tests: lib: c_lib: tests for C11 condition variables

Add tests for C11 condition variables.

Signed-off-by: Christopher Friedt <cfriedt@meta.com>

tests/lib/c_lib/thrd/src/cnd.c

@@ -0,0 +1,172 @@
+/*
+ * Copyright (c) 2023, Meta
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include "thrd.h"
+
+#include <stdint.h>
+#include <threads.h>
+
+#include <zephyr/ztest.h>
+
+#define WAIT_TIME_MS 100
+
+static struct libc_cnd_fixture {
+	/* shared between threads in tests */
+	cnd_t cond;
+	mtx_t mutex;
+
+	/* de-duplicate local variables in test cases */
+	int res1;
+	int res2;
+	thrd_t thrd1;
+	thrd_t thrd2;
+	bool do_timedwait;
+	bool is_broadcast;
+	struct timespec time_point;
+} _libc_cnd_fixture;
+
+ZTEST_F(libc_cnd, test_cnd_init_destroy)
+{
+	/* degenerate cases */
+	if (false) {
+		/* pthread_cond_init() pthread_cond_destroy() are not hardened against these */
+		zassert_equal(thrd_error, cnd_init(NULL));
+		zassert_equal(thrd_error, cnd_init((cnd_t *)BIOS_FOOD));
+		cnd_destroy(NULL);
+		cnd_destroy((cnd_t *)BIOS_FOOD);
+	}
+
+	/* happy path tested in before() / after() */
+}
+
+ZTEST_F(libc_cnd, test_cnd_errors)
+{
+	/* degenerate test cases */
+	if (false) {
+		/* pthread_cond_*() are not hardened against these */
+		zassert_equal(thrd_error, cnd_signal(NULL));
+		zassert_equal(thrd_error, cnd_broadcast(NULL));
+		zassert_equal(thrd_error, cnd_wait(NULL, NULL));
+		zassert_equal(thrd_error, cnd_wait(NULL, &fixture->mutex));
+		zassert_equal(thrd_error, cnd_wait(&fixture->cond, NULL));
+		zassert_equal(thrd_error, cnd_timedwait(NULL, NULL, NULL));
+		zassert_equal(thrd_error, cnd_timedwait(NULL, NULL, &fixture->time_point));
+		zassert_equal(thrd_error, cnd_timedwait(NULL, &fixture->mutex, NULL));
+		zassert_equal(thrd_error,
+			      cnd_timedwait(NULL, &fixture->mutex, &fixture->time_point));
+		zassert_equal(thrd_error, cnd_timedwait(&fixture->cond, NULL, NULL));
+		zassert_equal(thrd_error,
+			      cnd_timedwait(&fixture->cond, NULL, &fixture->time_point));
+		zassert_equal(thrd_error, cnd_timedwait(&fixture->cond, &fixture->mutex, NULL));
+	}
+}
+
+static int test_cnd_thread_fn(void *arg)
+{
+	int res = thrd_success;
+	struct timespec time_point;
+	struct libc_cnd_fixture *const fixture = arg;
+
+	if (fixture->do_timedwait) {
+		zassume_ok(clock_gettime(CLOCK_MONOTONIC, &time_point));
+		timespec_add_ms(&time_point, WAIT_TIME_MS);
+		res = cnd_timedwait(&fixture->cond, &fixture->mutex, &time_point);
+	} else {
+		res = cnd_wait(&fixture->cond, &fixture->mutex);
+	}
+
+	if (fixture->is_broadcast) {
+		/* re-signal so that the next thread wakes up too */
+		zassert_equal(thrd_success, cnd_signal(&fixture->cond));
+	}
+
+	(void)mtx_unlock(&fixture->mutex);
+
+	return res;
+}
+
+static void tst_cnd_common(struct libc_cnd_fixture *fixture, size_t wait_ms, bool th2, int exp1,
+			   int exp2)
+{
+	zassert_equal(thrd_success, mtx_lock(&fixture->mutex));
+
+	zassert_equal(thrd_success, thrd_create(&fixture->thrd1, test_cnd_thread_fn, fixture));
+	if (th2) {
+		zassert_equal(thrd_success,
+			      thrd_create(&fixture->thrd2, test_cnd_thread_fn, fixture));
+	}
+
+	k_msleep(wait_ms);
+
+	if (fixture->is_broadcast) {
+		zassert_equal(thrd_success, cnd_broadcast(&fixture->cond));
+	} else {
+		zassert_equal(thrd_success, cnd_signal(&fixture->cond));
+	}
+
+	zassert_equal(thrd_success, mtx_unlock(&fixture->mutex));
+
+	zassert_equal(thrd_success, thrd_join(fixture->thrd1, &fixture->res1));
+	if (th2) {
+		zassert_equal(thrd_success, thrd_join(fixture->thrd2, &fixture->res2));
+	}
+
+	zassert_equal(exp1, fixture->res1);
+	if (th2) {
+		zassert_equal(exp2, fixture->res2);
+	}
+}
+
+ZTEST_F(libc_cnd, test_cnd_signal_wait)
+{
+	tst_cnd_common(fixture, WAIT_TIME_MS / 2, false, thrd_success, DONT_CARE);
+}
+
+ZTEST_F(libc_cnd, test_cnd_signal_timedwait)
+{
+	fixture->do_timedwait = true;
+	tst_cnd_common(fixture, WAIT_TIME_MS / 2, false, thrd_success, DONT_CARE);
+}
+
+ZTEST_F(libc_cnd, test_cnd_timedwait_timeout)
+{
+	fixture->do_timedwait = true;
+	tst_cnd_common(fixture, WAIT_TIME_MS * 2, false, thrd_timedout, DONT_CARE);
+}
+
+ZTEST_F(libc_cnd, test_cnd_broadcast_wait)
+{
+	fixture->is_broadcast = true;
+	tst_cnd_common(fixture, WAIT_TIME_MS, true, thrd_success, thrd_success);
+}
+
+static void *setup(void)
+{
+	return &_libc_cnd_fixture;
+}
+
+static void before(void *arg)
+{
+	struct libc_cnd_fixture *const fixture = arg;
+
+	*fixture = (struct libc_cnd_fixture){
+		.res1 = FORTY_TWO,
+		.res2 = SEVENTY_THREE,
+	};
+
+	zassert_equal(thrd_success, mtx_init(&fixture->mutex, mtx_plain));
+	zassert_equal(thrd_success, cnd_init(&fixture->cond));
+}
+
+static void after(void *arg)
+{
+	struct libc_cnd_fixture *const fixture = arg;
+
+	cnd_destroy(&fixture->cond);
+	mtx_destroy(&fixture->mutex);
+}
+
+ZTEST_SUITE(libc_cnd, NULL, setup, before, after, NULL);