lisp/net/mailcap.el

   1 ;;; mailcap.el --- MIME media types configuration -*- lexical-binding: t -*-
   2
   3 ;; Copyright (C) 1998-2018 Free Software Foundation, Inc.
   4
   5 ;; Author: William M. Perry <wmperry@aventail.com>
   6 ;;      Lars Magne Ingebrigtsen <larsi@gnus.org>
   7 ;; Keywords: news, mail, multimedia
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software: you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation, either version 3 of the License, or
  14 ;; (at your option) any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
  23
  24 ;;; Commentary:
  25
  26 ;; Provides configuration of MIME media types from directly from Lisp
  27 ;; and via the usual mailcap mechanism (RFC 1524).  Deals with
  28 ;; mime.types similarly.
  29
  30 ;;; Code:
  31
  32 (autoload 'mail-header-parse-content-type "mail-parse")
  33
  34 (defgroup mailcap nil
  35   "Definition of viewers for MIME types."
  36   :version "21.1"
  37   :group 'mime)
  38
  39 (defvar mailcap-parse-args-syntax-table
  40   (let ((table (copy-syntax-table emacs-lisp-mode-syntax-table)))
  41     (modify-syntax-entry ?' "\"" table)
  42     (modify-syntax-entry ?` "\"" table)
  43     (modify-syntax-entry ?{ "(" table)
  44     (modify-syntax-entry ?} ")" table)
  45     table)
  46   "A syntax table for parsing SGML attributes.")
  47
  48 (defvar mailcap-print-command
  49   (mapconcat 'identity
  50              (cons (if (boundp 'lpr-command)
  51                        lpr-command
  52                      "lpr")
  53                    (when (boundp 'lpr-switches)
  54                      (if (stringp lpr-switches)
  55                          (list lpr-switches)
  56                        lpr-switches)))
  57              " ")
  58   "Shell command (including switches) used to print PostScript files.")
  59
  60 (defun mailcap--get-user-mime-data (sym)
  61   (let ((val (default-value sym))
  62         res)
  63     (dolist (entry val)
  64       (push (list (cdr (assq 'viewer entry))
  65                   (cdr (assq 'type entry))
  66                   (cdr (assq 'test entry)))
  67             res))
  68     (nreverse res)))
  69
  70 (defun mailcap--set-user-mime-data (sym val)
  71   (let (res)
  72     (pcase-dolist (`(,viewer ,type ,test) val)
  73       (push `((viewer . ,viewer)
  74               (type . ,type)
  75               ,@(when test `((test . ,test))))
  76             res))
  77     (set-default sym (nreverse res))))
  78
  79 (defcustom mailcap-user-mime-data nil
  80   "A list of viewers preferred for different MIME types.
  81 The elements of the list are alists of the following structure
  82
  83   ((viewer . VIEWER)
  84    (type   . MIME-TYPE)
  85    (test   . TEST))
  86
  87 where VIEWER is either a lisp command, e.g., a major-mode, or a
  88 string containing a shell command for viewing files of the
  89 defined MIME-TYPE.  In case of a shell command, %s will be
  90 replaced with the file.
  91
  92 MIME-TYPE is a regular expression being matched against the
  93 actual MIME type.  It is implicitly surrounded with ^ and $.
  94
  95 TEST is a lisp form which is evaluated in order to test if the
  96 entry should be chosen.  The `test' entry is optional.
  97
  98 When selecting a viewer for a given MIME type, the first viewer
  99 in this list with a matching MIME-TYPE and successful TEST is
 100 selected.  Only if none matches, the standard `mailcap-mime-data'
 101 is consulted."
 102   :version "26.1"
 103   :type '(repeat
 104           (list
 105            (choice (function :tag "Function or mode")
 106                    (string :tag "Shell command"))
 107            (regexp :tag "MIME Type")
 108            (sexp :tag "Test (optional)")))
 109   :get #'mailcap--get-user-mime-data
 110   :set #'mailcap--set-user-mime-data
 111   :group 'mailcap)
 112
 113 ;; Postpone using defcustom for this as it's so big and we essentially
 114 ;; have to have two copies of the data around then.  Perhaps just
 115 ;; customize the Lisp viewers and rely on the normal configuration
 116 ;; files for the rest?  -- fx
 117 (defvar mailcap-mime-data
 118   `(("application"
 119      ("vnd\\.ms-excel"
 120       (viewer . "gnumeric %s")
 121       (test   . (getenv "DISPLAY"))
 122       (type . "application/vnd.ms-excel"))
 123      ("octet-stream"
 124       (viewer . mailcap-save-binary-file)
 125       (non-viewer . t)
 126       (type . "application/octet-stream"))
 127      ("dvi"
 128       (viewer . "xdvi -safer %s")
 129       (test   . (eq window-system 'x))
 130       ("needsx11")
 131       (type   . "application/dvi")
 132       ("print" . "dvips -qRP %s"))
 133      ("dvi"
 134       (viewer . "dvitty %s")
 135       (test   . (not (getenv "DISPLAY")))
 136       (type   . "application/dvi")
 137       ("print" . "dvips -qRP %s"))
 138      ("emacs-lisp"
 139       (viewer . mailcap-maybe-eval)
 140       (type   . "application/emacs-lisp"))
 141      ("x-emacs-lisp"
 142       (viewer . mailcap-maybe-eval)
 143       (type   . "application/x-emacs-lisp"))
 144      ("x-tar"
 145       (viewer . mailcap-save-binary-file)
 146       (non-viewer . t)
 147       (type   . "application/x-tar"))
 148      ("x-latex"
 149       (viewer . tex-mode)
 150       (type   . "application/x-latex"))
 151      ("x-tex"
 152       (viewer . tex-mode)
 153       (type   . "application/x-tex"))
 154      ("latex"
 155       (viewer . tex-mode)
 156       (type   . "application/latex"))
 157      ("tex"
 158       (viewer . tex-mode)
 159       (type   . "application/tex"))
