[PATCH v54 0/1] MR10192: Draft: 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]

--
  v54: kernelbase: Handle extended length path prefix in GetLongPathNameW
 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10192

[PATCH v54 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.

Added test.

Signed-off-by: Vishnunithyasoundhar S <[e-mail]>
---
 dlls/kernel32/tests/path.c | 17 ++++++++++++++---
 dlls/kernelbase/file.c     | 28 ++++++++++++++++++++++++++--
 2 files changed, 40 insertions(+), 5 deletions(-)

diff --git a/dlls/kernel32/tests/path.c b/dlls/kernel32/tests/path.c
index aa1833504d8..1b60de6d692 100644
--- a/dlls/kernel32/tests/path.c
+++ b/dlls/kernel32/tests/path.c
@@ -1255,6 +1255,8 @@ static void test_GetLongPathNameW(void)
     static const WCHAR prefix[] = { '\\','\\','?','\\', 0};
     static const WCHAR backslash[] = { '\\', 0};
     static const WCHAR letterX[] = { 'X', 0};
+    WCHAR shortpath2[MAX_PATH];
+    WCHAR longpath[MAX_PATH];
 
     SetLastError(0xdeadbeef); 
     length = GetLongPathNameW(NULL,NULL,0);
@@ -1298,12 +1300,9 @@ static void test_GetLongPathNameW(void)
     /* With prefix */
     SetLastError(0xdeadbeef);
     length = GetLongPathNameW(shortpath, NULL, 0);
-    todo_wine
-    {
     ok(length == 0, "Expected 0, got %ld\n", length);
     ok(GetLastError() == ERROR_FILE_NOT_FOUND,
        "Expected ERROR_PATH_NOT_FOUND, got %ld\n", GetLastError());
-    }
 
     file = CreateFileW(shortpath, GENERIC_READ|GENERIC_WRITE, 0, NULL,
                        CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
@@ -1327,6 +1326,18 @@ static void test_GetLongPathNameW(void)
     length = GetLongPathNameW(shortpath, NULL, 0);
     ok(length == expanded, "Expected %ld, got %ld\n", expanded, length);
 
+    /* Test that extended prefix is preserved in output when converting from
+     * short to long path */
+    shortpath2[0] = 0;
+    length = GetShortPathNameW(dirpath, shortpath2, ARRAY_SIZE(shortpath2));
+    ok(length > 0, "GetShortPathNameW failed: %lu\n", GetLastError());
+    ok(lstrcmpiW(dirpath, shortpath2) != 0, "short path name isn't created, got %s\n", debugstr_w(shortpath2));
+
+    SetLastError(0xdeadbeef);
+    length = GetLongPathNameW(shortpath2, longpath, ARRAY_SIZE(longpath));
+    ok(length > 0, "GetLongPathNameW failed: %lu\n", GetLastError());
+    ok(lstrcmpiW(longpath, dirpath) == 0, "Expected path: %s, got: %s\n", wine_dbgstr_w(dirpath), wine_dbgstr_w(longpath));
+
     /* NULL buffer with length crashes on Windows */
     if (0)
         GetLongPathNameW(shortpath, NULL, 20);
diff --git a/dlls/kernelbase/file.c b/dlls/kernelbase/file.c
index 83977a2c40b..5fc84ced607 100644
--- a/dlls/kernelbase/file.c
+++ b/dlls/kernelbase/file.c
@@ -20,6 +20,7 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  */
 
+#include <ctype.h>
 #include <stdarg.h>
 #include <stdio.h>
 
@@ -2096,7 +2097,7 @@ DWORD WINAPI DECLSPEC_HOTPATCH GetLongPathNameA( LPCSTR shortpath, LPSTR longpat
  */
 DWORD WINAPI DECLSPEC_HOTPATCH GetLongPathNameW( LPCWSTR shortpath, LPWSTR longpath, DWORD longlen )
 {
-    WCHAR tmplongpath[1024];
+    WCHAR tmplongpath[32767];
     DWORD sp = 0, lp = 0, tmplen;
     WIN32_FIND_DATAW wfd;
     UNICODE_STRING nameW;
@@ -2116,7 +2117,30 @@ DWORD WINAPI DECLSPEC_HOTPATCH GetLongPathNameW( LPCWSTR shortpath, LPWSTR longp
         return 0;
     }
 
-    if (shortpath[0] == '\\' && shortpath[1] == '\\')
+    /* Handle \\?\ prefix (Extended Length Path) */
+    if (lstrlenW(shortpath) >= 4 && shortpath[0] == '\\' && shortpath[1] == '\\'
+        && shortpath[2] == '?' && shortpath[3] == '\\')
+    {
+        if (wcsnicmp(shortpath + 4, L"UNC\\", 4) == 0)
+        {
+            FIXME("UNC Extended pathname %s\n", debugstr_w(shortpath));
+            tmplen = lstrlenW(shortpath);
+            if (tmplen < longlen)
+            {
+                if (longpath != shortpath) lstrcpyW(longpath, shortpath);
+                return tmplen;
+            }
+            return tmplen + 1;
+        }
+        else if ( isalpha(shortpath[4]) && shortpath[5] == ':')
+        {
+            lstrcpynW(tmplongpath, shortpath, 7);
+            lp = 6;
+            sp = 6;
+        }
+    }
+
+    if (sp == 0 && shortpath[0] == '\\' && shortpath[1] == '\\')
     {
         FIXME( "UNC pathname %s\n", debugstr_w(shortpath) );
         tmplen = lstrlenW( shortpath );
-- 
GitLab

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