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date Mon, 13 Aug 2007 08:51:32 +0200
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1 ;;; url-cache.el --- Uniform Resource Locator retrieval tool
2 ;; Author: wmperry
3 ;; Created: 1997/02/20 15:33:47
4 ;; Version: 1.3
5 ;; Keywords: comm, data, processes, hypermedia
6
7 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
8 ;;; Copyright (c) 1993-1996 by William M. Perry (wmperry@cs.indiana.edu)
9 ;;; Copyright (c) 1996, 1997 Free Software Foundation, Inc.
10 ;;;
11 ;;; This file is not part of GNU Emacs, but the same permissions apply.
12 ;;;
13 ;;; GNU Emacs is free software; you can redistribute it and/or modify
14 ;;; it under the terms of the GNU General Public License as published by
15 ;;; the Free Software Foundation; either version 2, or (at your option)
16 ;;; any later version.
17 ;;;
18 ;;; GNU Emacs is distributed in the hope that it will be useful,
19 ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
20 ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 ;;; GNU General Public License for more details.
22 ;;;
23 ;;; You should have received a copy of the GNU General Public License
24 ;;; along with GNU Emacs; see the file COPYING. If not, write to the
25 ;;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
26 ;;; Boston, MA 02111-1307, USA.
27 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
28 (require 'md5)
29
30 ;; Cache manager
31 (defun url-cache-file-writable-p (file)
32 "Follows the documentation of file-writable-p, unlike file-writable-p."
33 (and (file-writable-p file)
34 (if (file-exists-p file)
35 (not (file-directory-p file))
36 (file-directory-p (file-name-directory file)))))
37
38 (defun url-prepare-cache-for-file (file)
39 "Makes it possible to cache data in FILE.
40 Creates any necessary parent directories, deleting any non-directory files
41 that would stop this. Returns nil if parent directories can not be
42 created. If FILE already exists as a non-directory, it changes
43 permissions of FILE or deletes FILE to make it possible to write a new
44 version of FILE. Returns nil if this can not be done. Returns nil if
45 FILE already exists as a directory. Otherwise, returns t, indicating that
46 FILE can be created or overwritten."
47
48 ;; COMMENT: We don't delete directories because that requires
49 ;; recursively deleting the directories's contents, which might
50 ;; eliminate a substantial portion of the cache.
51
52 (cond
53 ((url-cache-file-writable-p file)
54 t)
55 ((file-directory-p file)
56 nil)
57 (t
58 (catch 'upcff-tag
59 (let ((dir (file-name-directory file))
60 dir-parent dir-last-component)
61 (if (string-equal dir file)
62 ;; *** Should I have a warning here?
63 ;; FILE must match a pattern like /foo/bar/, indicating it is a
64 ;; name only suitable for a directory. So presume we won't be
65 ;; able to overwrite FILE and return nil.
66 (throw 'upcff-tag nil))
67
68 ;; Make sure the containing directory exists, or throw a failure
69 ;; if we can't create it.
70 (if (file-directory-p dir)
71 nil
72 (or (fboundp 'make-directory)
73 (throw 'upcff-tag nil))
74 (make-directory dir t)
75 ;; make-directory silently fails if there is an obstacle, so
76 ;; we must verify its results.
77 (if (file-directory-p dir)
78 nil
79 ;; Look at prefixes of the path to find the obstacle that is
80 ;; stopping us from making the directory. Unfortunately, there
81 ;; is no portable function in Emacs to find the parent directory
82 ;; of a *directory*. So this code may not work on VMS.
83 (while (progn
84 (if (eq ?/ (aref dir (1- (length dir))))
85 (setq dir (substring dir 0 -1))
86 ;; Maybe we're on VMS where the syntax is different.
87 (throw 'upcff-tag nil))
88 (setq dir-parent (file-name-directory dir))
89 (not (file-directory-p dir-parent)))
90 (setq dir dir-parent))
91 ;; We have found the longest path prefix that exists as a
92 ;; directory. Deal with any obstacles in this directory.