 160      ("texinfo"
 161       (viewer . texinfo-mode)
 162       (type   . "application/tex"))
 163      ("zip"
 164       (viewer . mailcap-save-binary-file)
 165       (non-viewer . t)
 166       (type   . "application/zip")
 167       ("copiousoutput"))
 168      ("pdf"
 169       (viewer . pdf-view-mode)
 170       (type . "application/pdf")
 171       (test . window-system))
 172      ("pdf"
 173       (viewer . doc-view-mode)
 174       (type . "application/pdf")
 175       (test . window-system))
 176      ("pdf"
 177       (viewer . "gv -safer %s")
 178       (type . "application/pdf")
 179       (test . window-system)
 180       ("print" . ,(concat "pdf2ps %s - | " mailcap-print-command)))
 181      ("pdf"
 182       (viewer . "gpdf %s")
 183       (type . "application/pdf")
 184       ("print" . ,(concat "pdftops %s - | " mailcap-print-command))
 185       (test . (eq window-system 'x)))
 186      ("pdf"
 187       (viewer . "xpdf %s")
 188       (type . "application/pdf")
 189       ("print" . ,(concat "pdftops %s - | " mailcap-print-command))
 190       (test . (eq window-system 'x)))
 191      ("pdf"
 192       (viewer . ,(concat "pdftotext %s -"))
 193       (type   . "application/pdf")
 194       ("print" . ,(concat "pdftops %s - | " mailcap-print-command))
 195       ("copiousoutput"))
 196      ("postscript"
 197       (viewer . "gv -safer %s")
 198       (type . "application/postscript")
 199       (test   . window-system)
 200       ("print" . ,(concat mailcap-print-command " %s"))
 201       ("needsx11"))
 202      ("postscript"
 203       (viewer . "ghostview -dSAFER %s")
 204       (type . "application/postscript")
 205       (test   . (eq window-system 'x))
 206       ("print" . ,(concat mailcap-print-command " %s"))
 207       ("needsx11"))
 208      ("postscript"
 209       (viewer . "ps2ascii %s")
 210       (type . "application/postscript")
 211       (test . (not (getenv "DISPLAY")))
 212       ("print" . ,(concat mailcap-print-command " %s"))
 213       ("copiousoutput"))
 214      ("sieve"
 215       (viewer . sieve-mode)
 216       (type   . "application/sieve"))
 217      ("pgp-keys"
 218       (viewer . "gpg --import --interactive --verbose")
 219       (type   . "application/pgp-keys")
 220       ("needsterminal")))
 221     ("audio"
 222      ("x-mpeg"
 223       (viewer . "maplay %s")
 224       (type   . "audio/x-mpeg"))
 225      (".*"
 226       (viewer . "showaudio")
 227       (type   . "audio/*")))
 228     ("message"
 229      ("rfc-*822"
 230       (viewer . mm-view-message)
 231       (test   . (and (featurep 'gnus)
 232                      (gnus-alive-p)))
 233       (type   . "message/rfc822"))
 234      ("rfc-*822"
 235       (viewer . vm-mode)
 236       (type   . "message/rfc822"))
 237      ("rfc-*822"
 238       (viewer . view-mode)
 239       (type   . "message/rfc822")))
 240     ("image"
 241      ("x-xwd"
 242       (viewer  . "xwud -in %s")
 243       (type    . "image/x-xwd")
 244       ("compose" . "xwd -frame > %s")
 245       (test    . (eq window-system 'x))
 246       ("needsx11"))
 247      ("x11-dump"
 248       (viewer . "xwud -in %s")
 249       (type . "image/x-xwd")
 250       ("compose" . "xwd -frame > %s")
 251       (test   . (eq window-system 'x))
 252       ("needsx11"))
 253      ("windowdump"
 254       (viewer . "xwud -in %s")
 255       (type . "image/x-xwd")
 256       ("compose" . "xwd -frame > %s")
 257       (test   . (eq window-system 'x))
 258       ("needsx11"))
 259      (".*"
 260       (viewer . "display %s")
 261       (type . "image/*")
 262       (test   . (eq window-system 'x))
 263       ("needsx11"))
 264      (".*"
 265       (viewer . "ee %s")
 266       (type . "image/*")
 267       (test   . (eq window-system 'x))
 268       ("needsx11")))
 269     ("text"
 270      ("plain"
 271       (viewer  . view-mode)
 272       (type    . "text/plain"))
 273      ("plain"
 274       (viewer  . fundamental-mode)
 275       (type    . "text/plain"))
 276      ("enriched"
 277       (viewer . enriched-decode)
 278       (type   . "text/enriched"))
 279      ("dns"
 280       (viewer . dns-mode)
 281       (type   . "text/dns")))
 282     ("video"
 283      ("mpeg"
 284       (viewer . "mpeg_play %s")
 285       (type   . "video/mpeg")
 286       (test   . (eq window-system 'x))
 287       ("needsx11")))
 288     ("x-world"
 289      ("x-vrml"
 290       (viewer  . "webspace -remote %s -URL %u")
 291       (type    . "x-world/x-vrml")
 292       ("description"
 293        "VRML document")))
 294     ("archive"
 295      ("tar"
 296       (viewer . tar-mode)
 297       (type . "archive/tar"))))
 298   "The mailcap structure is an assoc list of assoc lists.
 299 1st assoc list is keyed on the major content-type
 300 2nd assoc list is keyed on the minor content-type (which can be a regexp)
 301
 302 Which looks like:
 303 -----------------
 304  ((\"application\"
 305    (\"postscript\" . <info>))
 306   (\"text\"
 307    (\"plain\" . <info>)))
 308
 309 Where <info> is another assoc list of the various information
 310 related to the mailcap RFC 1524.  This is keyed on the lowercase
 311 attribute name (viewer, test, etc).  This looks like:
 312  ((viewer . VIEWERINFO)
 313   (test   . TESTINFO)
 314   (xxxx   . \"STRING\")
 315   FLAG)
 316
 317 Where VIEWERINFO specifies how the content-type is viewed.  Can be
 318 a string, in which case it is run through a shell, with appropriate
 319 parameters, or a symbol, in which case the symbol is `funcall'ed if
 320 and only if it exists as a function, with the buffer as an argument.
