lisp/url/url-handlers.el

   1 ;;; url-handlers.el --- file-name-handler stuff for URL loading  -*- lexical-binding:t -*-
   2
   3 ;; Copyright (C) 1996-1999, 2004-2017 Free Software Foundation, Inc.
   4
   5 ;; Keywords: comm, data, processes, hypermedia
   6
   7 ;; This file is part of GNU Emacs.
   8 ;;
   9 ;; GNU Emacs is free software: you can redistribute it and/or modify
  10 ;; it under the terms of the GNU General Public License as published by
  11 ;; the Free Software Foundation, either version 3 of the License, or
  12 ;; (at your option) any later version.
  13
  14 ;; GNU Emacs is distributed in the hope that it will be useful,
  15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 ;; GNU General Public License for more details.
  18
  19 ;; You should have received a copy of the GNU General Public License
  20 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  21
  22 ;;; Commentary:
  23
  24 ;;; Code:
  25
  26 ;; (require 'url)
  27 (require 'url-parse)
  28 ;; (require 'url-util)
  29 (eval-when-compile (require 'mm-decode))
  30 ;; (require 'mailcap)
  31 ;; The following are autoloaded instead of `require'd to avoid eagerly
  32 ;; loading all of URL when turning on url-handler-mode in the .emacs.
  33 (autoload 'url-expand-file-name "url-expand" "Convert url to a fully specified url, and canonicalize it.")
  34 (autoload 'mm-dissect-buffer "mm-decode" "Dissect the current buffer and return a list of MIME handles.")
  35 (autoload 'url-scheme-get-property "url-methods" "Get property of a URL SCHEME.")
  36
  37 ;; Always used after mm-dissect-buffer and defined in the same file.
  38 (declare-function mm-save-part-to-file "mm-decode" (handle file))
  39 (declare-function mm-destroy-parts "mm-decode" (handles))
  40 ;; mm-decode loads mm-bodies.
  41 (declare-function mm-decode-string "mm-bodies" (string charset))
  42 ;; mm-decode loads mail-parse.
  43 (declare-function mail-content-type-get "mail-parse" (ct attribute))
  44
  45 ;; Implementation status
  46 ;; ---------------------
  47 ;; Function                             Status
  48 ;; ------------------------------------------------------------
  49 ;; add-name-to-file                     Needs DAV Bindings
  50 ;; copy-file                            Broken (assumes 1st item is URL)
  51 ;; delete-directory                     Finished (DAV)
  52 ;; delete-file                          Finished (DAV)
  53 ;; diff-latest-backup-file
  54 ;; directory-file-name                  unnecessary
  55 ;; directory-files                      Finished (DAV)
  56 ;; dired-call-process
  57 ;; dired-compress-file
  58 ;; dired-uncache
  59 ;; expand-file-name                     Finished
  60 ;; file-accessible-directory-p
  61 ;; file-attributes                      Finished, better with DAV
  62 ;; file-directory-p                     Needs DAV, finished
  63 ;; file-executable-p                    Finished
  64 ;; file-exists-p                        Finished
  65 ;; file-local-copy
  66 ;; file-modes
  67 ;; file-name-all-completions            Finished (DAV)
  68 ;; file-name-as-directory
  69 ;; file-name-completion                 Finished (DAV)
  70 ;; file-name-directory
  71 ;; file-name-nondirectory
  72 ;; file-name-sans-versions              why?
  73 ;; file-newer-than-file-p
  74 ;; file-ownership-preserved-p           No way to know
  75 ;; file-readable-p                      Finished
  76 ;; file-regular-p                       !directory_p
  77 ;; file-remote-p                        Finished
  78 ;; file-symlink-p                       Needs DAV bindings
  79 ;; file-truename                        Needs DAV bindings
  80 ;; file-writable-p                      Check for LOCK?
  81 ;; find-backup-file-name                why?
  82 ;; get-file-buffer                      why?
  83 ;; insert-directory                     Use DAV
  84 ;; insert-file-contents                 Finished
  85 ;; load
  86 ;; make-directory                       Finished (DAV)
  87 ;; make-symbolic-link                   Needs DAV bindings
  88 ;; rename-file                          Finished (DAV)
  89 ;; set-file-modes                       Use mod_dav specific executable flag?
