bug#973: marked as done (Support for moving files to freedesktop.org-style trashcan.)

[owner@emacsbugs.donarmstrong.com (Emacs bug Tracking System)]

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Your message dated Sun, 28 Jun 2009 00:59:42 -0400
with message-id <87skhl0x8h.fsf@stupidchicken.com>
and subject line Re: Support for moving files to freedesktop.org-style trashcan
has caused the Emacs bug report #973,
regarding Support for moving files to freedesktop.org-style trashcan.
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
bug report if necessary, and/or fix the problem forthwith.

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-- 
973: http://emacsbugs.donarmstrong.com/cgi-bin/bugreport.cgi?bug=973
Emacs Bug Tracking System
Contact owner@emacsbugs.donarmstrong.com with problems

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Package: emacs
Version: 23.0.60
Severity: normal
Tags: patch


delete-by-moving-to-trash was recently introduced, but doesn't
really work as expected for typical gnu+linux desktop users, and I had
some procrastination to do, so...

Attached patch adds basic support for moving files to a fd.o-style
trashcan, as used in KDE/GNOME/XFCE/etc. and documented at:
http://www.freedesktop.org/wiki/Specifications/trash-spec

Unlike "Microsoft Windows? -> use Windows Recycle Bin" or "MacOSX? ->
use MacOSX trash can", one maybe can't say "GNU/Linux/BSD? -> use
freedesktop-style Trash", so whether the freedesktop-style trashcan
should be preferred over the simple emacs fallback "trash-directory"
scheme is decided a bit roughly.

Maybe a move-file-to-trash-scheme should just be a user-visible
customisation.

... I hate trashcans anyway.



















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Index: lisp/files.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/files.el,v
retrieving revision 1.995
diff -U 8 -r1.995 files.el
--- lisp/files.el	2 Sep 2008 16:10:44 -0000	1.995
+++ lisp/files.el	13 Sep 2008 03:05:31 -0000
@@ -5793,24 +5793,165 @@
 not defined.  Relative paths are interpreted relative to `default-directory'.
 See also `delete-by-moving-to-trash'."
   :type 'directory
   :group 'auto-save
   :version "23.1")
 
 (declare-function system-move-file-to-trash "w32fns.c" (filename))
 