93 (if (file-exists-p dir)
94 (condition-case nil
95 (delete-file dir)
96 (error (throw 'upcff-tag nil))))
97 (if (file-exists-p dir)
98 (throw 'upcff-tag nil))
99 ;; Try making the directory again.
100 (setq dir (file-name-directory file))
101 (make-directory dir t)
102 (or (file-directory-p dir)
103 (throw 'upcff-tag nil))))
104
105 ;; The containing directory exists. Let's see if there is
106 ;; something in the way in this directory.
107 (if (url-cache-file-writable-p file)
108 (throw 'upcff-tag t)
109 (condition-case nil
110 (delete-file file)
111 (error (throw 'upcff-tag nil))))
112
113 ;; The return value, if we get this far.
114 (url-cache-file-writable-p file))))))
115
116 (defvar url-cache-ignored-protocols
117 '("www" "about" "https" "mailto")
118 "*A list of protocols that we should never cache.")
119
120 (defun url-cache-cachable-p (obj)
121 ;; return t iff the current buffer is cachable
122 (cond
123 ((null obj) ; Something horribly confused
124 nil)
125 ((member (url-type obj) url-cache-ignored-protocols)
126 ;; We have been told to ignore this type of object
127 nil)
128 ((and (member (url-type obj) '("file" "ftp")) (not (url-host obj)))
129 ;; We never want to cache local files... what's the point?
130 nil)
131 ((member (url-type obj) '("http" "https"))
132 (let* ((status (cdr-safe (assoc "status" url-current-mime-headers)))
133 (class (if status (/ status 100) 0)))
134 (case class
135 (2 ; Various 'OK' statuses
136 (memq status '(200)))
137 (otherwise nil))))
138 (t
139 nil)))
140
141 ;;;###autoload
142 (defun url-store-in-cache (&optional buff)
143 "Store buffer BUFF in the cache"
144 (if (and buff (get-buffer buff))
145 nil
146 (save-excursion
147 (and buff (set-buffer buff))
148 (if (not (url-cache-cachable-p url-current-object))
149 nil
150 (let* ((fname (url-create-cached-filename (url-view-url t)))
151 (fname-hdr (concat fname ".hdr"))
152 (info (mapcar (function (lambda (var)
153 (cons (symbol-name var)
154 (symbol-value var))))
155 '( url-current-content-length
156 url-current-object
157 url-current-isindex
158 url-current-mime-encoding
159 url-current-mime-headers
160 url-current-mime-type
161 ))))
162 (cond ((and (url-prepare-cache-for-file fname)
163 (url-prepare-cache-for-file fname-hdr))
164 (write-region (point-min) (point-max) fname nil 5)
165 (set-buffer (get-buffer-create " *cache-tmp*"))
166 (erase-buffer)
167 (insert "(setq ")
168 (mapcar
169 (function
170 (lambda (x)
171 (insert (car x) " "
172 (cond ((null (setq x (cdr x))) "nil")
173 ((stringp x) (prin1-to-string x))
174 ((listp x) (concat "'" (prin1-to-string x)))
175 ((vectorp x) (prin1-to-string x))
176 ((numberp x) (int-to-string x))
177 (t "'???")) "\n")))
178 info)
179 (insert ")\n")
180 (write-region (point-min) (point-max) fname-hdr nil 5))))))))
181
182
183 ;;;###autoload
184 (defun url-is-cached (url)
185 "Return non-nil if the URL is cached."
186 (let* ((fname (url-create-cached-filename url))
187 (attribs (file-attributes fname)))
188 (and fname ; got a filename
189 (file-exists-p fname) ; file exists
190 (not (eq (nth 0 attribs) t)) ; Its not a directory
191 (nth 5 attribs)))) ; Can get last mod-time
192
193 (defun url-create-cached-filename-using-md5 (url)
194 (if url
195 (expand-file-name (md5 url)
196 (concat url-temporary-directory "/"
197 (user-real-login-name)))))
198
199 ;;;###autoload
200 (defun url-create-cached-filename (url)
201 "Return a filename in the local cache for URL"
202 (if url
203 (let* ((url url)
204 (urlobj (if (vectorp url)
205 url
206 (url-generic-parse-url url)))
207 (protocol (url-type urlobj))
208 (hostname (url-host urlobj))
209 (host-components
210 (cons
211 (user-real-login-name)
212 (cons (or protocol "file")
213 (nreverse
214 (delq nil
215 (mm-string-to-tokens
216 (or hostname "localhost") ?.))))))