 321
 322 TESTINFO is a test for the viewer's applicability, or nil.  If nil, it
 323 means the viewer is always valid.  If it is a Lisp function, it is
 324 called with a list of items from any extra fields from the
 325 Content-Type header as argument to return a boolean value for the
 326 validity.  Otherwise, if it is a non-function Lisp symbol or list
 327 whose car is a symbol, it is `eval'uated to yield the validity.  If it
 328 is a string or list of strings, it represents a shell command to run
 329 to return a true or false shell value for the validity.")
 330 (put 'mailcap-mime-data 'risky-local-variable t)
 331
 332 (defcustom mailcap-download-directory nil
 333   "Directory to which `mailcap-save-binary-file' downloads files by default.
 334 nil means your home directory."
 335   :type '(choice (const :tag "Home directory" nil)
 336                  directory)
 337   :group 'mailcap)
 338
 339 (defvar mailcap-poor-system-types
 340   '(ms-dos windows-nt)
 341   "Systems that don't have a Unix-like directory hierarchy.")
 342
 343 ;;;
 344 ;;; Utility functions
 345 ;;;
 346
 347 (defun mailcap-save-binary-file ()
 348   (goto-char (point-min))
 349   (unwind-protect
 350       (let ((file (read-file-name
 351                    "Filename to save as: "
 352                    (or mailcap-download-directory "~/")))
 353             (require-final-newline nil))
 354         (write-region (point-min) (point-max) file))
 355     (kill-buffer (current-buffer))))
 356
 357 (defvar mailcap-maybe-eval-warning
 358   "*** WARNING ***
 359
 360 This MIME part contains untrusted and possibly harmful content.
 361 If you evaluate the Emacs Lisp code contained in it, a lot of nasty
 362 things can happen.  Please examine the code very carefully before you
 363 instruct Emacs to evaluate it.  You can browse the buffer containing
 364 the code using \\[scroll-other-window].
 365
 366 If you are unsure what to do, please answer \"no\"."
 367   "Text of warning message displayed by `mailcap-maybe-eval'.
 368 Make sure that this text consists only of few text lines.  Otherwise,
 369 Gnus might fail to display all of it.")
 370
 371 (defun mailcap-maybe-eval ()
 372   "Maybe evaluate a buffer of Emacs Lisp code."
 373   (let ((lisp-buffer (current-buffer)))
 374     (goto-char (point-min))
 375     (when
 376         (save-window-excursion
 377           (delete-other-windows)
 378           (let ((buffer (get-buffer-create (generate-new-buffer-name
 379                                             "*Warning*"))))
 380             (unwind-protect
 381                 (with-current-buffer buffer
 382                   (insert (substitute-command-keys
 383                            mailcap-maybe-eval-warning))
 384                   (goto-char (point-min))
 385                   (display-buffer buffer)
 386                   (yes-or-no-p "This is potentially dangerous emacs-lisp code, evaluate it? "))
 387               (kill-buffer buffer))))
 388       (eval-buffer (current-buffer)))
 389     (when (buffer-live-p lisp-buffer)
 390       (with-current-buffer lisp-buffer
 391         (emacs-lisp-mode)))))
 392
 393
 394 ;;;
 395 ;;; The mailcap parser
 396 ;;;
 397
 398 (defun mailcap-replace-regexp (regexp to-string)
 399   ;; Quiet replace-regexp.
 400   (goto-char (point-min))
 401   (while (re-search-forward regexp nil t)
 402     (replace-match to-string t nil)))
 403
 404 (defvar mailcap-parsed-p nil)
 405
 406 (defun mailcap-parse-mailcaps (&optional path force)
 407   "Parse out all the mailcaps specified in a path string PATH.
 408 Components of PATH are separated by the `path-separator' character
 409 appropriate for this system.  If FORCE, re-parse even if already
 410 parsed.  If PATH is omitted, use the value of environment variable
 411 MAILCAPS if set; otherwise (on Unix) use the path from RFC 1524, plus
 412 /usr/local/etc/mailcap."
 413   (interactive (list nil t))
 414   (when (or (not mailcap-parsed-p)
 415             force)
 416     (cond
 417      (path nil)
 418      ((getenv "MAILCAPS") (setq path (getenv "MAILCAPS")))
 419      ((memq system-type mailcap-poor-system-types)
 420       (setq path '("~/.mailcap" "~/mail.cap" "~/etc/mail.cap")))
 421      (t (setq path
 422               ;; This is per RFC 1524, specifically
 423               ;; with /usr before /usr/local.
 424               '("~/.mailcap" "/etc/mailcap" "/usr/etc/mailcap"
 425                 "/usr/local/etc/mailcap"))))
 426     (dolist (fname (reverse
 427                     (if (stringp path)
 428                         (split-string path path-separator t)
 429                       path)))
 430       (when (and (file-readable-p fname) (file-regular-p fname))
 431         (mailcap-parse-mailcap fname)))
 432     (setq mailcap-parsed-p t)))
 433
 434 (defun mailcap-parse-mailcap (fname)
 435   "Parse out the mailcap file specified by FNAME."
