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emacs/lisp/gnus/mm-view.el

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;;; mm-view.el --- functions for viewing MIME objects -*- lexical-binding: t; -*-
;; Copyright (C) 1998-2024 Free Software Foundation, Inc.
;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
;; 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:
;;; Code:
(require 'cl-lib)
(require 'mail-parse)
(require 'mailcap)
(require 'mm-bodies)
(require 'mm-decode)
(require 'smime)
(require 'mml-smime)
(autoload 'gnus-completing-read "gnus-util")
(autoload 'gnus-article-prepare-display "gnus-art")
(autoload 'vcard-parse-string "vcard")
(autoload 'vcard-format-string "vcard")
(autoload 'fill-flowed "flow-fill")
(autoload 'html2text "html2text" nil t)
(defvar gnus-article-mime-handles)
(defvar gnus-newsgroup-charset)
(defvar smime-keys)
(defvar w3m-cid-retrieve-function-alist)
(defvar w3m-current-buffer)
(defvar w3m-display-inline-images)
(defvar w3m-minor-mode-map)
(defvar mm-text-html-renderer-alist
'((shr . mm-shr)
(w3m . mm-inline-text-html-render-with-w3m)
(w3m-standalone . mm-inline-text-html-render-with-w3m-standalone)
(gnus-w3m . gnus-article-html)
(links . mm-inline-render-with-links)
(lynx mm-inline-render-with-stdin nil
"lynx" "-dump" "-force_html" "-stdin" "-nolist")
(html2text mm-inline-render-with-function html2text))
"The attributes of renderer types for text/html.")
(defcustom mm-fill-flowed t
"If non-nil, format=flowed articles will be displayed flowed."
:type 'boolean
:version "22.1"
:group 'mime-display)
;; Not a defcustom, since it's usually overridden by the callers of
;; the mm functions.
(defvar mm-inline-font-lock t
"If non-nil, do font locking of inline media types that support it.")
(defcustom mm-inline-large-images-proportion 0.9
"Maximum proportion large images can occupy in the buffer.
This is only used if `mm-inline-large-images' is set to
`resize'."
:type 'float
:version "24.1"
:group 'mime-display)
;;; Internal variables.
;;;
;;; Functions for displaying various formats inline
;;;
(autoload 'gnus-rescale-image "gnus-util")
(defun mm-inline-image (handle)
(let ((b (point-marker))
(inhibit-read-only t))
(insert-image
(let ((image (mm-get-image handle)))
(if (eq mm-inline-large-images 'resize)
(gnus-rescale-image
image
(let ((edges (window-inside-pixel-edges
(get-buffer-window (current-buffer)))))
(cons (truncate (* mm-inline-large-images-proportion
(- (nth 2 edges) (nth 0 edges))))
(truncate (* mm-inline-large-images-proportion
(- (nth 3 edges) (nth 1 edges)))))))
image))
"x")
(insert "\n")
(mm-handle-set-undisplayer
handle
(lambda ()
(let ((inhibit-read-only t))
(remove-images b b)
(delete-region b (+ b 2)))))))
(defvar mm-w3m-setup nil
"Whether `gnus-article-mode' has been setup to use emacs-w3m.")
;; External.
(declare-function w3m-detect-meta-charset "ext:w3m" ())
(declare-function w3m-region "ext:w3m" (start end &optional url charset))
(defun mm-setup-w3m ()
"Setup `gnus-article-mode' to use emacs-w3m."
(unless mm-w3m-setup
(require 'w3m)
(unless (assq 'gnus-article-mode w3m-cid-retrieve-function-alist)
(push (cons 'gnus-article-mode 'mm-w3m-cid-retrieve)
w3m-cid-retrieve-function-alist))
(setq mm-w3m-setup t))
(setq w3m-display-inline-images (not mm-html-inhibit-images)))
(defun mm-w3m-cid-retrieve-1 (url handle)
(dolist (elem handle)
(when (consp elem)
(when (equal url (mm-handle-id elem))
(mm-insert-part elem)
(throw 'found-handle (mm-handle-media-type elem)))
(when (and (stringp (car elem))
(equal "multipart" (mm-handle-media-supertype elem)))
(mm-w3m-cid-retrieve-1 url elem)))))
(defun mm-w3m-cid-retrieve (url &rest _args)
"Insert a content pointed by URL if it has the cid: scheme."