+(defun move-file-to-trash-freedesktop (filename)
+  "Attempt to move file/dir to trash the freedesktop.org way (like e.g. GNOME,
+KDE and XFCE desktop environment trash facilities). Usually called automatically
+by `move-file-to-trash'.
+
+Only moves to 'home trash', per-volume trash storage areas are never used, as
+permitted by freedesktop.org trash-spec 0.7."
+
+  (interactive "fMove file to trash: ")
+  (let* ((saved-default-file-modes (default-file-modes))
+	 (xdg-data-home-dir (directory-file-name (expand-file-name
+						  (or (getenv "XDG_DATA_HOME")
+						      "~/.local/share"))))
+	 (trash-dir (concat xdg-data-home-dir "/Trash"))
+	 (trash-files-dir (concat trash-dir "/files"))
+	 (trash-info-dir (concat trash-dir "/info"))
+	 (fn (directory-file-name (expand-file-name filename)))
+	 (fn-nondir (file-name-nondirectory fn)))
+
+    ;; trash-spec 0.7 says to check if we have permissions to
+    ;; delete before attempting to delete.
+    (unless (file-writable-p (directory-file-name (file-name-directory fn)))
+      (error "Cannot move file `%s' to Trash, insufficient permissions" filename))
+
+    ;; stop processing if fn is same or parent directory of trash-dir.
+    (when (or (string-match fn trash-files-dir)
+	      (string-match fn trash-info-dir)
+	      (string-match fn trash-dir))
+      (error "Filename `%s' is same or parent directory of Trash."
+	     filename))
+
+    ;; ensure trash directory exists, using appropriate permissions if creating it.
+    (set-default-file-modes #o700)
+    (make-directory trash-files-dir t)
+    (make-directory trash-info-dir t)
+    (set-default-file-modes saved-default-file-modes)
+
+    ;; try to move to trash with associated .trashinfo undo information
+    (save-excursion
+      (with-temp-buffer
+	(set-buffer-file-coding-system 'utf-8-unix)
+	;; url-encode path, though allow literal "/" for path separators.
+	;; trash-spec 0.7 is slightly confusing on that point. At time of writing,
+	;; KDE Konqueror accepts both literal and %2f-encoded slashes, XFCE Thunar
+	;; only literal slashes.
+	;; Using / makes .trashinfo files much more readable, and while / is a
+	;; reserved character in url components, it is a valid separator in urls,
+	;; so the intent was likely to allow it.
+	;; yes, this is lifted from url-hexify-string
+	;; but don't want to pull in url/*.el , and it's not quite the same due to /
+	(insert "[Trash Info]\n"
+		"Path=" (mapconcat
+			 (lambda (byte)
+			   (if (memq byte
+				     '(?/ ?a ?b ?c ?d ?e ?f ?g ?h ?i ?j
+					  ?k ?l ?m ?n ?o ?p ?q ?r ?s ?t
+					  ?u ?v ?w ?x ?y ?z ?A ?B ?C ?D
+					  ?E ?F ?G ?H ?I ?J ?K ?L ?M ?N
+					  ?O ?P ?Q ?R ?S ?T ?U ?V ?W ?X
+					  ?Y ?Z ?0 ?1 ?2 ?3 ?4 ?5 ?6 ?7
+					  ?8 ?9 ?- ?_ ?. ?! ?~ ?* ?' ?\( ?\)))
+			       (char-to-string byte)
+			     (format "%%%02x" byte)))
+			 (if (multibyte-string-p fn)
+			     (encode-coding-string fn 'utf-8)
+			   fn)
+			 "")
+		"\nDeletionDate=" (format-time-string "%Y-%m-%dT%T") "\n")
+	(let* ((maxtries 5)
+	       (tries maxtries)
+	       (success nil)
+	       (base-fn (expand-file-name fn-nondir trash-files-dir))
+	       (new-fn base-fn)
+	       (info-fn (concat new-fn ".trashinfo")))
+	  ;; attempt to make .trashinfo file, retries up to 5
+	  ;; times (arbitrarily chosen, spec just says "pick
+	  ;; another filename"). .trashinfo file opened o_excl _is_
+	  ;; lock as per trash-spec 0.7 (even if that can be a
+	  ;; problem on old NFS versions...)
+	  (while (and (not success) (> tries 0))
+	    ;; make new-fn unique.
+	    ;; Unfortunately, contemporary file managers with fd.o trashcan support
+	    ;; do not like emacs backup file naming scheme here (as used in default emacs
+	    ;; trash implementation) - see  bug 4381 in XFCE Thunar bug tracker,
+	    ;; bug 170956 in KDE Konqueror bug tracker.
+	    ;;  (let ((version-control t))
+	    ;;   (setq new-fn (car (find-backup-file-name base-fn))))
+	    (when (< tries maxtries)
+	      (setq new-fn (make-temp-name (concat base-fn "_"))))
+	    (setq info-fn (concat (expand-file-name (file-name-nondirectory new-fn)
+						    trash-info-dir)
+				  ".trashinfo"))
+	    (unless (condition-case nil
+			(progn
+			  (write-region nil nil info-fn nil 'quiet info-fn 'excl)
+			  (setq success t))
+		      (file-already-exists nil))
+	      (setq tries (- tries 1))
+	      (sleep-for 0.1)))
+	  (unless success (error "Failed to lock Trash for filename `%s'" filename))
+	  ;; Finally... if we've got this far, let's
+	  ;; try to actually move the file to the trashcan.
+	  (let ((delete-by-moving-to-trash nil))
+	    (rename-file fn new-fn)))))))
+
+(defvar move-file-to-trash--freedesktop-p-memo nil)
+(defun move-file-to-trash--freedesktop-p ()
+  "Guess if the system should be considered freedesktop.org -oid
+for `move-file-to-trash' purposes. Only used in absence of
+overriding `system-move-file-to-trash' "
+  ;; presumably constant throughout an emacs session.
+  (or move-file-to-trash--freedesktop-p-memo
+      (setq move-file-to-trash--freedesktop-p-memo
+	    (if (and
+		 ;; assume macosx and windows folk are going to want their own
+		 ;; trashcans even though people might sometimes compile
+		 ;; and run freedesktop.org apps on them.
+		 (not (eq system-type 'darwin))
+		 (not (eq system-type 'windows))
+		 (or
+		  ;; dead giveaway.
+		  (file-exists-p "~/.local/share/Trash")
+		  (getenv "XDG_DATA_HOME")
+		  (getenv "XDG_CONFIG_HOME")
+		  (getenv "XDG_DATA_DIRS")
+		  (getenv "XDG_CONFIG_DIRS")
+		  (getenv "XDG_CACHE_HOME")
+		  (file-exists-p "/etc/xdg")
+		  (file-exists-p "~/.local")
+		  (file-exists-p "~/.config")))
+		t
+	      nil))))
+
 (defun move-file-to-trash (filename)
   "Move file (or directory) name FILENAME to the trash.
 This function is called by `delete-file' and `delete-directory' when
 `delete-by-moving-to-trash' is non-nil.  On platforms that define
 `system-move-file-to-trash', that function is used to move FILENAME to the
-system trash, otherwise FILENAME is moved to `trash-directory'.
+system trash, otherwise on systems that appear to be using a
+freedesktop.org compliant trashcan `move-file-to-trash-freedesktop'
+is used (and bound to `system-move-file-to-trash'), otherwise
+FILENAME is moved to `trash-directory'.
 Returns nil on success."
   (interactive "fMove file to trash: ")
+  (unless (fboundp 'system-move-file-to-trash)
+    (when (move-file-to-trash--freedesktop-p)
+      (fset 'system-move-file-to-trash
+	    (lambda (filename)
+	      (move-file-to-trash-freedesktop filename)))))
   (cond
    ((fboundp 'system-move-file-to-trash)
     (system-move-file-to-trash filename))
    (t
     (let* ((trash-dir   (expand-file-name trash-directory))
            (fn          (directory-file-name (expand-file-name filename)))
            (fn-nondir   (file-name-nondirectory fn))
            (new-fn      (expand-file-name fn-nondir trash-dir)))

