Test: add a unit test for the fd tracker

[lttng-tools.git] / tests / unit / test_fd_tracker.c

/*
 * Copyright (c) - 2018 Jérémie Galarneau <jeremie.galarneau@efficios.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by as
 * published by the Free Software Foundation; only version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <stdlib.h>
#include <inttypes.h>
#include <stdbool.h>
#include <assert.h>
#include <string.h>
#include <stdarg.h>
#include <tap/tap.h>
#include <sys/types.h>
#include <dirent.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>

#include <urcu.h>

#include <common/fd-tracker/fd-tracker.h>
#include <common/error.h>

/* For error.h */
int lttng_opt_quiet = 1;
int lttng_opt_verbose;
int lttng_opt_mi;

/* Number of TAP tests in this file */
#define NUM_TESTS 35
/* 3 for stdin, stdout, and stderr */
#define STDIO_FD_COUNT 3
#define TRACKER_FD_LIMIT 50
#define TMP_DIR_PATTERN "/tmp/fd-tracker-XXXXXX"

/*
 * Count of fds, beyond stdin, stderr, stdout that were open
 * at the launch of the test. This allows the test to succeed when
 * run by automake's test runner or valgrind which both open
 * fds behind our back.
 */
int unknown_fds_count;

const char file_contents[] = "Bacon ipsum dolor amet jerky drumstick sirloin "
	"strip steak venison boudin filet mignon picanha doner shoulder. "
	"Strip steak brisket alcatra, venison beef chuck cupim pastrami. "
	"Landjaeger tri-tip salami leberkas ball tip, ham hock chuck sausage "
	"flank jerky cupim. Pig bacon chuck pancetta andouille.";

int fd_count(void)
{
	DIR *dir;
	struct dirent *entry;
        int count = 0;

	dir = opendir("/proc/self/fd");
	if (!dir) {
		perror("# Failed to enumerate /proc/self/fd/ to count the number of used file descriptors");
	        count = -1;
		goto end;
	}

	while ((entry = readdir(dir)) != NULL) {
		if (!strcmp(entry->d_name, ".") || !strcmp(entry->d_name, "..")) {
			continue;
		}
	        count++;
	}
	/* Don't account for the file descriptor opened by opendir(). */
        count--;
	closedir(dir);
end:
	return count;
}

static
void check_fd_count(int expected_count)
{
        int count = 0;

        count = fd_count();
	ok(count == expected_count, "Expected %d open file descriptors (%d are open)",
			expected_count, count);
}

static
int noop_open(void *data, int *fds)
{
        *fds = *((int *) data);
	return 0;
}

static
int noop_close(void *data, int *fds)
{
	return 0;
}

static
void track_std_fds(struct fd_tracker *tracker)
{
	int i;
        struct { int fd; const char *name; } files[] = {
		{ .fd = fileno(stdin), .name = "stdin" },
		{ .fd = fileno(stdout), .name = "stdout" },
		{ .fd = fileno(stderr), .name = "stderr" },
	};

	for (i = 0; i < sizeof(files) / sizeof(*files); i++) {
		int out_fd, ret;

		ret = fd_tracker_open_unsuspendable_fd(tracker, &out_fd,
				&files[i].name, 1, noop_open, &files[i].fd);
		assert(out_fd == files[i].fd);

		ok(ret == 0, "Track unsuspendable fd %d (%s)", files[i].fd,
				files[i].name);
	}
}

static
void untrack_std_fds(struct fd_tracker *tracker)
{
	int i;
        struct { int fd; const char *name; } files[] = {
		{ .fd = fileno(stdin), .name = "stdin" },
		{ .fd = fileno(stdout), .name = "stdout" },
		{ .fd = fileno(stderr), .name = "stderr" },
	};
	unsigned int fds_set_to_minus_1 = 0;

	for (i = 0; i < sizeof(files) / sizeof(*files); i++) {
		int fd = files[i].fd;
		int ret = fd_tracker_close_unsuspendable_fd(tracker,
				&files[i].fd, 1, noop_close, NULL);

		ok(ret == 0, "Untrack unsuspendable fd %d (%s)", fd,
				files[i].name);
		fds_set_to_minus_1 += (files[i].fd == -1);
	}
}