(when (string-match "\\`cid:" url)
(or (catch 'found-handle
(mm-w3m-cid-retrieve-1
(setq url (concat "<" (substring url (match-end 0)) ">"))
(with-current-buffer w3m-current-buffer
gnus-article-mime-handles)))
(prog1
nil
(message "Failed to find \"Content-ID: %s\"" url)))))
(defvar w3m-force-redisplay)
(defvar w3m-safe-url-regexp)
(defun mm-inline-text-html-render-with-w3m (handle)
"Render a text/html part using emacs-w3m."
(mm-setup-w3m)
(let ((text (mm-get-part handle))
(b (point))
(charset (or (mail-content-type-get (mm-handle-type handle) 'charset)
mail-parse-charset)))
(save-excursion
(insert (if charset (mm-decode-string text charset) text))
(save-restriction
(narrow-to-region b (point))
(unless charset
(goto-char (point-min))
(when (setq charset (w3m-detect-meta-charset))
(delete-region (point-min) (point-max))
(insert (mm-decode-string text charset))))
(let ((w3m-safe-url-regexp mm-w3m-safe-url-regexp)
w3m-force-redisplay)
(w3m-region (point-min) (point-max) nil charset))
;; Put the mark meaning this part was rendered by emacs-w3m.
(put-text-property (point-min) (point-max)
'mm-inline-text-html-with-w3m t)
(when (and mm-inline-text-html-with-w3m-keymap
(boundp 'w3m-minor-mode-map)
w3m-minor-mode-map)
(if (and (boundp 'w3m-link-map)
w3m-link-map)
(let* ((start (point-min))
(end (point-max))
(on (get-text-property start 'w3m-href-anchor))
(map (copy-keymap w3m-link-map))
next)
(set-keymap-parent map w3m-minor-mode-map)
(while (< start end)
(if on
(progn
(setq next (or (text-property-any start end
'w3m-href-anchor nil)
end))
(put-text-property start next 'keymap map))
(setq next (or (text-property-not-all start end
'w3m-href-anchor nil)
end))
(put-text-property start next 'keymap w3m-minor-mode-map))
(setq start next
on (not on))))
(put-text-property (point-min) (point-max)
'keymap w3m-minor-mode-map)))
(mm-handle-set-undisplayer
handle
(let ((beg (point-min-marker))
(end (point-max-marker)))
(lambda ()
(let ((inhibit-read-only t))
(delete-region beg end)))))))))
(defcustom mm-w3m-standalone-supports-m17n-p 'undecided
"T means the w3m command supports the m17n feature."
:type '(choice (const nil) (const t) (other :tag "detect" undecided))
:group 'mime-display)
(defun mm-w3m-standalone-supports-m17n-p ()
"Say whether the w3m command supports the m17n feature."
(cond ((eq mm-w3m-standalone-supports-m17n-p t) t)
((eq mm-w3m-standalone-supports-m17n-p nil) nil)
((condition-case nil
(let ((coding-system-for-write 'iso-2022-jp)
(coding-system-for-read 'iso-2022-jp)
(str (decode-coding-string "\
\e$B#D#o#e#s!!#w#3#m!!#s#u#p#p#o#r#t!!#m#1#7#n!)\e(B" 'iso-2022-jp)))
(mm-with-multibyte-buffer
(insert str)
(call-process-region
(point-min) (point-max) "w3m" t t nil "-dump"
"-T" "text/html" "-I" "iso-2022-jp" "-O" "iso-2022-jp")
(goto-char (point-min))
(search-forward str nil t)))
(error nil))
(setq mm-w3m-standalone-supports-m17n-p t))
(t
;;(message "You had better upgrade your w3m command")
(setq mm-w3m-standalone-supports-m17n-p nil))))
(defun mm-inline-text-html-render-with-w3m-standalone (handle)
"Render a text/html part using w3m."
