311 lines
9.8 KiB
EmacsLisp
311 lines
9.8 KiB
EmacsLisp
;;; rfc2231.el --- Functions for decoding rfc2231 headers -*- 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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;; 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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;;; Code:
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(eval-when-compile (require 'cl-lib))
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(require 'ietf-drums)
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(require 'rfc2047)
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(autoload 'mm-encode-body "mm-bodies")
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(autoload 'mail-header-remove-whitespace "mail-parse")
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(autoload 'mail-header-remove-comments "mail-parse")
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(defun rfc2231-get-value (ct attribute)
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"Return the value of ATTRIBUTE from CT."
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(cdr (assq attribute (cdr ct))))
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(defun rfc2231-parse-qp-string (string)
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"Parse QP-encoded string using `rfc2231-parse-string'.
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N.B. This is in violation with RFC2047, but it seem to be in common use."
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(rfc2231-parse-string (rfc2047-decode-string string)))
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(defun rfc2231-parse-string (string &optional signal-error)
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"Parse STRING and return a list.
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The list will be on the form
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`(name (attribute . value) (attribute . value)...)'.
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If the optional SIGNAL-ERROR is non-nil, signal an error when this
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function fails in parsing of parameters. Otherwise, this function
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must never cause a Lisp error."
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(with-temp-buffer
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(let ((ttoken (ietf-drums-token-to-list ietf-drums-text-token))
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(stoken (ietf-drums-token-to-list ietf-drums-tspecials))
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(ntoken (ietf-drums-token-to-list "0-9"))
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c type attribute encoded number parameters value)
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(ietf-drums-init
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(condition-case nil
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(mail-header-remove-whitespace
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(mail-header-remove-comments string))
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;; The most likely cause of an error is unbalanced parentheses
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;; or double-quotes. If all parentheses and double-quotes are
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;; quoted meaninglessly with backslashes, removing them might
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;; make it parsable. Let's try...
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(error
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(let (mod)
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(when (and (string-search "\\\"" string)
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(not (string-match "\\`\"\\|[^\\]\"" string)))
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(setq string (string-replace "\\\"" "\"" string)
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mod t))
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(when (and (string-search "\\(" string)
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(string-search "\\)" string)
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(not (string-match "\\`(\\|[^\\][()]" string)))
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(setq string (replace-regexp-in-string
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"\\\\\\([()]\\)" "\\1" string)
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mod t))
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(or (and mod
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(ignore-errors
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(mail-header-remove-whitespace
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(mail-header-remove-comments string))))
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;; Finally, attempt to extract only type.
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(if (string-match
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(concat "\\`[\t\n ]*\\([^" ietf-drums-tspecials "\t\n ]+"
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"\\(?:/[^" ietf-drums-tspecials
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"\t\n ]+\\)?\\)\\(?:[\t\n ;]\\|\\'\\)")
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string)
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(match-string 1 string)
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""))))))
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(let ((table (copy-syntax-table ietf-drums-syntax-table)))
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(modify-syntax-entry ?\' "w" table)
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(modify-syntax-entry ?* " " table)
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(modify-syntax-entry ?\; " " table)
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(modify-syntax-entry ?= " " table)
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;; The following isn't valid, but one should be liberal
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;; in what one receives.
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(modify-syntax-entry ?\: "w" table)
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(set-syntax-table table))
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(setq c (char-after))
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(when (and (memq c ttoken)
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(not (memq c stoken))
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(setq type (ignore-errors
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(downcase
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(buffer-substring (point) (progn
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(forward-sexp 1)
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(point)))))))
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;; Do the params
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(condition-case err
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(progn
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(while (not (eobp))
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(setq c (char-after))
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(unless (eq c ?\;)
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(error "Invalid header: %s" string))
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(forward-char 1)
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;; If c in nil, then this is an invalid header, but
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;; since elm generates invalid headers on this form,
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;; we allow it.
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(when (setq c (char-after))
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(if (and (memq c ttoken)
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(not (memq c stoken)))
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(setq attribute
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(intern
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(downcase
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(buffer-substring
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(point) (progn (forward-sexp 1) (point))))))
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(error "Invalid header: %s" string))
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(setq c (char-after))
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(if (eq c ?*)
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(progn
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(forward-char 1)
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(setq c (char-after))
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(if (not (memq c ntoken))
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(setq encoded t
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number nil)
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(setq number
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(string-to-number
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(buffer-substring
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(point) (progn (forward-sexp 1) (point)))))
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(setq c (char-after))
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(when (eq c ?*)
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(setq encoded t)
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(forward-char 1)
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(setq c (char-after)))))
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(setq number nil
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encoded nil))
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(unless (eq c ?=)
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(error "Invalid header: %s" string))
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(forward-char 1)
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(setq c (char-after))
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(cond
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((eq c ?\")
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(setq value (buffer-substring (1+ (point))
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(progn
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(forward-sexp 1)
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(1- (point)))))
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(when encoded
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(setq value (mapconcat (lambda (c) (format "%%%02x" c))
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value ""))))
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((and (or (memq c ttoken)
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;; EXTENSION: Support non-ascii chars.
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(> c ?\177))
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(not (memq c stoken)))
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(setq value
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(buffer-substring
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(point)
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(progn
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;; Jump over asterisk, non-ASCII
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;; and non-boundary characters.
