From 7fd7e8264f4430e642ac21dc386aed2f99f5f567 Mon Sep 17 00:00:00 2001
From: Darshan Sen <raisinten@gmail.com>
Date: Wed, 18 Jan 2023 08:34:52 +0530
Subject: [PATCH] win,fs: fix readlink errno for a non-symlink file (#3719)

In Node.js, fs.readlink() on a non-symlink file used to throw an UNKNOWN
error on Windows. This change maps ERROR_NOT_A_REPARSE_POINT to
UV_EINVAL, so that now it throws EINVAL just like other platforms.

This is handled explicitly in `fs__readlink`, since elsewhere it might
map to EPERM instead (such as in `link`).
---
 src/win/fs.c   |  5 ++++-
 test/test-fs.c | 57 +++++++++++++++++++++++++++++++++++++++-----------
 2 files changed, 49 insertions(+), 13 deletions(-)

diff --git a/src/win/fs.c b/src/win/fs.c
index efc23934..1f813c3e 100644
--- a/src/win/fs.c
+++ b/src/win/fs.c
@@ -2662,7 +2662,10 @@ static void fs__readlink(uv_fs_t* req) {
   }
 
   if (fs__readlink_handle(handle, (char**) &req->ptr, NULL) != 0) {
-    SET_REQ_WIN32_ERROR(req, GetLastError());
+    DWORD error = GetLastError();
+    SET_REQ_WIN32_ERROR(req, error);
+    if (error == ERROR_NOT_A_REPARSE_POINT)
+      req->result = UV_EINVAL;
     CloseHandle(handle);
     return;
   }
diff --git a/test/test-fs.c b/test/test-fs.c
index ebf41050..3d7b7008 100644
--- a/test/test-fs.c
+++ b/test/test-fs.c
@@ -2047,20 +2047,53 @@ TEST_IMPL(fs_link) {
 
 
 TEST_IMPL(fs_readlink) {
-  uv_fs_t req;
+  /* Must return UV_ENOENT on an inexistent file */
+  {
+    uv_fs_t req;
 
-  loop = uv_default_loop();
-  ASSERT(0 == uv_fs_readlink(loop, &req, "no_such_file", dummy_cb));
-  ASSERT(0 == uv_run(loop, UV_RUN_DEFAULT));
-  ASSERT(dummy_cb_count == 1);
-  ASSERT_NULL(req.ptr);
-  ASSERT(req.result == UV_ENOENT);
-  uv_fs_req_cleanup(&req);
+    loop = uv_default_loop();
+    ASSERT(0 == uv_fs_readlink(loop, &req, "no_such_file", dummy_cb));
+    ASSERT(0 == uv_run(loop, UV_RUN_DEFAULT));
+    ASSERT(dummy_cb_count == 1);
+    ASSERT_NULL(req.ptr);
+    ASSERT(req.result == UV_ENOENT);
+    uv_fs_req_cleanup(&req);
 
-  ASSERT(UV_ENOENT == uv_fs_readlink(NULL, &req, "no_such_file", NULL));
-  ASSERT_NULL(req.ptr);
-  ASSERT(req.result == UV_ENOENT);
-  uv_fs_req_cleanup(&req);
+    ASSERT(UV_ENOENT == uv_fs_readlink(NULL, &req, "no_such_file", NULL));
+    ASSERT_NULL(req.ptr);
+    ASSERT(req.result == UV_ENOENT);
+    uv_fs_req_cleanup(&req);
+  }
+
+  /* Must return UV_EINVAL on a non-symlink file */
+  {
+    int r;
+    uv_fs_t req;
+    uv_file file;
+
+    /* Setup */
+
+    /* Create a non-symlink file */
+    r = uv_fs_open(NULL, &req, "test_file", O_RDWR | O_CREAT,
+                   S_IWUSR | S_IRUSR, NULL);
+    ASSERT_GE(r, 0);
+    ASSERT_GE(req.result, 0);
+    file = req.result;
+    uv_fs_req_cleanup(&req);
+
+    r = uv_fs_close(NULL, &req, file, NULL);
+    ASSERT_EQ(r, 0);
+    ASSERT_EQ(req.result, 0);
+    uv_fs_req_cleanup(&req);
+
+    /* Test */
+    r = uv_fs_readlink(NULL, &req, "test_file", NULL);
+    ASSERT_EQ(r, UV_EINVAL);
+    uv_fs_req_cleanup(&req);
+
+    /* Cleanup */
+    unlink("test_file");
+  }
 
   MAKE_VALGRIND_HAPPY();
   return 0;