--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/test/test-loop-handles.c	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,337 @@
+/* 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.
+ */
+
+/* Tests commented out with XXX are ones that are failing on Linux */
+
+/*
+ * Purpose of this test is to check semantics of starting and stopping
+ * prepare, check and idle watchers.
+ *
+ * - A watcher must be able to safely stop or close itself;
+ * - Once a watcher is stopped or closed its callback should never be called.
+ * - If a watcher is closed, it is implicitly stopped and its close_cb should
+ *   be called exactly once.
+ * - A watcher can safely start and stop other watchers of the same type.
+ * - Prepare and check watchers are called once per event loop iterations.
+ * - All active idle watchers are queued when the event loop has no more work
+ *   to do. This is done repeatedly until all idle watchers are inactive.
+ * - If a watcher starts another watcher of the same type its callback is not
+ *   immediately queued. For check and prepare watchers, that means that if
+ *   a watcher makes another of the same type active, it'll not be called until
+ *   the next event loop iteration. For idle. watchers this means that the
+ *   newly activated idle watcher might not be queued immediately.
+ * - Prepare, check, idle watchers keep the event loop alive even when they're
+ *   not active.
+ *
+ * This is what the test globally does:
+ *
+ * - prepare_1 is always active and counts event loop iterations. It also
+ *   creates and starts prepare_2 every other iteration. Finally it verifies
+ *   that no idle watchers are active before polling.
+ * - prepare_2 is started by prepare_1 every other iteration. It immediately
+ *   stops itself. It verifies that a watcher is not queued immediately
+ *   if created by another watcher of the same type.
+ * - There's a check watcher that stops the event loop after a certain number
+ *   of iterations. It starts a varying number of idle_1 watchers.
+ * - Idle_1 watchers stop themselves after being called a few times. All idle_1
+ *   watchers try to start the idle_2 watcher if it is not already started or
+ *   awaiting its close callback.
+ * - The idle_2 watcher always exists but immediately closes itself after
+ *   being started by a check_1 watcher. It verifies that a watcher is
+ *   implicitly stopped when closed, and that a watcher can close itself
+ *   safely.
+ * - There is a repeating timer. It does not keep the event loop alive
+ *   (ev_unref) but makes sure that the loop keeps polling the system for
+ *   events.
+ */
+
+
+#include "uv.h"
+#include "task.h"
+
+#include <math.h>
+
+
+#define IDLE_COUNT      7
+#define ITERATIONS      21
+#define TIMEOUT         100
+
+
+static uv_prepare_t prepare_1_handle;
+static uv_prepare_t prepare_2_handle;
+
+static uv_check_t check_handle;
+
+static uv_idle_t idle_1_handles[IDLE_COUNT];
+static uv_idle_t idle_2_handle;
+
+static uv_timer_t timer_handle;
+
+
+static int loop_iteration = 0;
+
+static int prepare_1_cb_called = 0;
+static int prepare_1_close_cb_called = 0;
