On some Linux 2.2.x systems, there
114 is no stack limit for user processes at all. We don't want
115 to kill such systems. */
117 rl.rlim_cur = rl.rlim_max = 0x100000; /* 1 MB */
118 setrlimit (RLIMIT_STACK, &rl);
122 return recurse ("\1");
125 [ac_cv_sys_xsi_stack_overflow_heuristic=yes],
126 [ac_cv_sys_xsi_stack_overflow_heuristic=no],
127 [ac_cv_sys_xsi_stack_overflow_heuristic=cross-compiling])])
129 if test $ac_cv_sys_xsi_stack_overflow_heuristic = yes; then
130 AC_DEFINE(HAVE_XSI_STACK_OVERFLOW_HEURISTIC, 1,
131 [Define to 1 if extending the stack slightly past the limit causes
132 a SIGSEGV, and an alternate stack can be established with sigaltstack,
133 and the signal handler is passed a context that specifies the
134 run time stack. This behavior is defined by POSIX 1003.1-2001
135 with the X/Open System Interface (XSI) option
136 and is a standardized way to implement a SEGV-based stack
137 overflow detection heuristic.])
141 AC_DEFUN([jm_PREREQ_C_STACK],
142 [AC_REQUIRE([AC_SYS_XSI_STACK_OVERFLOW_HEURISTIC])
144 # for STACK_DIRECTION
145 AC_REQUIRE([AC_FUNC_ALLOCA])
147 AC_CHECK_FUNCS(getcontext sigaltstack)
148 AC_CHECK_DECLS([getcontext], , , [#include <ucontext.h>])
149 AC_CHECK_DECLS([sigaltstack], , , [#include <signal.h>])
151 AC_CHECK_HEADERS_ONCE(sys/time.h unistd.h)
152 AC_CHECK_HEADERS(sys/resource.h ucontext.h)
154 AC_CHECK_TYPES([stack_t], , , [#include <signal.h>])])
156 AC_DEFUN([gl_C_STACK],
158 dnl Prerequisites of lib/c-stack.c.