memcheck/tests/sigaltstack.c

   1 #include <inttypes.h>
   2 #include <stdio.h>
   3 #include <stdlib.h>
   4 #include <signal.h>
   5 #include "tests/sys_mman.h"
   6
   7 void sig_handler(int sig){
   8   int var;
   9   fprintf(stderr, "caught signal, local var is on %#" PRIxPTR "\n",
  10           (uintptr_t)&var);
  11 }
  12
  13 int main(int argv, char** argc) {
  14   int res, i;
  15   stack_t sigstk;
  16   struct sigaction act;
  17   static const int size = SIGSTKSZ*2;
  18   // We give EXEC permissions because this won't work on ppc32 unless you
  19   // ask for an alt stack with EXEC permissions,
  20   // since signal returning requires execution of code on the stack.
  21   char *stk = (char *)mmap(0, size, PROT_READ|PROT_WRITE|PROT_EXEC,
  22                                     MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
  23   sigstk.ss_sp = stk;
  24
  25   sigstk.ss_size = size;
  26   sigstk.ss_flags = 0;
  27   fprintf(stderr, "calling sigaltstack, stack base is %#" PRIxPTR "\n",
  28           (uintptr_t)sigstk.ss_sp);
  29   if (sigaltstack(&sigstk,0)<0) perror("sigaltstack");
  30
  31   fprintf(stderr,"setting sigaction\n");
  32   act.sa_flags=SA_ONSTACK;
  33   act.sa_handler=&sig_handler;
  34   sigemptyset(&act.sa_mask);
  35   res = sigaction(SIGUSR1,&act,0);
  36   fprintf(stderr, "res = %d\n", res);
  37   fprintf(stderr, "raising the signal\n");
  38   raise(SIGUSR1);
  39
  40   /* Loop long enough so valgrind has a forced context switch and
  41      actually delivers the signal before the thread exits. */
  42   for (i = 0; i < 1000000; i++) ;
  43
  44   fprintf(stderr, "done\n");
  45   return 0;
  46 }