emacs/lisp/mail/mail-utils.el

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;;; mail-utils.el --- utility functions used both by rmail and rnews -*- lexical-binding: t -*-
;; Copyright (C) 1985, 2001-2024 Free Software Foundation, Inc.
;; Maintainer: emacs-devel@gnu.org
;; Keywords: mail, news
;; 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 of the License, 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. If not, see <https://www.gnu.org/licenses/>.
;;; Commentary:
;; Utility functions for mail and netnews handling. These handle fine
;; points of header parsing.
;;; Code:
;;;###autoload
(defcustom mail-use-rfc822 nil
"If non-nil, use a full, hairy RFC 822 (or later) parser on mail addresses.
Otherwise, (the default) use a smaller, somewhat faster, and
often correct parser."
:type 'boolean
:group 'mail)
;;;###autoload
(defcustom mail-dont-reply-to-names nil
"Regexp specifying addresses to prune from a reply message.
If this is nil, it is set the first time you compose a reply, to
a value which excludes your own email address.
Matching addresses are excluded from the Cc field in replies, and
also the To field, unless this would leave an empty To field."
:type '(choice regexp (const :tag "Your Name" nil))
:group 'mail)
(defvar epa-inhibit)
;; Returns t if file FILE is an Rmail file.
;;;###autoload
(defun mail-file-babyl-p (file)
"Return non-nil if FILE is a Babyl file."
(let ((epa-inhibit t))
(with-temp-buffer
(insert-file-contents file nil 0 100)
(looking-at "BABYL OPTIONS:"))))
(defun mail-string-delete (string start end)
"Return a string containing all of STRING except the part
from START (inclusive) to END (exclusive)."
(declare (obsolete substring "29.1"))
(if (null end) (substring string 0 start)
(concat (substring string 0 start)
(substring string end nil))))
;;;###autoload
(defun mail-quote-printable (string &optional wrapper)
"Convert a string to the \"quoted printable\" Q encoding if necessary.
If the string contains only ASCII characters and no troublesome ones,
we return it unconverted.
If the optional argument WRAPPER is non-nil,
we add the wrapper characters =?ISO-8859-1?Q?....?=."
(let ((i 0) (result ""))
(save-match-data
(while (or (string-match "[?=\"]" string i)
(string-match "[^\000-\177]" string i))
(setq result
(concat result (substring string i (match-beginning 0))
(upcase (format "=%02x"
(aref string (match-beginning 0))))))
(setq i (match-end 0)))
(if wrapper
(concat "=?ISO-8859-1?Q?"
result (substring string i)
"?=")
(concat result (substring string i))))))
;;;###autoload
(defun mail-quote-printable-region (beg end &optional wrapper)
"Convert the region to the \"quoted printable\" Q encoding.
If the optional argument WRAPPER is non-nil,
we add the wrapper characters =?ISO-8859-1?Q?....?=."
(interactive "r\nP")
(save-match-data
(save-excursion
(goto-char beg)
(save-restriction
(narrow-to-region beg end)
(while (re-search-forward "[?=\"\200-\377]" nil t)
(replace-match (upcase (format "=%02x" (preceding-char)))
t t))
(when wrapper
(goto-char beg)
(insert "=?ISO-8859-1?Q?")
(goto-char end)
(insert "?="))))))
(defun mail-unquote-printable-hexdigit (char)
(setq char (upcase char))
(if (>= char ?A)
(+ (- char ?A) 10)
(- char ?0)))
;;;###autoload
(defun mail-unquote-printable (string &optional wrapper)
"Undo the \"quoted printable\" encoding.
If the optional argument WRAPPER is non-nil,
we expect to find and remove the wrapper characters =?ISO-8859-1?Q?....?=."
(save-match-data
(and wrapper
(string-match "\\`=\\?ISO-8859-1\\?Q\\?\\([^?]*\\)\\?" string)
(setq string (match-string 1 string)))
(let ((i 0) strings)
(while (string-match "=\\(..\\|\n\\)" string i)
(setq strings (cons (substring string i (match-beginning 0)) strings))
(unless (= (aref string (match-beginning 1)) ?\n)
(setq strings
(cons (make-string 1
(+ (* 16 (mail-unquote-printable-hexdigit
(aref string (match-beginning 1))))
(mail-unquote-printable-hexdigit
(aref string (1+ (match-beginning 1))))))
strings)))
(setq i (match-end 0)))
(apply #'concat (nreverse (cons (substring string i) strings))))))
;; FIXME Gnus for some reason has `quoted-printable-decode-region' in qp.el.
;;;###autoload
(defun mail-unquote-printable-region (beg end &optional wrapper noerror
unibyte)
"Undo the \"quoted printable\" encoding in buffer from BEG to END.
If the optional argument WRAPPER is non-nil,
we expect to find and remove the wrapper characters =?ISO-8859-1?Q?....?=.