(if (mm-w3m-standalone-supports-m17n-p)
(let ((source (mm-get-part handle))
(charset (or (mail-content-type-get (mm-handle-type handle)
'charset)
(symbol-name mail-parse-charset)))
cs)
(if (and charset
(setq cs (mm-charset-to-coding-system charset nil t))
(not (eq cs 'ascii)))
(setq charset (format "%s" (mm-coding-system-to-mime-charset cs)))
;; The default.
(setq charset "iso-8859-1"
cs 'iso-8859-1))
(mm-insert-inline
handle
(mm-with-unibyte-buffer
(insert source)
(mm-enable-multibyte)
(let ((coding-system-for-write 'binary)
(coding-system-for-read cs))
(call-process-region
(point-min) (point-max)
"w3m" t t nil "-dump" "-T" "text/html"
"-I" charset "-O" charset))
(buffer-string))))
(mm-inline-render-with-stdin handle nil "w3m" "-dump" "-T" "text/html")))
(defun mm-links-remove-leading-blank ()
(declare (obsolete nil "28.1"))
;; Delete the annoying three spaces preceding each line of links
;; output.
(goto-char (point-min))
(while (re-search-forward "^ " nil t)
(delete-region (match-beginning 0) (match-end 0))))
(defun mm-inline-wash-with-file (post-func cmd &rest args)
(declare (obsolete nil "28.1"))
(with-suppressed-warnings ((lexical file))
(dlet ((file (make-temp-file
(expand-file-name "mm" mm-tmp-directory))))
(let ((coding-system-for-write 'binary))
(write-region (point-min) (point-max) file nil 'silent))
(delete-region (point-min) (point-max))
(unwind-protect
(apply #'call-process cmd nil t nil
(mapcar (lambda (e) (eval e t)) args))
(delete-file file))
(and post-func (funcall post-func)))))
(defun mm-inline-wash-with-stdin (post-func cmd &rest args)
(let ((coding-system-for-write 'binary))
(apply #'call-process-region (point-min) (point-max)
cmd t t nil args))
(and post-func (funcall post-func)))
(defun mm-inline-render-with-file (handle post-func cmd &rest args)
(declare (obsolete nil "28.1"))
(let ((source (mm-get-part handle)))
(mm-insert-inline
handle
(mm-with-unibyte-buffer
(insert source)
(with-suppressed-warnings ((obsolete mm-inline-wash-with-file))
(apply #'mm-inline-wash-with-file post-func cmd args))
(buffer-string)))))
(defun mm-inline-render-with-links (handle)
(let ((source (mm-get-part handle))
file charset)
(mm-insert-inline
handle
(with-temp-buffer
(setq charset (mail-content-type-get (mm-handle-type handle) 'charset))
(insert source)
(unwind-protect
(progn
(setq file (make-temp-file (expand-file-name
"mm" mm-tmp-directory)))
(let ((coding-system-for-write 'binary))
(write-region (point-min) (point-max) file nil 'silent))
(delete-region (point-min) (point-max))
(if charset
(with-environment-variables (("LANG" (format "en-US.%s"
charset)))
(call-process "links" nil t nil "-dump" file))
(call-process "links" nil t nil "-dump" file))
(goto-char (point-min))
(while (re-search-forward "^ " nil t)
(delete-region (match-beginning 0) (match-end 0))))
(when (and file (file-exists-p file))
(delete-file file)))
(buffer-string)))))
(defun mm-inline-render-with-stdin (handle post-func cmd &rest args)
(let ((source (mm-get-part handle)))
(mm-insert-inline
handle
(mm-with-unibyte-buffer
(insert source)
(apply #'mm-inline-wash-with-stdin post-func cmd args)
(buffer-string)))))
(defun mm-inline-render-with-function (handle func &rest args)
(let ((source (mm-get-part handle))
(charset (or (mail-content-type-get (mm-handle-type handle) 'charset)
mail-parse-charset)))
(mm-insert-inline
handle
(mm-with-multibyte-buffer
(insert (if charset
(mm-decode-string source charset)
source))
(apply func args)
(buffer-string)))))
(defun mm-inline-text-html (handle)
(if (stringp (car handle))
(mapcar #'mm-inline-text-html (cdr handle))
(let* ((func mm-text-html-renderer)
(entry (assq func mm-text-html-renderer-alist))
