Avoid corrupting archive-contents file.

* emacs-lisp/package.el (package--download-one-archive): Ensure
that archive-contents is valid before saving it.
(package-activate-1, package-mark-obsolete, define-package)
(package-compute-transaction, package-list-maybe-add): Use push.

2 files changed, 32 insertions, 28 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index fbee96a4fd7..efec2b3fcb4 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,10 @@
+2010-09-02  Chong Yidong  <cyd@stupidchicken.com>
+
+        * emacs-lisp/package.el (package--download-one-archive): Ensure
+        that archive-contents is valid before saving it.
+        (package-activate-1, package-mark-obsolete, define-package)
+        (package-compute-transaction, package-list-maybe-add): Use push.
+
 2010-09-03  Stefan Monnier  <monnier@iro.umontreal.ca>
 
         Use SMIE's blink-paren for octave-mode.
diff --git a/lisp/emacs-lisp/package.el b/lisp/emacs-lisp/package.el
index c1c4e2b6015..6c5aee2a735 100644
--- a/lisp/emacs-lisp/package.el
+++ b/lisp/emacs-lisp/package.el
@@ -406,16 +406,15 @@ updates `package-alist' and `package-obsolete-alist'."
       (error "Internal error: could not find directory for %s-%s"
              name version-str))
     ;; Add info node.
-    (if (file-exists-p (expand-file-name "dir" pkg-dir))
-        (progn
-          ;; FIXME: not the friendliest, but simple.
-          (require 'info)
-          (info-initialize)
-          (setq Info-directory-list (cons pkg-dir Info-directory-list))))
+    (when (file-exists-p (expand-file-name "dir" pkg-dir))
+      ;; FIXME: not the friendliest, but simple.
+      (require 'info)
+      (info-initialize)
+      (push pkg-dir Info-directory-list))
     ;; Add to load path, add autoloads, and activate the package.
-    (setq load-path (cons pkg-dir load-path))
+    (push pkg-dir load-path)
     (load (expand-file-name (concat name "-autoloads") pkg-dir) nil t)
-    (setq package-activated-list (cons package package-activated-list))
+    (push package package-activated-list)
     ;; Don't return nil.
     t))
 
@@ -466,10 +465,9 @@ Return nil if the package could not be activated."
           (setcdr elt (cons (cons (package-desc-vers pkg-vec) pkg-vec)
                             (cdr elt))))
       ;; Make a new association.
-      (setq package-obsolete-alist
-            (cons (cons package (list (cons (package-desc-vers pkg-vec)
-                                            pkg-vec)))
-                  package-obsolete-alist)))))
+      (push (cons package (list (cons (package-desc-vers pkg-vec)
+                                      pkg-vec)))
+            package-obsolete-alist))))
 
 (defun define-package (name-str version-string
                                 &optional docstring requirements
@@ -505,7 +503,7 @@ EXTRA-PROPERTIES is currently unused."
             (setq package-alist (delq pkg-desc package-alist))
             (package-mark-obsolete (car pkg-desc) (cdr pkg-desc)))
           ;; Add package to the alist.
-          (setq package-alist (cons new-pkg-desc package-alist)))
+          (push new-pkg-desc package-alist))
       ;; You can have two packages with the same version, for instance
       ;; one in the system package directory and one in your private
       ;; directory.  We just let the first one win.
@@ -707,7 +705,7 @@ but version %s required"
              (package-version-join (package-desc-vers (cdr pkg-desc)))))
           ;; Only add to the transaction if we don't already have it.
           (unless (memq next-pkg package-list)
-            (setq package-list (cons next-pkg package-list)))
+            (push next-pkg package-list))
           (setq package-list
                 (package-compute-transaction package-list
                                              (package-desc-reqs
@@ -992,17 +990,19 @@ The file can either be a tar file or an Emacs Lisp file."
       (re-search-forward "^$" nil 'move)
       (forward-char)
       (delete-region (point-min) (point))
-      (make-directory dir t)
-      (setq buffer-file-name (expand-file-name file dir))
-      (let ((version-control 'never))
-        (save-buffer)))
+      ;; Read the retrieved buffer to make sure it is valid (e.g. it
+      ;; may fetch a URL redirect page).
+      (when (listp (read buffer))
+        (make-directory dir t)
+        (setq buffer-file-name (expand-file-name file dir))
+        (let ((version-control 'never))
+          (save-buffer))))
     (kill-buffer buffer)))
 
 (defun package-refresh-contents ()
   "Download the ELPA archive description if needed.
-Invoking this will ensure that Emacs knows about the latest versions
-of all packages.  This will let Emacs make them available for
-download."
+This informs Emacs about the latest versions of all packages, and
+makes them available for download."
   (interactive)
   (unless (file-exists-p package-user-dir)
     (make-directory package-user-dir t))
@@ -1301,11 +1301,9 @@ Letters do not insert themselves; instead, they are commands.
   (run-mode-hooks 'package-menu-mode-hook))
 
 (defun package-menu-refresh ()
-  "Download the ELPA archive.
-This fetches the file describing the current contents of
-the Emacs Lisp Package Archive, and then refreshes the
-package menu.  This lets you see what new packages are
-available for download."
+  "Download the Emacs Lisp package archive.
+This fetches the contents of each archive specified in
+`package-archives', and then refreshes the package menu."
   (interactive)
   (unless (eq major-mode 'package-menu-mode)
     (error "The current buffer is not a Package Menu"))
@@ -1460,8 +1458,7 @@ Emacs."
 
 (defun package-list-maybe-add (package version status description result)
   (unless (assoc (cons package version) result)
-    (setq result (cons (list (cons package version) status description)
-                       result)))
+    (push (list (cons package version) status description) result))
   result)
 
 (defvar package-menu-package-list nil