+
+static int prepare_2_cb_called = 0;
+static int prepare_2_close_cb_called = 0;
+
+static int check_cb_called = 0;
+static int check_close_cb_called = 0;
+
+static int idle_1_cb_called = 0;
+static int idle_1_close_cb_called = 0;
+static int idles_1_active = 0;
+
+static int idle_2_cb_called = 0;
+static int idle_2_close_cb_called = 0;
+static int idle_2_cb_started = 0;
+static int idle_2_is_active = 0;
+
+
+static void timer_cb(uv_timer_t* handle) {
+  ASSERT_PTR_EQ(handle, &timer_handle);
+}
+
+
+static void idle_2_close_cb(uv_handle_t* handle) {
+  fprintf(stderr, "%s", "IDLE_2_CLOSE_CB\n");
+  fflush(stderr);
+
+  ASSERT_PTR_EQ(handle, (uv_handle_t*)&idle_2_handle);
+
+  ASSERT(idle_2_is_active);
+
+  idle_2_close_cb_called++;
+  idle_2_is_active = 0;
+}
+
+
+static void idle_2_cb(uv_idle_t* handle) {
+  fprintf(stderr, "%s", "IDLE_2_CB\n");
+  fflush(stderr);
+
+  ASSERT_PTR_EQ(handle, &idle_2_handle);
+
+  idle_2_cb_called++;
+
+  uv_close((uv_handle_t*)handle, idle_2_close_cb);
+}
+
+
+static void idle_1_cb(uv_idle_t* handle) {
+  int r;
+
+  fprintf(stderr, "%s", "IDLE_1_CB\n");
+  fflush(stderr);
+
+  ASSERT_NOT_NULL(handle);
+  ASSERT_GT(idles_1_active, 0);
+
+  /* Init idle_2 and make it active */
+  if (!idle_2_is_active && !uv_is_closing((uv_handle_t*)&idle_2_handle)) {
+    r = uv_idle_init(uv_default_loop(), &idle_2_handle);
+    ASSERT_OK(r);
+    r = uv_idle_start(&idle_2_handle, idle_2_cb);
+    ASSERT_OK(r);
+    idle_2_is_active = 1;
+    idle_2_cb_started++;
+  }
+
+  idle_1_cb_called++;
+
+  if (idle_1_cb_called % 5 == 0) {
+    r = uv_idle_stop((uv_idle_t*)handle);
+    ASSERT_OK(r);
+    idles_1_active--;
+  }
+}
+
+
+static void idle_1_close_cb(uv_handle_t* handle) {
+  fprintf(stderr, "%s", "IDLE_1_CLOSE_CB\n");
+  fflush(stderr);
+
+  ASSERT_NOT_NULL(handle);
+
+  idle_1_close_cb_called++;
+}
+
+
+static void prepare_1_close_cb(uv_handle_t* handle) {
+  fprintf(stderr, "%s", "PREPARE_1_CLOSE_CB");
+  fflush(stderr);
+  ASSERT_PTR_EQ(handle, (uv_handle_t*)&prepare_1_handle);
+
+  prepare_1_close_cb_called++;
+}
+
+
+static void check_close_cb(uv_handle_t* handle) {
+  fprintf(stderr, "%s", "CHECK_CLOSE_CB\n");
+  fflush(stderr);
+  ASSERT_PTR_EQ(handle, (uv_handle_t*)&check_handle);
+
+  check_close_cb_called++;
+}
+
+
+static void prepare_2_close_cb(uv_handle_t* handle) {
+  fprintf(stderr, "%s", "PREPARE_2_CLOSE_CB\n");
+  fflush(stderr);
+  ASSERT_PTR_EQ(handle, (uv_handle_t*)&prepare_2_handle);
+
+  prepare_2_close_cb_called++;
+}
+
+
+static void check_cb(uv_check_t* handle) {
+  int i, r;
+
+  fprintf(stderr, "%s", "CHECK_CB\n");
+  fflush(stderr);
+  ASSERT_PTR_EQ(handle, &check_handle);
+
+  if (loop_iteration < ITERATIONS) {
+    /* Make some idle watchers active */
+    for (i = 0; i < 1 + (loop_iteration % IDLE_COUNT); i++) {
+      r = uv_idle_start(&idle_1_handles[i], idle_1_cb);
+      ASSERT_OK(r);
+      idles_1_active++;
+    }
+
+  } else {
+    /* End of the test - close all handles */
+    uv_close((uv_handle_t*)&prepare_1_handle, prepare_1_close_cb);
+    uv_close((uv_handle_t*)&check_handle, check_close_cb);