(inhibit-read-only t))
(if entry
(setq func (cdr entry)))
(cond
((null func)
(mm-insert-inline handle (mm-get-part handle)))
((functionp func)
(funcall func handle))
(t
(apply (car func) handle (cdr func)))))))
(defun mm-inline-text-vcard (handle)
(let ((inhibit-read-only t))
(mm-insert-inline
handle
(concat "\n-- \n"
(ignore-errors
(if (fboundp 'vcard-pretty-print)
(vcard-pretty-print (mm-get-part handle))
(vcard-format-string
(vcard-parse-string (mm-get-part handle)
'vcard-standard-filter))))))))
(defun mm-inline-text (handle)
(let ((b (point))
(type (mm-handle-media-subtype handle))
(charset (mail-content-type-get
(mm-handle-type handle) 'charset))
(inhibit-read-only t))
(if (or (eq charset 'gnus-decoded)
;; This is probably not entirely correct, but
;; makes rfc822 parts with embedded multiparts work.
(eq mail-parse-charset 'gnus-decoded))
(save-restriction
(narrow-to-region (point) (point))
(mm-insert-part handle)
(goto-char (point-max)))
(mm-display-inline-fontify handle))
(when (and mm-fill-flowed
(equal type "plain")
(equal (cdr (assoc 'format (mm-handle-type handle)))
"flowed"))
(save-restriction
(narrow-to-region b (point))
(goto-char b)
(fill-flowed nil (cl-equalp (cdr (assoc 'delsp (mm-handle-type handle)))
"yes"))
(goto-char (point-max))))
(save-restriction
(narrow-to-region b (point))
(when (member type '("enriched" "richtext"))
(set-text-properties (point-min) (point-max) nil)
(ignore-errors
(enriched-decode (point-min) (point-max))))
(mm-handle-set-undisplayer
handle
(if (= (point-min) (point-max))
#'ignore
(let ((beg (copy-marker (point-min) t))
(end (point-max-marker)))
(lambda ()
(let ((inhibit-read-only t))
(delete-region beg end)))))))))
(defun mm-insert-inline (handle text)
"Insert TEXT inline from HANDLE."
(let ((b (point)))
(insert text)
(unless (bolp)
(insert "\n"))
(mm-handle-set-undisplayer
handle
(let ((beg (copy-marker b t))
(end (point-marker)))
(lambda ()
(let ((inhibit-read-only t))
(delete-region beg end)))))))
(defun mm-inline-audio (_handle)
(message "Not implemented"))
(defun mm-view-message ()
(mm-enable-multibyte)
(let (handles)
(let (gnus-article-mime-handles)
;; Double decode problem may happen. See mm-inline-message.
(run-hooks 'gnus-article-decode-hook)
(gnus-article-prepare-display)
(setq handles gnus-article-mime-handles))
(when handles
(setq gnus-article-mime-handles
(mm-merge-handles gnus-article-mime-handles handles))))
(fundamental-mode)
(goto-char (point-min)))
(defvar mm-inline-message-prepare-function nil
"Function called by `mm-inline-message' to do client specific setup.
It is called with two parameters -- the MIME handle and the charset.")
(defun mm-inline-message (handle)
"Insert HANDLE (a message/rfc822 part) into the current buffer.
This function will call `mm-inline-message-prepare-function'
after inserting the part."
(let ((b (point))
(bolp (bolp))
(charset (mail-content-type-get
(mm-handle-type handle) 'charset)))
(when (and charset
(stringp charset))
(setq charset (intern (downcase charset)))
(when (eq charset 'us-ascii)
(setq charset nil)))
(save-excursion
(save-restriction
(narrow-to-region b b)
(mm-insert-part handle)
(when mm-inline-message-prepare-function
(funcall mm-inline-message-prepare-function handle charset))
(goto-char (point-min))
(unless bolp
(insert "\n"))
(goto-char (point-max))
(unless (bolp)
(insert "\n"))
(insert "----------\n\n")
(mm-handle-set-undisplayer
handle
(let ((beg (point-min-marker))
(end (point-max-marker)))
(lambda ()
(let ((inhibit-read-only t))
(delete-region beg end)))))))))
(defun mm-display-inline-fontify (handle &optional mode)
"Insert HANDLE inline fontifying with MODE.