  90 ;; set-visited-file-modtime             Impossible?
  91 ;; shell-command                        Impossible?
  92 ;; unhandled-file-name-directory
  93 ;; vc-registered                        Finished (DAV)
  94 ;; verify-visited-file-modtime
  95 ;; write-region
  96
  97 (defvar url-handler-regexp) ; defined below to avoid recursive load (revno:108572)
  98
  99 ;;;###autoload
 100 (define-minor-mode url-handler-mode
 101   "Toggle using `url' library for URL filenames (URL Handler mode).
 102 With a prefix argument ARG, enable URL Handler mode if ARG is
 103 positive, and disable it otherwise.  If called from Lisp, enable
 104 the mode if ARG is omitted or nil."
 105   :global t :group 'url
 106   ;; Remove old entry, if any.
 107   (setq file-name-handler-alist
 108         (delq (rassq 'url-file-handler file-name-handler-alist)
 109               file-name-handler-alist))
 110   (if url-handler-mode
 111       (push (cons url-handler-regexp 'url-file-handler)
 112             file-name-handler-alist)))
 113
 114 (defcustom url-handler-regexp "\\`\\(https?\\|ftp\\|file\\|nfs\\|ssh\\|scp\\|rsync\\|telnet\\)://"
 115   "Regular expression for URLs handled by `url-handler-mode'.
 116 When URL Handler mode is enabled, this regular expression is
 117 added to `file-name-handler-alist'.
 118
 119 Some valid URL protocols just do not make sense to visit
 120 interactively \(about, data, info, irc, mailto, etc.).  This
 121 regular expression avoids conflicts with local files that look
 122 like URLs \(Gnus is particularly bad at this)."
 123   :group 'url
 124   :type 'regexp
 125   :version "25.1"
 126   :set (lambda (symbol value)
 127          (let ((enable url-handler-mode))
 128            (url-handler-mode 0)
 129            (set-default symbol value)
 130            (if enable
 131                (url-handler-mode)))))
 132
 133 (defun url-run-real-handler (operation args)
 134   (let ((inhibit-file-name-handlers (cons 'url-file-handler
 135                                           (if (eq operation inhibit-file-name-operation)
 136                                               inhibit-file-name-handlers)))
 137         (inhibit-file-name-operation operation))
 138     (apply operation args)))
 139
 140 (defvar url-file-handler-load-in-progress nil
 141   "Check for recursive load.")
 142
 143 ;;;###autoload
 144 (defun url-file-handler (operation &rest args)
 145   "Function called from the `file-name-handler-alist' routines.
 146 OPERATION is what needs to be done (`file-exists-p', etc).  ARGS are
 147 the arguments that would have been passed to OPERATION."
 148   ;; Avoid recursive load.
 149   (if (and load-in-progress url-file-handler-load-in-progress)
 150       (url-run-real-handler operation args)
 151     (let ((url-file-handler-load-in-progress load-in-progress))
 152       ;; Check, whether there are arguments we want pass to Tramp.
 153       (if (catch :do
 154             (dolist (url (cons default-directory args))
 155               (and (member
 156                     (url-type (url-generic-parse-url (and (stringp url) url)))
 157                     url-tramp-protocols)
 158                    (throw :do t))))
 159           (apply 'url-tramp-file-handler operation args)
 160         ;; Otherwise, let's do the job.
