| |
| |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <signal.h> |
| #include <sys/mman.h> |
| |
| void sig_handler(int sig){ |
| int var; |
| fprintf(stderr, "caught signal, local var is on %p\n", &var); |
| } |
| |
| int main(int argv, char** argc) { |
| int res, i; |
| stack_t sigstk; |
| struct sigaction act; |
| static const int size = SIGSTKSZ*2; |
| // We give EXEC permissions because this won't work on ppc32 unless you |
| // ask for an alt stack with EXEC permissions, |
| // since signal returning requires execution of code on the stack. |
| char *stk = (char *)mmap(0, size, PROT_READ|PROT_WRITE|PROT_EXEC, |
| MAP_ANON|MAP_PRIVATE, -1, 0); |
| sigstk.ss_sp = stk; |
| |
| sigstk.ss_size = size; |
| sigstk.ss_flags = 0; |
| fprintf(stderr, "calling sigaltstack, stack base is %p\n", sigstk.ss_sp); |
| if (sigaltstack(&sigstk,0)<0) perror("sigaltstack"); |
| |
| fprintf(stderr,"setting sigaction\n"); |
| act.sa_flags=SA_ONSTACK; |
| act.sa_handler=&sig_handler; |
| sigemptyset(&act.sa_mask); |
| res = sigaction(SIGUSR1,&act,0); |
| fprintf(stderr, "res = %d\n", res); |
| fprintf(stderr, "raising the signal\n"); |
| raise(SIGUSR1); |
| |
| /* Loop long enough so valgrind has a forced context switch and |
| actually delivers the signal before the thread exits. */ |
| for (i = 0; i < 1000000; i++) ; |
| |
| fprintf(stderr, "done\n"); |
| return 0; |
| } |