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1 | \input texinfo |
2 | ||
db78a8cb | 3 | @setfilename ../../info/emacs-mime |
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4 | @settitle Emacs MIME Manual |
5 | @synindex fn cp | |
6 | @synindex vr cp | |
7 | @synindex pg cp | |
8 | ||
9 | @copying | |
10 | This file documents the Emacs MIME interface functionality. | |
11 | ||
12 | Copyright @copyright{} 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, | |
5df4f04c | 13 | 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc. |
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14 | |
15 | @quotation | |
16 | Permission is granted to copy, distribute and/or modify this document | |
6a2c4aec | 17 | under the terms of the GNU Free Documentation License, Version 1.3 or |
4009494e | 18 | any later version published by the Free Software Foundation; with no |
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19 | Invariant Sections, with the Front-Cover texts being ``A GNU Manual'', |
20 | and with the Back-Cover Texts as in (a) below. A copy of the license | |
21 | is included in the section entitled ``GNU Free Documentation License''. | |
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23 | (a) The FSF's Back-Cover Text is: ``You have the freedom to copy and |
24 | modify this GNU manual. Buying copies from the FSF supports it in | |
25 | developing GNU and promoting software freedom.'' | |
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26 | @end quotation |
27 | @end copying | |
28 | ||
29 | @c Node ``Interface Functions'' uses Latin-1 characters | |
30 | @documentencoding ISO-8859-1 | |
31 | ||
32 | @dircategory Emacs | |
33 | @direntry | |
62e034c2 | 34 | * Emacs MIME: (emacs-mime). Emacs MIME de/composition library. |
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35 | @end direntry |
36 | @iftex | |
37 | @finalout | |
38 | @end iftex | |
39 | @setchapternewpage odd | |
40 | ||
41 | @titlepage | |
42 | @title Emacs MIME Manual | |
43 | ||
44 | @author by Lars Magne Ingebrigtsen | |
45 | @page | |
46 | @vskip 0pt plus 1filll | |
47 | @insertcopying | |
48 | @end titlepage | |
49 | ||
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50 | @contents |
51 | ||
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52 | @node Top |
53 | @top Emacs MIME | |
54 | ||
55 | This manual documents the libraries used to compose and display | |
56 | @acronym{MIME} messages. | |
57 | ||
58 | This manual is directed at users who want to modify the behavior of | |
59 | the @acronym{MIME} encoding/decoding process or want a more detailed | |
60 | picture of how the Emacs @acronym{MIME} library works, and people who want | |
61 | to write functions and commands that manipulate @acronym{MIME} elements. | |
62 | ||
63 | @acronym{MIME} is short for @dfn{Multipurpose Internet Mail Extensions}. | |
64 | This standard is documented in a number of RFCs; mainly RFC2045 (Format | |
65 | of Internet Message Bodies), RFC2046 (Media Types), RFC2047 (Message | |
66 | Header Extensions for Non-@acronym{ASCII} Text), RFC2048 (Registration | |
67 | Procedures), RFC2049 (Conformance Criteria and Examples). It is highly | |
68 | recommended that anyone who intends writing @acronym{MIME}-compliant software | |
69 | read at least RFC2045 and RFC2047. | |
70 | ||
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71 | @ifnottex |
72 | @insertcopying | |
73 | @end ifnottex | |
74 | ||
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75 | @menu |
76 | * Decoding and Viewing:: A framework for decoding and viewing. | |
77 | * Composing:: @acronym{MML}; a language for describing @acronym{MIME} parts. | |
78 | * Interface Functions:: An abstraction over the basic functions. | |
79 | * Basic Functions:: Utility and basic parsing functions. | |
80 | * Standards:: A summary of RFCs and working documents used. | |
