rust-kernel

/*
 * timerfdtest.c -- stage 20: timerfd, a timer you read() like a file.
 * Built with the stock `musl-gcc -static` (a plain ET_EXEC).
 *
 * Each expiration adds 1 to a counter; read() returns it as 8 bytes and
 * resets it. poll/select/epoll say "readable" while it isn't 0. Rustbelt's
 * timers tick every ~55 ms, so the checks leave room for that.
 *
 * Exit code = number of failed checks.
 */
#define _GNU_SOURCE
#include <errno.h>
#include <poll.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/select.h>
#include <sys/timerfd.h>
#include <sys/utsname.h>
#include <time.h>
#include <unistd.h>

static int fails;
#define CHECK(cond, ...)                             \
	do {                                         \
		if (!(cond)) {                       \
			fails++;                     \
			printf("timerfdtest: FAIL "); \
			printf(__VA_ARGS__);         \
			printf("\n");                \
		}                                    \
	} while (0)

static long long now_ms(void)
{
	struct timespec ts;
	clock_gettime(CLOCK_MONOTONIC, &ts);
	return ts.tv_sec * 1000LL + ts.tv_nsec / 1000000;
}

static void ms_sleep(long ms)
{
	struct timespec ts = { ms / 1000, ms % 1000 * 1000000L };
	nanosleep(&ts, NULL);
}

/* Arm `fd`: first expiry after `ms`, then every `every_ms` (0 = once). */
static int arm(int fd, long ms, long every_ms)
{
	struct itimerspec its = { { every_ms / 1000, every_ms % 1000 * 1000000L }, { ms / 1000, ms % 1000 * 1000000L } };
	return timerfd_settime(fd, 0, &its, NULL);
}

static void one_shot(void)
{
	int fd = timerfd_create(CLOCK_MONOTONIC, TFD_CLOEXEC);
	CHECK(fd >= 0, "timerfd_create: errno %d", errno);
	long long t0 = now_ms();
	CHECK(arm(fd, 150, 0) == 0, "settime: errno %d", errno);
	struct itimerspec cur;
	CHECK(timerfd_gettime(fd, &cur) == 0 && cur.it_value.tv_nsec + cur.it_value.tv_sec > 0, "gettime while armed");
	uint64_t n = 0;
	CHECK(read(fd, &n, sizeof n) == 8, "blocking read: errno %d", errno); /* waits for it */
	long long took = now_ms() - t0;
	CHECK(n == 1, "one-shot count %llu", (unsigned long long)n);
	CHECK(took >= 140 && took < 1000, "one-shot fired after %lld ms", took);
	CHECK(timerfd_gettime(fd, &cur) == 0 && cur.it_value.tv_sec == 0 && cur.it_value.tv_nsec == 0, "disarmed after firing");
	close(fd);
}

static void interval(void)
{
	int fd = timerfd_create(CLOCK_BOOTTIME, TFD_NONBLOCK);
	CHECK(fd >= 0, "timerfd_create(BOOTTIME): errno %d", errno);
	CHECK(arm(fd, 60, 60) == 0, "settime interval");
	struct itimerspec cur;
	timerfd_gettime(fd, &cur);
	CHECK(cur.it_interval.tv_sec == 0 && cur.it_interval.tv_nsec == 60000000, "gettime interval %ld", cur.it_interval.tv_nsec);
	ms_sleep(700); /* ~11 periods go by without a read: they add up */
	uint64_t n = 0;
	CHECK(read(fd, &n, sizeof n) == 8, "read interval: errno %d", errno);
	CHECK(n >= 5 && n <= 14, "interval count %llu after 700 ms of 60 ms periods", (unsigned long long)n);
	/* Read reset it; the next expirations count from 0 again. */
	ms_sleep(250);
	uint64_t m = 0;
	CHECK(read(fd, &m, sizeof m) == 8 && m >= 1 && m <= 7, "count after reset %llu", (unsigned long long)m);
	/* Disarm: no more expirations. */
	struct itimerspec off = { 0 };
	CHECK(timerfd_settime(fd, 0, &off, &cur) == 0 && cur.it_interval.tv_nsec == 60000000, "disarm returns old");
	ms_sleep(150);
	CHECK(read(fd, &m, sizeof m) == -1 && errno == EAGAIN, "disarmed: EAGAIN");
	close(fd);
}