/*
 * Basic test opening and closing three unsuspendable fds. 
 */
static
void test_unsuspendable_basic(void)
{
	struct fd_tracker *tracker;

        tracker = fd_tracker_create(TRACKER_FD_LIMIT);
	ok(tracker, "Created an fd tracker with a limit of %d simulateously opened file descriptors",
			TRACKER_FD_LIMIT);
	if (!tracker) {
		return;
	}

	track_std_fds(tracker);
	untrack_std_fds(tracker);

	fd_tracker_destroy(tracker);
}

static
int error_open(void *data, int *fds)
{
	return *((int *) data);
}

static
int error_close(void *data, int *fds)
{
	return *((int *) data);
}

/*
 * Validate that user callback return values are returned to the
 * caller of the fd tracker.
 */
static
void test_unsuspendable_cb_return(void)
{
	int ret, stdout_fd = fileno(stdout), out_fd = 42;
	struct fd_tracker *tracker;
	int expected_error = -ENETDOWN;

        tracker = fd_tracker_create(TRACKER_FD_LIMIT);
	assert(tracker);

	/* The error_open callback should fail and return 'expected_error'. */
	ret = fd_tracker_open_unsuspendable_fd(tracker, &out_fd,
			NULL, 1, error_open, &expected_error);
	ok(ret == expected_error, "fd_tracker_open_unsuspendable_fd() forwards the user callback's error code");
	ok(out_fd == 42, "Output fd parameter is unaffected on error of fd_tracker_open_unsuspendable_fd()");

	/*
	 * Track a valid fd since we don't want the tracker to fail with an
	 * invalid fd error for this test.
	 */
	ret = fd_tracker_open_unsuspendable_fd(tracker, &out_fd,
			NULL, 1, noop_open, &stdout_fd);
	ok(out_fd == stdout_fd, "fd_tracker_open_unsuspendable_fd() sets the output fd parameter to the newly-tracked fd's value");
	assert(!ret);

	ret = fd_tracker_close_unsuspendable_fd(tracker,
			&stdout_fd, 1, error_close, &expected_error);
	ok(ret == expected_error, "fd_tracker_close_unsuspendable_fd() forwards the user callback's error code");
	ret = fd_tracker_close_unsuspendable_fd(tracker,
			&stdout_fd, 1, noop_close, &expected_error);
	assert(!ret);

	fd_tracker_destroy(tracker);
}

/*
 * Validate that the tracker refuses to track two identical unsuspendable
 * file descriptors.
 */
static
void test_unsuspendable_duplicate(void)
{
	int ret, stdout_fd = fileno(stdout), out_fd;
	struct fd_tracker *tracker;

        tracker = fd_tracker_create(TRACKER_FD_LIMIT);
	assert(tracker);

	ret = fd_tracker_open_unsuspendable_fd(tracker, &out_fd,
			NULL, 1, noop_open, &stdout_fd);
	assert(!ret);
	ret = fd_tracker_open_unsuspendable_fd(tracker, &out_fd,
			NULL, 1, noop_open, &stdout_fd);
	ok(ret == -EEXIST, "EEXIST reported on open of an already tracked file descriptor");

	ret = fd_tracker_close_unsuspendable_fd(tracker,
			&stdout_fd, 1, noop_close, NULL);
	assert(!ret);

	fd_tracker_destroy(tracker);
}

static
int open_pipes(void *data, int *out_fds)
{
	unsigned int i;
	const unsigned int pipe_count = TRACKER_FD_LIMIT / 2;

	for (i = 0; i < pipe_count; i++) {
		int ret = pipe(&out_fds[i * 2]);

		if (ret) {
			return -errno;
		}
	}
	return 0;
}

static
int close_pipes(void *data, int *fds)
{
	int i;
	int *pipes = fds;

	for (i = 0; i < TRACKER_FD_LIMIT; i++) {
		int ret = close(pipes[i]);

		if (ret) {
			return -errno;
		}
	}
	return 0;
}

/*
 * Validate that the tracker enforces the open file descriptor limit
 * when unsuspendable file descritptors are being opened.
 */
static
void test_unsuspendable_limit(void)
{
	struct fd_tracker *tracker;
	int ret, stdout_fd = fileno(stdout), out_fd;
	int fds[TRACKER_FD_LIMIT];