81 | * GNU Free Documentation License:: The license for this documentation. | |
82 | * Index:: Function and variable index. | |
83 | @end menu | |
84 | ||
85 | ||
86 | @node Decoding and Viewing | |
87 | @chapter Decoding and Viewing | |
88 | ||
89 | This chapter deals with decoding and viewing @acronym{MIME} messages on a | |
90 | higher level. | |
91 | ||
92 | The main idea is to first analyze a @acronym{MIME} article, and then allow | |
93 | other programs to do things based on the list of @dfn{handles} that are | |
94 | returned as a result of this analysis. | |
95 | ||
96 | @menu | |
97 | * Dissection:: Analyzing a @acronym{MIME} message. | |
98 | * Non-MIME:: Analyzing a non-@acronym{MIME} message. | |
99 | * Handles:: Handle manipulations. | |
100 | * Display:: Displaying handles. | |
101 | * Display Customization:: Variables that affect display. | |
102 | * Files and Directories:: Saving and naming attachments. | |
103 | * New Viewers:: How to write your own viewers. | |
104 | @end menu | |
105 | ||
106 | ||
107 | @node Dissection | |
108 | @section Dissection | |
109 | ||
110 | The @code{mm-dissect-buffer} is the function responsible for dissecting | |
111 | a @acronym{MIME} article. If given a multipart message, it will recursively | |
112 | descend the message, following the structure, and return a tree of | |
113 | @acronym{MIME} handles that describes the structure of the message. | |
114 | ||
115 | @node Non-MIME | |
116 | @section Non-MIME | |
117 | @vindex mm-uu-configure-list | |
118 | ||
119 | Gnus also understands some non-@acronym{MIME} attachments, such as | |
120 | postscript, uuencode, binhex, yenc, shar, forward, gnatsweb, pgp, | |
121 | diff. Each of these features can be disabled by add an item into | |
122 | @code{mm-uu-configure-list}. For example, | |
123 | ||
124 | @lisp | |
125 | (require 'mm-uu) | |
126 | (add-to-list 'mm-uu-configure-list '(pgp-signed . disabled)) | |
127 | @end lisp | |
128 | ||
129 | @table @code | |
130 | @item postscript | |
131 | @findex postscript | |
132 | PostScript file. | |
133 | ||
134 | @item uu | |
135 | @findex uu | |
136 | Uuencoded file. | |
137 | ||
138 | @item binhex | |
139 | @findex binhex | |
140 | Binhex encoded file. | |
141 | ||
142 | @item yenc | |
143 | @findex yenc | |
144 | Yenc encoded file. | |
145 | ||
146 | @item shar | |
147 | @findex shar | |
148 | Shar archive file. | |
149 | ||
150 | @item forward | |
151 | @findex forward | |
152 | Non-@acronym{MIME} forwarded message. | |
153 | ||
154 | @item gnatsweb | |
155 | @findex gnatsweb | |
156 | Gnatsweb attachment. | |
157 | ||
158 | @item pgp-signed | |
159 | @findex pgp-signed | |
160 | @acronym{PGP} signed clear text. | |
161 | ||
162 | @item pgp-encrypted | |
163 | @findex pgp-encrypted | |
164 | @acronym{PGP} encrypted clear text. | |
165 | ||
166 | @item pgp-key | |
167 | @findex pgp-key | |
168 | @acronym{PGP} public keys. | |
169 | ||
170 | @item emacs-sources | |
171 | @findex emacs-sources | |
172 | @vindex mm-uu-emacs-sources-regexp | |
173 | Emacs source code. This item works only in the groups matching | |
174 | @code{mm-uu-emacs-sources-regexp}. | |
175 | ||
176 | @item diff | |
177 | @vindex diff | |
178 | @vindex mm-uu-diff-groups-regexp | |
179 | Patches. This is intended for groups where diffs of committed files | |
180 | are automatically sent to. It only works in groups matching | |
181 | @code{mm-uu-diff-groups-regexp}. | |
182 | ||
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183 | @item verbatim-marks |
184 | @cindex verbatim-marks | |
185 | Slrn-style verbatim marks. | |
186 | ||
187 | @item LaTeX | |
188 | @cindex LaTeX | |
189 | LaTeX documents. It only works in groups matching | |
190 | @code{mm-uu-tex-groups-regexp}. | |
191 | ||
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192 | @end table |
193 | ||
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194 | @cindex text/x-verbatim |
