config/auto-aux/stackov.c

   1 /***********************************************************************/
   2 /*                                                                     */
   3 /*                           Objective Caml                            */
   4 /*                                                                     */
   5 /*            Xavier Leroy, projet Cristal, INRIA Rocquencourt         */
   6 /*                                                                     */
   7 /*  Copyright 2001 Institut National de Recherche en Informatique et   */
   8 /*  en Automatique.  All rights reserved.  This file is distributed    */
   9 /*  under the terms of the GNU Library General Public License, with    */
  10 /*  the special exception on linking described in file ../../LICENSE.  */
  11 /*                                                                     */
  12 /***********************************************************************/
  13
  14 /* $Id$ */
  15
  16 #include <stdio.h>
  17 #include <signal.h>
  18 #include <sys/resource.h>
  19
  20 static char sig_alt_stack[SIGSTKSZ];
  21 static char * system_stack_top;
  22
  23 #if defined(TARGET_i386) && defined(SYS_linux_elf)
  24 static void segv_handler(int signo, struct sigcontext sc)
  25 {
  26   char * fault_addr = (char *) sc.cr2;
  27 #else
  28 static void segv_handler(int signo, siginfo_t * info, void * context)
  29 {
  30   char * fault_addr = (char *) info->si_addr;
  31 #endif
  32   struct rlimit limit;
  33
  34   if (getrlimit(RLIMIT_STACK, &limit) == 0 &&
  35       ((long) fault_addr & (sizeof(long) - 1)) == 0 &&
  36       fault_addr < system_stack_top &&
  37       fault_addr >= system_stack_top - limit.rlim_cur - 0x2000) {
  38     _exit(0);
  39   } else {
  40     _exit(4);
  41   }
  42 }
  43
  44 int main(int argc, char ** argv)
  45 {
  46   stack_t stk;
  47   struct sigaction act;
  48
  49   stk.ss_sp = sig_alt_stack;
  50   stk.ss_size = SIGSTKSZ;
  51   stk.ss_flags = 0;
  52 #if defined(TARGET_i386) && defined(SYS_linux_elf)
  53   act.sa_handler = (void (*)(int)) segv_handler;
  54   act.sa_flags = SA_ONSTACK | SA_NODEFER;
  55 #else
  56   act.sa_sigaction = segv_handler;
  57   act.sa_flags = SA_SIGINFO | SA_ONSTACK | SA_NODEFER;
  58 #endif
  59   sigemptyset(&act.sa_mask);
  60   system_stack_top = (char *) &act;
  61   if (sigaltstack(&stk, NULL) != 0) { perror("sigaltstack"); return 2; }
  62   if (sigaction(SIGSEGV, &act, NULL) != 0) { perror("sigaction"); return 2; }
  63   /* We used to trigger a stack overflow at this point to test whether
  64      the code above works, but this causes problems with POSIX threads
  65      on some BSD systems.  So, instead, we just test that all this
  66      code compiles, indicating that the required syscalls are there. */
  67   return 0;
  68 }