On encountering malformed quoted-printable text, exits with an error,
unless NOERROR is non-nil, in which case it continues, and returns nil
when finished. Returns non-nil on successful completion.
If UNIBYTE is non-nil, insert converted characters as unibyte.
That is useful if you are going to character code decoding afterward,
as Rmail does."
;; FIXME: `unibyte' should always be non-nil, and the iso-latin-1
;; specific handling should be removed (or moved elsewhere and generalized).
(interactive "r\nP")
(let (failed)
(save-match-data
(save-excursion
(save-restriction
(narrow-to-region beg end)
(goto-char (point-min))
(when (and wrapper
(looking-at "\\`=\\?ISO-8859-1\\?Q\\?\\([^?]*\\)\\?"))
(delete-region (match-end 1) end)
(delete-region (point) (match-beginning 1)))
(while (re-search-forward "=\\(\\([0-9A-F][0-9A-F]\\)\\|[=\n]\\|..\\)" nil t)
(goto-char (match-end 0))
(cond ((= (char-after (match-beginning 1)) ?\n)
(replace-match ""))
((= (char-after (match-beginning 1)) ?=)
(replace-match "="))
((match-beginning 2)
(let ((char (+ (* 16 (mail-unquote-printable-hexdigit
(char-after (match-beginning 2))))
(mail-unquote-printable-hexdigit
(char-after (1+ (match-beginning 2)))))))
(if unibyte
(progn
(replace-match "")
;; insert-byte will insert this as a
;; corresponding eight-bit character.
(insert-byte char 1))
(replace-match (make-string 1 char) t t))))
(noerror
(setq failed t))
(t
(error "Malformed MIME quoted-printable message"))))
(not failed))))))
(autoload 'rfc822-addresses "rfc822")
(defun mail-strip-quoted-names (address)
"Delete comments and quoted strings in an address list ADDRESS.
Also delete leading/trailing whitespace and replace FOO <BAR> with just BAR.
Return a modified address list."
(when address
(if mail-use-rfc822
(mapconcat #'identity (rfc822-addresses address) ", ")
(let (pos)
;; Strip comments.
(while (setq pos (string-match
"[ \t]*(\\([^()\\]\\|\\\\.\\|\\\\\n\\)*)"
address))
(setq address (replace-match "" nil nil address 0)))
;; strip surrounding whitespace
(string-match "\\`[ \t\n]*" address)
(setq address (substring address
(match-end 0)
(string-match "[ \t\n]*\\'" address
(match-end 0))))
;; strip `quoted' names (This is supposed to hack `"Foo Bar" <bar@host>')
(setq pos 0)
(while (setq pos (string-match
"\\([ \t]?\\)\\([ \t]*\"\\([^\"\\]\\|\\\\.\\|\\\\\n\\)*\"[ \t\n]*\\)"
address pos))
;; If the next thing is "@", we have "foo bar"@host. Leave it.
(if (and (> (length address) (match-end 0))
(= (aref address (match-end 0)) ?@))
(setq pos (match-end 0))
;; Otherwise discard the "..." part.
(setq address (replace-match "" nil nil address 2))))
;; If this address contains <...>, replace it with just
;; the part between the <...>.
(while (setq pos (string-match "\\(,\\s-*\\|\\`\\)\\([^,]*<\\([^>,:]*\\)>[^,]*\\)\\(\\s-*,\\|\\'\\)"
address))
(setq address (replace-match (match-string 3 address)
nil 'literal address 2)))
address))))
(defun mail-dont-reply-to (destinations)
"Prune addresses from DESTINATIONS, a list of recipient addresses.
Remove all addresses matching `mail-dont-reply-to-names' from the
comma-separated list, and return the pruned list."
;; FIXME this (setting a user option the first time a command is used)
;; is somewhat strange. Normally one would never set the option,
;; but instead fall back to the default so long as it was nil.
;; Or just set the default directly in the defcustom.
(if (null mail-dont-reply-to-names)
(setq mail-dont-reply-to-names
(if (> (length user-mail-address) 0)
(concat "\\`" (regexp-quote user-mail-address) "\\'"))))
;; Split up DESTINATIONS and match each element separately.
(let ((start-pos 0) (cur-pos 0)
(case-fold-search t))
(while start-pos
(setq cur-pos (string-match "[,\"]" destinations cur-pos))
(if (and cur-pos (equal (match-string 0 destinations) "\""))
;; Search for matching quote.
(let ((next-pos (string-search "\"" destinations (1+ cur-pos))))
(if next-pos
(setq cur-pos (1+ next-pos))
;; If the open-quote has no close-quote,
;; delete the open-quote to get something well-defined.
;; This case is not valid, but it can happen if things
;; are weird elsewhere.
