lisp/nxml/rng-uri.el

   1 ;;; rng-uri.el --- URI parsing and manipulation  -*- lexical-binding:t -*-
   2
   3 ;; Copyright (C) 2003, 2007-2017 Free Software Foundation, Inc.
   4
   5 ;; Author: James Clark
   6 ;; Keywords: wp, hypermedia, languages, XML
   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 ;;; Commentary:
  24
  25 ;;; Code:
  26
  27 (defun rng-file-name-uri (f)
  28   "Return a URI for the filename F.
  29 Multibyte characters are left as is.  Use `rng-uri-escape-multibyte' to
  30 escape them using %HH."
  31   (setq f (expand-file-name f))
  32   (let ((url
  33          (replace-regexp-in-string "[\000-\032\177<>#%\"{}|\\^[]`%?;]"
  34                                    'rng-percent-encode
  35                                    f)))
  36     (concat "file:"
  37             (if (and (> (length url) 0)
  38                      (= (aref url 0) ?/))
  39                 "//"
  40               "///")
  41             url)))
  42
  43 (defun rng-uri-escape-multibyte (uri)
  44   "Escape multibyte characters in URI."
  45   (replace-regexp-in-string "[:nonascii:]"
  46                             'rng-percent-encode
  47                             (encode-coding-string uri 'utf-8)))
  48
  49 (defun rng-percent-encode (str)
  50   (apply 'concat
  51          (mapcar (lambda (ch)
  52                    (format "%%%x%x" (/ ch 16) (% ch 16)))
  53                  (string-to-list str))))
  54
  55
  56 (defun rng-uri-file-name (uri)
  57   "Return the filename represented by a URI.
  58 Signal an error if URI is not a valid file URL."
  59   (rng-uri-file-name-1 uri nil))
  60
  61 (defun rng-uri-pattern-file-name-regexp (pattern)
  62   "Return a regexp for filenames represented by URIs that match PATTERN."
  63   (rng-uri-file-name-1 pattern 'match))
  64
  65 (defun rng-uri-pattern-file-name-replace-match (pattern)
  66   (rng-uri-file-name-1 pattern 'replace))
  67
  68 ;; pattern is either nil or match or replace
  69 (defun rng-uri-file-name-1 (uri pattern)
  70   (unless (string-match "\\`\\(?:[^%]\\|%[0-9a-fA-F]{2}\\)*\\'" uri)
  71     (rng-uri-error "Bad escapes in URI `%s'" uri))
  72   (setq uri (rng-uri-unescape-multibyte uri))
  73   (let* ((components
  74           (or (rng-uri-split uri)
  75               (rng-uri-error "Cannot split URI `%s' into its components" uri)))
  76          (scheme (nth 0 components))
  77          (authority (nth 1 components))
  78          (path (nth 2 components))
  79          (absolutep (string-match "\\`/" path))
  80          (query (nth 3 components))
  81          (fragment-id (nth 4 components)))
  82     (cond ((not scheme)
  83            (unless pattern
  84              (rng-uri-error "URI `%s' does not have a scheme" uri)))
  85           ((not (string= (downcase scheme) "file"))
  86            (rng-uri-error "URI `%s' does not use the `file:' scheme" uri)))
  87     (when (not (member authority
  88                        (cons (system-name) '(nil "" "localhost"))))
  89       (rng-uri-error "URI `%s' does not start with `file:///' or `file://localhost/'"
  90              uri))
  91     (when query
  92       (rng-uri-error "`?' not escaped in file URI `%s'" uri))
  93     (when fragment-id
  94       (rng-uri-error "URI `%s' has a fragment identifier" uri))
  95     (when (string-match ";" path)
  96       (rng-uri-error "`;' not escaped in URI `%s'" uri))
  97     (when (string-match "%2[fF]" path) ;; 2f is hex code of slash
  98       (rng-uri-error "Escaped slash in URI `%s'" uri))
  99     (when (and (eq system-type 'windows-nt)
 100                absolutep
 101                (file-name-absolute-p (substring path 1)))
 102       (setq path (substring path 1)))
 103     (when (and pattern (string-match "\\`\\./" path))
 104       (setq path (substring path 2)))
 105     (setq path
 106           (cond ((eq pattern 'match)
 107                  (rng-uri-unescape-unibyte-match path))
 108                 ((eq pattern 'replace)
 109                  (rng-uri-unescape-unibyte-replace path 2))
 110                 (t
 111                  (rng-uri-unescape-unibyte path))))
 112     (when (string-match "\000" path)
 113       (rng-uri-error "URI `%s' has NUL character in path" uri))
 114     (when (eq pattern 'match)
 115       (setq path
 116             (concat (if absolutep