195 | @c Is @vindex suitable for a face? | |
196 | @vindex mm-uu-extract | |
197 | Some inlined non-@acronym{MIME} attachments are displayed using the face | |
198 | @code{mm-uu-extract}. By default, no @acronym{MIME} button for these | |
199 | parts is displayed. You can force displaying a button using @kbd{K b} | |
200 | (@code{gnus-summary-display-buttonized}) or add @code{text/x-verbatim} | |
201 | to @code{gnus-buttonized-mime-types}, @xref{MIME Commands, ,MIME | |
202 | Commands, gnus, Gnus Manual}. | |
203 | ||
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204 | @node Handles |
205 | @section Handles | |
206 | ||
207 | A @acronym{MIME} handle is a list that fully describes a @acronym{MIME} | |
208 | component. | |
209 | ||
210 | The following macros can be used to access elements in a handle: | |
211 | ||
212 | @table @code | |
213 | @item mm-handle-buffer | |
214 | @findex mm-handle-buffer | |
215 | Return the buffer that holds the contents of the undecoded @acronym{MIME} | |
216 | part. | |
217 | ||
218 | @item mm-handle-type | |
219 | @findex mm-handle-type | |
220 | Return the parsed @code{Content-Type} of the part. | |
221 | ||
222 | @item mm-handle-encoding | |
223 | @findex mm-handle-encoding | |
224 | Return the @code{Content-Transfer-Encoding} of the part. | |
225 | ||
226 | @item mm-handle-undisplayer | |
227 | @findex mm-handle-undisplayer | |
228 | Return the object that can be used to remove the displayed part (if it | |
229 | has been displayed). | |
230 | ||
231 | @item mm-handle-set-undisplayer | |
232 | @findex mm-handle-set-undisplayer | |
233 | Set the undisplayer object. | |
234 | ||
235 | @item mm-handle-disposition | |
236 | @findex mm-handle-disposition | |
237 | Return the parsed @code{Content-Disposition} of the part. | |
238 | ||
239 | @item mm-get-content-id | |
240 | Returns the handle(s) referred to by @code{Content-ID}. | |
241 | ||
242 | @end table | |
243 | ||
244 | ||
245 | @node Display | |
246 | @section Display | |
247 | ||
248 | Functions for displaying, removing and saving. | |
249 | ||
250 | @table @code | |
251 | @item mm-display-part | |
252 | @findex mm-display-part | |
253 | Display the part. | |
254 | ||
255 | @item mm-remove-part | |
256 | @findex mm-remove-part | |
257 | Remove the part (if it has been displayed). | |
258 | ||
259 | @item mm-inlinable-p | |
260 | @findex mm-inlinable-p | |
261 | Say whether a @acronym{MIME} type can be displayed inline. | |
262 | ||
263 | @item mm-automatic-display-p | |
264 | @findex mm-automatic-display-p | |
265 | Say whether a @acronym{MIME} type should be displayed automatically. | |
266 | ||
267 | @item mm-destroy-part | |
268 | @findex mm-destroy-part | |
269 | Free all resources occupied by a part. | |
270 | ||
271 | @item mm-save-part | |
272 | @findex mm-save-part | |
273 | Offer to save the part in a file. | |
274 | ||
275 | @item mm-pipe-part | |
276 | @findex mm-pipe-part | |
277 | Offer to pipe the part to some process. | |
278 | ||
279 | @item mm-interactively-view-part | |
280 | @findex mm-interactively-view-part | |
281 | Prompt for a mailcap method to use to view the part. | |
282 | ||
283 | @end table | |
284 | ||
285 | ||
286 | @node Display Customization | |
287 | @section Display Customization | |
288 | ||
289 | @table @code | |
290 | ||
291 | @item mm-inline-media-tests | |
292 | @vindex mm-inline-media-tests | |
293 | This is an alist where the key is a @acronym{MIME} type, the second element | |
294 | is a function to display the part @dfn{inline} (i.e., inside Emacs), and | |
295 | the third element is a form to be @code{eval}ed to say whether the part | |
296 | can be displayed inline. | |
297 | ||
298 | This variable specifies whether a part @emph{can} be displayed inline, | |
299 | and, if so, how to do it. It does not say whether parts are | |
300 | @emph{actually} displayed inline. | |
301 | ||