 436   (let (major                           ; The major mime type (image/audio/etc)
 437         minor                           ; The minor mime type (gif, basic, etc)
 438         save-pos                        ; Misc saved positions used in parsing
 439         viewer                          ; How to view this mime type
 440         info                            ; Misc info about this mime type
 441         )
 442     (with-temp-buffer
 443       (insert-file-contents fname)
 444       (set-syntax-table mailcap-parse-args-syntax-table)
 445       (mailcap-replace-regexp "#.*" "") ; Remove all comments
 446       (mailcap-replace-regexp "\\\\[ \t]*\n" " ") ; And collapse spaces
 447       (mailcap-replace-regexp "\n+" "\n") ; And blank lines
 448       (goto-char (point-max))
 449       (skip-chars-backward " \t\n")
 450       (delete-region (point) (point-max))
 451       (while (not (bobp))
 452         (skip-chars-backward " \t\n")
 453         (beginning-of-line)
 454         (setq save-pos (point)
 455               info nil)
 456         (skip-chars-forward "^/; \t\n")
 457         (downcase-region save-pos (point))
 458         (setq major (buffer-substring save-pos (point)))
 459         (skip-chars-forward " \t")
 460         (setq minor "")
 461         (when (eq (char-after) ?/)
 462           (forward-char)
 463           (skip-chars-forward " \t")
 464           (setq save-pos (point))
 465           (skip-chars-forward "^; \t\n")
 466           (downcase-region save-pos (point))
 467           (setq minor
 468                 (cond
 469                  ((eq ?* (or (char-after save-pos) 0)) ".*")
 470                  ((= (point) save-pos) ".*")
 471                  (t (regexp-quote (buffer-substring save-pos (point)))))))
 472         (skip-chars-forward " \t")
 473         ;;; Got the major/minor chunks, now for the viewers/etc
 474         ;;; The first item _must_ be a viewer, according to the
 475         ;;; RFC for mailcap files (#1524)
 476         (setq viewer "")
 477         (when (eq (char-after) ?\;)
 478           (forward-char)
 479           (skip-chars-forward " \t")
 480           (setq save-pos (point))
 481           (skip-chars-forward "^;\n")
 482           ;; skip \;
 483           (while (eq (char-before) ?\\)
 484             (backward-delete-char 1)
 485             (forward-char)
 486             (skip-chars-forward "^;\n"))
 487           (if (eq (or (char-after save-pos) 0) ?')
 488               (setq viewer (progn
 489                              (narrow-to-region (1+ save-pos) (point))
 490                              (goto-char (point-min))
 491                              (prog1
 492                                  (read (current-buffer))
 493                                (goto-char (point-max))
 494                                (widen))))
 495             (setq viewer (buffer-substring save-pos (point)))))
 496         (setq save-pos (point))
 497         (end-of-line)
 498         (unless (equal viewer "")
 499           (setq info (nconc (list (cons 'viewer viewer)
 500                                   (cons 'type (concat major "/"
 501                                                       (if (string= minor ".*")
 502                                                           "*" minor))))
 503                             (mailcap-parse-mailcap-extras save-pos (point))))
 504           (mailcap-mailcap-entry-passes-test info)
 505           (mailcap-add-mailcap-entry major minor info))
 506         (beginning-of-line)))))
 507
 508 (defun mailcap-parse-mailcap-extras (st nd)
 509   "Grab all the extra stuff from a mailcap entry."
 510   (let (
 511         name                            ; From name=
 512         value                           ; its value
 513         results                         ; Assoc list of results
 514         name-pos                        ; Start of XXXX= position
 515         val-pos                         ; Start of value position
 516         done                            ; Found end of \'d ;s?
 517         )
 518     (save-restriction
 519       (narrow-to-region st nd)
 520       (goto-char (point-min))
 521       (skip-chars-forward " \n\t;")
 522       (while (not (eobp))
 523         (setq done nil)
 524         (setq name-pos (point))
 525         (skip-chars-forward "^ \n\t=;")
 526         (downcase-region name-pos (point))
 527         (setq name (buffer-substring name-pos (point)))
 528         (skip-chars-forward " \t\n")
 529         (if (not (eq (char-after (point)) ?=)) ; There is no value
 530             (setq value t)
 531           (skip-chars-forward " \t\n=")
 532           (setq val-pos (point))
 533           (if (memq (char-after val-pos) '(?\" ?'))
 534               (progn
 535                 (setq val-pos (1+ val-pos))
 536                 (condition-case nil
 537                     (progn
 538                       (forward-sexp 1)
 539                       (backward-char 1))
 540                   (error (goto-char (point-max)))))
 541             (while (not done)
 542               (skip-chars-forward "^;")
 543               (if (eq (char-after (1- (point))) ?\\ )
 544                   (progn
 545                     (subst-char-in-region (1- (point)) (point) ?\\ ? )
 546                     (skip-chars-forward ";"))
 547                 (setq done t))))
 548           (setq value (buffer-substring val-pos (point))))
 549         ;; `test' as symbol, others like "copiousoutput" and "needsx11" as
 550         ;; strings
 551         (push (cons (if (string-equal name "test") 'test name) value) results)
 552         (skip-chars-forward " \";\n\t"))
 553       results)))
 554
 555 (defun mailcap-mailcap-entry-passes-test (info)
 556   "Replace the test clause of INFO itself with a boolean for some cases.
 557 This function supports only `test -n $DISPLAY' and `test -z $DISPLAY',
 558 replaces them with t or nil.  As for others or if INFO has an interactive
 559 spec (needsterm, needsterminal, or needsx11) but DISPLAY is not set,
 560 the test clause will be unchanged."
 561   (let ((test (assq 'test info))        ; The test clause
 562         status)
 563     (setq status (and test (split-string (cdr test) " ")))
 564     (if (and (or (assoc "needsterm" info)
 565                  (assoc "needsterminal" info)
 566                  (assoc "needsx11" info))
 567              (not (getenv "DISPLAY")))
 568         (setq status nil)
 569       (cond
 570        ((and (equal (nth 0 status) "test")
 571              (equal (nth 1 status) "-n")
 572              (or (equal (nth 2 status) "$DISPLAY")
 573                  (equal (nth 2 status) "\"$DISPLAY\"")))
 574         (setq status (if (getenv "DISPLAY") t nil)))
 575        ((and (equal (nth 0 status) "test")
 576              (equal (nth 1 status) "-z")
 577              (or (equal (nth 2 status) "$DISPLAY")
 578                  (equal (nth 2 status) "\"$DISPLAY\"")))
 579         (setq status (if (getenv "DISPLAY") nil t)))
 580        (test nil)
 581        (t nil)))
 582     (and test (listp test) (setcdr test status))))
 583
 584 ;;;
 585 ;;; The action routines.
