Gnus: delete temporary files when Gnus exits instead of using timers

lisp/gnus/mm-decode.el (mm-temp-files-to-be-deleted,
  mm-temp-files-cache-file): New internal variables.
(mm-temp-files-delete): New function; add it to gnus-exit-gnus-hook.
(mm-display-external): Use it to delete temporary files instead of
  using timers.

2 files changed, 55 insertions, 15 deletions

diff --git a/lisp/gnus/ChangeLog b/lisp/gnus/ChangeLog
index 96187c48844..ab776bfbb54 100644
--- a/lisp/gnus/ChangeLog
+++ b/lisp/gnus/ChangeLog
@@ -1,3 +1,11 @@
+2013-08-09  Katsumi Yamaoka  <yamaoka@jpl.org>
+
+        * mm-decode.el (mm-temp-files-to-be-deleted, mm-temp-files-cache-file):
+        New internal variables.
+        (mm-temp-files-delete): New function; add it to gnus-exit-gnus-hook.
+        (mm-display-external): Use it to delete temporary files instead of
+        using timers.
+
 2013-08-06  Jan Tatarik  <jan.tatarik@gmail.com>
 
         * gnus-icalendar.el (gnus-icalendar-event-from-ical): Replace pcase
diff --git a/lisp/gnus/mm-decode.el b/lisp/gnus/mm-decode.el
index 98d854340ee..2bfd145f174 100644
--- a/lisp/gnus/mm-decode.el
+++ b/lisp/gnus/mm-decode.el
@@ -47,6 +47,7 @@
 (defvar gnus-current-window-configuration)
 
 (add-hook 'gnus-exit-gnus-hook 'mm-destroy-postponed-undisplay-list)
+(add-hook 'gnus-exit-gnus-hook 'mm-temp-files-delete)
 
 (defgroup mime-display ()
   "Display of MIME in mail and news articles."
@@ -470,6 +471,11 @@ If not set, `default-directory' will be used."
 (defvar mm-content-id-alist nil)
 (defvar mm-postponed-undisplay-list nil)
 (defvar mm-inhibit-auto-detect-attachment nil)
+(defvar mm-temp-files-to-be-deleted nil
+  "List of temporary files scheduled to be deleted.")
+(defvar mm-temp-files-cache-file (concat ".mm-temp-files-" (user-login-name))
+  "Name of a file that caches a list of temporary files to be deleted.
+The file will be saved in the directory `mm-tmp-directory'.")
 
 ;; According to RFC2046, in particular, in a digest, the default
 ;; Content-Type value for a body part is changed from "text/plain" to
@@ -586,6 +592,45 @@ Postpone undisplaying of viewers for types in
     (message "Destroying external MIME viewers")
     (mm-destroy-parts mm-postponed-undisplay-list)))
 
+(defun mm-temp-files-delete ()
+  "Delete temporary files and those parent directories.
+Note that the deletion may fail if a program is catching hold of a file
+under Windows or Cygwin.  In that case, it schedules the deletion of
+files left at the next time."
+  (let* ((coding-system-for-read mm-universal-coding-system)
+         (coding-system-for-write mm-universal-coding-system)
+         (cache-file (expand-file-name mm-temp-files-cache-file
+                                       mm-tmp-directory))
+         (cache (when (file-exists-p cache-file)
+                  (mm-with-multibyte-buffer
+                    (insert-file-contents cache-file)
+                    (split-string (buffer-string) "\n" t))))
+         fails)
+    (dolist (temp (append cache mm-temp-files-to-be-deleted))
+      (unless (and (file-exists-p temp)
+                   (if (file-directory-p temp)
+                       ;; A parent directory left at the previous time.
+                       (progn
+                         (ignore-errors (delete-directory temp))
+                         (not (file-exists-p temp)))
+                     ;; Delete a temporary file and its parent directory.
+                     (ignore-errors (delete-file temp))
+                     (and (not (file-exists-p temp))
+                          (progn
+                            (setq temp (file-name-directory temp))
+                            (ignore-errors (delete-directory temp))
+                            (not (file-exists-p temp))))))
+        (push temp fails)))
+    (if fails
+        ;; Schedule the deletion of the files left at the next time.
+        (progn
+          (write-region (concat (mapconcat 'identity (nreverse fails) "\n")
+                                "\n")
+                        nil cache-file nil 'silent)
+          (set-file-modes cache-file #o600))
+      (when (file-exists-p cache-file)
+        (ignore-errors (delete-file cache-file))))))
+
 (autoload 'message-fetch-field "message")
 
 (defun mm-dissect-buffer (&optional no-strict-mime loose-mime from)
@@ -975,22 +1020,8 @@ external if displayed external."
                                    (buffer buffer)
                                    (command command)
                                    (handle handle))
-                       (run-at-time
-                        30.0 nil
-                        (lambda ()
-                          (ignore-errors
-                            (delete-file file))
-                          (ignore-errors
-                            (delete-directory (file-name-directory file)))))
                        (lambda (process state)
                          (when (eq (process-status process) 'exit)
-                           (run-at-time
-                            10.0 nil
-                            (lambda ()
-                              (ignore-errors
-                                (delete-file file))
-                              (ignore-errors
-                                (delete-directory (file-name-directory file)))))
                            (when (buffer-live-p outbuf)
                              (with-current-buffer outbuf
                                (let ((buffer-read-only nil)
@@ -1007,7 +1038,8 @@ external if displayed external."
                              (kill-buffer buffer)))
                          (message "Displaying %s...done" command)))))
                 (mm-handle-set-external-undisplayer
-                 handle (cons file buffer)))
+                 handle (cons file buffer))
+                (add-to-list 'mm-temp-files-to-be-deleted file t))
               (message "Displaying %s..." command))
             'external)))))))