1#include <signal.h>
 2#include <errno.h>
 3#include "syscall.h"
 4
 5int sigaltstack(const stack_t *restrict ss, stack_t *restrict old)
 6{
 7	if (ss) {
 8		if (!(ss->ss_flags & SS_DISABLE) && ss->ss_size < MINSIGSTKSZ) {
 9			errno = ENOMEM;
10			return -1;
11		}
12		if (ss->ss_flags & SS_ONSTACK) {
13			errno = EINVAL;
14			return -1;
15		}
16	}
17	return syscall(SYS_sigaltstack, ss, old);
18}