lisp/url/url-handlers.el

   1 ;;; url-handlers.el --- file-name-handler stuff for URL loading
   2
   3 ;; Copyright (C) 1996, 1997, 1998, 1999, 2004,
   4 ;;   2005, 2006  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.
 101 Some valid URL protocols just do not make sense to visit interactively
 102 \(about, data, info, irc, mailto, etc\).  This regular expression
 103 avoids conflicts with local files that look like URLs \(Gnus is
 104 particularly bad at this\).")
 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.
 130 OPERATION is what needs to be done (`file-exists-p', etc).  ARGS are
 131 the 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.
 190 Signals a `file-already-exists' error if file NEWNAME already exists,
 191 unless a third argument OK-IF-ALREADY-EXISTS is supplied and non-nil.
 192 A number as third arg means request confirmation if NEWNAME already exists.
 193 This is what happens in interactive use with M-x.
 194 Fourth arg KEEP-TIME non-nil means give the new file the same
 195 last-modified time as the old one.  (This works on only some systems.)
 196 A 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.
 213 Returns the name of the local copy, or nil, if FILE is directly
 214 accessible."
 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.
 221 BUFFER should be a complete URL buffer as returned by `url-retrieve'.
 222 If the headers specify a coding-system, it is applied to the body before it is inserted.
 223 Returns a list of the form (SIZE CHARSET), where SIZE is the size in bytes
 224 of the inserted text and CHARSET is the charset that was specified in the header,
 225 or nil if none was found.
 226 BEG and END can be used to only insert a subpart of the body.
 227 They 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