 161         (let ((fn (get operation 'url-file-handlers))
 162               (val nil)
 163               (hooked nil))
 164           (if (and (not fn) (intern-soft (format "url-%s" operation))
 165                    (fboundp (intern-soft (format "url-%s" operation))))
 166               (error "Missing URL handler mapping for %s" operation))
 167           (if fn
 168               (setq hooked t
 169                     val (save-match-data (apply fn args)))
 170             (setq hooked nil
 171                   val (url-run-real-handler operation args)))
 172           (url-debug 'handlers "%s %S%S => %S" (if hooked "Hooked" "Real")
 173                      operation args val)
 174           val)))))
 175
 176 (defun url-file-handler-identity (&rest args)
 177   ;; Identity function
 178   (car args))
 179
 180 ;; These are operations that we can fully support
 181 (put 'file-readable-p 'url-file-handlers 'url-file-exists-p)
 182 (put 'substitute-in-file-name 'url-file-handlers 'url-file-handler-identity)
 183 (put 'file-name-absolute-p 'url-file-handlers (lambda (&rest ignored) t))
 184 (put 'expand-file-name 'url-file-handlers 'url-handler-expand-file-name)
 185 (put 'directory-file-name 'url-file-handlers 'url-handler-directory-file-name)
 186 (put 'unhandled-file-name-directory 'url-file-handlers 'url-handler-unhandled-file-name-directory)
 187 (put 'file-remote-p 'url-file-handlers 'url-handler-file-remote-p)
 188 ;; (put 'file-name-as-directory 'url-file-handlers 'url-handler-file-name-as-directory)
 189
 190 ;; These are operations that we do not support yet (DAV!!!)
 191 (put 'file-writable-p 'url-file-handlers 'ignore)
 192 (put 'file-symlink-p 'url-file-handlers 'ignore)
 193 ;; Just like for ange-ftp: let's not waste time trying to look for RCS/foo,v
 194 ;; files and such since we can't do anything clever with them anyway.
 195 (put 'vc-registered 'url-file-handlers 'ignore)
 196
 197 (defun url-handler-expand-file-name (file &optional base)
 198   ;; When we see "/foo/bar" in a file whose working dir is "http://bla/bla",
 199   ;; there are two interpretations possible: either it's a local "/foo/bar"
 200   ;; or it's "http:/bla/foo/bar".  When working with URLs, the second
 201   ;; interpretation is the right one, but when working with Emacs file
 202   ;; names, the first is preferred.
 203   (if (file-name-absolute-p file)
 204       (expand-file-name file "/")
 205     (url-expand-file-name file base)))
 206
 207 ;; directory-file-name and file-name-as-directory are kind of hard to
 208 ;; implement really right for URLs since URLs can have repeated / chars.
 209 ;; We'd want the following behavior:
 210 ;; idempotence: (d-f-n (d-f-n X) == (d-f-n X)
 211 ;; idempotence: (f-n-a-d (f-n-a-d X) == (f-n-a-d X)
 212 ;; reversible:  (d-f-n (f-n-a-d (d-f-n X))) == (d-f-n X)
 213 ;; reversible:  (f-n-a-d (d-f-n (f-n-a-d X))) == (f-n-a-d X)
 214 (defun url-handler-directory-file-name (dir)
 215   ;; When there's more than a single /, just don't touch the slashes at all.
 216   (if (string-match "//\\'" dir) dir
 217     (url-run-real-handler 'directory-file-name (list dir))))
 218
 219 (defun url-handler-unhandled-file-name-directory (filename)
 220   (let ((url (url-generic-parse-url filename)))
 221     (if (equal (url-type url) "file")
 222         ;; `file' URLs are actually local.  The filename part may be ""
 223         ;; which really stands for "/".
 224         ;; FIXME: maybe we should check that the host part is "" or "localhost"
 225         ;; or some name that represents the local host?
 226         (or (file-name-as-directory (url-filename url)) "/")
 227       ;; All other URLs are not expected to be directly accessible from
 228       ;; a local process.
 229       nil)))
 230
 231 (defun url-handler-file-remote-p (filename &optional identification _connected)
 232   (let ((url (url-generic-parse-url filename)))
 233     (if (and (url-type url) (not (equal (url-type url) "file")))
 234         ;; Maybe we can find a suitable check for CONNECTED.  For now,
 235         ;; we ignore it.
 236         (cond
 237          ((eq identification 'method) (url-type url))
 238          ((eq identification 'user) (url-user url))
 239          ((eq identification 'host) (url-host url))
 240          ((eq identification 'localname) (url-filename url))
 241          (t (url-recreate-url
 242              (url-parse-make-urlobj (url-type url) (url-user url) nil
 243                                     (url-host url) (url-port url)))))
 244       ;; If there is no URL type, or it is a "file://" URL, the
 245       ;; filename is expected to be non remote.  A more subtle check
 246       ;; for "file://" URLs could be applied, as said in
 247       ;; `url-handler-unhandled-file-name-directory'.
