lisp/mail/metamail.el

   1 ;;; metamail.el --- Metamail interface for GNU Emacs
   2
   3 ;; Copyright (C) 1993, 1996, 2001-2015 Free Software Foundation, Inc.
   4
   5 ;; Author: Masanobu UMEDA <umerin@mse.kyutech.ac.jp>
   6 ;; Keywords: mail, news, mime, multimedia
   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 ;; Note: Metamail does not have all the options which are compatible with
  26 ;; the environment variables.  For that reason, metamail.el has to
  27 ;; hack the environment variables.  In addition, there is no way to
  28 ;; display all header fields without extra informative body messages
  29 ;; which are suppressed by the "-q" option.
  30
  31 ;; The idea of using metamail to process MIME messages is from
  32 ;; gnus-mime.el by Spike <Spike@world.std.com>.
  33
  34 ;;; Code:
  35
  36 (defvar rmail-current-message)
  37 (defvar rmail-message-vector)
  38
  39 (defgroup metamail nil
  40   "Metamail interface for Emacs."
  41   :group 'mail
  42   :group 'processes)
  43
  44 (defcustom metamail-program-name "metamail"
  45   "Metamail program name."
  46   :type 'string
  47   :group 'metamail)
  48
  49 (defcustom metamail-mailer-name "emacs"
  50   "Mailer name set to MM_MAILER environment variable."
  51   :type 'string
  52   :group 'metamail)
  53
  54 (defvar metamail-environment '("KEYHEADS=*" "MM_QUIET=1")
  55   "Environment variables passed to `metamail'.
  56 It must be a list of strings that have the format ENVVARNAME=VALUE.
  57 It is not expected to be altered globally by `set' or `setq'.
  58 Instead, change its value temporary using `let' or `let*' form.")
  59
  60 (defcustom metamail-switches '("-x" "-d" "-z")
  61   "Switches for `metamail' program.
  62 `-z' is required to remove zap file.
  63 It is not expected to be altered globally by `set' or `setq'.
  64 Instead, change its value temporary using `let' or `let*' form.
  65 `-m MAILER' argument is automatically generated from the
  66 `metamail-mailer-name' variable."
  67   :type '(repeat (string :tag "Switch"))
  68   :group 'metamail)
  69
  70 ;;;###autoload
  71 (defun metamail-interpret-header ()
  72   "Interpret a header part of a MIME message in current buffer.
  73 Its body part is not interpreted at all."
  74   (interactive)
  75   (save-excursion
  76     (let* ((buffer-read-only nil)
  77            (metamail-switches           ;Inhibit processing an empty body.
  78             (append metamail-switches '("-c" "text/plain" "-E" "7bit")))
  79            (end (progn
  80                   (goto-char (point-min))
  81                   (search-forward "\n\n" nil 'move)
  82                   ;; An extra newline is inserted by metamail if there
  83                   ;; is no body part.  So, insert a dummy body by
  84                   ;; itself.
  85                   (insert "\n")
  86                   (point))))
  87       (metamail-region (point-min) end nil nil 'nodisplay)
  88       ;; Remove an extra newline inserted by myself.
  89       (goto-char (point-min))
  90       (if (search-forward "\n\n\n" nil t)
  91           (delete-char -1))
  92       )))
  93
  94 ;;;###autoload
  95 (defun metamail-interpret-body (&optional viewmode nodisplay)
  96   "Interpret a body part of a MIME message in current buffer.
  97 Optional argument VIEWMODE specifies the value of the
  98 EMACS_VIEW_MODE environment variable (defaulted to 1).
  99 Optional argument NODISPLAY non-nil means buffer is not
 100 redisplayed as output is inserted.
 101 Its header part is not interpreted at all."
 102   (interactive "p")
 103   (save-excursion
 104     (let ((contype nil)
 105           (encoding nil)
 106           (end (progn
 107                  (goto-char (point-min))
 108                  (search-forward "\n\n" nil t)
 109                  (point))))
 110       ;; Find Content-Type and Content-Transfer-Encoding from the header.