If MODE is not set, try to find mode automatically."
(let ((charset (mail-content-type-get (mm-handle-type handle) 'charset))
text coding-system ovs)
(unless (eq charset 'gnus-decoded)
(mm-with-unibyte-buffer
(mm-insert-part handle)
(mm-decompress-buffer
(mm-handle-filename handle)
t t)
(unless charset
(setq coding-system (mm-find-buffer-file-coding-system)))
(setq text (buffer-string))))
(with-temp-buffer
(setq untrusted-content t)
(insert (cond ((eq charset 'gnus-decoded)
(with-current-buffer (mm-handle-buffer handle)
(buffer-string)))
(coding-system
(decode-coding-string text coding-system))
(t
(mm-decode-string text (or charset 'undecided)))))
(let ((font-lock-verbose nil) ; font-lock is a bit too verbose.
(enable-local-variables nil))
;; We used to set font-lock-mode-hook to nil to avoid enabling
;; support modes, but now that we use font-lock-ensure, support modes
;; aren't a problem any more. So we could probably get rid of this
;; setting now, but it seems harmless and potentially still useful.
(setq-local font-lock-mode-hook nil)
(setq buffer-file-name (mm-handle-filename handle))
(with-demoted-errors "Error setting mode: %S"
(if mode
(save-window-excursion
;; According to Katsumi Yamaoka <yamaoka@jpl.org>, org-mode
;; requires the buffer to be temporarily displayed here, but
;; I could not reproduce this problem. Furthermore, if
;; there's such a problem, we should fix org-mode rather than
;; use switch-to-buffer which can have undesirable
;; side-effects!
;;(switch-to-buffer (current-buffer))
(funcall mode))
(let ((auto-mode-alist
(delq (rassq 'doc-view-mode-maybe auto-mode-alist)
(copy-sequence auto-mode-alist))))
;; Don't run hooks that might assume buffer-file-name
;; really associates buffer with a file (bug#39190).
(delay-mode-hooks (set-auto-mode))
(setq mode major-mode)))
;; Do not fontify if the guess mode is fundamental.
(when (and (not (eq major-mode 'fundamental-mode))
mm-inline-font-lock)
(font-lock-ensure))))
(setq text (buffer-string))
(when (eq mode 'diff-mode)
(setq ovs (mapcar (lambda (ov) (list ov (overlay-start ov)
(overlay-end ov)))
(overlays-in (point-min) (point-max)))))
;; Set buffer unmodified to avoid confirmation when killing the
;; buffer.
(set-buffer-modified-p nil))
(let ((b (- (point) (save-restriction (widen) (point-min)))))
(mm-insert-inline handle text)
(dolist (ov ovs)
(move-overlay (nth 0 ov) (+ (nth 1 ov) b)
(+ (nth 2 ov) b) (current-buffer))))))
;; Shouldn't these functions check whether the user even wants to use
;; font-lock? Also, it would be nice to change for the size of the
;; fontified region.
(defun mm-display-patch-inline (handle)
(mm-display-inline-fontify handle 'diff-mode))
(defun mm-display-elisp-inline (handle)
(mm-display-inline-fontify handle 'emacs-lisp-mode))
(defun mm-display-dns-inline (handle)
(mm-display-inline-fontify handle 'dns-mode))
(defun mm-display-org-inline (handle)
"Show an Org mode text from HANDLE inline."
(mm-display-inline-fontify handle 'org-mode))
(defun mm-display-shell-script-inline (handle)
"Show a shell script from HANDLE inline."
(mm-display-inline-fontify handle 'shell-script-mode))
(defun mm-display-javascript-inline (handle)
"Show JavaScript code from HANDLE inline."
