code.delx.au - gnu-emacs/blob - lisp/url/url-cache.el

   1 ;;; url-cache.el --- Uniform Resource Locator retrieval tool
   2
   3 ;; Copyright (C) 1996, 1997, 1998, 1999, 2004, 2005, 2006, 2007, 2008,
   4 ;;   2009, 2010, 2011  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 3 of the License, or
  13 ;; (at your option) 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.  If not, see <http://www.gnu.org/licenses/>.
  22
  23 ;;; Code:
  24
  25 (require 'url-parse)
  26 (require 'url-util)
  27 (require 'url)                        ;E.g. for url-configuration-directory.
  28
  29 (defcustom url-cache-directory
  30   (expand-file-name "cache" url-configuration-directory)
  31   "*The directory where cache files should be stored."
  32   :type 'directory
  33   :group 'url-file)
  34
  35 ;; Cache manager
  36 (defun url-cache-file-writable-p (file)
  37   "Follows the documentation of `file-writable-p', unlike `file-writable-p'."
  38   (and (file-writable-p file)
  39        (if (file-exists-p file)
  40            (not (file-directory-p file))
  41          (file-directory-p (file-name-directory file)))))
  42
  43 (defun url-cache-prepare (file)
  44   "Makes it possible to cache data in FILE.
  45 Creates any necessary parent directories, deleting any non-directory files
  46 that would stop this.  Returns nil if parent directories can not be
  47 created.  If FILE already exists as a non-directory, it changes
  48 permissions of FILE or deletes FILE to make it possible to write a new
  49 version of FILE.  Returns nil if this can not be done, or if FILE already
  50 exists as a directory.  Otherwise, returns t, indicating that
  51 FILE can be created or overwritten."
  52   (cond
  53    ((url-cache-file-writable-p file)
  54     t)
  55    ((file-directory-p file)
  56     nil)
  57    (t
  58     (condition-case ()
  59         (or (make-directory (file-name-directory file) t) t)
  60       (error nil)))))
  61
  62 ;;;###autoload
  63 (defun url-store-in-cache (&optional buff)
  64   "Store buffer BUFF in the cache."
  65     (with-current-buffer (get-buffer (or buff (current-buffer)))
  66       (let ((fname (url-cache-create-filename (url-view-url t))))
  67         (if (url-cache-prepare fname)
  68             (let ((coding-system-for-write 'binary))
  69               (write-region (point-min) (point-max) fname nil 5))))))
  70
  71 ;;;###autoload
  72 (defun url-is-cached (url)
  73   "Return non-nil if the URL is cached.
  74 The actual return value is the last modification time of the cache file."
  75   (let* ((fname (url-cache-create-filename url))
  76          (attribs (file-attributes fname)))
  77     (and fname                          ; got a filename
  78          (file-exists-p fname)          ; file exists
  79          (not (eq (nth 0 attribs) t))   ; Its not a directory
  80          (nth 5 attribs))))             ; Can get last mod-time
  81
  82 (defun url-cache-create-filename-human-readable (url)
  83   "Return a filename in the local cache for URL."
  84   (if url
  85       (let* ((url (if (vectorp url) (url-recreate-url url) url))
  86              (urlobj (url-generic-parse-url url))
  87              (protocol (url-type urlobj))
  88              (hostname (url-host urlobj))
  89              (host-components
  90               (cons
  91                (user-real-login-name)
  92                (cons (or protocol "file")
  93                      (reverse (split-string (or hostname "localhost")
  94                                             (eval-when-compile
  95                                               (regexp-quote ".")))))))