217 (fname (url-filename urlobj)))
218 (if (and fname (/= (length fname) 0) (= (aref fname 0) ?/))
219 (setq fname (substring fname 1 nil)))
220 (if fname
221 (let ((slash nil))
222 (setq fname
223 (mapconcat
224 (function
225 (lambda (x)
226 (cond
227 ((and (= ?/ x) slash)
228 (setq slash nil)
229 "%2F")
230 ((= ?/ x)
231 (setq slash t)
232 "/")
233 (t
234 (setq slash nil)
235 (char-to-string x))))) fname ""))))
236
237 (if (and fname (memq system-type '(ms-windows ms-dos windows-nt))
238 (string-match "\\([A-Za-z]\\):[/\\]" fname))
239 (setq fname (concat (url-match fname 1) "/"
240 (substring fname (match-end 0)))))
241
242 (setq fname (and fname
243 (mapconcat
244 (function (lambda (x)
245 (if (= x ?~) "" (char-to-string x))))
246 fname ""))
247 fname (cond
248 ((null fname) nil)
249 ((or (string= "" fname) (string= "/" fname))
250 url-directory-index-file)
251 ((= (string-to-char fname) ?/)
252 (if (string= (substring fname -1 nil) "/")
253 (concat fname url-directory-index-file)
254 (substring fname 1 nil)))
255 (t
256 (if (string= (substring fname -1 nil) "/")
257 (concat fname url-directory-index-file)
258 fname))))
259
260 ;; Honor hideous 8.3 filename limitations on dos and windows
261 ;; we don't have to worry about this in Windows NT/95 (or OS/2?)
262 (if (and fname (memq system-type '(ms-windows ms-dos)))
263 (let ((base (url-file-extension fname t))
264 (ext (url-file-extension fname nil)))
265 (setq fname (concat (substring base 0 (min 8 (length base)))
266 (substring ext 0 (min 4 (length ext)))))
267 (setq host-components
268 (mapcar
269 (function
270 (lambda (x)
271 (if (> (length x) 8)
272 (concat
273 (substring x 0 8) "."
274 (substring x 8 (min (length x) 11)))
275 x)))
276 host-components))))
277
278 (and fname
279 (expand-file-name fname
280 (expand-file-name
281 (mapconcat 'identity host-components "/")
282 url-temporary-directory))))))
283
284 ;;;###autoload
285 (defun url-extract-from-cache (fnam)
286 "Extract FNAM from the local disk cache"
287 (set-buffer (get-buffer-create url-working-buffer))
288 (erase-buffer)
289 (setq url-current-mime-viewer nil)
290 (insert-file-contents-literally fnam)
291 (load (concat (if (memq system-type '(ms-windows ms-dos os2))
292 (url-file-extension fnam t)
293 fnam) ".hdr") t t))
294
295 ;;;###autoload
296 (defun url-cache-expired (url mod)
297 "Return t iff a cached file has expired."
298 (if (not (string-match url-nonrelative-link url))
299 t
300 (let* ((urlobj (url-generic-parse-url url))
301 (type (url-type urlobj)))
302 (cond
303 (url-standalone-mode
304 (not (file-exists-p (url-create-cached-filename urlobj))))
305 ((string= type "http")
306 (if (not url-standalone-mode) t
307 (not (file-exists-p (url-create-cached-filename urlobj)))))
308 ((not (fboundp 'current-time))
309 t)
310 ((member type '("file" "ftp"))
311 (if (or (equal mod '(0 0)) (not mod))
312 (return t)
313 (or (> (nth 0 mod) (nth 0 (current-time)))
314 (> (nth 1 mod) (nth 1 (current-time))))))
315 (t nil)))))
316
317 (provide 'url-cache)