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