(file-relative-name): Protect the match-data.

diff --git a/lisp/files.el b/lisp/files.el
index 251177e64fbca36dc52b5431da4cca9418114734..ad5fa847813f6526fa8962a4cf495650746743d2 100644 (file)
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -1830,14 +1830,15 @@ If the value is nil, don't make a backup."
 
 (defun file-relative-name (filename &optional directory)
   "Convert FILENAME to be relative to DIRECTORY (default: default-directory)."
-  (setq filename (expand-file-name filename)
-       directory (file-name-as-directory (expand-file-name
-                                          (or directory default-directory))))
-  (let ((ancestor ""))
-    (while (not (string-match (concat "^" (regexp-quote directory)) filename))
-      (setq directory (file-name-directory (substring directory 0 -1))
-           ancestor (concat "../" ancestor)))
-    (concat ancestor (substring filename (match-end 0)))))
+  (save-match-data
+   (setq filename (expand-file-name filename)
+        directory (file-name-as-directory
+                   (expand-file-name (or directory default-directory))))
+   (let ((ancestor ""))
+     (while (not (string-match (concat "^" (regexp-quote directory)) filename))
+       (setq directory (file-name-directory (substring directory 0 -1))
+            ancestor (concat "../" ancestor)))
+     (concat ancestor (substring filename (match-end 0))))))
 \f
 (defun save-buffer (&optional args)
   "Save current buffer in visited file if modified.  Versions described below.