1;;; url-cache.el --- Uniform Resource Locator retrieval tool
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;;; Code:
26
27(require 'url-parse)
28(require 'url-util)
29(require 'url)                        ;E.g. for url-configuration-directory.
30
31(defcustom url-cache-directory
32  (expand-file-name "cache" url-configuration-directory)
33  "*The directory where cache files should be stored."
34  :type 'directory
35  :group 'url-file)
36
37;; Cache manager
38(defun url-cache-file-writable-p (file)
39  "Follows the documentation of `file-writable-p', unlike `file-writable-p'."
40  (and (file-writable-p file)
41       (if (file-exists-p file)
42           (not (file-directory-p file))
43         (file-directory-p (file-name-directory file)))))
44
45(defun url-cache-prepare (file)
46  "Makes it possible to cache data in FILE.
47Creates any necessary parent directories, deleting any non-directory files
48that would stop this.  Returns nil if parent directories can not be
49created.  If FILE already exists as a non-directory, it changes
50permissions of FILE or deletes FILE to make it possible to write a new
51version of FILE.  Returns nil if this can not be done.  Returns nil if
52FILE already exists as a directory.  Otherwise, returns t, indicating that
53FILE can be created or overwritten."
54  (cond
55   ((url-cache-file-writable-p file)
56    t)
57   ((file-directory-p file)
58    nil)
59   (t
60    (condition-case ()
61	(or (make-directory (file-name-directory file) t) t)
62      (error nil)))))
63
64;;;###autoload
65(defun url-store-in-cache (&optional buff)
66  "Store buffer BUFF in the cache."
67  (if (not (and buff (get-buffer buff)))
68      nil
69    (save-current-buffer
70      (and buff (set-buffer buff))
71      (let* ((fname (url-cache-create-filename (url-view-url t))))
72	(if (url-cache-prepare fname)
73	    (let ((coding-system-for-write 'binary))
74	      (write-region (point-min) (point-max) fname nil 5)))))))
75
76;;;###autoload
77(defun url-is-cached (url)
78  "Return non-nil if the URL is cached."
79  (let* ((fname (url-cache-create-filename url))
80	 (attribs (file-attributes fname)))
81    (and fname				; got a filename
82	 (file-exists-p fname)		; file exists
83	 (not (eq (nth 0 attribs) t))	; Its not a directory
84	 (nth 5 attribs))))		; Can get last mod-time
85
86(defun url-cache-create-filename-human-readable (url)
87  "Return a filename in the local cache for URL"
88  (if url
89      (let* ((url (if (vectorp url) (url-recreate-url url) url))
90	     (urlobj (url-generic-parse-url url))
91	     (protocol (url-type urlobj))
92	     (hostname (url-host urlobj))
93	     (host-components
94	      (cons
95	       (user-real-login-name)
96	       (cons (or protocol "file")
97		     (reverse (split-string (or hostname "localhost")
98					    (eval-when-compile
99					      (regexp-quote ".")))))))
100	     (fname    (url-filename urlobj)))
101	(if (and fname (/= (length fname) 0) (= (aref fname 0) ?/))
102	    (setq fname (substring fname 1 nil)))
103	(if fname
104	    (let ((slash nil))
105	      (setq fname
106		    (mapconcat
107		     (function
108		      (lambda (x)
109			(cond
110			 ((and (= ?/ x) slash)
111			  (setq slash nil)
112			  "%2F")
113			 ((= ?/ x)
114			  (setq slash t)
115			  "/")
116			 (t
117			  (setq slash nil)
118			  (char-to-string x))))) fname ""))))
119
120	(setq fname (and fname
121			 (mapconcat
122			  (function (lambda (x)
123				      (if (= x ?~) "" (char-to-string x))))
124			  fname ""))
125	      fname (cond
126		     ((null fname) nil)
127		     ((or (string= "" fname) (string= "/" fname))
128		      url-directory-index-file)
129		     ((= (string-to-char fname) ?/)
130		      (if (string= (substring fname -1 nil) "/")
131			  (concat fname url-directory-index-file)
132			(substring fname 1 nil)))
133		     (t
134		      (if (string= (substring fname -1 nil) "/")
135			  (concat fname url-directory-index-file)
136			fname))))
137	(and fname
138	     (expand-file-name fname
139			       (expand-file-name
140				(mapconcat 'identity host-components "/")
141				url-cache-directory))))))
142
143(defun url-cache-create-filename-using-md5 (url)
144  "Create a cached filename using MD5.
145Very fast if you have an `md5' primitive function, suitably fast otherwise."
146  (require 'md5)
147  (if url
148      (let* ((url (if (vectorp url) (url-recreate-url url) url))
149	     (checksum (md5 url))
150	     (urlobj (url-generic-parse-url url))
151	     (protocol (url-type urlobj))
152	     (hostname (url-host urlobj))
153	     (host-components
154	      (cons
155	       (user-real-login-name)
156	       (cons (or protocol "file")
157		     (nreverse
158		      (delq nil
159			    (split-string (or hostname "localhost")
160					  (eval-when-compile
161					    (regexp-quote "."))))))))
162	     (fname    (url-filename urlobj)))
163	(and fname
164	     (expand-file-name checksum
165			       (expand-file-name
166				(mapconcat 'identity host-components "/")
167				url-cache-directory))))))
168
169(defcustom url-cache-creation-function 'url-cache-create-filename-using-md5
170  "*What function to use to create a cached filename."
171  :type '(choice (const :tag "MD5 of filename (low collision rate)"
172			:value url-cache-create-filename-using-md5)
173		 (const :tag "Human readable filenames (higher collision rate)"
174			:value url-cache-create-filename-human-readable)
175		 (function :tag "Other"))
176  :group 'url-cache)
177
178(defun url-cache-create-filename (url)
179  (funcall url-cache-creation-function url))
180
181;;;###autoload
182(defun url-cache-extract (fnam)
183  "Extract FNAM from the local disk cache"
184  (erase-buffer)
185  (insert-file-contents-literally fnam))
186
187;;;###autoload
188(defun url-cache-expired (url mod)
189  "Return t iff a cached file has expired."
190  (let* ((urlobj (if (vectorp url) url (url-generic-parse-url url)))
191	 (type (url-type urlobj)))
192    (cond
193     (url-standalone-mode
194      (not (file-exists-p (url-cache-create-filename url))))
195     ((string= type "http")
196      t)
197     ((member type '("file" "ftp"))
198      (if (or (equal mod '(0 0)) (not mod))
199	  t
200	(or (> (nth 0 mod) (nth 0 (current-time)))
201	    (> (nth 1 mod) (nth 1 (current-time))))))
202     (t nil))))
203
204(provide 'url-cache)
205
206;; arch-tag: 95b050a6-8e81-4f23-8e63-191b9d1d657c
207;;; url-cache.el ends here
208