 586 ;;;
 587
 588 (defun mailcap-possible-viewers (major minor)
 589   "Return a list of possible viewers from MAJOR for minor type MINOR."
 590   (let ((exact '())
 591         (wildcard '()))
 592     (pcase-dolist (`(,type . ,attrs) major)
 593       (cond
 594        ((equal type minor)
 595         (push attrs exact))
 596        ((and minor (string-match (concat "^" type "$") minor))
 597         (push attrs wildcard))))
 598     (nconc exact wildcard)))
 599
 600 (defun mailcap-unescape-mime-test (test type-info)
 601   (let (save-pos save-chr subst)
 602     (cond
 603      ((symbolp test) test)
 604      ((and (listp test) (symbolp (car test))) test)
 605      ((or (stringp test)
 606           (and (listp test) (stringp (car test))
 607                (setq test (mapconcat 'identity test " "))))
 608       (with-temp-buffer
 609         (insert test)
 610         (goto-char (point-min))
 611         (while (not (eobp))
 612           (skip-chars-forward "^%")
 613           (if (/= (- (point)
 614                      (progn (skip-chars-backward "\\\\")
 615                             (point)))
 616                   0)                    ; It is an escaped %
 617               (progn
 618                 (delete-char 1)
 619                 (skip-chars-forward "%."))
 620             (setq save-pos (point))
 621             (skip-chars-forward "%")
 622             (setq save-chr (char-after (point)))
 623             ;; Escapes:
 624             ;; %s: name of a file for the body data
 625             ;; %t: content-type
 626             ;; %{<parameter name}: value of parameter in mailcap entry
 627             ;; %n: number of sub-parts for multipart content-type
 628             ;; %F: a set of content-type/filename pairs for multiparts
 629             (cond
 630              ((null save-chr) nil)
 631              ((= save-chr ?t)
 632               (delete-region save-pos (progn (forward-char 1) (point)))
 633               (insert (or (cdr (assq 'type type-info)) "\"\"")))
 634              ((memq save-chr '(?M ?n ?F))
 635               (delete-region save-pos (progn (forward-char 1) (point)))
 636               (insert "\"\""))
 637              ((= save-chr ?{)
 638               (forward-char 1)
 639               (skip-chars-forward "^}")
 640               (downcase-region (+ 2 save-pos) (point))
 641               (setq subst (buffer-substring (+ 2 save-pos) (point)))
 642               (delete-region save-pos (1+ (point)))
 643               (insert (or (cdr (assoc subst type-info)) "\"\"")))
 644              (t nil))))
 645         (buffer-string)))
 646      (t (error "Bad value to mailcap-unescape-mime-test: %s" test)))))
 647
 648 (defvar mailcap-viewer-test-cache nil)
 649
 650 (defun mailcap-viewer-passes-test (viewer-info type-info)
 651   "Return non-nil if viewer specified by VIEWER-INFO passes its test clause.
 652 Also return non-nil if it has no test clause.  TYPE-INFO is an argument
 653 to supply to the test."
 654   (let* ((test-info (assq 'test viewer-info))
 655          (test (cdr test-info))
 656          (otest test)
 657          (viewer (cdr (assq 'viewer viewer-info)))
 658          (default-directory (expand-file-name "~/"))
 659          status cache result)
 660     (cond ((not (or (stringp viewer) (fboundp viewer)))
 661            nil)                         ; Non-existent Lisp function
 662           ((setq cache (assoc test mailcap-viewer-test-cache))
 663            (cadr cache))
 664           ((not test-info) t)           ; No test clause
 665           (t
 666            (setq
 667             result
 668             (cond
 669              ((not test) nil)           ; Already failed test
 670              ((eq test t) t)            ; Already passed test
 671              ((functionp test)          ; Lisp function as test
 672               (funcall test type-info))
 673              ((and (symbolp test)       ; Lisp variable as test
 674                    (boundp test))
 675               (symbol-value test))
 676              ((and (listp test)         ; List to be eval'd
 677                    (symbolp (car test)))
 678               (eval test))
 679              (t
 680               (setq test (mailcap-unescape-mime-test test type-info)
 681                     test (list shell-file-name nil nil nil
 682                                shell-command-switch test)
 683                     status (apply 'call-process test))
 684               (eq 0 status))))
 685            (push (list otest result) mailcap-viewer-test-cache)
 686            result))))
 687
 688 (defun mailcap-add-mailcap-entry (major minor info)
 689   (let ((old-major (assoc major mailcap-mime-data)))
 690     (if (null old-major)                ; New major area
 691         (push (cons major (list (cons minor info))) mailcap-mime-data)
 692       (let ((cur-minor (assoc minor old-major)))
 693         (cond
 694          ((or (null cur-minor)          ; New minor area, or
 695               (assq 'test info))        ; Has a test, insert at beginning
 696           (setcdr old-major (cons (cons minor info) (cdr old-major))))
 697          ((and (not (assq 'test info))  ; No test info, replace completely
 698                (not (assq 'test cur-minor))
 699                (equal (assq 'viewer info)  ; Keep alternative viewer
 700                       (assq 'viewer cur-minor)))
 701           (setcdr cur-minor info))
 702          (t
 703           (setcdr old-major (cons (cons minor info) (cdr old-major))))))
 704       )))
 705
 706 (defun mailcap-add (type viewer &optional test)
 707   "Add VIEWER as a handler for TYPE.
