1;;; qp.el --- Quoted-Printable functions
2
3;; Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004,
4;;   2005, 2006, 2007 Free Software Foundation, Inc.
5
6;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
7;; Keywords: mail, extensions
8
9;; This file is part of GNU Emacs.
10
11;; GNU Emacs is free software; you can redistribute it and/or modify
12;; it under the terms of the GNU General Public License as published by
13;; the Free Software Foundation; either version 2, or (at your option)
14;; any later version.
15
16;; GNU Emacs is distributed in the hope that it will be useful,
17;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
19;; GNU General Public License for more details.
20
21;; You should have received a copy of the GNU General Public License
22;; along with GNU Emacs; see the file COPYING.  If not, write to the
23;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
24;; Boston, MA 02110-1301, USA.
25
26;;; Commentary:
27
28;; Functions for encoding and decoding quoted-printable text as
29;; defined in RFC 2045.
30
31;;; Code:
32
33(require 'mm-util)
34(eval-when-compile (defvar mm-use-ultra-safe-encoding))
35
36;;;###autoload
37(defun quoted-printable-decode-region (from to &optional coding-system)
38  "Decode quoted-printable in the region between FROM and TO, per RFC 2045.
39If CODING-SYSTEM is non-nil, decode bytes into characters with that
40coding-system.
41
42Interactively, you can supply the CODING-SYSTEM argument
43with \\[universal-coding-system-argument].
44
45The CODING-SYSTEM argument is a historical hangover and is deprecated.
46QP encodes raw bytes and should be decoded into raw bytes.  Decoding
47them into characters should be done separately."
48  (interactive
49   ;; Let the user determine the coding system with "C-x RET c".
50   (list (region-beginning) (region-end) coding-system-for-read))
51  (unless (mm-coding-system-p coding-system) ; e.g. `ascii' from Gnus
52    (setq coding-system nil))
53  (save-excursion
54    (save-restriction
55      ;; RFC 2045:  ``An "=" followed by two hexadecimal digits, one
56      ;; or both of which are lowercase letters in "abcdef", is
57      ;; formally illegal. A robust implementation might choose to
58      ;; recognize them as the corresponding uppercase letters.''
59      (let ((case-fold-search t))
60	(narrow-to-region from to)
61	;; Do this in case we're called from Gnus, say, in a buffer
62	;; which already contains non-ASCII characters which would
63	;; then get doubly-decoded below.
64	(if coding-system
65	    (mm-encode-coding-region (point-min) (point-max) coding-system))
66	(goto-char (point-min))
67	(while (and (skip-chars-forward "^=")
68		    (not (eobp)))
69	  (cond ((eq (char-after (1+ (point))) ?\n)
70		 (delete-char 2))
71		((looking-at "=[0-9A-F][0-9A-F]")
72		 (let ((byte (string-to-number (buffer-substring (1+ (point))
73								 (+ 3 (point)))
74					       16)))
75		   (mm-insert-byte byte 1)
76		   (delete-char 3)))
77		(t
78		 (message "Malformed quoted-printable text")
79		 (forward-char)))))
80      (if coding-system
81	  (mm-decode-coding-region (point-min) (point-max) coding-system)))))
82
83(defun quoted-printable-decode-string (string &optional coding-system)
84  "Decode the quoted-printable encoded STRING and return the result.
85If CODING-SYSTEM is non-nil, decode the region with coding-system.
86Use of CODING-SYSTEM is deprecated; this function should deal with
87raw bytes, and coding conversion should be done separately."
88  (mm-with-unibyte-buffer
89    (insert string)
90    (quoted-printable-decode-region (point-min) (point-max) coding-system)
91    (buffer-string)))
92
93(defun quoted-printable-encode-region (from to &optional fold class)
94  "Quoted-printable encode the region between FROM and TO per RFC 2045.
95
96If FOLD, fold long lines at 76 characters (as required by the RFC).
97If CLASS is non-nil, translate the characters not matched by that
98regexp class, which is in the form expected by `skip-chars-forward'.
99You should probably avoid non-ASCII characters in this arg.
100
101If `mm-use-ultra-safe-encoding' is set, fold lines unconditionally and
102encode lines starting with \"From\"."
103  (interactive "r")
104  (unless class
105    ;; Avoid using 8bit characters. = is \075.
106    ;; Equivalent to "^\000-\007\013\015-\037\200-\377="
107    (setq class "\010-\012\014\040-\074\076-\177"))
108  (save-excursion
109    (goto-char from)
110    (if (re-search-forward (mm-string-to-multibyte "[^\x0-\x7f\x80-\xff]")
111			   to t)
112	(error "Multibyte character in QP encoding region"))
113    (save-restriction
114      (narrow-to-region from to)
115      ;; Encode all the non-ascii and control characters.
116      (goto-char (point-min))
117      (while (and (skip-chars-forward class)
118		  (not (eobp)))
119	(insert
120	 (prog1
121	     ;; To unibyte in case of Emacs 23 (unicode) eight-bit.
122	     (format "=%02X" (mm-multibyte-char-to-unibyte (char-after)))
123	   (delete-char 1))))
124      ;; Encode white space at the end of lines.
125      (goto-char (point-min))
126      (while (re-search-forward "[ \t]+$" nil t)
127	(goto-char (match-beginning 0))
128	(while (not (eolp))
129	  (insert
130	   (prog1
131	       (format "=%02X" (char-after))
132	     (delete-char 1)))))
133      (let ((mm-use-ultra-safe-encoding
134	     (and (boundp 'mm-use-ultra-safe-encoding)
135		  mm-use-ultra-safe-encoding)))
136	(when (or fold mm-use-ultra-safe-encoding)
137	  (let ((tab-width 1))		; HTAB is one character.
138	    (goto-char (point-min))
139	    (while (not (eobp))
140	      ;; In ultra-safe mode, encode "From " at the beginning
141	      ;; of a line.
142	      (when mm-use-ultra-safe-encoding
143		(if (looking-at "From ")
144		    (replace-match "From=20" nil t)
145		  (if (looking-at "-")
146		      (replace-match "=2D" nil t))))
147	      (end-of-line)
148	      ;; Fold long lines.
149	      (while (> (current-column) 76) ; tab-width must be 1.
150		(beginning-of-line)
151		(forward-char 75)	; 75 chars plus an "="
152		(search-backward "=" (- (point) 2) t)
153		(insert "=\n")
154		(end-of-line))
155	      (forward-line))))))))
156
157(defun quoted-printable-encode-string (string)
158  "Encode the STRING as quoted-printable and return the result."
159  (let ((default-enable-multibyte-characters (mm-multibyte-string-p string)))
160    (with-temp-buffer
161      (insert string)
162      (quoted-printable-encode-region (point-min) (point-max))
163      (buffer-string))))
164
165(provide 'qp)
166
167;;; arch-tag: db89e52a-e4a1-4b69-926f-f434f04216ba
168;;; qp.el ends here
169