selftests/timens: Add a test for futex()

TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs exec

TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs exec futex

TEST_GEN_PROGS_EXTENDED := gettime_perf

CFLAGS := -Wall -Werror -pthread

// SPDX-License-Identifier: GPL-2.0

#define _GNU_SOURCE

#include <sched.h>

#include <linux/unistd.h>

#include <linux/futex.h>

#include <stdio.h>

#include <string.h>

#include <sys/syscall.h>

#include <sys/types.h>

#include <sys/wait.h>

#include <time.h>

#include <unistd.h>

#include "log.h"

#include "timens.h"

#define NSEC_PER_SEC 1000000000ULL

static int run_test(int clockid)

{

	int futex_op = FUTEX_WAIT_BITSET;

	struct timespec timeout, end;

	int val = 0;

	if (clockid == CLOCK_REALTIME)

		futex_op |= FUTEX_CLOCK_REALTIME;

	clock_gettime(clockid, &timeout);

	timeout.tv_nsec += NSEC_PER_SEC / 10; // 100ms

	if (timeout.tv_nsec > NSEC_PER_SEC) {

		timeout.tv_sec++;

		timeout.tv_nsec -= NSEC_PER_SEC;

	}

	if (syscall(__NR_futex, &val, futex_op, 0,

		    &timeout, 0, FUTEX_BITSET_MATCH_ANY) >= 0) {

		ksft_test_result_fail("futex didn't return ETIMEDOUT\n");

		return 1;

	}

	if (errno != ETIMEDOUT) {

		ksft_test_result_fail("futex didn't return ETIMEDOUT: %s\n",

							strerror(errno));

		return 1;

	}

	clock_gettime(clockid, &end);

	if (end.tv_sec < timeout.tv_sec ||

	    (end.tv_sec == timeout.tv_sec && end.tv_nsec < timeout.tv_nsec)) {

		ksft_test_result_fail("futex slept less than 100ms\n");

		return 1;

	}

	ksft_test_result_pass("futex with the %d clockid\n", clockid);

	return 0;

}

int main(int argc, char *argv[])

{

	int status, len, fd;

	char buf[4096];

	pid_t pid;

	struct timespec mtime_now;

	nscheck();

	ksft_set_plan(2);

	clock_gettime(CLOCK_MONOTONIC, &mtime_now);

	if (unshare_timens())

		return 1;

	len = snprintf(buf, sizeof(buf), "%d %d 0",

			CLOCK_MONOTONIC, 70 * 24 * 3600);

	fd = open("/proc/self/timens_offsets", O_WRONLY);

	if (fd < 0)

		return pr_perror("/proc/self/timens_offsets");

	if (write(fd, buf, len) != len)

		return pr_perror("/proc/self/timens_offsets");

	close(fd);

	pid = fork();

	if (pid < 0)

		return pr_perror("Unable to fork");

	if (pid == 0) {

		int ret = 0;

		ret |= run_test(CLOCK_REALTIME);

		ret |= run_test(CLOCK_MONOTONIC);

		if (ret)

			ksft_exit_fail();

		ksft_exit_pass();

		return 0;

	}

	if (waitpid(pid, &status, 0) != pid)

		return pr_perror("Unable to wait the child process");

	if (WIFEXITED(status))

		return WEXITSTATUS(status);

	return 1;

}