(mm-display-inline-fontify handle 'javascript-mode))
;; id-signedData OBJECT IDENTIFIER ::= { iso(1) member-body(2)
;; us(840) rsadsi(113549) pkcs(1) pkcs7(7) 2 }
(defvar mm-pkcs7-signed-magic
(concat
"0"
"\\(\\(\x80\\)"
"\\|\\(\x81\\(.\\|\n\\)\\{1\\}\\)"
"\\|\\(\x82\\(.\\|\n\\)\\{2\\}\\)"
"\\|\\(\x83\\(.\\|\n\\)\\{3\\}\\)"
"\\)"
"\x06\x09\\*\x86H\x86\xf7\x0d\x01\x07\x02"))
;; id-envelopedData OBJECT IDENTIFIER ::= { iso(1) member-body(2)
;; us(840) rsadsi(113549) pkcs(1) pkcs7(7) 3 }
(defvar mm-pkcs7-enveloped-magic
(concat
"0"
"\\(\\(\x80\\)"
"\\|\\(\x81\\(.\\|\n\\)\\{1\\}\\)"
"\\|\\(\x82\\(.\\|\n\\)\\{2\\}\\)"
"\\|\\(\x83\\(.\\|\n\\)\\{3\\}\\)"
"\\)"
"\x06\x09\\*\x86H\x86\xf7\x0d\x01\x07\x03"))
(defun mm-view-pkcs7-get-type (handle)
(mm-with-unibyte-buffer
(mm-insert-part handle)
(cond ((looking-at mm-pkcs7-enveloped-magic)
'enveloped)
((looking-at mm-pkcs7-signed-magic)
'signed)
(t
(error "Could not identify PKCS#7 type")))))
(defun mm-view-pkcs7 (handle &optional from)
(cl-case (mm-view-pkcs7-get-type handle)
(enveloped (mm-view-pkcs7-decrypt handle from))
(signed (mm-view-pkcs7-verify handle))
(otherwise (error "Unknown or unimplemented PKCS#7 type"))))
(defun mm-view-pkcs7-verify (handle)
(let ((verified nil))
(if (eq mml-smime-use 'epg)
;; Use EPG/gpgsm
(insert
(with-temp-buffer
(insert-buffer-substring (mm-handle-buffer handle))
(goto-char (point-min))
(let ((part (base64-decode-string (buffer-string)))
(context (epg-make-context 'CMS)))
(prog1
(epg-verify-string context part)
(let ((result (epg-context-result-for context 'verify)))
(mm-sec-status
'gnus-info (epg-verify-result-to-string result)))))))
(with-temp-buffer
(insert "MIME-Version: 1.0\n")
(mm-insert-headers "application/pkcs7-mime" "base64" "smime.p7m")
(insert-buffer-substring (mm-handle-buffer handle))
(setq verified (smime-verify-region (point-min) (point-max))))
(if verified
(insert verified)
(insert-buffer-substring smime-details-buffer)))
t))
(autoload 'epg-decrypt-string "epg")
(defun mm-view-pkcs7-decrypt (handle &optional from)
(insert-buffer-substring (mm-handle-buffer handle))
(goto-char (point-min))
(if (eq mml-smime-use 'epg)
;; Use EPG/gpgsm
(let ((part (base64-decode-string (buffer-string))))
(erase-buffer)
(insert
(let ((context (epg-make-context 'CMS)))
(prog1
(epg-decrypt-string context part)
(mm-sec-status 'gnus-info "OK")))))
;; Use openssl
(insert "MIME-Version: 1.0\n")
(mm-insert-headers "application/pkcs7-mime" "base64" "smime.p7m")
(smime-decrypt-region
(point-min) (point-max)
(if (= (length smime-keys) 1)
(cadar smime-keys)
(smime-get-key-by-email
(gnus-completing-read
"Decipher using key"
smime-keys nil nil nil (car-safe (car-safe smime-keys)))))
from))
(goto-char (point-min))
(while (search-forward "\r\n" nil t)
(replace-match "\n"))
(goto-char (point-min)))
(provide 'mm-view)
;;; mm-view.el ends here
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