(setq destinations (concat (substring destinations 0 cur-pos)
(substring destinations (1+ cur-pos))))
(setq cur-pos start-pos)))
(let* ((address (substring destinations start-pos cur-pos))
(naked-address (mail-strip-quoted-names address)))
(if (and mail-dont-reply-to-names
(string-match mail-dont-reply-to-names naked-address))
(setq destinations (concat (substring destinations 0 start-pos)
(and cur-pos (substring destinations
(1+ cur-pos))))
cur-pos start-pos)
(setq cur-pos (and cur-pos (1+ cur-pos))
start-pos cur-pos))))))
;; get rid of any trailing commas
(let ((pos (string-match "[ ,\t\n]*\\'" destinations)))
(if pos
(setq destinations (substring destinations 0 pos))))
;; remove leading spaces. they bother me.
(if (string-match "\\(\\s \\|,\\)*" destinations)
(substring destinations (match-end 0))
destinations))
;;;###autoload
(defun mail-fetch-field (field-name &optional last all list delete)
"Return the value of the header field whose type is FIELD-NAME.
If second arg LAST is non-nil, use the last field of type FIELD-NAME.
If third arg ALL is non-nil, concatenate all such fields with commas between.
If 4th arg LIST is non-nil, return a list of all such fields.
If 5th arg DELETE is non-nil, delete all header lines that are
included in the result.
The buffer should be narrowed to just the header, else false
matches may be returned from the message body."
(save-excursion
(goto-char (point-min))
(let ((case-fold-search t)
(name (concat "^" (regexp-quote field-name) "[ \t]*:[ \t]*")))
(if (or all list)
(let ((value (if all "")))
(while (re-search-forward name nil t)
(let ((opoint (point)))
(while (progn (forward-line 1)
(looking-at "[ \t]")))
;; Back up over newline, then trailing spaces or tabs
(forward-char -1)
(skip-chars-backward " \t" opoint)
(if list
(setq value (cons (buffer-substring-no-properties
opoint (point))
value))
(setq value (concat value
(if (string= value "") "" ", ")
(buffer-substring-no-properties
opoint (point)))))
(if delete
(delete-region (line-beginning-position) (point)))))
(if list
value
(and (not (string= value "")) value)))
(if (re-search-forward name nil t)
(progn
(if last (while (re-search-forward name nil t)))
(let ((opoint (point)))
(while (progn (forward-line 1)
(looking-at "[ \t]")))
;; Back up over newline, then trailing spaces or tabs
(forward-char -1)
(skip-chars-backward " \t" opoint)
(prog1
(buffer-substring-no-properties opoint (point))
(if delete
(delete-region (line-beginning-position)
(1+ (point))))))))))))
;; Parse a list of tokens separated by commas.
;; It runs from point to the end of the visible part of the buffer.
;; Whitespace before or after tokens is ignored,
;; but whitespace within tokens is kept.
(defun mail-parse-comma-list ()
(let (accumulated
beg)
(skip-chars-forward " \t\n")
(while (not (eobp))
(setq beg (point))
(skip-chars-forward "^,")
(skip-chars-backward " \t\n")
(setq accumulated
(cons (buffer-substring-no-properties beg (point))
accumulated))
(skip-chars-forward "^,")
(skip-chars-forward ", \t\n"))
accumulated))
(defun mail-comma-list-regexp (labels)
(let (pos)
(setq pos (or (string-match "[^ \t]" labels) 0))
;; Remove leading and trailing whitespace.
(setq labels (substring labels pos (string-match "[ \t]*$" labels pos)))
;; Change each comma to \|, and flush surrounding whitespace.
(while (setq pos (string-match "[ \t]*,[ \t]*" labels))
(setq labels
(concat (substring labels 0 pos)
"\\|"
(substring labels (match-end 0))))))
labels)
(defun mail-rfc822-time-zone (time)
(declare (obsolete format-time-string "29.1"))
(format-time-string "%z" time))
(defun mail-rfc822-date ()
(let ((system-time-locale "C"))
(format-time-string "%-d %b %Y %T %z")))
(defun mail-mbox-from ()
"Return an mbox \"From \" line for the current message.
The buffer should be narrowed to just the header."
(let* ((from (mail-strip-quoted-names (or (mail-fetch-field "from")
(mail-fetch-field "really-from")
(mail-fetch-field "sender")
(mail-fetch-field "return-path")
"unknown")))
(date (mail-fetch-field "date"))
;; A From: header can contain multiple addresses, a "From "
;; line must contain only one. (Bug#7760)
;; See, e.g., RFC 5322, 3.6.2. Originator Fields.
(end (string-match "[ \t]*[,\n]" from)))
(format "From %s %s\n" (if end
(substring from 0 end)
from)
(or (and date
(ignore-errors
(current-time-string (date-to-time date))))
(current-time-string)))))
(provide 'mail-utils)
;;; mail-utils.el ends here