302 | @item mm-inlined-types | |
303 | @vindex mm-inlined-types | |
304 | This, on the other hand, says what types are to be displayed inline, if | |
305 | they satisfy the conditions set by the variable above. It's a list of | |
306 | @acronym{MIME} media types. | |
307 | ||
308 | @item mm-automatic-display | |
309 | @vindex mm-automatic-display | |
310 | This is a list of types that are to be displayed ``automatically'', but | |
311 | only if the above variable allows it. That is, only inlinable parts can | |
312 | be displayed automatically. | |
313 | ||
314 | @item mm-automatic-external-display | |
315 | @vindex mm-automatic-external-display | |
316 | This is a list of types that will be displayed automatically in an | |
317 | external viewer. | |
318 | ||
319 | @item mm-keep-viewer-alive-types | |
320 | @vindex mm-keep-viewer-alive-types | |
321 | This is a list of media types for which the external viewer will not | |
322 | be killed when selecting a different article. | |
323 | ||
324 | @item mm-attachment-override-types | |
325 | @vindex mm-attachment-override-types | |
326 | Some @acronym{MIME} agents create parts that have a content-disposition of | |
327 | @samp{attachment}. This variable allows overriding that disposition and | |
328 | displaying the part inline. (Note that the disposition is only | |
329 | overridden if we are able to, and want to, display the part inline.) | |
330 | ||
331 | @item mm-discouraged-alternatives | |
332 | @vindex mm-discouraged-alternatives | |
333 | List of @acronym{MIME} types that are discouraged when viewing | |
334 | @samp{multipart/alternative}. Viewing agents are supposed to view the | |
335 | last possible part of a message, as that is supposed to be the richest. | |
336 | However, users may prefer other types instead, and this list says what | |
337 | types are most unwanted. If, for instance, @samp{text/html} parts are | |
338 | very unwanted, and @samp{text/richtext} parts are somewhat unwanted, | |
339 | you could say something like: | |
340 | ||
341 | @lisp | |
342 | (setq mm-discouraged-alternatives | |
343 | '("text/html" "text/richtext") | |
344 | mm-automatic-display | |
345 | (remove "text/html" mm-automatic-display)) | |
346 | @end lisp | |
347 | ||
348 | Adding @code{"image/.*"} might also be useful. Spammers use images as | |
349 | the preferred part of @samp{multipart/alternative} messages, so you might | |
350 | not notice there are other parts. See also | |
351 | @code{gnus-buttonized-mime-types}, @ref{MIME Commands, ,MIME Commands, | |
352 | gnus, Gnus Manual}. After adding @code{"multipart/alternative"} to | |
353 | @code{gnus-buttonized-mime-types} you can choose manually which | |
354 | alternative you'd like to view. For example, you can set those | |
355 | variables like: | |
356 | ||
357 | @lisp | |
358 | (setq gnus-buttonized-mime-types | |
359 | '("multipart/alternative" "multipart/signed") | |
360 | mm-discouraged-alternatives | |
361 | '("text/html" "image/.*")) | |
362 | @end lisp | |
363 | ||
364 | In this case, Gnus will display radio buttons for such a kind of spam | |
365 | message as follows: | |
366 | ||
367 | @example | |
368 | 1. (*) multipart/alternative ( ) image/gif | |
369 | ||
370 | 2. (*) text/plain ( ) text/html | |
371 | @end example | |
372 | ||
373 | @item mm-inline-large-images | |
374 | @vindex mm-inline-large-images | |
375 | When displaying inline images that are larger than the window, Emacs | |
376 | does not enable scrolling, which means that you cannot see the whole | |
377 | image. To prevent this, the library tries to determine the image size | |
378 | before displaying it inline, and if it doesn't fit the window, the | |
379 | library will display it externally (e.g. with @samp{ImageMagick} or | |
380 | @samp{xv}). Setting this variable to @code{t} disables this check and | |
381 | makes the library display all inline images as inline, regardless of | |
