// commit: 6871fd773dcedbf056317d5d5e87b4859e97c4a4 2011-03-10

// commit: 9505bfbc40fec217820abad7142663eda60cd6be 2014-03-18

// catching stackoverflow SIGSEGV using sigaltstack

// mips stack_t is inconsistent with other archs

#define _XOPEN_SOURCE 700

#include <signal.h>

#include <setjmp.h>

#include <stdlib.h>

#include <string.h>

#include <errno.h>

#include "test.h"

#define T(f) ((f)==0 || (t_error(#f " failed: %s\n", strerror(errno)),0))

static char stack[SIGSTKSZ];

static sigjmp_buf sbuf;

static volatile sig_atomic_t state;

static void handler(int sig)

{

	uintptr_t i;

	stack_t ss;

	if (state!=1)

		t_error("handler is not invoked in fillstack (after sigsetjmp returned 0), "

			"state is %d, want 1\n", state);

	state++;

	i = (uintptr_t)&i;

	if (i < (uintptr_t)stack || i >= (uintptr_t)stack+SIGSTKSZ)

		t_error("signal handler was not invoked on the altstack\n");

	T(sigaltstack(0, &ss);;

	if (ss.ss_flags != SS_ONSTACK)

		t_error("ss_flags is not SS_ONSTACK in the signal handler\n");

	siglongjmp(sbuf, 1);

}

static unsigned fillstack(unsigned x)

{

	x++;

	if (x==0) {

		t_error("wrap around\n");

		return x;

	}

	return fillstack(fillstack(x)) + 1;

}

int main(void)

{

	stack_t ss;

	struct sigaction sa;

	ss.ss_sp = stack;

	ss.ss_size = sizeof stack;

	ss.ss_flags = 0;

	sa.sa_handler = handler;

	sa.sa_flags = SA_ONSTACK;

	T(sigaltstack(&ss, 0));

	T(sigfillset(&sa.sa_mask));

	T(sigaction(SIGSEGV, &sa, 0));

	if (sigsetjmp(sbuf,0) == 0) {

		state++;

		fillstack(0);

		t_error("infinite recursion finished\n");

	}

	if (state != 2)

		t_error("sigsetjmp returned non-zero before running handler, "

			"state is %d, want 2\n", state);

	errno = 0;

	ss.ss_size = MINSIGSTKSZ-1;

	if (sigaltstack(&ss, 0) != -1 || errno != ENOMEM)

		t_error("sigaltstack with stack size < MINSIGSTKSZ should have failed with ENOMEM, "

			"got %s\n", strerror(errno));

	errno = 0;

	ss.ss_flags = -1;

	ss.ss_size = MINSIGSTKSZ;

	if (sigaltstack(&ss, 0) != -1 || errno != EINVAL)

		t_error("sigaltstack with bad ss_flags should have failed with EINVAL, "

			"got %s\n", strerror(errno));

	errno = 0;

	T(sigaltstack(0, 0));

	return t_status;

}