 111       (save-restriction
 112         (narrow-to-region (point-min) end)
 113         (setq contype
 114               (or (mail-fetch-field "Content-Type") "text/plain"))
 115         (setq encoding
 116               (or (mail-fetch-field "Content-Transfer-Encoding") "7bit")))
 117       ;; Interpret the body part only.
 118       (let ((metamail-switches          ;Process body part only.
 119              (append metamail-switches
 120                      (list "-b" "-c" contype "-E" encoding))))
 121         (metamail-region end (point-max) viewmode nil nodisplay))
 122       ;; This mode specific hack is no longer appropriate in mbox Rmail.
 123       ;; Pre-mbox, we have just modified the actual folder, so we
 124       ;; update the message-vector with the new end position of the
 125       ;; current message.  In mbox Rmail, all we have done is modify a
 126       ;; display copy of the message.  Note also that point-max is a
 127       ;; marker in the wrong buffer: the message-vector contains
 128       ;; markers in rmail-view-buffer (which is not in rmail-mode).
 129       ;; So this hack actually breaks the message-vector.
 130       ;; If you're calling this on the actual rmail-view-buffer (or a
 131       ;; non-swapped rmail-buffer), you would still need this hack.
 132       ;; But you're not going to do that.
 133 ;;;      (cond ((eq major-mode 'rmail-mode)
 134 ;;;          ;; Adjust the marker of this message if in Rmail mode buffer.
 135 ;;;          (set-marker (aref rmail-message-vector (1+ rmail-current-message))
 136 ;;;                      (point-max))))
 137       )))
 138
 139 ;;;###autoload
 140 (defun metamail-buffer (&optional viewmode buffer nodisplay)
 141   "Process current buffer through `metamail'.
 142 Optional argument VIEWMODE specifies the value of the
 143 EMACS_VIEW_MODE environment variable (defaulted to 1).
 144 Optional argument BUFFER specifies a buffer to be filled (nil
 145 means current).
 146 Optional argument NODISPLAY non-nil means buffer is not
 147 redisplayed as output is inserted."
 148   (interactive "p")
 149   (metamail-region (point-min) (point-max) viewmode buffer nodisplay))
 150
 151 ;;;###autoload
 152 (defun metamail-region (beg end &optional viewmode buffer nodisplay)
 153   "Process current region through `metamail'.
 154 Optional argument VIEWMODE specifies the value of the
 155 EMACS_VIEW_MODE environment variable (defaulted to 1).
 156 Optional argument BUFFER specifies a buffer to be filled (nil
 157 means current).
 158 Optional argument NODISPLAY non-nil means buffer is not
 159 redisplayed as output is inserted."
 160   (interactive "r\np")
 161   (let ((curbuf (current-buffer))
 162         (buffer-read-only nil)
 163         (metafile (make-temp-file "metamail"))
 164         (option-environment
 165          (list (format "EMACS_VIEW_MODE=%d"
 166                        (if (numberp viewmode) viewmode 1)))))
 167     (save-excursion
 168       ;; Gee!  Metamail does not output to stdout if input comes from
 169       ;; stdin.
 170       (let ((selective-display nil))    ;Disable ^M to nl translation.
 171         (write-region beg end metafile nil 'nomessage))
 172       (if buffer
 173           (set-buffer buffer))
 174       (setq buffer-read-only nil)
 175       ;; Clear destination buffer.
 176       (if (eq curbuf (current-buffer))
 177           (delete-region beg end)
 178         (delete-region (point-min) (point-max)))
 179       ;; We have to pass the environment variable KEYHEADS to display
 180       ;; all header fields.  Metamail should have an optional argument
 181       ;; to pass such information directly.
 182       (let ((process-environment
 183              (append process-environment
 184                      metamail-environment option-environment))
 185             (coding-system-for-read 'undecided))
 186         (apply (function call-process)
 187                metamail-program-name
 188                nil
 189                t                        ;Output to current buffer
 190                (not nodisplay)          ;Force redisplay
 191                (append metamail-switches
 192                        (list "-m" (or metamail-mailer-name "emacs"))
 193                        (list metafile))))
 194       ;; `metamail' may not delete the temporary file!
 195       (condition-case error
 196           (delete-file metafile)
 197         (error nil))
 198       )))
 199
 200 (provide 'metamail)
 201
 202 ;;; metamail.el ends here