	/* This test assumes TRACKER_FD_LIMIT is a multiple of 2. */
	assert((TRACKER_FD_LIMIT % 2 == 0) && TRACKER_FD_LIMIT);

        tracker = fd_tracker_create(TRACKER_FD_LIMIT);
	assert(tracker);

	ret = fd_tracker_open_unsuspendable_fd(tracker, fds,
			NULL, TRACKER_FD_LIMIT, open_pipes, NULL);
	ok(ret == 0, "File descriptor tracker allowed the user to meet its limit with unsuspendable file descritptors (%d)",
			TRACKER_FD_LIMIT);

	ret = fd_tracker_open_unsuspendable_fd(tracker, &out_fd,
			NULL, 1, noop_open, &stdout_fd);
	ok(ret == -EMFILE, "EMFILE reported when exceeding the file descriptor limit while opening an unsuspendable fd");

	ret = fd_tracker_close_unsuspendable_fd(tracker,
			fds, TRACKER_FD_LIMIT, close_pipes, NULL);
	assert(!ret);

	fd_tracker_destroy(tracker);
}

/*
 * Validate that the tracker refuses to track two identical unsuspendable
 * file descriptors.
 */
static
void test_unsuspendable_close_untracked(void)
{
	int ret, stdout_fd = fileno(stdout), unknown_fds[2], out_fd;
	struct fd_tracker *tracker;

        tracker = fd_tracker_create(TRACKER_FD_LIMIT);
	if (!tracker) {
		return;
	}

	ret = pipe(unknown_fds);
	assert(!ret);
	assert(close(unknown_fds[0]) == 0);
	assert(close(unknown_fds[1]) == 0);

	ret = fd_tracker_open_unsuspendable_fd(tracker, &out_fd,
			NULL, 1, noop_open, &stdout_fd);
	assert(!ret);

	ret = fd_tracker_close_unsuspendable_fd(tracker,
			unknown_fds, 1, noop_close, NULL);
	ok(ret == -EINVAL, "EINVAL reported on close of an untracked file descriptor");

	ret = fd_tracker_close_unsuspendable_fd(tracker,
			&stdout_fd, 1, noop_close, NULL);
	assert(!ret);

	fd_tracker_destroy(tracker);
}

static
int open_files(struct fd_tracker *tracker, const char *dir, unsigned int count,
		struct fs_handle **handles, char **file_paths)
{
	int ret = 0;
	unsigned int i;

	for (i = 0; i < count; i++) {
		int ret;
	        char *file_path;
		struct fs_handle *handle;
		mode_t mode = S_IWUSR | S_IRUSR;

		ret = asprintf(&file_path, "%s/file-%u", dir, i);
		assert(ret >= 0);
	        file_paths[i] = file_path;

		handle = fd_tracker_open_fs_handle(tracker, file_path,
				O_RDWR | O_CREAT, &mode);
		if (!handle) {
			ret = -1;
			break;
		}
		handles[i] = handle;
	}
	return ret;
}

static
int cleanup_files(struct fd_tracker *tracker, const char *dir,
		unsigned int count, struct fs_handle **handles,
		char **file_paths)
{
	int ret = 0;
	unsigned int i;

	for (i = 0; i < count; i++) {
		char *file_path = file_paths[i];

		if (!file_path) {
			break;
		}
		(void) unlink(file_path);
		free(file_path);
	        if (fs_handle_close(handles[i])) {
			ret = -1;
		}
	}
	return ret;
}

static
void test_suspendable_limit(void)
{
	int ret;
	const int files_to_create = TRACKER_FD_LIMIT * 10;
	struct fd_tracker *tracker;
	char tmp_path_pattern[] = TMP_DIR_PATTERN;
	const char *output_dir;
	char *output_files[files_to_create];
	struct fs_handle *handles[files_to_create];

	memset(output_files, 0, sizeof(output_files));
	memset(handles, 0, sizeof(handles));