  96              (fname    (url-filename urlobj)))
  97         (if (and fname (/= (length fname) 0) (= (aref fname 0) ?/))
  98             (setq fname (substring fname 1 nil)))
  99         (if fname
 100             (let ((slash nil))
 101               (setq fname
 102                     (mapconcat
 103                      (function
 104                       (lambda (x)
 105                         (cond
 106                          ((and (= ?/ x) slash)
 107                           (setq slash nil)
 108                           "%2F")
 109                          ((= ?/ x)
 110                           (setq slash t)
 111                           "/")
 112                          (t
 113                           (setq slash nil)
 114                           (char-to-string x))))) fname ""))))
 115
 116         (setq fname (and fname
 117                          (mapconcat
 118                           (function (lambda (x)
 119                                       (if (= x ?~) "" (char-to-string x))))
 120                           fname ""))
 121               fname (cond
 122                      ((null fname) nil)
 123                      ((or (string= "" fname) (string= "/" fname))
 124                       url-directory-index-file)
 125                      ((= (string-to-char fname) ?/)
 126                       (if (string= (substring fname -1 nil) "/")
 127                           (concat fname url-directory-index-file)
 128                         (substring fname 1 nil)))
 129                      (t
 130                       (if (string= (substring fname -1 nil) "/")
 131                           (concat fname url-directory-index-file)
 132                         fname))))
 133         (and fname
 134              (expand-file-name fname
 135                                (expand-file-name
 136                                 (mapconcat 'identity host-components "/")
 137                                 url-cache-directory))))))
 138
 139 (defun url-cache-create-filename-using-md5 (url)
 140   "Create a cached filename using MD5.
 141 Very fast if you have an `md5' primitive function, suitably fast otherwise."
 142   (require 'md5)
 143   (if url
 144       (let* ((url (if (vectorp url) (url-recreate-url url) url))
 145              (checksum (md5 url))
 146              (urlobj (url-generic-parse-url url))
 147              (protocol (url-type urlobj))
 148              (hostname (url-host urlobj))
 149              (host-components
 150               (cons
 151                (user-real-login-name)
 152                (cons (or protocol "file")
 153                      (nreverse
 154                       (delq nil
 155                             (split-string (or hostname "localhost")
 156                                           (eval-when-compile
 157                                             (regexp-quote "."))))))))
 158              (fname    (url-filename urlobj)))
 159         (and fname
 160              (expand-file-name checksum
 161                                (expand-file-name
 162                                 (mapconcat 'identity host-components "/")
 163                                 url-cache-directory))))))
 164
 165 (defcustom url-cache-creation-function 'url-cache-create-filename-using-md5
 166   "*What function to use to create a cached filename."
 167   :type '(choice (const :tag "MD5 of filename (low collision rate)"
 168                         :value url-cache-create-filename-using-md5)
 169                  (const :tag "Human readable filenames (higher collision rate)"
 170                         :value url-cache-create-filename-human-readable)
 171                  (function :tag "Other"))
 172   :group 'url-cache)
 173
 174 (defun url-cache-create-filename (url)
 175   (funcall url-cache-creation-function url))
 176
 177 ;;;###autoload
 178 (defun url-cache-extract (fnam)
 179   "Extract FNAM from the local disk cache."
 180   (erase-buffer)
 181   (insert-file-contents-literally fnam))
 182
 183 ;;;###autoload
 184 (defun url-cache-expired (url mod)
 185   "Return t if a cached file has expired."
 186   (let* ((urlobj (if (vectorp url) url (url-generic-parse-url url)))
 187          (type (url-type urlobj)))
 188     (cond
 189      (url-standalone-mode
 190       (not (file-exists-p (url-cache-create-filename url))))
 191      ((string= type "http")
 192       t)
 193      ((member type '("file" "ftp"))
 194       (if (or (equal mod '(0 0)) (not mod))
 195           t
 196         (or (> (nth 0 mod) (nth 0 (current-time)))
 197             (> (nth 1 mod) (nth 1 (current-time))))))
 198      (t nil))))
 199
 200 (provide 'url-cache)
 201
 202 ;; arch-tag: 95b050a6-8e81-4f23-8e63-191b9d1d657c
 203 ;;; url-cache.el ends here