bug#19865: tar-untar-buffer: should honor default-directory

[Ivan Shmakov]

>>>>> Stefan Monnier <monnier@IRO.UMontreal.CA> writes:

[…]

 >> Please thus consider the revised patch MIMEd, which I’ve tried to
 >> make consistent with such an approach.

 > I think it's better, indeed.

        I’ve revised the change to apply default-directory just once
        and use the result consistently throughout the function.

 > BTW, the (set-buffer-multibyte nil) should probably just be remove
 > (or replaced by a cl-assert)

        Done.

Fix default-directory handling in tar-untar-buffer.

* lisp/tar-mode.el (tar-untar-buffer): Fixed: use the value of
default-directory local to the tar-mode buffer (was:
tar-data-buffer); clean-up.
    
Fixes: debbugs:19865

PS.  Should the pending objections be resolved by sometime around
        18:00 UTC today, I’d happily push the change to ‘master’.

-- 
FSF associate member #7257  http://boycottsystemd.org/  … 3013 B6A0 230E 334A

--- a/lisp/tar-mode.el
+++ b/lisp/tar-mode.el
@@ -533,27 +533,32 @@
 
 (defun tar-untar-buffer ()
   "Extract all archive members in the tar-file into the current directory."
   (interactive)
   ;; FIXME: make it work even if we're not in tar-mode.
-  (let ((descriptors tar-parse-info))   ;Read the var in its buffer.
-    (with-current-buffer
-        (if (tar-data-swapped-p) tar-data-buffer (current-buffer))
-      (set-buffer-multibyte nil)          ;Hopefully, a no-op.
-      (dolist (descriptor descriptors)
-        (let* ((name (tar-header-name descriptor))
-               (dir (if (eq (tar-header-link-type descriptor) 5)
-                        name
-                      (file-name-directory name)))
-               (start (tar-header-data-start descriptor))
-               (end (+ start (tar-header-size descriptor))))
-          (unless (file-directory-p name)
-            (message "Extracting %s" name)
-            (if (and dir (not (file-exists-p dir)))
-                (make-directory dir t))
-            (unless (file-directory-p name)
+  (let ((data-buf (if (tar-data-swapped-p) tar-data-buffer
+                    (current-buffer))))
+    (with-current-buffer data-buf
+      (cl-assert (not enable-multibyte-characters)))
+    (dolist (descriptor tar-parse-info)
+      (let* ((orig (tar-header-name descriptor))
+            ;; Note that default-directory may have different values
+            ;; in the tar-mode and data buffers, so we stick to the
+            ;; absolute file name from now on.
+            (name (expand-file-name orig))
+            (dir (if (eq (tar-header-link-type descriptor) 5)
+                     name
+                   (file-name-directory name)))
+            (start (tar-header-data-start descriptor))
+            (end (+ start (tar-header-size descriptor))))
+       (unless (file-directory-p name)
+         (message "Extracting %s" orig)
+         (if (and dir (not (file-exists-p dir)))
+             (make-directory dir t))
+         (unless (file-directory-p name)
+           (with-current-buffer data-buf
              (let ((coding-system-for-write 'no-conversion))
-               (write-region start end name)))
-            (set-file-modes name (tar-header-mode descriptor))))))))
+               (write-region start end name))))
+         (set-file-modes name (tar-header-mode descriptor)))))))
 
 (defun tar-summarize-buffer ()
   "Parse the contents of the tar file in the current buffer."