1;;; url-handlers.el --- file-name-handler stuff for URL loading
2
3;; Copyright (C) 1996, 1997, 1998, 1999, 2004,
4;;   2005, 2006, 2007  Free Software Foundation, Inc.
5
6;; Keywords: comm, data, processes, hypermedia
7
8;; This file is part of GNU Emacs.
9;;
10;; GNU Emacs is free software; you can redistribute it and/or modify
11;; it under the terms of the GNU General Public License as published by
12;; the Free Software Foundation; either version 2, or (at your option)
13;; any later version.
14;;
15;; GNU Emacs is distributed in the hope that it will be useful,
16;; but WITHOUT ANY WARRANTY; without even the implied warranty of
17;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18;; GNU General Public License for more details.
19;;
20;; You should have received a copy of the GNU General Public License
21;; along with GNU Emacs; see the file COPYING.  If not, write to the
22;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
23;; Boston, MA 02110-1301, USA.
24
25;;; Commentary:
26
27;;; Code:
28
29;; (require 'url)
30(eval-when-compile (require 'url-parse))
31;; (require 'url-util)
32(eval-when-compile (require 'mm-decode))
33;; (require 'mailcap)
34;; The following functions in the byte compiler's warnings are known not
35;; to cause any real problem for the following reasons:
36;; - mm-save-part-to-file, mm-destroy-parts: always used
37;;   after mm-dissect-buffer and defined in the same file.
38;; The following are autoloaded instead of `require'd to avoid eagerly
39;; loading all of URL when turning on url-handler-mode in the .emacs.
40(autoload 'url-expand-file-name "url-expand" "Convert url to a fully specified url, and canonicalize it.")
41(autoload 'mm-dissect-buffer "mm-decode" "Dissect the current buffer and return a list of MIME handles.")
42(autoload 'url-scheme-get-property "url-methods" "Get property of a URL SCHEME.")
43
44(eval-when-compile
45  (require 'cl))
46
47;; Implementation status
48;; ---------------------
49;; Function				Status
50;; ------------------------------------------------------------
51;; add-name-to-file			Needs DAV Bindings
52;; copy-file				Broken (assumes 1st item is URL)
53;; delete-directory			Finished (DAV)
54;; delete-file				Finished (DAV)
55;; diff-latest-backup-file
56;; directory-file-name			unnecessary (what about VMS)?
57;; directory-files			Finished (DAV)
58;; dired-call-process
59;; dired-compress-file
60;; dired-uncache
61;; expand-file-name			Finished
62;; file-accessible-directory-p
63;; file-attributes			Finished, better with DAV
64;; file-directory-p			Needs DAV, finished
65;; file-executable-p			Finished
66;; file-exists-p			Finished
67;; file-local-copy
68;; file-modes
69;; file-name-all-completions		Finished (DAV)
70;; file-name-as-directory
71;; file-name-completion			Finished (DAV)
72;; file-name-directory
73;; file-name-nondirectory
74;; file-name-sans-versions		why?
75;; file-newer-than-file-p
76;; file-ownership-preserved-p		No way to know
77;; file-readable-p			Finished
78;; file-regular-p			!directory_p
79;; file-symlink-p			Needs DAV bindings
80;; file-truename			Needs DAV bindings
81;; file-writable-p			Check for LOCK?
82;; find-backup-file-name		why?
83;; get-file-buffer			why?
84;; insert-directory			Use DAV
85;; insert-file-contents			Finished
86;; load
87;; make-directory			Finished (DAV)
88;; make-symbolic-link			Needs DAV bindings
89;; rename-file				Finished (DAV)
90;; set-file-modes			Use mod_dav specific executable flag?
91;; set-visited-file-modtime		Impossible?
92;; shell-command			Impossible?
93;; unhandled-file-name-directory
94;; vc-registered			Finished (DAV)
95;; verify-visited-file-modtime
96;; write-region
97
98(defvar url-handler-regexp
99  "\\`\\(https?\\|ftp\\|file\\|nfs\\)://"
100  "*A regular expression for matching  URLs handled by file-name-handler-alist.
101Some valid URL protocols just do not make sense to visit interactively
102\(about, data, info, irc, mailto, etc\).  This regular expression
103avoids conflicts with local files that look like URLs \(Gnus is
104particularly bad at this\).")
105
106;;;###autoload
107(define-minor-mode url-handler-mode
108  "Use URL to handle URL-like file names."
109  :global t :group 'url
110  (if (not (boundp 'file-name-handler-alist))
111      ;; Can't be turned ON anyway.
