ntdll: Check for existing Unix path name in RtlGetFullPathName_U().

dlls/ntdll/path.c

@@ -543,16 +543,18 @@ static ULONG get_full_path_helper(LPCWSTR name, LPWSTR buffer, ULONG size)
             WCHAR *nt_str;
             SIZE_T buflen;
             NTSTATUS status;
-
-            unix_name = RtlAllocateHeap( GetProcessHeap(), 0, 3 * wcslen(name) + 1 );
-            ntdll_wcstoumbs( name, wcslen(name) + 1, unix_name, 3 * wcslen(name) + 1, FALSE );
-            buflen = strlen(unix_name) + 10;
-            for (;;)
+            UNICODE_STRING str;
+
+            nt_str = RtlAllocateHeap( GetProcessHeap(), 0, (wcslen(name) + 9) * sizeof(WCHAR) );
+            wcscpy( nt_str, L"\\??\\unix" );
+            wcscat( nt_str, name );
+            RtlInitUnicodeString( &str, nt_str );
+            buflen = 3 * wcslen(name) + 1;
+            unix_name = RtlAllocateHeap( GetProcessHeap(), 0, buflen );
+            if (!(status = wine_nt_to_unix_file_name( &str, unix_name, &buflen, FILE_OPEN )))
             {
-                if (!(nt_str = RtlAllocateHeap( GetProcessHeap(), 0, buflen * sizeof(WCHAR) ))) break;
+                buflen = wcslen(name) + 9;
                 status = wine_unix_to_nt_file_name( unix_name, nt_str, &buflen );
-                if (status != STATUS_BUFFER_TOO_SMALL) break;
-                RtlFreeHeap( GetProcessHeap(), 0, nt_str );
             }
             RtlFreeHeap( GetProcessHeap(), 0, unix_name );
             if (!status && buflen > 6 && nt_str[5] == ':')