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;;; url-cache.el --- Uniform Resource Locator retrieval tool
;; Copyright (C) 1996, 1997, 1998, 1999, 2004, 2005, 2006, 2007, 2008,
;; 2009, 2010 Free Software Foundation, Inc.
;; Keywords: comm, data, processes, hypermedia
;; This file is part of GNU Emacs.
;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
;;; Code:
(require 'url-parse)
(require 'url-util)
(require 'url) ;E.g. for url-configuration-directory.
(defcustom url-cache-directory
(expand-file-name "cache" url-configuration-directory)
"The directory where cache files should be stored."
:type 'directory
:group 'url-file)
;; Cache manager
(defun url-cache-file-writable-p (file)
"Follows the documentation of `file-writable-p', unlike `file-writable-p'."
(and (file-writable-p file)
(if (file-exists-p file)
(not (file-directory-p file))
(file-directory-p (file-name-directory file)))))
(defun url-cache-prepare (file)
"Makes it possible to cache data in FILE.
Creates any necessary parent directories, deleting any non-directory files
that would stop this. Returns nil if parent directories can not be
created. If FILE already exists as a non-directory, it changes
permissions of FILE or deletes FILE to make it possible to write a new
version of FILE. Returns nil if this can not be done, or if FILE already
exists as a directory. Otherwise, returns t, indicating that
FILE can be created or overwritten."
(cond
((url-cache-file-writable-p file)
t)
((file-directory-p file)
nil)
(t
(condition-case ()
(or (make-directory (file-name-directory file) t) t)
(error nil)))))
;;;###autoload
(defun url-store-in-cache (&optional buff)
"Store buffer BUFF in the cache."
(if (not (and buff (get-buffer buff)))
nil
(save-current-buffer
(and buff (set-buffer buff))
(let* ((fname (url-cache-create-filename (url-view-url t))))
(if (url-cache-prepare fname)
(let ((coding-system-for-write 'binary))
(write-region (point-min) (point-max) fname nil 5)))))))
;;;###autoload
(defun url-is-cached (url)
"Return non-nil if the URL is cached."
(let* ((fname (url-cache-create-filename url))
(attribs (file-attributes fname)))
(and fname ; got a filename
(file-exists-p fname) ; file exists
(not (eq (nth 0 attribs) t)) ; Its not a directory
(nth 5 attribs)))) ; Can get last mod-time
(defun url-cache-create-filename-human-readable (url)
"Return a filename in the local cache for URL."
(if url
(let* ((url (if (vectorp url) (url-recreate-url url) url))
(urlobj (url-generic-parse-url url))
(protocol (url-type urlobj))
(hostname (url-host urlobj))
(host-components
(cons
(user-real-login-name)
(cons (or protocol "file")
(reverse (split-string (or hostname "localhost")
(eval-when-compile
(regexp-quote ".")))))))
(fname (url-filename urlobj)))
(if (and fname (/= (length fname) 0) (= (aref fname 0) ?/))
(setq fname (substring fname 1 nil)))
(if fname
(let ((slash nil))
(setq fname
(mapconcat
(function
(lambda (x)
(cond
((and (= ?/ x) slash)
(setq slash nil)
"%2F")
((= ?/ x)
(setq slash t)
"/")
(t
(setq slash nil)
(char-to-string x))))) fname ""))))
(setq fname (and fname
(mapconcat
(function (lambda (x)
(if (= x ?~) "" (char-to-string x))))
fname ""))
fname (cond
((null fname) nil)
((or (string= "" fname) (string= "/" fname))
url-directory-index-file)
((= (string-to-char fname) ?/)
(if (string= (substring fname -1 nil) "/")
(concat fname url-directory-index-file)
(substring fname 1 nil)))
(t
(if (string= (substring fname -1 nil) "/")
(concat fname url-directory-index-file)
fname))))
(and fname
(expand-file-name fname
(expand-file-name
(mapconcat 'identity host-components "/")
url-cache-directory))))))
(defun url-cache-create-filename-using-md5 (url)
"Create a cached filename using MD5.
Very fast if you have an `md5' primitive function, suitably fast otherwise."
(require 'md5)
(if url
(let* ((url (if (vectorp url) (url-recreate-url url) url))
(checksum (md5 url))
(urlobj (url-generic-parse-url url))
(protocol (url-type urlobj))
(hostname (url-host urlobj))
(host-components
(cons
(user-real-login-name)
(cons (or protocol "file")
(nreverse
(delq nil
(split-string (or hostname "localhost")
(eval-when-compile
(regexp-quote "."))))))))
(fname (url-filename urlobj)))
(and fname
(expand-file-name checksum
(expand-file-name
(mapconcat 'identity host-components "/")
url-cache-directory))))))
(defcustom url-cache-creation-function 'url-cache-create-filename-using-md5
"What function to use to create a cached filename."
:type '(choice (const :tag "MD5 of filename (low collision rate)"
:value url-cache-create-filename-using-md5)
(const :tag "Human readable filenames (higher collision rate)"
:value url-cache-create-filename-human-readable)
(function :tag "Other"))
:group 'url-cache)
(defun url-cache-create-filename (url)
(funcall url-cache-creation-function url))
;;;###autoload
(defun url-cache-extract (fnam)
"Extract FNAM from the local disk cache."
(erase-buffer)
(insert-file-contents-literally fnam))
;;;###autoload
(defun url-cache-expired (url mod)
"Return t if a cached file has expired."
(let* ((urlobj (if (vectorp url) url (url-generic-parse-url url)))
(type (url-type urlobj)))
(cond
(url-standalone-mode
(not (file-exists-p (url-cache-create-filename url))))
((string= type "http")
t)
((member type '("file" "ftp"))
(if (or (equal mod '(0 0)) (not mod))
t
(or (> (nth 0 mod) (nth 0 (current-time)))
(> (nth 1 mod) (nth 1 (current-time))))))
(t nil))))
(provide 'url-cache)
;; arch-tag: 95b050a6-8e81-4f23-8e63-191b9d1d657c
;;; url-cache.el ends here
|