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(while (and c
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(or (eq c ?*)
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(> c ?\177)
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(not (eq (char-syntax c) ? ))))
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(forward-char 1)
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(setq c (char-after)))
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(point)))))
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(t
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(error "Invalid header: %s" string)))
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(push (list attribute value number encoded)
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parameters))))
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(error
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(setq parameters nil)
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(when signal-error
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(signal (car err) (cdr err)))))
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;; Now collect and concatenate continuation parameters.
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(let ((cparams nil)
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elem)
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(cl-loop for (attribute value part encoded)
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in (sort parameters (lambda (e1 e2)
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(< (or (caddr e1) 0)
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(or (caddr e2) 0))))
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do (cond
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;; First part.
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((or (not (setq elem (assq attribute cparams)))
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(and (numberp part)
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(zerop part)))
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(push (list attribute value encoded) cparams))
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;; Repetition of a part; do nothing.
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((and elem
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(null number))
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)
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;; Concatenate continuation parts.
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(t
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(setcar (cdr elem) (concat (cadr elem) value)))))
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;; Finally decode encoded values.
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(cons type (mapcar
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(lambda (elem)
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(cons (car elem)
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(if (nth 2 elem)
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(rfc2231-decode-encoded-string (nth 1 elem))
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(nth 1 elem))))
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(nreverse cparams))))))))
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(defun rfc2231-decode-encoded-string (string)
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"Decode an RFC2231-encoded string.
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These look like:
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\"us-ascii\\='en-us\\='This%20is%20%2A%2A%2Afun%2A%2A%2A\",
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\"us-ascii\\='\\='This%20is%20%2A%2A%2Afun%2A%2A%2A\",
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\"\\='en-us\\='This%20is%20%2A%2A%2Afun%2A%2A%2A\",
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\"\\='\\='This%20is%20%2A%2A%2Afun%2A%2A%2A\", or
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\"This is ***fun***\"."
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(if (not (string-match "\\`\\(?:\\([^']+\\)?'\\([^']+\\)?'\\)?\\(.+\\)\\'"
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string))
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(error "Unrecognized RFC2231 format: %S" string)
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(let ((value (match-string 3 string))
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;;(language (match-string 2 string))
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(coding-system (mm-charset-to-coding-system
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(match-string 1 string) nil t)))
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(mm-with-unibyte-buffer
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(insert value)
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(goto-char (point-min))
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(while (re-search-forward "%\\([[:xdigit:]][[:xdigit:]]\\)" nil t)
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(insert
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(prog1
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(string-to-number (match-string 1) 16)
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(delete-region (match-beginning 0) (match-end 0)))))
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;; Decode using the charset, if any.
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(if (memq coding-system '(nil ascii))
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(buffer-string)
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(decode-coding-string (buffer-string) coding-system))))))
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(defun rfc2231-encode-string (param value)
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"Return a PARAM=VALUE string encoded according to RFC2231.
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Use `mml-insert-parameter' or `mml-insert-parameter-string' to insert
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the result of this function."
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(let ((control (ietf-drums-token-to-list ietf-drums-no-ws-ctl-token))
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(tspecial (ietf-drums-token-to-list ietf-drums-tspecials))
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(special (ietf-drums-token-to-list "*'%\n\t"))
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(ascii (ietf-drums-token-to-list ietf-drums-text-token))
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(num -1)
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;; Don't make lines exceeding 76 column.
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(limit (- 74 (length param)))
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spacep encodep charsetp charset broken)
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(mm-with-multibyte-buffer
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(insert value)
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(goto-char (point-min))
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(while (not (eobp))
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(cond
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((or (memq (following-char) control)
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(memq (following-char) tspecial)
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(memq (following-char) special))
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(setq encodep t))
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((eq (following-char) ? )
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(setq spacep t))
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((not (memq (following-char) ascii))
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(setq charsetp t)))
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(forward-char 1))
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(when charsetp
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(setq charset (mm-encode-body)))
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(mm-disable-multibyte)
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(cond
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((or encodep charsetp
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(progn
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(end-of-line)
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(> (current-column) (if spacep (- limit 2) limit))))
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(setq limit (- limit 6))
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(goto-char (point-min))
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(insert (symbol-name (or charset 'us-ascii)) "''")
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(while (not (eobp))
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(if (or (not (memq (following-char) ascii))
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(memq (following-char) control)
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(memq (following-char) tspecial)
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(memq (following-char) special)
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(eq (following-char) ? ))
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(progn
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(when (>= (current-column) (1- limit))
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(insert ";\n")
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(setq broken t))
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(insert "%" (format "%02x" (following-char)))
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(delete-char 1))
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(when (> (current-column) limit)
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(insert ";\n")
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(setq broken t))
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(forward-char 1)))
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(goto-char (point-min))
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(if (not broken)
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(insert param "*=")
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(while (not (eobp))
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(insert (if (>= num 0) " " "")
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param "*" (format "%d" (cl-incf num)) "*=")
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(forward-line 1))))
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(spacep
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(goto-char (point-min))
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(insert param "=\"")
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(goto-char (point-max))
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(insert "\""))
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(t
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(goto-char (point-min))
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(insert param "=")))
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(buffer-string))))
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(provide 'rfc2231)
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;;; rfc2231.el ends here
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