177 lines
6.5 KiB
EmacsLisp
177 lines
6.5 KiB
EmacsLisp
;;; qp.el --- Quoted-Printable functions -*- lexical-binding:t -*-
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;; Copyright (C) 1998-2024 Free Software Foundation, Inc.
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;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
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;; Keywords: mail, extensions
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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 3 of the License, or
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;; (at your option) 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. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;; Functions for encoding and decoding quoted-printable text as
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;; defined in RFC 2045.
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;;; Code:
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;;;###autoload
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(defun quoted-printable-decode-region (from to &optional coding-system)
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"Decode quoted-printable in the region between FROM and TO, per RFC 2045.
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If CODING-SYSTEM is non-nil, decode bytes into characters with that
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coding-system.
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Interactively, you can supply the CODING-SYSTEM argument
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with \\[universal-coding-system-argument].
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The CODING-SYSTEM argument is a historical hangover and is deprecated.
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QP encodes raw bytes and should be decoded into raw bytes. Decoding
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them into characters should be done separately."
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(interactive
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;; Let the user determine the coding system with "C-x RET c".
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(list (region-beginning) (region-end) coding-system-for-read))
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(when (and coding-system
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(not (coding-system-p coding-system))) ; e.g. `ascii' from Gnus
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(setq coding-system nil))
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(save-excursion
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(save-restriction
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;; RFC 2045: ``An "=" followed by two hexadecimal digits, one
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;; or both of which are lowercase letters in "abcdef", is
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;; formally illegal. A robust implementation might choose to
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;; recognize them as the corresponding uppercase letters.''
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(let ((case-fold-search t))
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(narrow-to-region from to)
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;; Do this in case we're called from Gnus, say, in a buffer
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;; which already contains non-ASCII characters which would
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;; then get doubly-decoded below.
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(if coding-system
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(encode-coding-region (point-min) (point-max) coding-system))
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(goto-char (point-min))
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(while (and (skip-chars-forward "^=")
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(not (eobp)))
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(cond ((eq (char-after (1+ (point))) ?\n)
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(delete-char 2))
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((looking-at "\\(=[0-9A-F][0-9A-F]\\)+")
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;; Decode this sequence at once; i.e. by a single
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;; deletion and insertion.
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(let* ((n (/ (- (match-end 0) (point)) 3))
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(str (make-string n 0)))
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(dotimes (i n)
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(let ((n1 (char-after (1+ (point))))
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(n2 (char-after (+ 2 (point)))))
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(aset str i
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(+ (* 16 (- n1 (if (<= n1 ?9) ?0
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(if (<= n1 ?F) (- ?A 10)
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(- ?a 10)))))
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(- n2 (if (<= n2 ?9) ?0
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(if (<= n2 ?F) (- ?A 10)
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(- ?a 10)))))))
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(forward-char 3))
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(delete-region (match-beginning 0) (match-end 0))
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(insert str)))
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(t
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(message "Malformed quoted-printable text")
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(forward-char)))))
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(if coding-system
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(decode-coding-region (point-min) (point-max) coding-system)))))
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(defun quoted-printable-decode-string (string &optional coding-system)
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"Decode the quoted-printable encoded STRING and return the result.
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If CODING-SYSTEM is non-nil, decode the string with coding-system.
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Use of CODING-SYSTEM is deprecated; this function should deal with
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raw bytes, and coding conversion should be done separately."
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(with-temp-buffer
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(set-buffer-multibyte nil)
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(insert string)
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(quoted-printable-decode-region (point-min) (point-max) coding-system)
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(buffer-string)))
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(defun quoted-printable-encode-region (from to &optional fold class)
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"Quoted-printable encode the region between FROM and TO per RFC 2045.
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If FOLD, fold long lines at 76 characters (as required by the RFC).
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If CLASS is non-nil, translate the characters not matched by that
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regexp class, which is in the form expected by `skip-chars-forward'.
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You should probably avoid non-ASCII characters in this arg.
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If `mm-use-ultra-safe-encoding' is set, fold lines unconditionally and
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encode lines starting with \"From\"."
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(interactive "r")
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(unless class
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;; Avoid using 8bit characters. = is \075.
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;; Equivalent to "^\000-\007\013\015-\037\200-\377="
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(setq class "\010-\012\014\040-\074\076-\177"))
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(save-excursion
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(goto-char from)
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(if (re-search-forward "[^\x0-\x7f\x80-\xff]" to t)
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(error "Multibyte character in QP encoding region"))
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(save-restriction
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(narrow-to-region from to)
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;; Encode all the non-ascii and control characters.
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(goto-char (point-min))
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(while (and (skip-chars-forward class)
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(not (eobp)))
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(insert
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(prog1
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(format "=%02X" (get-byte))
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(delete-char 1))))
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;; Encode white space at the end of lines.
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(goto-char (point-min))
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(while (re-search-forward "[ \t]+$" nil t)
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(goto-char (match-beginning 0))
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(while (not (eolp))
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(insert
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(prog1
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(format "=%02X" (get-byte))
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(delete-char 1)))))
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(let ((ultra
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(and (boundp 'mm-use-ultra-safe-encoding)
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mm-use-ultra-safe-encoding)))
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(when (or fold ultra)
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(let ((tab-width 1) ; HTAB is one character.
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(case-fold-search nil))
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(goto-char (point-min))
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(while (not (eobp))
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;; In ultra-safe mode, encode "From " at the beginning
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;; of a line.
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(when ultra
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(if (looking-at "From ")
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(replace-match "From=20" nil t)
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(if (looking-at "-")
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(replace-match "=2D" nil t))))
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(end-of-line)
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;; Fold long lines.
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(while (> (current-column) 76) ; tab-width must be 1.
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(beginning-of-line)
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(forward-char 75) ; 75 chars plus an "="
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(search-backward "=" (- (point) 2) t)
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(insert "=\n")
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(end-of-line))
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(forward-line))))))))
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(defun quoted-printable-encode-string (string)
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"Encode the STRING as quoted-printable and return the result."
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(with-temp-buffer
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(if (multibyte-string-p string)
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(set-buffer-multibyte 'to)
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(set-buffer-multibyte nil))
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(insert string)
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(quoted-printable-encode-region (point-min) (point-max))
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(buffer-string)))
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(provide 'qp)
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;;; qp.el ends here
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