[PATCH v20 0/1] MR10192: kernelbase: Handle \\?\ prefix in GetLongPathNameW

[Vishnunithyasoundhar S (＠svishnunithyasoundhar)]

The current implementation of GetLongPathNameW triggers a FIXME and

returns the original path when it encounters a UNC prefix. While

true network UNC paths remain unimplemented, this change allows

extended-length local paths (starting with \\\\?) to be resolved by

stripping the prefix and processing the underlying local path.

This fixes issues where applications (such as xalia) passing

absolute paths with the extended-length prefix would fail to

receive a normalized or resolved long path.

```
881.036:00d4:00d8:fixme:file:GetLongPathNameW UNC pathname L"\\\\?\\Z:\\home\\vishnunithyasoundhars\\.steam\\debian-installation\\compatibilitytools.d\\debug_build\\files\\share\\wine/../xalia/xalia.exe"
```

Tested:

After change with added debug log

```
22272.558:00d4:00d8:fixme:file:GetLongPathNameW DEBUG: Success! Returning path: L"Z:\\home\\vishnunithyasoundhars\\.steam\\debian-installation\\compatibilitytools.d\\debug_build\\files\\share\\wine/../xalia/xalia.exe" (Length: 125)
```

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

--
  v20: fix: extended-file-name support
 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10192

[PATCH v20 1/1] fix: extended-file-name support

[Vishnunithyasoundhar S]

From: Vishnunithyasoundhar S <[e-mail]>

Signed-off-by: Vishnunithyasoundhar S <[e-mail]>
---
 dlls/kernelbase/file.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/dlls/kernelbase/file.c b/dlls/kernelbase/file.c
index c206e2f9cc2..c9e46ab6f5b 100644
--- a/dlls/kernelbase/file.c
+++ b/dlls/kernelbase/file.c
@@ -2117,6 +2117,14 @@ 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] == '\\')
+    {
+      if (iswalpha(shortpath[4]) && shortpath[5] == ':' && shortpath[6] == '\\')
+        return GetLongPathNameW(shortpath + 4, longpath, longlen);
+    }
+
     if (shortpath[0] == '\\' && shortpath[1] == '\\')
     {
         FIXME( "UNC pathname %s\n", debugstr_w(shortpath) );
-- 
GitLab

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