 248       nil)))
 249
 250 ;; The actual implementation
 251 ;;;###autoload
 252 (defun url-copy-file (url newname &optional ok-if-already-exists
 253                           _keep-time _preserve-uid-gid)
 254   "Copy URL to NEWNAME.  Both args must be strings.
 255 Signals a `file-already-exists' error if file NEWNAME already exists,
 256 unless a third argument OK-IF-ALREADY-EXISTS is supplied and non-nil.
 257 A number as third arg means request confirmation if NEWNAME already exists.
 258 This is what happens in interactive use with M-x.
 259 Fourth arg KEEP-TIME non-nil means give the new file the same
 260 last-modified time as the old one.  (This works on only some systems.)
 261 Fifth arg PRESERVE-UID-GID is ignored.
 262 A prefix arg makes KEEP-TIME non-nil."
 263   (if (and (file-exists-p newname)
 264            (not ok-if-already-exists))
 265       (signal 'file-already-exists (list "File exists" newname)))
 266   (let ((buffer (url-retrieve-synchronously url))
 267         (handle nil))
 268     (if (not buffer)
 269         (signal 'file-missing (list "Opening URL" "No such file or directory"
 270                                     url)))
 271     (with-current-buffer buffer
 272       (setq handle (mm-dissect-buffer t)))
 273     (let ((mm-attachment-file-modes (default-file-modes)))
 274       (mm-save-part-to-file handle newname))
 275     (kill-buffer buffer)
 276     (mm-destroy-parts handle)))
 277 (put 'copy-file 'url-file-handlers 'url-copy-file)
 278
 279 ;;;###autoload
 280 (defun url-file-local-copy (url &rest ignored)
 281   "Copy URL into a temporary file on this machine.
 282 Returns the name of the local copy, or nil, if FILE is directly
 283 accessible."
 284   (let ((filename (make-temp-file "url")))
 285     (url-copy-file url filename 'ok-if-already-exists)
 286     filename))
 287 (put 'file-local-copy 'url-file-handlers 'url-file-local-copy)
 288
 289 (defun url-insert (buffer &optional beg end)
 290   "Insert the body of a URL object.
 291 BUFFER should be a complete URL buffer as returned by `url-retrieve'.
 292 If the headers specify a coding-system, it is applied to the body before it is inserted.
 293 Returns a list of the form (SIZE CHARSET), where SIZE is the size in bytes
 294 of the inserted text and CHARSET is the charset that was specified in the header,
 295 or nil if none was found.
 296 BEG and END can be used to only insert a subpart of the body.
 297 They count bytes from the beginning of the body."
 298   (let* ((handle (with-current-buffer buffer (mm-dissect-buffer t)))
 299          (data (with-current-buffer (mm-handle-buffer handle)
 300                  (if beg
 301                      (buffer-substring (+ (point-min) beg)
 302                                        (if end (+ (point-min) end) (point-max)))
 303                    (buffer-string))))
 304          (charset (mail-content-type-get (mm-handle-type handle)
 305                                           'charset)))
 306     (mm-destroy-parts handle)
 307     (if charset
 308         (insert (mm-decode-string data (mm-charset-to-coding-system charset)))
 309       (insert data))
 310     (list (length data) charset)))
 311
 312 (defvar url-http-codes)
 313
 314 ;;;###autoload
 315 (defun url-insert-buffer-contents (buffer url &optional visit beg end replace)
 316   "Insert the contents of BUFFER into current buffer.
 317 This is like `url-insert', but also decodes the current buffer as
 318 if it had been inserted from a file named URL."
 319   (if visit (setq buffer-file-name url))
 320   (save-excursion
 321     (let* ((start (point))
 322            (size-and-charset (url-insert buffer beg end)))
 323       (kill-buffer buffer)
 324       (when replace
 325         (delete-region (point-min) start)
 326         (delete-region (point) (point-max)))
 327       (unless (cadr size-and-charset)
 328         ;; If the headers don't specify any particular charset, use the
 329         ;; usual heuristic/rules that we apply to files.