382 | their size. | |
383 | ||
384 | @item mm-inline-override-types | |
385 | @vindex mm-inline-override-types | |
386 | @code{mm-inlined-types} may include regular expressions, for example to | |
387 | specify that all @samp{text/.*} parts be displayed inline. If a user | |
388 | prefers to have a type that matches such a regular expression be treated | |
389 | as an attachment, that can be accomplished by setting this variable to a | |
390 | list containing that type. For example assuming @code{mm-inlined-types} | |
391 | includes @samp{text/.*}, then including @samp{text/html} in this | |
392 | variable will cause @samp{text/html} parts to be treated as attachments. | |
393 | ||
394 | @item mm-text-html-renderer | |
395 | @vindex mm-text-html-renderer | |
396 | This selects the function used to render @acronym{HTML}. The predefined | |
397 | renderers are selected by the symbols @code{w3}, | |
398 | @code{w3m}@footnote{See @uref{http://emacs-w3m.namazu.org/} for more | |
399 | information about emacs-w3m}, @code{links}, @code{lynx}, | |
400 | @code{w3m-standalone} or @code{html2text}. If @code{nil} use an | |
401 | external viewer. You can also specify a function, which will be | |
402 | called with a @acronym{MIME} handle as the argument. | |
403 | ||
404 | @item mm-inline-text-html-with-images | |
405 | @vindex mm-inline-text-html-with-images | |
406 | Some @acronym{HTML} mails might have the trick of spammers using | |
407 | @samp{<img>} tags. It is likely to be intended to verify whether you | |
408 | have read the mail. You can prevent your personal informations from | |
409 | leaking by setting this option to @code{nil} (which is the default). | |
410 | It is currently ignored by Emacs/w3. For emacs-w3m, you may use the | |
411 | command @kbd{t} on the image anchor to show an image even if it is | |
412 | @code{nil}.@footnote{The command @kbd{T} will load all images. If you | |
413 | have set the option @code{w3m-key-binding} to @code{info}, use @kbd{i} | |
414 | or @kbd{I} instead.} | |
415 | ||
416 | @item mm-w3m-safe-url-regexp | |
417 | @vindex mm-w3m-safe-url-regexp | |
418 | A regular expression that matches safe URL names, i.e. URLs that are | |
419 | unlikely to leak personal information when rendering @acronym{HTML} | |
420 | email (the default value is @samp{\\`cid:}). If @code{nil} consider | |
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421 | all URLs safe. In Gnus, this will be overridden according to the value |
422 | of the variable @code{gnus-safe-html-newsgroups}, @xref{Various | |
423 | Various, ,Various Various, gnus, Gnus Manual}. | |
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424 | |
425 | @item mm-inline-text-html-with-w3m-keymap | |
426 | @vindex mm-inline-text-html-with-w3m-keymap | |
427 | You can use emacs-w3m command keys in the inlined text/html part by | |
428 | setting this option to non-@code{nil}. The default value is @code{t}. | |
429 | ||
430 | @item mm-external-terminal-program | |
431 | @vindex mm-external-terminal-program | |
432 | The program used to start an external terminal. | |
433 | ||
434 | @item mm-enable-external | |
435 | @vindex mm-enable-external | |
436 | Indicate whether external @acronym{MIME} handlers should be used. | |
437 | ||
438 | If @code{t}, all defined external @acronym{MIME} handlers are used. If | |
439 | @code{nil}, files are saved to disk (@code{mailcap-save-binary-file}). | |
440 | If it is the symbol @code{ask}, you are prompted before the external | |
441 | @acronym{MIME} handler is invoked. | |
442 | ||
443 | When you launch an attachment through mailcap (@pxref{mailcap}) an | |
444 | attempt is made to use a safe viewer with the safest options---this isn't | |
445 | the case if you save it to disk and launch it in a different way | |
446 | (command line or double-clicking). Anyhow, if you want to be sure not | |