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2008-09-13  David De La Harpe Golden  <david@harpegolden.net>

	* files.el: Add basic support for moving files to freedesktop.org
	Trash cans (as used by KDE/GNOME/XFCE/etc.).

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From: Chong Yidong <cyd@stupidchicken.com>
To: David De La Harpe Golden <david@harpegolden.net>
Cc: 973-done@emacsbugs.donarmstrong.com
Subject: Re: Support for moving files to freedesktop.org-style trashcan
Date: Sun, 28 Jun 2009 00:59:42 -0400
Message-ID: <87skhl0x8h.fsf@stupidchicken.com>

Hi David,

I've checked your code for freedesktop.org-style trashing into CVS
trunk, with modifications.

> Unlike "Microsoft Windows? -> use Windows Recycle Bin" or "MacOSX? ->
> use MacOSX trash can", one maybe can't say "GNU/Linux/BSD? -> use
> freedesktop-style Trash", so whether the freedesktop-style trashcan
> should be preferred over the simple emacs fallback "trash-directory"
> scheme is decided a bit roughly.

I changed it so that Emacs supports freedesktop.org style trashing
whenever `trash-directory' is nil, the new default.  (This is subject,
as before, to the `system-move-file-to-trash' override used under
Windows.)  Fancy autodetection is not worth it, since the user has to
manually enable this feature anyway.

Thanks very much for writing the code.