--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/test/test-tcp-try-write.c	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,135 @@
+/* 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 <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define MAX_BYTES 1024 * 1024
+
+static uv_tcp_t server;
+static uv_tcp_t client;
+static uv_tcp_t incoming;
+static int connect_cb_called;
+static int close_cb_called;
+static int connection_cb_called;
+static int bytes_read;
+static int bytes_written;
+
+
+static void close_cb(uv_handle_t* handle) {
+  close_cb_called++;
+}
+
+
+static void connect_cb(uv_connect_t* req, int status) {
+  int r;
+  uv_buf_t buf;
+  ASSERT_OK(status);
+  connect_cb_called++;
+
+  do {
+    buf = uv_buf_init("PING", 4);
+    r = uv_try_write((uv_stream_t*) &client, &buf, 1);
+    ASSERT(r > 0 || r == UV_EAGAIN);
+    if (r > 0) {
+      bytes_written += r;
+      break;
+    }
+  } while (1);
+
+  do {
+    buf = uv_buf_init("", 0);
+    r = uv_try_write((uv_stream_t*) &client, &buf, 1);
+  } while (r != 0);
+  uv_close((uv_handle_t*) &client, close_cb);
+}
+
+
+static void alloc_cb(uv_handle_t* handle, size_t size, uv_buf_t* buf) {
+  static char base[1024];
+
+  buf->base = base;
+  buf->len = sizeof(base);
+}
+
+
+static void read_cb(uv_stream_t* tcp, ssize_t nread, const uv_buf_t* buf) {
+  if (nread < 0) {
+    uv_close((uv_handle_t*) tcp, close_cb);
+    uv_close((uv_handle_t*) &server, close_cb);
+    return;
+  }
+
+  bytes_read += nread;
+}
+
+
+static void connection_cb(uv_stream_t* tcp, int status) {
+  ASSERT_OK(status);
+
+  ASSERT_OK(uv_tcp_init(tcp->loop, &incoming));
+  ASSERT_OK(uv_accept(tcp, (uv_stream_t*) &incoming));
+
+  connection_cb_called++;
+  ASSERT_OK(uv_read_start((uv_stream_t*) &incoming, alloc_cb, read_cb));
+}
+
+
+static void start_server(void) {
+  struct sockaddr_in addr;
+
+  ASSERT_OK(uv_ip4_addr("0.0.0.0", TEST_PORT, &addr));
+
+  ASSERT_OK(uv_tcp_init(uv_default_loop(), &server));
+  ASSERT_OK(uv_tcp_bind(&server, (struct sockaddr*) &addr, 0));
+  ASSERT_OK(uv_listen((uv_stream_t*) &server, 128, connection_cb));
+}
+
+
+TEST_IMPL(tcp_try_write) {
+  uv_connect_t connect_req;
+  struct sockaddr_in addr;
+
+  start_server();
+
+  ASSERT_OK(uv_ip4_addr("127.0.0.1", TEST_PORT, &addr));
+
+  ASSERT_OK(uv_tcp_init(uv_default_loop(), &client));
+  ASSERT_OK(uv_tcp_connect(&connect_req,
+                           &client,
+                           (struct sockaddr*) &addr,
+                           connect_cb));
+
+  ASSERT_OK(uv_run(uv_default_loop(), UV_RUN_DEFAULT));
+
+  ASSERT_EQ(1, connect_cb_called);
+  ASSERT_EQ(3, close_cb_called);
+  ASSERT_EQ(1, connection_cb_called);
+  ASSERT_EQ(bytes_read, bytes_written);
+  ASSERT_GT(bytes_written, 0);
+
+  MAKE_VALGRIND_HAPPY(uv_default_loop());
+  return 0;
+}