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206 lines
6.5 KiB
EmacsLisp
206 lines
6.5 KiB
EmacsLisp
;;; url-cache.el --- Uniform Resource Locator retrieval tool
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;; Copyright (c) 1996 - 1999 Free Software Foundation, Inc.
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;; Keywords: comm, data, processes, hypermedia
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 2, or (at your option)
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;; any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs; see the file COPYING. If not, write to the
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;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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;; Boston, MA 02111-1307, USA.
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;;; Code:
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(require 'url-parse)
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(require 'url-util)
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(defcustom url-cache-directory
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(expand-file-name "cache" url-configuration-directory)
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"*The directory where cache files should be stored."
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:type 'directory
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:group 'url-file)
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;; Cache manager
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(defun url-cache-file-writable-p (file)
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"Follows the documentation of `file-writable-p', unlike `file-writable-p'."
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(and (file-writable-p file)
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(if (file-exists-p file)
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(not (file-directory-p file))
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(file-directory-p (file-name-directory file)))))
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(defun url-cache-prepare (file)
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"Makes it possible to cache data in FILE.
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Creates any necessary parent directories, deleting any non-directory files
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that would stop this. Returns nil if parent directories can not be
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created. If FILE already exists as a non-directory, it changes
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permissions of FILE or deletes FILE to make it possible to write a new
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version of FILE. Returns nil if this can not be done. Returns nil if
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FILE already exists as a directory. Otherwise, returns t, indicating that
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FILE can be created or overwritten."
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(cond
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((url-cache-file-writable-p file)
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t)
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((file-directory-p file)
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nil)
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(t
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(condition-case ()
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(or (make-directory (file-name-directory file) t) t)
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(error nil)))))
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;;;###autoload
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(defun url-store-in-cache (&optional buff)
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"Store buffer BUFF in the cache."
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(if (not (and buff (get-buffer buff)))
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nil
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(save-excursion
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(and buff (set-buffer buff))
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(let* ((fname (url-cache-create-filename (url-view-url t))))
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(if (url-cache-prepare fname)
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(let ((coding-system-for-write 'binary))
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(write-region (point-min) (point-max) fname nil 5)))))))
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;;;###autoload
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(defun url-is-cached (url)
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"Return non-nil if the URL is cached."
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(let* ((fname (url-cache-create-filename url))
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(attribs (file-attributes fname)))
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(and fname ; got a filename
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(file-exists-p fname) ; file exists
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(not (eq (nth 0 attribs) t)) ; Its not a directory
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(nth 5 attribs)))) ; Can get last mod-time
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(defun url-cache-create-filename-human-readable (url)
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"Return a filename in the local cache for URL"
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(if url
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(let* ((url (if (vectorp url) (url-recreate-url url) url))
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(urlobj (url-generic-parse-url url))
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(protocol (url-type urlobj))
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(hostname (url-host urlobj))
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(host-components
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(cons
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(user-real-login-name)
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(cons (or protocol "file")
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(reverse (split-string (or hostname "localhost")
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(eval-when-compile
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(regexp-quote ".")))))))
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(fname (url-filename urlobj)))
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(if (and fname (/= (length fname) 0) (= (aref fname 0) ?/))
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(setq fname (substring fname 1 nil)))
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(if fname
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(let ((slash nil))
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(setq fname
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(mapconcat
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(function
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(lambda (x)
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(cond
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((and (= ?/ x) slash)
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(setq slash nil)
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"%2F")
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((= ?/ x)
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(setq slash t)
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"/")
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(t
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(setq slash nil)
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(char-to-string x))))) fname ""))))
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(setq fname (and fname
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(mapconcat
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(function (lambda (x)
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(if (= x ?~) "" (char-to-string x))))
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fname ""))
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fname (cond
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((null fname) nil)
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((or (string= "" fname) (string= "/" fname))
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url-directory-index-file)
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((= (string-to-char fname) ?/)
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(if (string= (substring fname -1 nil) "/")
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(concat fname url-directory-index-file)
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(substring fname 1 nil)))
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(t
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(if (string= (substring fname -1 nil) "/")
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(concat fname url-directory-index-file)
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fname))))
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(and fname
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(expand-file-name fname
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(expand-file-name
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(mapconcat 'identity host-components "/")
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url-cache-directory))))))
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(defun url-cache-create-filename-using-md5 (url)
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"Create a cached filename using MD5.
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Very fast if you have an `md5' primitive function, suitably fast otherwise."
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(require 'md5)
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(if url
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(let* ((url (if (vectorp url) (url-recreate-url url) url))
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(checksum (md5 url))
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(urlobj (url-generic-parse-url url))
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(protocol (url-type urlobj))
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(hostname (url-host urlobj))
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(host-components
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(cons
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(user-real-login-name)
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(cons (or protocol "file")
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(nreverse
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(delq nil
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(split-string (or hostname "localhost")
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(eval-when-compile
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(regexp-quote "."))))))))
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(fname (url-filename urlobj)))
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(and fname
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(expand-file-name checksum
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(expand-file-name
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(mapconcat 'identity host-components "/")
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url-cache-directory))))))
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(defcustom url-cache-creation-function 'url-cache-create-filename-using-md5
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"*What function to use to create a cached filename."
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:type '(choice (const :tag "MD5 of filename (low collision rate)"
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:value url-cache-create-filename-using-md5)
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(const :tag "Human readable filenames (higher collision rate)"
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:value url-cache-create-filename-human-readable)
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(function :tag "Other"))
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:group 'url-cache)
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(defun url-cache-create-filename (url)
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(funcall url-cache-creation-function url))
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;;;###autoload
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(defun url-cache-extract (fnam)
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"Extract FNAM from the local disk cache"
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(erase-buffer)
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(insert-file-contents-literally fnam))
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;;;###autoload
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(defun url-cache-expired (url mod)
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"Return t iff a cached file has expired."
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(let* ((urlobj (if (vectorp url) url (url-generic-parse-url url)))
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(type (url-type urlobj)))
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(cond
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(url-standalone-mode
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(not (file-exists-p (url-cache-create-filename url))))
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((string= type "http")
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t)
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((member type '("file" "ftp"))
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(if (or (equal mod '(0 0)) (not mod))
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t
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(or (> (nth 0 mod) (nth 0 (current-time)))
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(> (nth 1 mod) (nth 1 (current-time))))))
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(t nil))))
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(provide 'url-cache)
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;;; arch-tag: 95b050a6-8e81-4f23-8e63-191b9d1d657c
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;;; url-cache.el ends here
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