(archive-add-new-member): Use `derived-mode-p'.

(archive-*-extract): Use `zerop'
(archive-*-write-file-member): Use `or', use `zerop'.

1 files changed, 4 insertions, 5 deletions

diff --git a/lisp/arc-mode.el b/lisp/arc-mode.el
index 33d535c47a8..8070e95a671 100644
--- a/lisp/arc-mode.el
+++ b/lisp/arc-mode.el
@@ -1059,7 +1059,7 @@ using `make-temp-file', and the generated name is returned."
                  nil
                  nil
                  (append (cdr command) (list archive name))))
-    (cond ((and (numberp exit-status) (= exit-status 0))
+    (cond ((and (numberp exit-status) (zerop exit-status))
            (if (not (file-exists-p tmpfile))
                (ding (message "`%s': no such file or directory" tmpfile))
              (insert-file-contents tmpfile)
@@ -1117,7 +1117,7 @@ using `make-temp-file', and the generated name is returned."
                           (file-name-nondirectory buffer-file-name)
                         ""))))
   (with-current-buffer arcbuf
-    (or (eq major-mode 'archive-mode)
+    (or (derived-mode-p 'archive-mode)
         (error "Buffer is not an archive buffer"))
     (if archive-read-only
         (error "Archive is read-only")))
@@ -1190,9 +1190,8 @@ using `make-temp-file', and the generated name is returned."
                                   nil
                                   (append (cdr command)
                                           (list archive ename)))))
-            (if (equal exitcode 0)
-                nil
-              (error "Updating was unsuccessful (%S)" exitcode))))
+            (or (zerop exitcode)
+                (error "Updating was unsuccessful (%S)" exitcode))))
       (archive-delete-local tmpfile))))
 
 (defun archive-write-file (&optional file)