--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/test/test-tcp-writealot.c	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,185 @@
+/* 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>
+
+
+#define WRITES            3
+#if defined(__arm__) /* Decrease the chunks so the test passes on arm CI bots */
+#define CHUNKS_PER_WRITE  2048
+#else
+#define CHUNKS_PER_WRITE  4096
+#endif
+#define CHUNK_SIZE        10024 /* 10 kb */
+
+#define TOTAL_BYTES       (WRITES * CHUNKS_PER_WRITE * CHUNK_SIZE)
+
+static char* send_buffer;
+
+static int shutdown_cb_called = 0;
+static int connect_cb_called = 0;
+static int write_cb_called = 0;
+static int close_cb_called = 0;
+static size_t bytes_sent = 0;
+static size_t bytes_sent_done = 0;
+static size_t bytes_received_done = 0;
+
+static uv_connect_t connect_req;
+static uv_shutdown_t shutdown_req;
+static uv_write_t write_reqs[WRITES];
+
+
+static void alloc_cb(uv_handle_t* handle, size_t size, uv_buf_t* buf) {
+  buf->base = malloc(size);
+  buf->len = size;
+}
+
+
+static void close_cb(uv_handle_t* handle) {
+  ASSERT_NOT_NULL(handle);
+  close_cb_called++;
+}
+
+
+static void shutdown_cb(uv_shutdown_t* req, int status) {
+  uv_tcp_t* tcp;
+
+  ASSERT_PTR_EQ(req, &shutdown_req);
+  ASSERT_OK(status);
+
+  tcp = (uv_tcp_t*)(req->handle);
+
+  /* The write buffer should be empty by now. */
+  ASSERT_OK(tcp->write_queue_size);
+
+  /* Now we wait for the EOF */
+  shutdown_cb_called++;
+
+  /* We should have had all the writes called already. */
+  ASSERT_EQ(write_cb_called, WRITES);
+}
+
+
+static void read_cb(uv_stream_t* tcp, ssize_t nread, const uv_buf_t* buf) {
+  ASSERT_NOT_NULL(tcp);
+
+  if (nread >= 0) {
+    bytes_received_done += nread;
+  }
+  else {
+    ASSERT_EQ(nread, UV_EOF);
+    printf("GOT EOF\n");
+    uv_close((uv_handle_t*)tcp, close_cb);
+  }
+
+  free(buf->base);
+}
+
+
+static void write_cb(uv_write_t* req, int status) {
+  ASSERT_NOT_NULL(req);
+
+  if (status) {
+    fprintf(stderr, "uv_write error: %s\n", uv_strerror(status));
+    ASSERT(0);
+  }
+
+  bytes_sent_done += CHUNKS_PER_WRITE * CHUNK_SIZE;
+  write_cb_called++;
+}
+
+
+static void connect_cb(uv_connect_t* req, int status) {
+  uv_buf_t send_bufs[CHUNKS_PER_WRITE];
+  uv_stream_t* stream;
+  int i, j, r;
+
+  ASSERT_PTR_EQ(req, &connect_req);
+  ASSERT_OK(status);
+
+  stream = req->handle;
+  connect_cb_called++;
+
+  /* Write a lot of data */
+  for (i = 0; i < WRITES; i++) {
+    uv_write_t* write_req = write_reqs + i;
+
+    for (j = 0; j < CHUNKS_PER_WRITE; j++) {
+      send_bufs[j] = uv_buf_init(send_buffer + bytes_sent, CHUNK_SIZE);
+      bytes_sent += CHUNK_SIZE;
+    }
+
+    r = uv_write(write_req, stream, send_bufs, CHUNKS_PER_WRITE, write_cb);
+    ASSERT_OK(r);
+  }
+
+  /* Shutdown on drain. */
+  r = uv_shutdown(&shutdown_req, stream, shutdown_cb);
+  ASSERT_OK(r);
+
+  /* Start reading */
+  r = uv_read_start(stream, alloc_cb, read_cb);
+  ASSERT_OK(r);
+}
+
+
+TEST_IMPL(tcp_writealot) {
+  struct sockaddr_in addr;
+  uv_tcp_t client;
+  int r;
+
+#if defined(__MSAN__) || defined(__TSAN__)
+  RETURN_SKIP("Test is too slow to run under "
+              "MemorySanitizer or ThreadSanitizer");
+#endif
+
+  ASSERT_OK(uv_ip4_addr("127.0.0.1", TEST_PORT, &addr));
+
+  send_buffer = calloc(1, TOTAL_BYTES);
+  ASSERT_NOT_NULL(send_buffer);
+
+  r = uv_tcp_init(uv_default_loop(), &client);
+  ASSERT_OK(r);
+
+  r = uv_tcp_connect(&connect_req,
+                     &client,
+                     (const struct sockaddr*) &addr,
+                     connect_cb);
+  ASSERT_OK(r);
+
+  uv_run(uv_default_loop(), UV_RUN_DEFAULT);
+
+  ASSERT_EQ(1, shutdown_cb_called);
+  ASSERT_EQ(1, connect_cb_called);
+  ASSERT_EQ(write_cb_called, WRITES);
+  ASSERT_EQ(1, close_cb_called);
+  ASSERT_EQ(bytes_sent, TOTAL_BYTES);
+  ASSERT_EQ(bytes_sent_done, TOTAL_BYTES);
+  ASSERT_EQ(bytes_received_done, TOTAL_BYTES);
+
+  free(send_buffer);
+
+  MAKE_VALGRIND_HAPPY(uv_default_loop());
+  return 0;
+}