447 | to launch any external programs, set this variable to @code{nil} or | |
448 | @code{ask}. | |
449 | ||
450 | @end table | |
451 | ||
452 | @node Files and Directories | |
453 | @section Files and Directories | |
454 | ||
455 | @table @code | |
456 | ||
457 | @item mm-default-directory | |
458 | @vindex mm-default-directory | |
459 | The default directory for saving attachments. If @code{nil} use | |
460 | @code{default-directory}. | |
461 | ||
462 | @item mm-tmp-directory | |
463 | @vindex mm-tmp-directory | |
464 | Directory for storing temporary files. | |
465 | ||
466 | @item mm-file-name-rewrite-functions | |
467 | @vindex mm-file-name-rewrite-functions | |
468 | A list of functions used for rewriting file names of @acronym{MIME} | |
469 | parts. Each function is applied successively to the file name. | |
470 | Ready-made functions include | |
471 | ||
472 | @table @code | |
473 | @item mm-file-name-delete-control | |
474 | @findex mm-file-name-delete-control | |
475 | Delete all control characters. | |
476 | ||
477 | @item mm-file-name-delete-gotchas | |
478 | @findex mm-file-name-delete-gotchas | |
479 | Delete characters that could have unintended consequences when used | |
480 | with flawed shell scripts, i.e. @samp{|}, @samp{>} and @samp{<}; and | |
481 | @samp{-}, @samp{.} as the first character. | |
482 | ||
483 | @item mm-file-name-delete-whitespace | |
484 | @findex mm-file-name-delete-whitespace | |
485 | Remove all whitespace. | |
486 | ||
487 | @item mm-file-name-trim-whitespace | |
488 | @findex mm-file-name-trim-whitespace | |
489 | Remove leading and trailing whitespace. | |
490 | ||
491 | @item mm-file-name-collapse-whitespace | |
492 | @findex mm-file-name-collapse-whitespace | |
493 | Collapse multiple whitespace characters. | |
494 | ||
495 | @item mm-file-name-replace-whitespace | |
496 | @findex mm-file-name-replace-whitespace | |
497 | @vindex mm-file-name-replace-whitespace | |
498 | Replace whitespace with underscores. Set the variable | |
499 | @code{mm-file-name-replace-whitespace} to any other string if you do | |
500 | not like underscores. | |
501 | @end table | |
502 | ||
503 | The standard Emacs functions @code{capitalize}, @code{downcase}, | |
504 | @code{upcase} and @code{upcase-initials} might also prove useful. | |
505 | ||
506 | @item mm-path-name-rewrite-functions | |
507 | @vindex mm-path-name-rewrite-functions | |
508 | List of functions used for rewriting the full file names of @acronym{MIME} | |
509 | parts. This is used when viewing parts externally, and is meant for | |
510 | transforming the absolute name so that non-compliant programs can find | |
511 | the file where it's saved. | |
512 | ||
513 | @end table | |
514 | ||
515 | @node New Viewers | |
516 | @section New Viewers | |
517 | ||
518 | Here's an example viewer for displaying @code{text/enriched} inline: | |
519 | ||
520 | @lisp | |
521 | (defun mm-display-enriched-inline (handle) | |
522 | (let (text) | |
523 | (with-temp-buffer | |
524 | (mm-insert-part handle) | |
525 | (save-window-excursion | |
526 | (enriched-decode (point-min) (point-max)) | |
527 | (setq text (buffer-string)))) | |
528 | (mm-insert-inline handle text))) | |
529 | @end lisp | |
530 | ||
531 | We see that the function takes a @acronym{MIME} handle as its parameter. It | |
532 | then goes to a temporary buffer, inserts the text of the part, does some | |
533 | work on the text, stores the result, goes back to the buffer it was | |
534 | called from and inserts the result. | |
535 | ||
536 | The two important helper functions here are @code{mm-insert-part} and | |
537 | @code{mm-insert-inline}. The first function inserts the text of the | |
538 | handle in the current buffer. It handles charset and/or content | |
539 | transfer decoding. The second function just inserts whatever text you | |
540 | tell it to insert, but it also sets things up so that the text can be | |