112      (setq url-handler-mode nil)
113    ;; Remove old entry, if any.
114    (setq file-name-handler-alist
115	  (delq (rassq 'url-file-handler file-name-handler-alist)
116		file-name-handler-alist))
117    (if url-handler-mode
118	(push (cons url-handler-regexp 'url-file-handler)
119	      file-name-handler-alist))))
120
121(defun url-run-real-handler (operation args)
122  (let ((inhibit-file-name-handlers (cons 'url-file-handler
123					  (if (eq operation inhibit-file-name-operation)
124					      inhibit-file-name-handlers)))
125	(inhibit-file-name-operation operation))
126    (apply operation args)))
127
128(defun url-file-handler (operation &rest args)
129  "Function called from the `file-name-handler-alist' routines.
130OPERATION is what needs to be done (`file-exists-p', etc).  ARGS are
131the arguments that would have been passed to OPERATION."
132  (let ((fn (or (get operation 'url-file-handlers)
133		(intern-soft (format "url-%s" operation))))
134	(val nil)
135	(hooked nil))
136    (if (and fn (fboundp fn))
137	(setq hooked t
138	      val (apply fn args))
139      (setq hooked nil
140	    val (url-run-real-handler operation args)))
141    (url-debug 'handlers "%s %S%S => %S" (if hooked "Hooked" "Real")
142	       operation args val)
143    val))
144
145(defun url-file-handler-identity (&rest args)
146  ;; Identity function
147  (car args))
148
149;; These are operations that we can fully support
150(put 'file-readable-p 'url-file-handlers 'url-file-exists-p)
151(put 'substitute-in-file-name 'url-file-handlers 'url-file-handler-identity)
152(put 'file-name-absolute-p 'url-file-handlers (lambda (&rest ignored) t))
153(put 'expand-file-name 'url-file-handlers 'url-handler-expand-file-name)
154(put 'directory-file-name 'url-file-handlers 'url-handler-directory-file-name)
155;; (put 'file-name-as-directory 'url-file-handlers 'url-handler-file-name-as-directory)
156
157;; These are operations that we do not support yet (DAV!!!)
158(put 'file-writable-p 'url-file-handlers 'ignore)
159(put 'file-symlink-p 'url-file-handlers 'ignore)
160;; Just like for ange-ftp: let's not waste time trying to look for RCS/foo,v
161;; files and such since we can't do anything clever with them anyway.
162(put 'vc-registered 'url-file-handlers 'ignore)
163
164(defun url-handler-expand-file-name (file &optional base)
165  ;; When we see "/foo/bar" in a file whose working dir is "http://bla/bla",
166  ;; there are two interpretations possible: either it's a local "/foo/bar"
167  ;; or it's "http:/bla/foo/bar".  When working with URLs, the second
168  ;; interpretation is the right one, but when working with Emacs file
169  ;; names, the first is preferred.
170  (if (file-name-absolute-p file)
171      (expand-file-name file "/")
172    (url-expand-file-name file base)))
173
174;; directory-file-name and file-name-as-directory are kind of hard to
175;; implement really right for URLs since URLs can have repeated / chars.
176;; We'd want the following behavior:
177;; idempotence: (d-f-n (d-f-n X) == (d-f-n X)
178;; idempotence: (f-n-a-d (f-n-a-d X) == (f-n-a-d X)
179;; reversible:  (d-f-n (f-n-a-d (d-f-n X))) == (d-f-n X)
180;; reversible:  (f-n-a-d (d-f-n (f-n-a-d X))) == (f-n-a-d X)
181(defun url-handler-directory-file-name (dir)
182  ;; When there's more than a single /, just don't touch the slashes at all.
183  (if (string-match "//\\'" dir) dir
184    (url-run-real-handler 'directory-file-name (list dir))))
185
186;; The actual implementation
187;;;###autoload
188(defun url-copy-file (url newname &optional ok-if-already-exists keep-time)
189  "Copy URL to NEWNAME.  Both args must be strings.
190Signals a `file-already-exists' error if file NEWNAME already exists,
191unless a third argument OK-IF-ALREADY-EXISTS is supplied and non-nil.
192A number as third arg means request confirmation if NEWNAME already exists.
193This is what happens in interactive use with M-x.
194Fourth arg KEEP-TIME non-nil means give the new file the same
195last-modified time as the old one.  (This works on only some systems.)
196A prefix arg makes KEEP-TIME non-nil."