 708 If TEST is not given, it defaults to t."
 709   (let ((tl (split-string type "/")))
 710     (when (or (not (car tl))
 711               (not (cadr tl)))
 712       (error "%s is not a valid MIME type" type))
 713     (mailcap-add-mailcap-entry
 714      (car tl) (cadr tl)
 715      `((viewer . ,viewer)
 716        (test . ,(if test test t))
 717        (type . ,type)))))
 718
 719 ;;;
 720 ;;; The main whabbo
 721 ;;;
 722
 723 (defun mailcap-viewer-lessp (x y)
 724   "Return t if viewer X is more desirable than viewer Y."
 725   (let ((x-wild (string-match "[*?]" (or (cdr-safe (assq 'type x)) "")))
 726         (y-wild (string-match "[*?]" (or (cdr-safe (assq 'type y)) "")))
 727         (x-lisp (not (stringp (or (cdr-safe (assq 'viewer x)) ""))))
 728         (y-lisp (not (stringp (or (cdr-safe (assq 'viewer y)) "")))))
 729     (cond
 730      ((and x-wild (not y-wild))
 731       nil)
 732      ((and (not x-wild) y-wild)
 733       t)
 734      ((and (not y-lisp) x-lisp)
 735       t)
 736      (t nil))))
 737
 738 (defun mailcap-select-preferred-viewer (type-info)
 739   "Return an applicable viewer entry from `mailcap-user-mime-data'."
 740   (let ((info (mapcar (lambda (a) (cons (symbol-name (car a))
 741                                    (cdr a)))
 742                       (cdr type-info)))
 743         viewer)
 744     (dolist (entry mailcap-user-mime-data)
 745       (when (and (null viewer)
 746                  (string-match (concat "^" (cdr (assq 'type entry)) "$")
 747                                (car type-info))
 748                  (mailcap-viewer-passes-test entry info))
 749         (setq viewer entry)))
 750     viewer))
 751
 752 (defun mailcap-mime-info (string &optional request no-decode)
 753   "Get the MIME viewer command for STRING, return nil if none found.
 754 Expects a complete content-type header line as its argument.
 755
 756 Second argument REQUEST specifies what information to return.  If it is
 757 nil or the empty string, the viewer (second field of the mailcap
 758 entry) will be returned.  If it is a string, then the mailcap field
 759 corresponding to that string will be returned (print, description,
 760 whatever).  If a number, then all the information for this specific
 761 viewer is returned.  If `all', then all possible viewers for
 762 this type is returned.
 763
 764 If NO-DECODE is non-nil, don't decode STRING."
 765   ;; NO-DECODE avoids calling `mail-header-parse-content-type' from
 766   ;; `mail-parse.el'
 767   (let (
 768         major                           ; Major encoding (text, etc)
 769         minor                           ; Minor encoding (html, etc)
 770         info                            ; Other info
 771         major-info                      ; (assoc major mailcap-mime-data)
 772         viewers                         ; Possible viewers
 773         passed                          ; Viewers that passed the test
 774         viewer                          ; The one and only viewer
 775         ctl)
 776     (save-excursion
 777       (setq ctl
 778             (if no-decode
 779                 (list (or string "text/plain"))
 780               (mail-header-parse-content-type (or string "text/plain"))))
 781       ;; Check if there's a user-defined viewer from `mailcap-user-mime-data'.
 782       (setq viewer (mailcap-select-preferred-viewer ctl))
 783       (if viewer
 784           (setq passed (list viewer))
 785         ;; None found, so heuristically select some applicable viewer
 786         ;; from `mailcap-mime-data'.
 787         (setq major (split-string (car ctl) "/"))
 788         (setq minor (cadr major)
 789               major (car major))
 790         (when (setq major-info (cdr (assoc major mailcap-mime-data)))
 791           (when (setq viewers (mailcap-possible-viewers major-info minor))
 792             (setq info (mapcar (lambda (a) (cons (symbol-name (car a))
 793                                             (cdr a)))
 794                                (cdr ctl)))
 795             (dolist (entry viewers)
 796               (when (mailcap-viewer-passes-test entry info)
 797                 (push entry passed)))
 798             (setq passed (sort passed 'mailcap-viewer-lessp))
 799             (setq viewer (car passed))))
 800         (when (and (stringp (cdr (assq 'viewer viewer)))
 801                    passed)
 802           (setq viewer (car passed))))
 803       (cond
 804        ((and (null viewer) (not (equal major "default")) request)
 805         (mailcap-mime-info "default" request no-decode))
 806        ((or (null request) (equal request ""))
 807         (mailcap-unescape-mime-test (cdr (assq 'viewer viewer)) info))
 808        ((stringp request)
 809         (mailcap-unescape-mime-test
 810          (cdr-safe (assoc request viewer)) info))
 811        ((eq request 'all)
 812         passed)
 813        (t
 814         ;; MUST make a copy *sigh*, else we modify mailcap-mime-data
 815         (setq viewer (copy-sequence viewer))
 816         (let ((view (assq 'viewer viewer))
 817               (test (assq 'test viewer)))
 818           (if view (setcdr view (mailcap-unescape-mime-test (cdr view) info)))
 819           (if test (setcdr test (mailcap-unescape-mime-test (cdr test) info))))
