[PATCH v34 0/1] MR10192: kernelbase: Handle extended length path prefix in GetLongPathNameW

[Vishnunithyasoundhar S (＠svishnunithyasoundhar)]

```
Support the \\?\ prefix by skipping it during path resolution while 
preserving it in the output. Added specific handling for extended 
UNC paths (\\?\UNC\) to mirror standard UNC behavior, ensuring 
these paths are treated as network shares and not local devices.

Some paths that use the extended length path were filtered out as UNC 
paths - but not all of them are UNC. There can be UNC path that use
extended length path but not all extended length paths are UNC paths.
```

Signed-off-by: Vishnunithyasoundhar S [e-mail]

--
  v34: kernelbase: Handle extended length path prefix in GetLongPathNameW
 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10192

[PATCH v34 1/1] kernelbase: Handle extended length path prefix in GetLongPathNameW

[Vishnunithyasoundhar S]

From: Vishnunithyasoundhar S <[e-mail]>

Support the \\?\ prefix by skipping it during path resolution while
preserving it in the output. Added specific handling for extended
UNC paths (\\?\UNC\) to mirror standard UNC behavior, ensuring
these paths are treated as network shares and not local devices.

Some paths that use the extended length path were filtered out as UNC
paths - but not all of them are UNC. There can be UNC path that use
extended length path but not all extended length paths are UNC paths.

Signed-off-by: Vishnunithyasoundhar S <[e-mail]>
---
 dlls/kernelbase/file.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/dlls/kernelbase/file.c b/dlls/kernelbase/file.c
index 83977a2c40b..a4d85133909 100644
--- a/dlls/kernelbase/file.c
+++ b/dlls/kernelbase/file.c
@@ -2116,6 +2116,21 @@ DWORD WINAPI DECLSPEC_HOTPATCH GetLongPathNameW( LPCWSTR shortpath, LPWSTR longp
         return 0;
     }
 
+    /* Handle \\?\ prefix (Extended Length Path) */
+    if (shortpath[0] == '\\' && shortpath[1] == '\\' && shortpath[2] == '?' &&
+        shortpath[3] == '\\') {
+      /* Filter out entended UNC */
+      if (_wcsnicmp(shortpath + 4, L"UNC\\", 4) == 0) {
+        lstrcatW(tmplongpath, L"UNC\\");
+        lp = sp = 8;
+        FIXME("UNC Extended pathname %s\n", debugstr_w(shortpath));
+      }
+      else if (shortpath[4] && shortpath[5] == ':') {
+        tmplongpath[lp++] = shortpath[sp++];
+        tmplongpath[lp++] = shortpath[sp++];
+      }
+    }
+
     if (shortpath[0] == '\\' && shortpath[1] == '\\')
     {
         FIXME( "UNC pathname %s\n", debugstr_w(shortpath) );
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/10192

[Vishnunithyasoundhar S (＠svishnunithyasoundhar)]

On Fri Mar 20 21:44:58 2026 +0000, Akihiro Sagawa wrote:
> It looks like a test case was dropped somewhere during your Git operations.
> To make the intent clearer, could you add a todo_wine-style test in
> addition to the fix.
> Also, please use a module name prefix in your commit subject.
> I rebased it - hopefully should have fixed the `test case dropped` that you witnessed.

todo_wine-style test - I will add it.

I have edited the commit subject  to `kernelbase: Handle extended length path prefix in GetLongPathNameW`. I hope kernelbase is the module name.

Thanks

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10192#note_133170