--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/test/test-pipe-set-fchmod.c	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,92 @@
+/* Copyright libuv project 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>
+
+TEST_IMPL(pipe_set_chmod) {
+  uv_pipe_t pipe_handle;
+  uv_loop_t* loop;
+  int r;
+#ifndef _WIN32
+  struct stat stat_buf;
+#endif
+
+  loop = uv_default_loop();
+
+  r = uv_pipe_init(loop, &pipe_handle, 0);
+  ASSERT_OK(r);
+
+  r = uv_pipe_bind(&pipe_handle, TEST_PIPENAME);
+  ASSERT_OK(r);
+
+  /* No easy way to test if this works, we will only make sure that the call is
+   * successful. */
+  r = uv_pipe_chmod(&pipe_handle, UV_READABLE);
+  if (r == UV_EPERM) {
+    MAKE_VALGRIND_HAPPY(loop);
+    RETURN_SKIP("Insufficient privileges to alter pipe fmode");
+  }
+  ASSERT_OK(r);
+#ifndef _WIN32
+  memset(&stat_buf, 0, sizeof(stat_buf));
+  ASSERT_OK(stat(TEST_PIPENAME, &stat_buf));
+  ASSERT(stat_buf.st_mode & S_IRUSR);
+  ASSERT(stat_buf.st_mode & S_IRGRP);
+  ASSERT(stat_buf.st_mode & S_IROTH);
+#endif
+
+  r = uv_pipe_chmod(&pipe_handle, UV_WRITABLE);
+  ASSERT_OK(r);
+#ifndef _WIN32
+  stat(TEST_PIPENAME, &stat_buf);
+  ASSERT(stat_buf.st_mode & S_IWUSR);
+  ASSERT(stat_buf.st_mode & S_IWGRP);
+  ASSERT(stat_buf.st_mode & S_IWOTH);
+#endif
+
+  r = uv_pipe_chmod(&pipe_handle, UV_WRITABLE | UV_READABLE);
+  ASSERT_OK(r);
+#ifndef _WIN32
+  stat(TEST_PIPENAME, &stat_buf);
+  ASSERT(stat_buf.st_mode & S_IRUSR);
+  ASSERT(stat_buf.st_mode & S_IRGRP);
+  ASSERT(stat_buf.st_mode & S_IROTH);
+  ASSERT(stat_buf.st_mode & S_IWUSR);
+  ASSERT(stat_buf.st_mode & S_IWGRP);
+  ASSERT(stat_buf.st_mode & S_IWOTH);
+#endif
+
+  r = uv_pipe_chmod(NULL, UV_WRITABLE | UV_READABLE);
+  ASSERT_EQ(r, UV_EBADF);
+
+  r = uv_pipe_chmod(&pipe_handle, 12345678);
+  ASSERT_EQ(r, UV_EINVAL);
+
+  uv_close((uv_handle_t*)&pipe_handle, NULL);
+  r = uv_pipe_chmod(&pipe_handle, UV_WRITABLE | UV_READABLE);
+  ASSERT_EQ(r, UV_EBADF);
+
+  MAKE_VALGRIND_HAPPY(loop);
+  return 0;
+}