 820         viewer)))))
 821
 822 ;;;
 823 ;;; Experimental MIME-types parsing
 824 ;;;
 825
 826 (defvar mailcap-mime-extensions
 827   '((""       . "text/plain")
 828     (".1"     . "text/plain")  ;; Manual pages
 829     (".3"     . "text/plain")
 830     (".8"     . "text/plain")
 831     (".abs"   . "audio/x-mpeg")
 832     (".aif"   . "audio/aiff")
 833     (".aifc"  . "audio/aiff")
 834     (".aiff"  . "audio/aiff")
 835     (".ano"   . "application/x-annotator")
 836     (".au"    . "audio/ulaw")
 837     (".avi"   . "video/x-msvideo")
 838     (".bcpio" . "application/x-bcpio")
 839     (".bin"   . "application/octet-stream")
 840     (".cdf"   . "application/x-netcdr")
 841     (".cpio"  . "application/x-cpio")
 842     (".csh"   . "application/x-csh")
 843     (".css"   . "text/css")
 844     (".dvi"   . "application/x-dvi")
 845     (".diff"  . "text/x-patch")
 846     (".dpatch". "text/x-patch")
 847     (".el"    . "application/emacs-lisp")
 848     (".eps"   . "application/postscript")
 849     (".etx"   . "text/x-setext")
 850     (".exe"   . "application/octet-stream")
 851     (".fax"   . "image/x-fax")
 852     (".gif"   . "image/gif")
 853     (".hdf"   . "application/x-hdf")
 854     (".hqx"   . "application/mac-binhex40")
 855     (".htm"   . "text/html")
 856     (".html"  . "text/html")
 857     (".icon"  . "image/x-icon")
 858     (".ief"   . "image/ief")
 859     (".jpg"   . "image/jpeg")
 860     (".macp"  . "image/x-macpaint")
 861     (".man"   . "application/x-troff-man")
 862     (".me"    . "application/x-troff-me")
 863     (".mif"   . "application/mif")
 864     (".mov"   . "video/quicktime")
 865     (".movie" . "video/x-sgi-movie")
 866     (".mp2"   . "audio/x-mpeg")
 867     (".mp3"   . "audio/x-mpeg")
 868     (".mp2a"  . "audio/x-mpeg2")
 869     (".mpa"   . "audio/x-mpeg")
 870     (".mpa2"  . "audio/x-mpeg2")
 871     (".mpe"   . "video/mpeg")
 872     (".mpeg"  . "video/mpeg")
 873     (".mpega" . "audio/x-mpeg")
 874     (".mpegv" . "video/mpeg")
 875     (".mpg"   . "video/mpeg")
 876     (".mpv"   . "video/mpeg")
 877     (".ms"    . "application/x-troff-ms")
 878     (".nc"    . "application/x-netcdf")
 879     (".nc"    . "application/x-netcdf")
 880     (".oda"   . "application/oda")
 881     (".patch" . "text/x-patch")
 882     (".pbm"   . "image/x-portable-bitmap")
 883     (".pdf"   . "application/pdf")
 884     (".pgm"   . "image/portable-graymap")
 885     (".pict"  . "image/pict")
 886     (".png"   . "image/png")
 887     (".pnm"   . "image/x-portable-anymap")
 888     (".pod"   . "text/plain")
 889     (".ppm"   . "image/portable-pixmap")
 890     (".ps"    . "application/postscript")
 891     (".qt"    . "video/quicktime")
 892     (".ras"   . "image/x-raster")
 893     (".rgb"   . "image/x-rgb")
 894     (".rtf"   . "application/rtf")
 895     (".rtx"   . "text/richtext")
 896     (".sh"    . "application/x-sh")
 897     (".sit"   . "application/x-stuffit")
 898     (".siv"   . "application/sieve")
 899     (".snd"   . "audio/basic")
 900     (".soa"   . "text/dns")
 901     (".src"   . "application/x-wais-source")
 902     (".tar"   . "archive/tar")
 903     (".tcl"   . "application/x-tcl")
 904     (".tex"   . "application/x-tex")
 905     (".texi"  . "application/texinfo")
 906     (".tga"   . "image/x-targa")
 907     (".tif"   . "image/tiff")
 908     (".tiff"  . "image/tiff")
 909     (".tr"    . "application/x-troff")
 910     (".troff" . "application/x-troff")
 911     (".tsv"   . "text/tab-separated-values")
 912     (".txt"   . "text/plain")
 913     (".vbs"   . "video/mpeg")
 914     (".vox"   . "audio/basic")
 915     (".vrml"  . "x-world/x-vrml")
 916     (".wav"   . "audio/x-wav")
 917     (".xls"   . "application/vnd.ms-excel")
 918     (".wrl"   . "x-world/x-vrml")
 919     (".xbm"   . "image/xbm")
 920     (".xpm"   . "image/xpm")
 921     (".xwd"   . "image/windowdump")
 922     (".zip"   . "application/zip")
 923     (".ai"    . "application/postscript")
 924     (".jpe"   . "image/jpeg")
 925     (".jpeg"  . "image/jpeg")
 926     (".org"   . "text/x-org"))
 927   "An alist of file extensions and corresponding MIME content-types.
 928 This exists for you to customize the information in Lisp.  It is
 929 merged with values from mailcap files by `mailcap-parse-mimetypes'.")
 930
 931 (defvar mailcap-mimetypes-parsed-p nil)
 932
 933 (defun mailcap-parse-mimetypes (&optional path force)
 934   "Parse out all the mimetypes specified in a Unix-style path string PATH.
 935 Components of PATH are separated by the `path-separator' character
 936 appropriate for this system.  If PATH is omitted, use the value of
 937 environment variable MIMETYPES if set; otherwise use a default path.
 938 If FORCE, re-parse even if already parsed."
 939   (interactive (list nil t))
 940   (when (or (not mailcap-mimetypes-parsed-p)
 941             force)
 942     (cond
 943      (path nil)
 944      ((getenv "MIMETYPES") (setq path (getenv "MIMETYPES")))
 945      ((memq system-type mailcap-poor-system-types)
 946       (setq path '("~/mime.typ" "~/etc/mime.typ")))
 947      (t (setq path
 948               ;; mime.types seems to be the normal name, definitely so
 949               ;; on current GNUish systems.  The search order follows
 950               ;; that for mailcap.
