From 7cda217af3e0343b22d044a2bf34f50f5b676f4d Mon Sep 17 00:00:00 2001
From: Aizen200 <yatinbisht407@gmail.com>
Date: Fri, 5 Dec 2025 10:13:53 +0530
Subject: [PATCH] win,fs: fix mkdir returning EPERM on network drives

On Windows network drives (SSHFS/FTP), CreateDirectoryW returns
ERROR_ACCESS_DENIED instead of ERROR_ALREADY_EXISTS when a
directory already exists. This caused uv_fs_mkdir to return
UV_EPERM instead of the expected UV_EEXIST.

Fix by checking if ERROR_ACCESS_DENIED refers to an existing
directory and mapping it to UV_EEXIST.

Fixes: #4959
---
 src/win/fs.c     | 11 +++++++++++
 test/test-fs.c   | 27 +++++++++++++++++++++++++++
 test/test-list.h |  2 ++
 3 files changed, 40 insertions(+)

diff --git a/src/win/fs.c b/src/win/fs.c
index cc2e8db94..d7ee9ce76 100644
--- a/src/win/fs.c
+++ b/src/win/fs.c
@@ -1253,11 +1253,22 @@ static void fs__unlink(uv_fs_t* req) {
 
 
 void fs__mkdir(uv_fs_t* req) {
+  DWORD attr;
+
   /* TODO: use req->mode. */
   if (CreateDirectoryW(req->file.pathw, NULL)) {
     SET_REQ_RESULT(req, 0);
   } else {
     SET_REQ_WIN32_ERROR(req, GetLastError());
+    if (req->sys_errno_ == ERROR_ACCESS_DENIED) {
+      /* Check if the directory already exists. */
+      attr = GetFileAttributesW(req->file.pathw);
+      if (attr != INVALID_FILE_ATTRIBUTES &&
+          (attr & FILE_ATTRIBUTE_DIRECTORY)) {
+        req->sys_errno_ = ERROR_ALREADY_EXISTS;
+        req->result = UV_EEXIST;
+      }
+    }
     if (req->sys_errno_ == ERROR_INVALID_NAME ||
         req->sys_errno_ == ERROR_DIRECTORY)
       req->result = UV_EINVAL;
diff --git a/test/test-fs.c b/test/test-fs.c
index 4ce059c39..0e7abc0d2 100644
--- a/test/test-fs.c
+++ b/test/test-fs.c
@@ -4928,3 +4928,30 @@ TEST_IMPL(fs_wtf) {
   return 0;
 }
 #endif
+
+TEST_IMPL(fs_mkdir_existing) {
+  int r;
+  uv_fs_t req;
+
+  loop = uv_default_loop();
+
+  /* Setup */
+  unlink("test_dir/file");
+  rmdir("test_dir");
+
+  /* Create directory */
+  r = uv_fs_mkdir(NULL, &req, "test_dir", 0755, NULL);
+  ASSERT_OK(r);
+  uv_fs_req_cleanup(&req);
+
+  /* Create directory again - synchronous */
+  r = uv_fs_mkdir(NULL, &req, "test_dir", 0755, NULL);
+  ASSERT_EQ(r, UV_EEXIST);
+  uv_fs_req_cleanup(&req);
+
+  /* Cleanup */
+  rmdir("test_dir");
+
+  MAKE_VALGRIND_HAPPY(loop);
+  return 0;
+}
diff --git a/test/test-list.h b/test/test-list.h
index 954eff330..467130c32 100644
--- a/test/test-list.h
+++ b/test/test-list.h
@@ -365,6 +365,7 @@ TEST_DECLARE   (fs_async_dir)
 TEST_DECLARE   (fs_async_sendfile)
 TEST_DECLARE   (fs_async_sendfile_nodata)
 TEST_DECLARE   (fs_mkdtemp)
+TEST_DECLARE   (fs_mkdir_existing)
 TEST_DECLARE   (fs_mkstemp)
 TEST_DECLARE   (fs_fstat)
 TEST_DECLARE   (fs_fstat_stdio)
@@ -1089,6 +1090,7 @@ TASK_LIST_START
   TEST_ENTRY  (fs_async_sendfile)
   TEST_ENTRY  (fs_async_sendfile_nodata)
   TEST_ENTRY  (fs_mkdtemp)
+  TEST_ENTRY  (fs_mkdir_existing)
   TEST_ENTRY  (fs_mkstemp)
   TEST_ENTRY  (fs_fstat)
   TEST_ENTRY  (fs_fstat_stdio)