 330         (decode-coding-inserted-region (point-min) (point) url
 331                                        visit beg end replace))
 332       (let ((inserted (car size-and-charset)))
 333         (when (fboundp 'after-insert-file-set-coding)
 334           (let ((insval (after-insert-file-set-coding inserted visit)))
 335             (if insval (setq inserted insval))))
 336         (list url inserted)))))
 337
 338 ;;;###autoload
 339 (defun url-insert-file-contents (url &optional visit beg end replace)
 340   (let ((buffer (url-retrieve-synchronously url)))
 341     (unless buffer (signal 'file-error (list url "No Data")))
 342     (with-current-buffer buffer
 343       ;; XXX: This is HTTP/S specific and should be moved to url-http
 344       ;; instead.  See http://debbugs.gnu.org/17549.
 345       (when (bound-and-true-p url-http-response-status)
 346         ;; Don't signal an error if VISIT is non-nil, because
 347         ;; 'insert-file-contents' doesn't.  This is required to
 348         ;; support, e.g., 'browse-url-emacs', which is a fancy way of
 349         ;; visiting the HTML source of a URL: in that case, we want to
 350         ;; display a file buffer even if the URL does not exist and
 351         ;; 'url-retrieve-synchronously' returns 404 or whatever.
 352         (unless (or visit
 353                     (and (>= url-http-response-status 200)
 354                          (< url-http-response-status 300)))
 355           (let ((desc (nth 2 (assq url-http-response-status url-http-codes))))
 356             (kill-buffer buffer)
 357             ;; Signal file-error per http://debbugs.gnu.org/16733.
 358             (signal 'file-error (list url desc))))))
 359     (url-insert-buffer-contents buffer url visit beg end replace)))
 360
 361 (put 'insert-file-contents 'url-file-handlers 'url-insert-file-contents)
 362
 363 (defun url-file-name-completion (url _directory &optional _predicate)
 364   ;; Even if it's not implemented, it's not an error to ask for completion,
 365   ;; in case it's available (bug#14806).
 366   ;; (error "Unimplemented")
 367   url)
 368 (put 'file-name-completion 'url-file-handlers 'url-file-name-completion)
 369
 370 (defun url-file-name-all-completions (_file _directory)
 371   ;; Even if it's not implemented, it's not an error to ask for completion,
 372   ;; in case it's available (bug#14806).
 373   ;; (error "Unimplemented")
 374   nil)
 375 (put 'file-name-all-completions
 376      'url-file-handlers 'url-file-name-all-completions)
 377
 378 ;; All other handlers map onto their respective backends.
 379 (defmacro url-handlers-create-wrapper (method args)
 380   `(progn
 381      (defun ,(intern (format "url-%s" method)) ,args
 382        ,(format "URL file-name-handler wrapper for `%s' call.\n---\n%s" method
 383                 (or (documentation method t) "No original documentation."))
 384        (setq url (url-generic-parse-url url))
 385        (when (url-type url)
 386          (funcall (url-scheme-get-property (url-type url) (quote ,method))
 387                   ,@(remove '&rest (remove '&optional args)))))
 388      (unless (get ',method 'url-file-handlers)
 389        (put ',method 'url-file-handlers ',(intern (format "url-%s" method))))))
 390
 391 (url-handlers-create-wrapper file-exists-p (url))
 392 (url-handlers-create-wrapper file-attributes (url &optional id-format))
 393 (url-handlers-create-wrapper file-symlink-p (url))
 394 (url-handlers-create-wrapper file-writable-p (url))
 395 (url-handlers-create-wrapper file-directory-p (url))
 396 (url-handlers-create-wrapper file-executable-p (url))
 397 (url-handlers-create-wrapper directory-files (url &optional full match nosort))
 398 (url-handlers-create-wrapper file-truename (url &optional counter prev-dirs))
 399
 400 (add-hook 'find-file-hook 'url-handlers-set-buffer-mode)
 401
 402 (defun url-handlers-set-buffer-mode ()
 403   "Set correct modes for the current buffer if visiting a remote file."
 404   (and (stringp buffer-file-name)
 405        (string-match url-handler-regexp buffer-file-name)
 406        (auto-save-mode 0)))
 407
 408 (provide 'url-handlers)
 409
 410 ;;; url-handlers.el ends here