 951               '("~/.mime.types"
 952                 "/etc/mime.types"
 953                 "/usr/etc/mime.types"
 954                 "/usr/local/etc/mime.types"
 955                 "/usr/local/www/conf/mime.types"
 956                 "~/.mime-types"
 957                 "/etc/mime-types"
 958                 "/usr/etc/mime-types"
 959                 "/usr/local/etc/mime-types"
 960                 "/usr/local/www/conf/mime-types"))))
 961     (dolist (fname (reverse (if (stringp path)
 962                                 (split-string path path-separator t)
 963                               path)))
 964       (when (file-readable-p fname)
 965         (mailcap-parse-mimetype-file fname)))
 966     (setq mailcap-mimetypes-parsed-p t)))
 967
 968 (defun mailcap-parse-mimetype-file (fname)
 969   "Parse out a mime-types file FNAME."
 970   (let (type                            ; The MIME type for this line
 971         extns                           ; The extensions for this line
 972         save-pos                        ; Misc. saved buffer positions
 973         save-extn)
 974     (with-temp-buffer
 975       (insert-file-contents fname)
 976       (mailcap-replace-regexp "#.*" "")
 977       (mailcap-replace-regexp "\n+" "\n")
 978       (mailcap-replace-regexp "[ \t]+$" "")
 979       (goto-char (point-max))
 980       (skip-chars-backward " \t\n")
 981       (delete-region (point) (point-max))
 982       (goto-char (point-min))
 983       (while (not (eobp))
 984         (skip-chars-forward " \t\n")
 985         (setq save-pos (point))
 986         (skip-chars-forward "^ \t\n")
 987         (downcase-region save-pos (point))
 988         (setq type (buffer-substring save-pos (point)))
 989         (while (not (eolp))
 990           (skip-chars-forward " \t")
 991           (setq save-pos (point))
 992           (skip-chars-forward "^ \t\n")
 993           (setq save-extn (buffer-substring save-pos (point)))
 994           (push (cons (if (= (string-to-char save-extn) ?.)
 995                           save-extn (concat "." save-extn))
 996                       type)
 997                 extns))
 998         (setq mailcap-mime-extensions (append extns mailcap-mime-extensions)
 999               extns nil)))))
1000
1001 (defun mailcap-extension-to-mime (extn)
1002   "Return the MIME content type of the file extensions EXTN."
1003   (mailcap-parse-mimetypes)
1004   (if (and (stringp extn)
1005            (not (eq (string-to-char extn) ?.)))
1006       (setq extn (concat "." extn)))
1007   (cdr (assoc (downcase extn) mailcap-mime-extensions)))
1008
1009 (defun mailcap-file-name-to-mime-type (file-name)
1010   "Return the MIME content type based on the FILE-NAME's extension.
1011 For instance, \"foo.png\" will result in \"image/png\"."
1012   (mailcap-extension-to-mime
1013    (if (string-match "\\(\\.[^.]+\\)\\'" file-name)
1014        (match-string 1 file-name)
1015      "")))
1016
1017 (defun mailcap-mime-types ()
1018   "Return a list of MIME media types."
1019   (mailcap-parse-mimetypes)
1020   (delete-dups
1021    (nconc
1022     (mapcar 'cdr mailcap-mime-extensions)
1023     (let (res type)
1024       (dolist (data mailcap-mime-data)
1025         (dolist (info (cdr data))
1026           (setq type (cdr (assq 'type (cdr info))))
1027           (unless (string-match-p "\\*" type)
1028             (push type res))))
1029       (nreverse res)))))
1030
1031 ;;;
1032 ;;; Useful supplementary functions
1033 ;;;
1034
1035 (defun mailcap-file-default-commands (files)
1036   "Return a list of default commands for FILES."
1037   (mailcap-parse-mailcaps)
1038   (mailcap-parse-mimetypes)
1039   (let* ((all-mime-type
1040           ;; All unique MIME types from file extensions
1041           (delete-dups
1042            (mapcar (lambda (file)
1043                      (mailcap-extension-to-mime
1044                       (file-name-extension file t)))
1045                    files)))
1046          (all-mime-info
1047           ;; All MIME info lists
1048           (delete-dups
1049            (mapcar (lambda (mime-type)
1050                      (mailcap-mime-info mime-type 'all))
1051                    all-mime-type)))
1052          (common-mime-info
1053           ;; Intersection of mime-infos from different mime-types;
1054           ;; or just the first MIME info for a single MIME type
1055           (if (cdr all-mime-info)
1056               (let (res)
1057                 (dolist (mi1 (car all-mime-info))
1058                   (dolist (mi2 (cdr all-mime-info))
1059                     (when (member mi1 mi2)
1060                       (push mi1 res))))
1061                 (nreverse res))
1062             (car all-mime-info))))
1063     ;; Command strings from `viewer' field of the MIME info
1064     (delete-dups
1065      (let (res command)
1066        (dolist (mime-info common-mime-info)
1067          (setq command (cdr (assq 'viewer mime-info)))
1068          (when (stringp command)
1069            (push
1070             (replace-regexp-in-string
1071              ;; Replace mailcap's `%s' placeholder
1072              ;; with dired's `?' placeholder
1073              "%s" "?"
1074              (replace-regexp-in-string
1075               ;; Remove the final filename placeholder
1076               "[ \t\n]*\\('\\)?%s\\1?[ \t\n]*\\'" ""
1077               command nil t)
1078              nil t)
1079             res)))
1080        (nreverse res)))))
1081
1082 (defun mailcap-view-mime (type)
1083   "View the data in the current buffer that has MIME type TYPE.
1084 `mailcap-mime-data' determines the method to use."
1085   (let ((method (mailcap-mime-info type)))
1086     (if (stringp method)
1087         (shell-command-on-region (point-min) (point-max)
1088                                  ;; Use stdin as the "%s".
1089                                  (format method "-")
1090                                  (current-buffer)
1091                                  t)
1092       (funcall method))))
1093
1094 (provide 'mailcap)
1095
1096 ;;; mailcap.el ends here