(file-chase-links): When handling .., make newname absolute.

Simplify several places.
(file-relative-name): Handle directory names as well as file names.
Don't get fooled by empty directory names, etc.

diff --git a/lisp/files.el b/lisp/files.el
index 93ca1c7d275696da3574ce70f6c2b8093f19037d..c794719964cac9d59a9836a85602ab73e7458b06 100644 (file)
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -537,28 +537,27 @@ Does not examine containing directories for links,
 unlike `file-truename'."
   (let (tem (count 100) (newname filename))
     (while (setq tem (file-symlink-p newname))
-      (if (= count 0)
-         (error "Apparent cycle of symbolic links for %s" filename))
-      ;; In the context of a link, `//' doesn't mean what Emacs thinks.
-      (while (string-match "//+" tem)
-       (setq tem (concat (substring tem 0 (1+ (match-beginning 0)))
-                         (substring tem (match-end 0)))))
-      ;; Handle `..' by hand, since it needs to work in the
-      ;; target of any directory symlink.
-      ;; This code is not quite complete; it does not handle
-      ;; embedded .. in some cases such as ./../foo and foo/bar/../../../lose.
-      (while (string-match "\\`\\.\\./" tem)
-       (setq tem (substring tem 3))
-       (setq newname (file-name-as-directory
-                      ;; Do the .. by hand.
-                      (directory-file-name
-                       (file-name-directory
-                        ;; Chase links in the default dir of the symlink.
-                        (file-chase-links
-                         (directory-file-name
-                          (file-name-directory newname))))))))
-      (setq newname (expand-file-name tem (file-name-directory newname)))
-      (setq count (1- count)))
+      (save-match-data
+       (if (= count 0)
+           (error "Apparent cycle of symbolic links for %s" filename))
+       ;; In the context of a link, `//' doesn't mean what Emacs thinks.
+       (while (string-match "//+" tem)
+         (setq tem (replace-match "/" nil nil tem)))
+       ;; Handle `..' by hand, since it needs to work in the
+       ;; target of any directory symlink.
+       ;; This code is not quite complete; it does not handle
+       ;; embedded .. in some cases such as ./../foo and foo/bar/../../../lose.
+       (while (string-match "\\`\\.\\./" tem)
+         (setq tem (substring tem 3))
+         (setq newname (expand-file-name newname))
+         ;; Chase links in the default dir of the symlink.
+         (setq newname
+               (file-chase-links
+                (directory-file-name (file-name-directory newname))))
+         ;; Now find the parent of that dir.
+         (setq newname (file-name-directory newname)))
+       (setq newname (expand-file-name tem (file-name-directory newname)))
+       (setq count (1- count))))
     newname))
 \f
 (defun switch-to-buffer-other-window (buffer &optional norecord)
@@ -1964,11 +1963,26 @@ then it returns FILENAME."
               (not (string-equal (substring fname  0 2)
                                  (substring directory 0 2))))
          filename
-       (let ((ancestor ""))
-         (while (not (string-match (concat "^" (regexp-quote directory)) fname))
+       (let ((ancestor ".")
+             (fname-dir (file-name-as-directory fname)))
+         (while (and (not (string-match (concat "^" (regexp-quote directory)) fname-dir))
+                     (not (string-match (concat "^" (regexp-quote directory)) fname)))
            (setq directory (file-name-directory (substring directory 0 -1))
-                 ancestor (concat "../" ancestor)))
-         (concat ancestor (substring fname (match-end 0))))))))
+                 ancestor (if (equal ancestor ".")
+                              ".."
+                            (concat "../" ancestor))))
+         ;; Now ancestor is empty, or .., or ../.., etc.
+         (if (string-match (concat "^" (regexp-quote directory)) fname)
+             ;; We matched within FNAME's directory part.
+             ;; Add the rest of FNAME onto ANCESTOR.
+             (let ((rest (substring fname (match-end 0))))
+               (if (and (equal ancestor ".")
+                        (not (equal rest "")))
+                   ;; But don't bother with ANCESTOR if it would give us `./'.
+                   rest
+                 (concat (file-name-as-directory ancestor) rest)))
+           ;; We matched FNAME's directory equivalent.
+           ancestor))))))
 \f
 (defun save-buffer (&optional args)
   "Save current buffer in visited file if modified.  Versions described below.