        tracker = fd_tracker_create(TRACKER_FD_LIMIT);
	if (!tracker) {
		return;
	}

        output_dir = mkdtemp(tmp_path_pattern);
	if (!output_dir) {
		diag("Failed to create temporary path of the form %s",
				TMP_DIR_PATTERN);
		assert(0);
	}

	ret = open_files(tracker, output_dir, files_to_create, handles,
			output_files);
	ok(!ret, "Created %d files with a limit of %d simultaneously-opened file descriptor",
			files_to_create, TRACKER_FD_LIMIT);
	check_fd_count(TRACKER_FD_LIMIT + STDIO_FD_COUNT + unknown_fds_count);

	ret = cleanup_files(tracker, output_dir, files_to_create, handles,
			output_files);
	ok(!ret, "Close all opened filesystem handles");
	(void) rmdir(output_dir);
	fd_tracker_destroy(tracker);
}

static
void test_mixed_limit(void)
{
	int ret;
	const int files_to_create = TRACKER_FD_LIMIT;
	struct fd_tracker *tracker;
	char tmp_path_pattern[] = TMP_DIR_PATTERN;
	const char *output_dir;
	char *output_files[files_to_create];
	struct fs_handle *handles[files_to_create];

	memset(output_files, 0, sizeof(output_files));
	memset(handles, 0, sizeof(handles));

        tracker = fd_tracker_create(TRACKER_FD_LIMIT);
	if (!tracker) {
		return;
	}

        output_dir = mkdtemp(tmp_path_pattern);
	if (!output_dir) {
		diag("Failed to create temporary path of the form %s",
				TMP_DIR_PATTERN);
		assert(0);
	}

	ret = open_files(tracker, output_dir, files_to_create, handles,
			output_files);
	ok(!ret, "Created %d files with a limit of %d simultaneously-opened file descriptor",
			files_to_create, TRACKER_FD_LIMIT);
	diag("Check file descriptor count after opening %u files", files_to_create);
	check_fd_count(TRACKER_FD_LIMIT + STDIO_FD_COUNT + unknown_fds_count);

	/*
	 * Open unsuspendable fds (stdin, stdout, stderr) and verify that the fd
	 * cap is still respected.
	 */
	diag("Check file descriptor count after adding %d unsuspendable fds",
			STDIO_FD_COUNT);
	track_std_fds(tracker);
	check_fd_count(TRACKER_FD_LIMIT + unknown_fds_count);
	diag("Untrack unsuspendable file descriptors");
	untrack_std_fds(tracker);
	check_fd_count(TRACKER_FD_LIMIT + unknown_fds_count);

	ret = cleanup_files(tracker, output_dir, files_to_create, handles,
			output_files);
	ok(!ret, "Close all opened filesystem handles");
	(void) rmdir(output_dir);
	fd_tracker_destroy(tracker);
}

/*
 * Open more files than allowed by the fd tracker's cap and write,
 * byte-by-byte, and in round-robin, a string. The goal is to force
 * the fd tracker to suspend and resume the fs_handles often and
 * verify that the fd cap is always respected.
 *
 * The content of the files is also verified at the end.
 */
static
void test_suspendable_restore(void)
{
	int ret;
	const int files_to_create = TRACKER_FD_LIMIT * 10;
	struct fd_tracker *tracker;
	char tmp_path_pattern[] = TMP_DIR_PATTERN;
	const char *output_dir;
	char *output_files[files_to_create];
	struct fs_handle *handles[files_to_create];
	size_t content_index;
	int handle_index;
	bool write_success = true;
	bool fd_cap_respected = true;
	bool content_ok = true;

	memset(output_files, 0, sizeof(output_files));
	memset(handles, 0, sizeof(handles));

        tracker = fd_tracker_create(TRACKER_FD_LIMIT);
	if (!tracker) {
		return;
	}

        output_dir = mkdtemp(tmp_path_pattern);
	if (!output_dir) {
		diag("Failed to create temporary path of the form %s",
				TMP_DIR_PATTERN);
		assert(0);
	}

