--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/test/test-barrier.c	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,160 @@
+/* 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 <string.h>
+#include <errno.h>
+
+typedef struct {
+  uv_barrier_t barrier;
+  unsigned delay;
+  unsigned niter;
+  unsigned main_barrier_wait_rval;
+  unsigned worker_barrier_wait_rval;
+} worker_config;
+
+
+static void worker(void* arg) {
+  worker_config* c = arg;
+  unsigned i;
+
+  if (c->delay)
+    uv_sleep(c->delay);
+
+  for (i = 0; i < c->niter; i++)
+    c->worker_barrier_wait_rval += uv_barrier_wait(&c->barrier);
+}
+
+
+TEST_IMPL(barrier_1) {
+  uv_thread_t thread;
+  worker_config wc;
+
+  memset(&wc, 0, sizeof(wc));
+  wc.niter = 1;
+
+  ASSERT_OK(uv_barrier_init(&wc.barrier, 2));
+  ASSERT_OK(uv_thread_create(&thread, worker, &wc));
+
+  uv_sleep(100);
+  wc.main_barrier_wait_rval = uv_barrier_wait(&wc.barrier);
+
+  ASSERT_OK(uv_thread_join(&thread));
+  uv_barrier_destroy(&wc.barrier);
+
+  ASSERT_EQ(1, (wc.main_barrier_wait_rval ^ wc.worker_barrier_wait_rval));
+
+  return 0;
+}
+
+
+TEST_IMPL(barrier_2) {
+  uv_thread_t thread;
+  worker_config wc;
+
+  memset(&wc, 0, sizeof(wc));
+  wc.delay = 100;
+  wc.niter = 1;
+
+  ASSERT_OK(uv_barrier_init(&wc.barrier, 2));
+  ASSERT_OK(uv_thread_create(&thread, worker, &wc));
+
+  wc.main_barrier_wait_rval = uv_barrier_wait(&wc.barrier);
+
+  ASSERT_OK(uv_thread_join(&thread));
+  uv_barrier_destroy(&wc.barrier);
+
+  ASSERT_EQ(1, (wc.main_barrier_wait_rval ^ wc.worker_barrier_wait_rval));
+
+  return 0;
+}
+
+
+TEST_IMPL(barrier_3) {
+  uv_thread_t thread;
+  worker_config wc;
+  unsigned i;
+
+  memset(&wc, 0, sizeof(wc));
+  wc.niter = 5;
+
+  ASSERT_OK(uv_barrier_init(&wc.barrier, 2));
+  ASSERT_OK(uv_thread_create(&thread, worker, &wc));
+
+  for (i = 0; i < wc.niter; i++)
+    wc.main_barrier_wait_rval += uv_barrier_wait(&wc.barrier);
+
+  ASSERT_OK(uv_thread_join(&thread));
+  uv_barrier_destroy(&wc.barrier);
+
+  ASSERT_EQ(wc.niter, wc.main_barrier_wait_rval + wc.worker_barrier_wait_rval);
+
+  return 0;
+}
+
+static void serial_worker(void* data) {
+  uv_barrier_t* barrier;
+  unsigned i;
+
+  barrier = data;
+  for (i = 0; i < 5; i++)
+    uv_barrier_wait(barrier);
+  if (uv_barrier_wait(barrier) > 0)
+    uv_barrier_destroy(barrier);
+
+  uv_sleep(100);  /* Wait a bit before terminating. */
+}
+
+/* Ensure that uv_barrier_wait returns positive only after all threads have
+ * exited the barrier. If this value is returned too early and the barrier is
+ * destroyed prematurely, then this test may see a crash. */
+TEST_IMPL(barrier_serial_thread) {
+  uv_thread_t threads[4];
+  uv_barrier_t barrier;
+  unsigned i;
+
+  ASSERT_OK(uv_barrier_init(&barrier, ARRAY_SIZE(threads) + 1));
+
+  for (i = 0; i < ARRAY_SIZE(threads); ++i)
+    ASSERT_OK(uv_thread_create(&threads[i], serial_worker, &barrier));
+
+  for (i = 0; i < 5; i++)
+    uv_barrier_wait(&barrier);
+  if (uv_barrier_wait(&barrier) > 0)
+    uv_barrier_destroy(&barrier);
+
+  for (i = 0; i < ARRAY_SIZE(threads); ++i)
+    ASSERT_OK(uv_thread_join(&threads[i]));
+
+  return 0;
+}
+
+/* Single thread uv_barrier_wait should return correct return value. */
+TEST_IMPL(barrier_serial_thread_single) {
+  uv_barrier_t barrier;
+
+  ASSERT_OK(uv_barrier_init(&barrier, 1));
+  ASSERT_LT(0, uv_barrier_wait(&barrier));
+  uv_barrier_destroy(&barrier);
+  return 0;
+}