root/trunk/lisp/url/url-expand.el

;;; url-expand.el --- expand-file-name for URLs

;; Copyright (C) 1999, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.

;; Keywords: comm, data, processes

;; 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, 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; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Code:

(require 'url-methods)
(require 'url-util)
(require 'url-parse)

(defun url-expander-remove-relative-links (name)
  ;; Strip . and .. from pathnames
  (let ((new (if (not (string-match "^/" name))
                 (concat "/" name)
               name)))

    ;; If it ends with a '/.' or '/..', tack on a trailing '/' sot hat
    ;; the tests that follow are not too complicated in terms of
    ;; looking for '..' or '../', etc.
    (if (string-match "/\\.+$" new)
        (setq new (concat new "/")))

    ;; Remove '/./' first
    (while (string-match "/\\(\\./\\)" new)
      (setq new (concat (substring new 0 (match-beginning 1))
                        (substring new (match-end 1)))))

    ;; Then remove '/../'
    (while (string-match "/\\([^/]*/\\.\\./\\)" new)
      (setq new (concat (substring new 0 (match-beginning 1))
                        (substring new (match-end 1)))))

    ;; Remove cruft at the beginning of the string, so people that put
    ;; in extraneous '..' because they are morons won't lose.
    (while (string-match "^/\\.\\.\\(/\\)" new)
      (setq new (substring new (match-beginning 1) nil)))
    new))

(defun url-expand-file-name (url &optional default)
  "Convert URL to a fully specified URL, and canonicalize it.
Second arg DEFAULT is a URL to start with if URL is relative.
If DEFAULT is nil or missing, the current buffer's URL is used.
Path components that are `.' are removed, and 
path components followed by `..' are removed, along with the `..' itself."
  (if (and url (not (string-match "^#" url)))
      ;; Need to nuke newlines and spaces in the URL, or we open
      ;; ourselves up to potential security holes.
      (setq url (mapconcat (function (lambda (x)
                                       (if (memq x '(?  ?\n ?\r))
                                           ""
                                         (char-to-string x))))
                           url "")))

  ;; Need to figure out how/where to expand the fragment relative to
  (setq default (cond
                 ((vectorp default)
                  ;; Default URL has already been parsed
                  default)
                 (default
                   ;; They gave us a default URL in non-parsed format
                   (url-generic-parse-url default))
                 (url-current-object
                  ;; We are in a URL-based buffer, use the pre-parsed object
                  url-current-object)
                 ((string-match url-nonrelative-link url)
                  ;; The URL they gave us is absolute, go for it.
                  nil)
                 (t
                  ;; Hmmm - this shouldn't ever happen.
                  (error "url-expand-file-name confused - no default?"))))

  (cond
   ((= (length url) 0)                  ; nil or empty string
    (url-recreate-url default))
   ((string-match "^#" url)             ; Offset link, use it raw
    url)
   ((string-match url-nonrelative-link url) ; Fully-qualified URL, return it immediately
    url)
   (t
    (let* ((urlobj (url-generic-parse-url url))
           (inhibit-file-name-handlers t)
           (expander (url-scheme-get-property (url-type default) 'expand-file-name)))
      (if (string-match "^//" url)
          (setq urlobj (url-generic-parse-url (concat (url-type default) ":"
                                                      url))))
      (funcall expander urlobj default)
      (url-recreate-url urlobj)))))

(defun url-identity-expander (urlobj defobj)
  (url-set-type urlobj (or (url-type urlobj) (url-type defobj))))

(defun url-default-expander (urlobj defobj)
  ;; The default expansion routine - urlobj is modified by side effect!
  (if (url-type urlobj)
      ;; Well, they told us the scheme, let's just go with it.
      nil
    (url-set-type urlobj (or (url-type urlobj) (url-type defobj)))
    (url-set-port urlobj (or (url-port urlobj)
                             (and (string= (url-type urlobj)
                                           (url-type defobj))
                                  (url-port defobj))))
    (if (not (string= "file" (url-type urlobj)))
        (url-set-host urlobj (or (url-host urlobj) (url-host defobj))))
    (if (string= "ftp"  (url-type urlobj))
        (url-set-user urlobj (or (url-user urlobj) (url-user defobj))))
    (if (string= (url-filename urlobj) "")
        (url-set-filename urlobj "/"))
    (if (string-match "^/" (url-filename urlobj))
        nil
      (let ((query nil)
            (file nil)
            (sepchar nil))
        (if (string-match "[?#]" (url-filename urlobj))
            (setq query (substring (url-filename urlobj) (match-end 0))
                  file (substring (url-filename urlobj) 0 (match-beginning 0))
                  sepchar (substring (url-filename urlobj) (match-beginning 0) (match-end 0)))
          (setq file (url-filename urlobj)))
        (setq file (url-expander-remove-relative-links
                    (expand-file-name file
                                      (url-file-directory (url-filename defobj)))))
        (url-set-filename urlobj (if query (concat file sepchar query) file))))))

(provide 'url-expand)

;;; arch-tag: 7b5f744b-b721-49da-be47-484631680a5a
;;; url-expand.el ends here