--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/test/test-semaphore.c	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,111 @@
+/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "uv.h"
+#include "task.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct {
+  uv_mutex_t mutex;
+  uv_sem_t sem;
+  int delay;
+  volatile int posted;
+} worker_config;
+
+
+static void worker(void* arg) {
+  worker_config* c = arg;
+
+  if (c->delay)
+    uv_sleep(c->delay);
+
+  uv_mutex_lock(&c->mutex);
+  ASSERT_OK(c->posted);
+  uv_sem_post(&c->sem);
+  c->posted = 1;
+  uv_mutex_unlock(&c->mutex);
+}
+
+
+TEST_IMPL(semaphore_1) {
+  uv_thread_t thread;
+  worker_config wc;
+
+  memset(&wc, 0, sizeof(wc));
+
+  ASSERT_OK(uv_sem_init(&wc.sem, 0));
+  ASSERT_OK(uv_mutex_init(&wc.mutex));
+  ASSERT_OK(uv_thread_create(&thread, worker, &wc));
+
+  uv_sleep(100);
+  uv_mutex_lock(&wc.mutex);
+  ASSERT_EQ(1, wc.posted);
+  uv_sem_wait(&wc.sem); /* should not block */
+  uv_mutex_unlock(&wc.mutex); /* ergo, it should be ok to unlock after wait */
+
+  ASSERT_OK(uv_thread_join(&thread));
+  uv_mutex_destroy(&wc.mutex);
+  uv_sem_destroy(&wc.sem);
+
+  return 0;
+}
+
+
+TEST_IMPL(semaphore_2) {
+  uv_thread_t thread;
+  worker_config wc;
+
+  memset(&wc, 0, sizeof(wc));
+  wc.delay = 100;
+
+  ASSERT_OK(uv_sem_init(&wc.sem, 0));
+  ASSERT_OK(uv_mutex_init(&wc.mutex));
+  ASSERT_OK(uv_thread_create(&thread, worker, &wc));
+
+  uv_sem_wait(&wc.sem);
+
+  ASSERT_OK(uv_thread_join(&thread));
+  uv_mutex_destroy(&wc.mutex);
+  uv_sem_destroy(&wc.sem);
+
+  return 0;
+}
+
+
+TEST_IMPL(semaphore_3) {
+  uv_sem_t sem;
+
+  ASSERT_OK(uv_sem_init(&sem, 3));
+  uv_sem_wait(&sem); /* should not block */
+  uv_sem_wait(&sem); /* should not block */
+  ASSERT_OK(uv_sem_trywait(&sem));
+  ASSERT_EQ(UV_EAGAIN, uv_sem_trywait(&sem));
+
+  uv_sem_post(&sem);
+  ASSERT_OK(uv_sem_trywait(&sem));
+  ASSERT_EQ(UV_EAGAIN, uv_sem_trywait(&sem));
+
+  uv_sem_destroy(&sem);
+
+  return 0;
+}