 117                         "\\(\\)"
 118                       "\\(\\(?:[^/]*/\\)*\\)")
 119                     path)))
 120     (cond ((eq pattern 'match)
 121            (concat "\\`" path "\\'"))
 122           ((and (eq pattern 'replace)
 123                 (not absolutep))
 124            (concat "\\1" path))
 125           (t path))))
 126
 127 (defun rng-uri-error (&rest args)
 128   (signal 'rng-uri-error (list (apply #'format-message args))))
 129
 130 (define-error 'rng-uri-error "Invalid URI")
 131
 132 (defun rng-uri-split (str)
 133   (and (string-match "\\`\\(?:\\([^:/?#]+\\):\\)?\
 134 \\(?://\\([^/?#]*\\)\\)?\
 135 \\([^?#]*\\)\
 136 \\(?:\\?\\([^#]*\\)\\)?\
 137 \\(?:#\\(\\(?:.\\|\n\\)*\\)\\)?\\'"
 138                      str)
 139        (list (match-string 1 str)
 140              (match-string 2 str)
 141              (match-string 3 str)
 142              (match-string 4 str)
 143              (match-string 5 str))))
 144
 145 (defun rng-uri-join (scheme authority path &optional query fragment-id)
 146   (when path
 147     (let (parts)
 148       (when fragment-id
 149         (setq parts (list "#" fragment-id)))
 150       (when query
 151         (setq parts
 152               (cons "?"
 153                     (cons query parts))))
 154       (setq parts (cons path parts))
 155       (when authority
 156         (setq parts
 157               (cons "//"
 158                     (cons authority parts))))
 159       (when scheme
 160         (setq parts
 161               (cons scheme
 162                     (cons ":" parts))))
 163       (apply 'concat parts))))
 164
 165 (defun rng-uri-resolve (uri-ref base-uri)
 166   "Resolve a possibly relative URI reference into absolute form.
 167 URI-REF is the URI reference to be resolved.
 168 BASE-URI is the base URI to use for resolving it.
 169 The algorithm is specified by RFC 2396.
 170 If there is some problem with URI-REF or BASE-URI, then
 171 URI-REF will be returned."
 172   (let* ((components (rng-uri-split uri-ref))
 173          (scheme (nth 0 components))
 174          (authority (nth 1 components))
 175          (path (nth 2 components))
 176          (query (nth 3 components))
 177          (fragment-id (nth 4 components))
 178          (base-components (rng-uri-split base-uri)))
 179     (if (or (not components)
 180             scheme
 181             (not base-components)
 182             (not (nth 0 base-components)))
 183         uri-ref
 184       (setq scheme (nth 0 base-components))
 185       (when (not authority)
 186         (setq authority (nth 1 base-components))
 187         (if (and (equal path "") (not query))
 188             ;; Handle same document reference by returning
 189             ;; same URI (RFC 2396bis does this too).
 190             (setq path (nth 2 base-components)
 191                   query (nth 3 base-components))
 192           (setq path (rng-resolve-path path (nth 2 base-components)))))
 193       (rng-uri-join scheme
 194                     authority
 195                     path
 196                     query
 197                     fragment-id))))
 198
 199 ;; See RFC 2396 5.2, steps 5 and 6
 200 (defun rng-resolve-path (path base-path)
 201   ;; Step 5
 202   (if (or (string-match "\\`/" path)
 203           (not (string-match "\\`/" base-path)))
 204       path
 205     ;; Step 6
 206     ;; (a), (b)
 207     (let ((segments (rng-split-path path))
 208           (base-segments (rng-split-path base-path)))
 209       (if (> (length base-segments) 1)
 210           (setq segments (nconc (nbutlast base-segments)
 211                                 segments))
 212         (setcar segments
 213                 (concat (car base-segments) (car segments))))
 214       ;; (d)
 215       (let ((last-segment (last segments)))
 216         (when (equal (car last-segment) ".")
 217           (setcar last-segment "")))
 218       ;; (c)
 219       (setq segments (delete "." segments))
 220       ;; (e)
 221       (let (iter matched)
 222         (while (progn
 223                  (setq matched nil)
 224                  (setq iter (cdr segments))
 225                  (while (and iter (not matched))
 226                    (if (or (not (equal (cadr iter) ".."))
 227                            (equal (car iter) ".."))
