userdiff: add a builtin pattern for dts files

diff --git a/t/helper/test-drop-caches.c b/t/helper/test-drop-caches.c
index d6bcfddf13352b92d6be4d9d5b8e7d7f05cc06ee..f65e301f9ddc13f395b88a4b8cf994506beee292 100644 (file)
--- a/t/helper/test-drop-caches.c
+++ b/t/helper/test-drop-caches.c
@@ -16,8 +16,8 @@ static int cmd_sync(void)
        if ((0 == dwRet) || (dwRet > MAX_PATH))
                return error("Error getting current directory");
 
-       if ((Buffer[0] < 'A') || (Buffer[0] > 'Z'))
-               return error("Invalid drive letter '%c'", Buffer[0]);
+       if (!has_dos_drive_prefix(Buffer))
+               return error("'%s': invalid drive letter", Buffer);
 
        szVolumeAccessPath[4] = Buffer[0];
        hVolWrite = CreateFile(szVolumeAccessPath, GENERIC_READ | GENERIC_WRITE,