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/* $OpenBSD: stackjmp.c,v 1.3 2013/12/21 05:45:04 guenther Exp $ */
/*
* Written by Matthew Dempsky, 2012.
* Public domain.
*/
#include <assert.h>
#include <setjmp.h>
#include <signal.h>
#include <string.h>
#include <unistd.h>
static sigjmp_buf jb;
static char buf[SIGSTKSZ];
static volatile int handled;
static int
isaltstack()
{
stack_t os;
assert(sigaltstack(NULL, &os) == 0);
return (os.ss_flags & SS_ONSTACK) != 0;
}
static void
inthandler(int signo)
{
assert(isaltstack());
handled = 1;
siglongjmp(jb, 1);
}
int
main()
{
struct sigaction sa;
stack_t stack;
memset(&sa, 0, sizeof(sa));
sa.sa_handler = inthandler;
sa.sa_flags = SA_ONSTACK;
assert(sigaction(SIGINT, &sa, NULL) == 0);
memset(&stack, 0, sizeof(stack));
stack.ss_sp = buf;
stack.ss_size = sizeof(buf);
stack.ss_flags = 0;
assert(sigaltstack(&stack, NULL) == 0);
assert(!isaltstack());
sigsetjmp(jb, 1);
assert(!isaltstack());
if (!handled) {
kill(getpid(), SIGINT);
assert(0); /* Shouldn't reach here. */
}
return (0);
}
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