	ret = open_files(tracker, output_dir, files_to_create, handles,
			output_files);
	ok(!ret, "Created %d files with a limit of %d simultaneously-opened file descriptor",
			files_to_create, TRACKER_FD_LIMIT);
	diag("Check file descriptor count after opening %u files", files_to_create);
	check_fd_count(TRACKER_FD_LIMIT + STDIO_FD_COUNT + unknown_fds_count);

	for (content_index = 0; content_index < sizeof(file_contents); content_index++) {
		for (handle_index = 0; handle_index < files_to_create; handle_index++) {
			int fd;
			struct fs_handle *handle = handles[handle_index];
			const char *path = output_files[handle_index];

			fd = fs_handle_get_fd(handle);
			if (fd < 0) {
				write_success = false;
			        diag("Failed to restore fs_handle to %s",
					        path);
				goto skip_write;
			}

			do {
				ret = write(fd, file_contents + content_index, 1);
			} while (ret < 0 && errno == EINTR);

			if (ret != 1) {
				write_success = false;
			        PERROR("write() to %s failed", path);
				goto skip_write;
			}

			if (fd_count() >
					(TRACKER_FD_LIMIT + STDIO_FD_COUNT +
					unknown_fds_count)) {
				fd_cap_respected = false;
			}

		        fs_handle_put_fd(handle);
		}
	}
skip_write:
	ok(write_success, "Wrote reference string to %d files",
			files_to_create);
	ok(fd_cap_respected, "FD tracker enforced the file descriptor cap");

	/* Validate the contents of the files. */
	for (handle_index = 0; handle_index < files_to_create; handle_index++) {
		struct stat fd_stat;
		const char *path = output_files[handle_index];
		char read_buf[sizeof(file_contents)];
		char *read_pos;
		size_t to_read = sizeof(read_buf);
		int fd;

		fd = open(path, O_RDONLY);
		assert(fd >= 0);
		ret = fstat(fd, &fd_stat);
		assert(!ret);
		if (fd_stat.st_size != sizeof(file_contents)) {
			diag("Content size of file %s doesn't match, got %" PRId64 ", expected %zu",
					path, (int64_t) fd_stat.st_size,
					sizeof(file_contents));
			content_ok = false;
			(void) close(fd);
			break;
		}

		read_pos = read_buf;
		do {
			ret = read(fd, read_pos, to_read);
			if (ret > 0) {
				to_read -= ret;
				read_pos += ret;
			}
		} while (to_read && (ret < 0 && errno == EINTR));
		if (ret < 0) {
			content_ok = false;
			PERROR("Failed to read file %s", path);
			(void) close(fd);
			break;
		}

		if (strcmp(file_contents, read_buf)) {
			content_ok = false;
			diag("File content doesn't match the expectated string");
			(void) close(fd);
			break;
		}
		(void) close(fd);
	}
	ok(content_ok, "Files contain the expected content");
	ret = cleanup_files(tracker, output_dir, files_to_create, handles,
			output_files);
	ok(!ret, "Close all opened filesystem handles");
	(void) rmdir(output_dir);
	fd_tracker_destroy(tracker);	
}

int main(int argc, char **argv)
{
	plan_tests(NUM_TESTS);
	diag("File descriptor tracker unit tests");

	rcu_register_thread();

	unknown_fds_count = fd_count() - STDIO_FD_COUNT;
	assert(unknown_fds_count >= 0);

	diag("Unsuspendable - basic");
	test_unsuspendable_basic();
	diag("Unsuspendable - callback return values");
	test_unsuspendable_cb_return();
	diag("Unsuspendable - duplicate file descriptors");
	test_unsuspendable_duplicate();
	diag("Unsuspendable - closing an untracked file descriptor");
	test_unsuspendable_close_untracked();
	diag("Unsuspendable - check that file descritptor limit is enforced");
	test_unsuspendable_limit();

	diag("Suspendable - check that file descritptor limit is enforced");
	test_suspendable_limit();
	diag("Suspendable - restoration test");
	test_suspendable_restore();

	diag("Mixed - check that file descritptor limit is enforced");
	test_mixed_limit();

	rcu_unregister_thread();
	return exit_status();
}