197  (if (and (file-exists-p newname)
198	   (not ok-if-already-exists))
199      (error "Opening output file: File already exists, %s" newname))
200  (let ((buffer (url-retrieve-synchronously url))
201	(handle nil))
202    (if (not buffer)
203	(error "Opening input file: No such file or directory, %s" url))
204    (with-current-buffer buffer
205      (setq handle (mm-dissect-buffer t)))
206    (mm-save-part-to-file handle newname)
207    (kill-buffer buffer)
208    (mm-destroy-parts handle)))
209
210;;;###autoload
211(defun url-file-local-copy (url &rest ignored)
212  "Copy URL into a temporary file on this machine.
213Returns the name of the local copy, or nil, if FILE is directly
214accessible."
215  (let ((filename (make-temp-file "url")))
216    (url-copy-file url filename 'ok-if-already-exists)
217    filename))
218
219(defun url-insert (buffer &optional beg end)
220  "Insert the body of a URL object.
221BUFFER should be a complete URL buffer as returned by `url-retrieve'.
222If the headers specify a coding-system, it is applied to the body before it is inserted.
223Returns a list of the form (SIZE CHARSET), where SIZE is the size in bytes
224of the inserted text and CHARSET is the charset that was specified in the header,
225or nil if none was found.
226BEG and END can be used to only insert a subpart of the body.
227They count bytes from the beginning of the body."
228  (let* ((handle (with-current-buffer buffer (mm-dissect-buffer t)))
229         (data (with-current-buffer (mm-handle-buffer handle)
230                 (if beg
231                     (buffer-substring (+ (point-min) beg)
232                                       (if end (+ (point-min) end) (point-max)))
233		   (buffer-string))))
234         (charset (mail-content-type-get (mm-handle-type handle)
235                                          'charset)))
236    (mm-destroy-parts handle)
237    (if charset
238        (insert (mm-decode-string data (mm-charset-to-coding-system charset)))
239      (insert data))
240    (list (length data) charset)))
241
242;;;###autoload
243(defun url-insert-file-contents (url &optional visit beg end replace)
244  (let ((buffer (url-retrieve-synchronously url)))
245    (if (not buffer)
246	(error "Opening input file: No such file or directory, %s" url))
247    (if visit (setq buffer-file-name url))
248    (save-excursion
249      (let* ((start (point))
250             (size-and-charset (url-insert buffer beg end)))
251        (kill-buffer buffer)
252        (when replace
253          (delete-region (point-min) start)
254          (delete-region (point) (point-max)))
255        (unless (cadr size-and-charset)
256          ;; If the headers don't specify any particular charset, use the
257          ;; usual heuristic/rules that we apply to files.
258          (decode-coding-inserted-region start (point) url visit beg end replace))
259        (list url (car size-and-charset))))))
260
261(defun url-file-name-completion (url directory)
262  (error "Unimplemented"))
263
264(defun url-file-name-all-completions (file directory)
265  (error "Unimplemented"))
266
267;; All other handlers map onto their respective backends.
268(defmacro url-handlers-create-wrapper (method args)
269  `(defun ,(intern (format "url-%s" method)) ,args
270     ,(format "URL file-name-handler wrapper for `%s' call.\n---\n%s" method
271              (or (documentation method t) "No original documentation."))
272     (setq url (url-generic-parse-url url))
273     (when (url-type url)
274       (funcall (url-scheme-get-property (url-type url) (quote ,method))
275                ,@(remove '&rest (remove '&optional args))))))
276
277(url-handlers-create-wrapper file-exists-p (url))
278(url-handlers-create-wrapper file-attributes (url &optional id-format))
279(url-handlers-create-wrapper file-symlink-p (url))
280(url-handlers-create-wrapper file-writable-p (url))
281(url-handlers-create-wrapper file-directory-p (url))
282(url-handlers-create-wrapper file-executable-p (url))
283(url-handlers-create-wrapper directory-files (url &optional full match nosort))
284(url-handlers-create-wrapper file-truename (url &optional counter prev-dirs))
285
286(add-hook 'find-file-hook 'url-handlers-set-buffer-mode)
287
288(defun url-handlers-set-buffer-mode ()
289  "Set correct modes for the current buffer if visiting a remote file."
290  (and (stringp buffer-file-name)
291       (string-match url-handler-regexp buffer-file-name)
292       (auto-save-mode 0)))
293
294(provide 'url-handlers)
295
296;; arch-tag: 7300b99c-cc83-42ff-9147-79b2723c62ac
297;;; url-handlers.el ends here
298