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/* See LICENSE file for copyright and license details. */
#include <setjmp.h>
#include <signal.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
unsigned volatile just_one = 1;
static jmp_buf jmpenv;
static void
sigsegv(int signo)
{
(void) signo;
siglongjmp(jmpenv, 1);
}
static unsigned
overflow2(size_t depth)
{
if (!depth)
return just_one;
depth -= 1u;
return overflow2(depth) + overflow2(depth);
}
static unsigned
overflow(void)
{
return overflow2(SIZE_MAX);
}
int
main(void)
{
volatile unsigned sum = 0;
volatile int i;
struct sigaction sa;
stack_t ss;
ss.ss_sp = malloc((size_t)SIGSTKSZ);
if (!ss.ss_sp)
return 1;
ss.ss_size = (size_t)SIGSTKSZ;
ss.ss_flags = 0;
if (sigaltstack(&ss, NULL))
return 2;
memset(&sa, 0, sizeof(sa));
sa.sa_flags = SA_ONSTACK;
sa.sa_handler = &sigsegv;
sigfillset(&sa.sa_mask);
sigaction(SIGSEGV, &sa, NULL);
for (i = 1; i <= 10; i++) {
if (!sigsetjmp(jmpenv, 1)) {
printf("%i: before overflow dereference\n", i);
sum += overflow();
} else {
printf("%i: after overflow dereference\n", i);
}
}
fflush(stdout);
return (int)sum;
}
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