 228                        (setq iter (cdr iter))
 229                      (setcar iter nil)
 230                      (setcar (cdr iter)
 231                              ;; (f)
 232                              (if (cddr iter) nil ""))
 233                      (setq matched t)
 234                      (setq segments (delq nil segments))))
 235                  matched)))
 236       (rng-join-path segments))))
 237
 238 (defun rng-relative-uri (full base)
 239   "Return a URI that relative to BASE is equivalent to FULL.
 240 The returned URI will be relative if possible.
 241 Both FULL and BASE must be absolute URIs."
 242   (let* ((components (rng-uri-split full))
 243          (scheme (nth 0 components))
 244          (authority (nth 1 components))
 245          (path (nth 2 components))
 246          (query (nth 3 components))
 247          (fragment-id (nth 4 components))
 248          (base-components (rng-uri-split base)))
 249     (if (and components
 250              base-components
 251              scheme
 252              (equal scheme
 253                     (nth 0 base-components)))
 254         (progn
 255           (setq scheme nil)
 256           (when (and authority
 257                      (equal authority
 258                             (nth 1 base-components)))
 259             (setq authority nil)
 260             (setq path (rng-relative-path path (nth 2 base-components))))
 261           (rng-uri-join scheme authority path query fragment-id))
 262       full)))
 263
 264 (defun rng-relative-path (path base-path)
 265   (let ((segments (rng-split-path path))
 266         (base-segments (rng-split-path base-path)))
 267     (when (> (length base-segments) 1)
 268       (setq base-segments (nbutlast base-segments)))
 269     (if (or (member "." segments)
 270             (member ".." segments)
 271             (member "." base-segments)
 272             (member ".." base-segments))
 273         path
 274       (while (and segments
 275                   base-segments
 276                   (string= (car segments)
 277                            (car base-segments)))
 278         (setq segments (cdr segments))
 279         (setq base-segments (cdr base-segments)))
 280       (while base-segments
 281         (setq base-segments (cdr base-segments))
 282         (setq segments (cons ".." segments)))
 283       (when (equal (car segments) "")
 284         (setq segments (cons "." segments)))
 285       (rng-join-path segments))))
 286
 287 (defun rng-split-path (path)
 288   (let ((start 0)
 289         segments)
 290     (while (string-match "/" path start)
 291       (setq segments (cons (substring path start (match-beginning 0))
 292                            segments))
 293       (setq start (match-end 0)))
 294     (nreverse (cons (substring path start) segments))))
 295
 296 (defun rng-join-path (segments)
 297   (and segments
 298        (mapconcat 'identity segments "/")))
 299
 300 (defun rng-uri-unescape-multibyte (str)
 301   (replace-regexp-in-string "\\(?:%[89a-fA-F][0-9a-fA-F]\\)+"
 302                             'rng-multibyte-percent-decode
 303                             str))
 304
 305 (defun rng-multibyte-percent-decode (str)
 306   (decode-coding-string  (apply 'string
 307                                 (mapcar (lambda (h) (string-to-number h 16))
 308                                         (split-string str "%")))
 309                          'utf-8))
 310
 311 (defun rng-uri-unescape-unibyte (str)
 312   (replace-regexp-in-string "%[0-7][0-9a-fA-F]"
 313                             (lambda (h)
 314                               (string-to-number (substring h 1) 16))
 315                             str
 316                             t
 317                             t))
 318
 319 (defun rng-uri-unescape-unibyte-match (str)
 320   (replace-regexp-in-string "%[0-7][0-9a-fA-F]\\|[^%]"
 321                             (lambda (match)
 322                               (if (string= match "*")
 323                                   "\\([^/]*\\)"
 324                                 (regexp-quote
 325                                  (if (= (length match) 1)
 326                                      match
 327                                    (string-to-number (substring match 1)
 328                                                      16)))))
 329                             str
 330                             t
 331                             t))
 332
 333 (defun rng-uri-unescape-unibyte-replace (str next-match-index)
 334   (replace-regexp-in-string
 335    "%[0-7][0-9a-fA-F]\\|[^%]"
 336    (lambda (match)
 337      (if (string= match "*")
 338          (let ((n next-match-index))
 339            (setq next-match-index (1+ n))
 340            (format "\\%s" n))
 341        (let ((ch (if (= (length match) 1)
 342                      (aref match 0)
 343                    (string-to-number (substring match 1)
 344                                      16))))
 345          (if (eq ch ?\\)
 346              (string ?\\ ?\\)
 347            (string ch)))))
 348      str
 349      t
 350      t))
 351
 352 (provide 'rng-uri)
 353
 354 ;;; rng-uri.el ends here