static void nonblocking_and_errors(void)
{
	int fd = timerfd_create(CLOCK_REALTIME, TFD_NONBLOCK | TFD_CLOEXEC);
	CHECK(fd >= 0, "timerfd_create(REALTIME)");
	uint64_t n;
	CHECK(read(fd, &n, sizeof n) == -1 && errno == EAGAIN, "disarmed read: EAGAIN (errno %d)", errno);
	arm(fd, 5000, 0);
	CHECK(read(fd, &n, sizeof n) == -1 && errno == EAGAIN, "not yet expired: EAGAIN");
	char small[4];
	CHECK(read(fd, small, sizeof small) == -1 && errno == EINVAL, "4-byte buffer: EINVAL (errno %d)", errno);
	CHECK(write(fd, &n, sizeof n) == -1 && errno == EINVAL, "write: EINVAL");
	/* TFD_TIMER_ABSTIME on CLOCK_REALTIME: a wall-clock time 120 ms ahead. */
	struct timespec wall;
	clock_gettime(CLOCK_REALTIME, &wall);
	wall.tv_nsec += 120000000;
	if (wall.tv_nsec >= 1000000000) {
		wall.tv_sec++;
		wall.tv_nsec -= 1000000000;
	}
	struct itimerspec abs = { { 0, 0 }, wall };
	CHECK(timerfd_settime(fd, TFD_TIMER_ABSTIME, &abs, NULL) == 0, "ABSTIME settime");
	struct pollfd p = { fd, POLLIN, 0 };
	CHECK(poll(&p, 1, 2000) == 1 && (p.revents & POLLIN), "poll: ABSTIME timer fired");
	CHECK(read(fd, &n, sizeof n) == 8 && n == 1, "ABSTIME count");
	CHECK(poll(&p, 1, 0) == 0, "poll: not readable after read");
	/* Unsupported / bad arguments. */
	/* CANCEL_ON_SET ("wake me if someone sets the clock"): Linux has it,
	 * Rustbelt says EINVAL. (uname's version is "stage N: ..." on Rustbelt.) */
	struct utsname u;
	int rustbelt = uname(&u) == 0 && strncmp(u.version, "stage", 5) == 0;
	int r = timerfd_settime(fd, TFD_TIMER_ABSTIME | TFD_TIMER_CANCEL_ON_SET, &abs, NULL);
	CHECK(rustbelt ? r == -1 && errno == EINVAL : r == 0, "CANCEL_ON_SET: r %d errno %d", r, errno);
	CHECK(timerfd_create(CLOCK_PROCESS_CPUTIME_ID, 0) == -1 && errno == EINVAL, "bad clock: EINVAL");
	CHECK(timerfd_create(CLOCK_MONOTONIC, 1) == -1 && errno == EINVAL, "bad flags: EINVAL");
	struct itimerspec bad = { { 0, 0 }, { 0, 1000000000 } };
	CHECK(timerfd_settime(fd, 0, &bad, NULL) == -1 && errno == EINVAL, "tv_nsec too big: EINVAL");
	struct itimerspec cur;
	CHECK(timerfd_gettime(1, &cur) == -1 && errno == EINVAL, "not a timerfd: EINVAL");
	CHECK(timerfd_gettime(999, &cur) == -1 && errno == EBADF, "bad fd: EBADF");
	close(fd);
}

static void readiness(void)
{
	int fd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK);
	int ep = epoll_create1(EPOLL_CLOEXEC);
	struct epoll_event ev = { .events = EPOLLIN, .data.u64 = 0x1234 };
	CHECK(epoll_ctl(ep, EPOLL_CTL_ADD, fd, &ev) == 0, "epoll_ctl ADD: errno %d", errno);
	struct epoll_event out;
	CHECK(epoll_wait(ep, &out, 1, 0) == 0, "epoll: nothing yet");
	long long t0 = now_ms();
	arm(fd, 100, 0);
	int r = epoll_wait(ep, &out, 1, 3000); /* sleeps until the timer wakes it */
	long long took = now_ms() - t0;
	CHECK(r == 1 && out.data.u64 == 0x1234 && (out.events & EPOLLIN), "epoll_wait woke: r %d", r);
	CHECK(took >= 90 && took < 1500, "epoll woke after %lld ms", took);
	uint64_t n = 0;
	CHECK(read(fd, &n, sizeof n) == 8 && n == 1, "count after epoll");
	CHECK(epoll_wait(ep, &out, 1, 0) == 0, "epoll: drained");
	/* select too. */
	arm(fd, 80, 0);
	fd_set set;
	FD_ZERO(&set);
	FD_SET(fd, &set);
	struct timeval tv = { 2, 0 };
	CHECK(select(fd + 1, &set, NULL, NULL, &tv) == 1 && FD_ISSET(fd, &set), "select woke");
	read(fd, &n, sizeof n);
	close(ep);
	close(fd);
}

/* Lots of armed timerfds, closed (and some left open: exit closes them).
 * The kernel test checks no timer or memory is left behind. */
static void many(void)
{
	int fds[40];
	for (int i = 0; i < 40; i++) {
		fds[i] = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK);
		CHECK(fds[i] >= 0, "timerfd %d", i);
		arm(fds[i], 10 + i, 20);
	}
	ms_sleep(120);
	for (int i = 0; i < 30; i++)
		close(fds[i]);
}

int main(void)
{
	one_shot();
	interval();
	nonblocking_and_errors();
	readiness();
	many();
	printf("timerfdtest: %d failed\n", fails);
	return fails;
}