+    uv_close((uv_handle_t*)&prepare_2_handle, prepare_2_close_cb);
+
+    for (i = 0; i < IDLE_COUNT; i++) {
+      uv_close((uv_handle_t*)&idle_1_handles[i], idle_1_close_cb);
+    }
+
+    /* This handle is closed/recreated every time, close it only if it is
+     * active. */
+    if (idle_2_is_active) {
+      uv_close((uv_handle_t*)&idle_2_handle, idle_2_close_cb);
+    }
+  }
+
+  check_cb_called++;
+}
+
+
+static void prepare_2_cb(uv_prepare_t* handle) {
+  int r;
+
+  fprintf(stderr, "%s", "PREPARE_2_CB\n");
+  fflush(stderr);
+  ASSERT_PTR_EQ(handle, &prepare_2_handle);
+
+  /* Prepare_2 gets started by prepare_1 when (loop_iteration % 2 == 0), and it
+   * stops itself immediately. A started watcher is not queued until the next
+   * round, so when this callback is made (loop_iteration % 2 == 0) cannot be
+   * true. */
+  ASSERT_NE(0, loop_iteration % 2);
+
+  r = uv_prepare_stop((uv_prepare_t*)handle);
+  ASSERT_OK(r);
+
+  prepare_2_cb_called++;
+}
+
+
+static void prepare_1_cb(uv_prepare_t* handle) {
+  int r;
+
+  fprintf(stderr, "%s", "PREPARE_1_CB\n");
+  fflush(stderr);
+  ASSERT_PTR_EQ(handle, &prepare_1_handle);
+
+  if (loop_iteration % 2 == 0) {
+    r = uv_prepare_start(&prepare_2_handle, prepare_2_cb);
+    ASSERT_OK(r);
+  }
+
+  prepare_1_cb_called++;
+  loop_iteration++;
+
+  printf("Loop iteration %d of %d.\n", loop_iteration, ITERATIONS);
+}
+
+
+TEST_IMPL(loop_handles) {
+  int i;
+  int r;
+
+  r = uv_prepare_init(uv_default_loop(), &prepare_1_handle);
+  ASSERT_OK(r);
+  r = uv_prepare_start(&prepare_1_handle, prepare_1_cb);
+  ASSERT_OK(r);
+
+  r = uv_check_init(uv_default_loop(), &check_handle);
+  ASSERT_OK(r);
+  r = uv_check_start(&check_handle, check_cb);
+  ASSERT_OK(r);
+
+  /* initialize only, prepare_2 is started by prepare_1_cb */
+  r = uv_prepare_init(uv_default_loop(), &prepare_2_handle);
+  ASSERT_OK(r);
+
+  for (i = 0; i < IDLE_COUNT; i++) {
+    /* initialize only, idle_1 handles are started by check_cb */
+    r = uv_idle_init(uv_default_loop(), &idle_1_handles[i]);
+    ASSERT_OK(r);
+  }
+
+  /* don't init or start idle_2, both is done by idle_1_cb */
+
+  /* The timer callback is there to keep the event loop polling unref it as it
+   * is not supposed to keep the loop alive */
+  r = uv_timer_init(uv_default_loop(), &timer_handle);
+  ASSERT_OK(r);
+  r = uv_timer_start(&timer_handle, timer_cb, TIMEOUT, TIMEOUT);
+  ASSERT_OK(r);
+  uv_unref((uv_handle_t*)&timer_handle);
+
+  r = uv_run(uv_default_loop(), UV_RUN_DEFAULT);
+  ASSERT_OK(r);
+
+  ASSERT_EQ(loop_iteration, ITERATIONS);
+
+  ASSERT_EQ(prepare_1_cb_called, ITERATIONS);
+  ASSERT_EQ(1, prepare_1_close_cb_called);
+
+  ASSERT_EQ(prepare_2_cb_called, ITERATIONS / 2);
+  ASSERT_EQ(1, prepare_2_close_cb_called);
+
+  ASSERT_EQ(check_cb_called, ITERATIONS);
+  ASSERT_EQ(1, check_close_cb_called);
+
+  /* idle_1_cb should be called a lot */
+  ASSERT_EQ(idle_1_close_cb_called, IDLE_COUNT);
+
+  ASSERT_EQ(idle_2_close_cb_called, idle_2_cb_started);
+  ASSERT_OK(idle_2_is_active);
+
+  MAKE_VALGRIND_HAPPY(uv_default_loop());
+  return 0;
+}