From 7754a7c3664693aeab58f71c8fc4bb42e83f6c45 Mon Sep 17 00:00:00 2001
From: Eljees <3.14hell@gmail.com>
Date: Thu, 27 Aug 2026 13:35:41 +0300
Subject: [PATCH] Preserve the leading slashes of Windows UNC paths

`normalize()` collapses the leading double backslash of a plain UNC path,
so `\\server\share\file.css` becomes `/server/share/file.css` and the
path loses its network-path identity. The Win32 namespace prefixes
(`\\?\`, `\\.\`) are already special-cased to keep their doubled leading
slash; this applies the same treatment to plain UNC paths.

Forward-slash inputs like `//foo/bar` are intentionally left unchanged
(still collapse to `/foo/bar`), matching the existing test expectations,
since a leading double slash is only meaningful on Windows input paths
spelled with backslashes.

Downstream context: stylelint/stylelint#3045 (files addressed via a UNC
path silently produce no lint results, because the collapsed path no
longer matches anything when handed to fast-glob).

Signed-off-by: Eljees <3.14hell@gmail.com>
---
 index.js |  7 +++++++
 test.js  | 18 ++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/index.js b/index.js
index 6fac553..a02ed71 100644
--- a/index.js
+++ b/index.js
@@ -27,6 +27,13 @@ module.exports = function(path, stripTrailing) {
     }
   }
 
+  // preserve the leading slashes of a UNC path (`\\server\share\...`),
+  // consistent with the win32 namespace prefixes handled above
+  if (prefix === '' && len > 2 && path[0] === '\\' && path[1] === '\\' && path[2] !== '\\' && path[2] !== '/') {
+    path = path.slice(2);
+    prefix = '//';
+  }
+
   var segs = path.split(/[/\\]+/);
   if (stripTrailing !== false && segs[segs.length - 1] === '') {
     segs.pop();
diff --git a/test.js b/test.js
index 55b3bda..bedac48 100644
--- a/test.js
+++ b/test.js
@@ -84,4 +84,22 @@ describe('normalize-path', function() {
       });
     });
   });
+  describe('windows UNC paths', function() {
+    var units = [
+      ['\\\\Server01\\user\\docs\\Letter.txt', '//Server01/user/docs/Letter.txt'],
+      ['\\\\server\\share\\file.css', '//server/share/file.css'],
+      ['\\\\localhost\\c$\\temp\\file.txt', '//localhost/c$/temp/file.txt'],
+      ['\\\\server\\share\\', '//server/share'],
+    ];
+
+    units.forEach(function(unit) {
+      it('should preserve the leading slashes of ' + unit[0], function() {
+        assert.equal(normalize(unit[0]), unit[1]);
+      });
+    });
+
+    it('should keep a trailing slash when stripTrailing is false', function() {
+      assert.equal(normalize('\\\\server\\share\\', false), '//server/share/');
+    });
+  });
 });