541 | ``undisplayed'' in a convenient manner. | |
542 | ||
543 | ||
544 | @node Composing | |
545 | @chapter Composing | |
546 | @cindex Composing | |
547 | @cindex MIME Composing | |
548 | @cindex MML | |
549 | @cindex MIME Meta Language | |
550 | ||
551 | Creating a @acronym{MIME} message is boring and non-trivial. Therefore, | |
552 | a library called @code{mml} has been defined that parses a language | |
553 | called @acronym{MML} (@acronym{MIME} Meta Language) and generates | |
554 | @acronym{MIME} messages. | |
555 | ||
556 | @findex mml-generate-mime | |
557 | The main interface function is @code{mml-generate-mime}. It will | |
558 | examine the contents of the current (narrowed-to) buffer and return a | |
559 | string containing the @acronym{MIME} message. | |
560 | ||
561 | @menu | |
562 | * Simple MML Example:: An example @acronym{MML} document. | |
563 | * MML Definition:: All valid @acronym{MML} elements. | |
564 | * Advanced MML Example:: Another example @acronym{MML} document. | |
565 | * Encoding Customization:: Variables that affect encoding. | |
566 | * Charset Translation:: How charsets are mapped from @sc{mule} to @acronym{MIME}. | |
567 | * Conversion:: Going from @acronym{MIME} to @acronym{MML} and vice versa. | |
568 | * Flowed text:: Soft and hard newlines. | |
569 | @end menu | |
570 | ||
571 | ||
572 | @node Simple MML Example | |
573 | @section Simple MML Example | |
574 | ||
575 | Here's a simple @samp{multipart/alternative}: | |
576 | ||
577 | @example | |
578 | <#multipart type=alternative> | |
579 | This is a plain text part. | |
580 | <#part type=text/enriched> | |
581 | <center>This is a centered enriched part</center> | |
582 | <#/multipart> | |
583 | @end example | |
584 | ||
585 | After running this through @code{mml-generate-mime}, we get this: | |
586 | ||
587 | @example | |
588 | Content-Type: multipart/alternative; boundary="=-=-=" | |
589 | ||
590 | ||
591 | --=-=-= | |
592 | ||
593 | ||
594 | This is a plain text part. | |
595 | ||
596 | --=-=-= | |
597 | Content-Type: text/enriched | |
598 | ||
599 | ||
600 | <center>This is a centered enriched part</center> | |
601 | ||
602 | --=-=-=-- | |
603 | @end example | |
604 | ||
605 | ||
606 | @node MML Definition | |
607 | @section MML Definition | |
608 | ||
609 | The @acronym{MML} language is very simple. It looks a bit like an SGML | |
610 | application, but it's not. | |
611 | ||
612 | The main concept of @acronym{MML} is the @dfn{part}. Each part can be of a | |
613 | different type or use a different charset. The way to delineate a part | |
614 | is with a @samp{<#part ...>} tag. Multipart parts can be introduced | |
615 | with the @samp{<#multipart ...>} tag. Parts are ended by the | |
616 | @samp{<#/part>} or @samp{<#/multipart>} tags. Parts started with the | |
617 | @samp{<#part ...>} tags are also closed by the next open tag. | |
618 | ||
619 | There's also the @samp{<#external ...>} tag. These introduce | |
620 | @samp{external/message-body} parts. | |
621 | ||
622 | Each tag can contain zero or more parameters on the form | |
623 | @samp{parameter=value}. The values may be enclosed in quotation marks, | |
624 | but that's not necessary unless the value contains white space. So | |
625 | @samp{filename=/home/user/#hello$^yes} is perfectly valid. | |
626 | ||
627 | The following parameters have meaning in @acronym{MML}; parameters that have no | |
628 | meaning are ignored. The @acronym{MML} parameter names are the same as the | |
629 | @acronym{MIME} parameter names; the things in the parentheses say which | |
630 | header it will be used in. | |
631 | ||
632 | @table @samp | |
633 | @item type | |
634 | The @acronym{MIME} type of the part (@code{Content-Type}). | |
635 | ||
636 | @item filename | |
637 | Use the contents of the file in the body of the part | |
638 | (@code{Content-Disposition}). | |
639 | ||
640 | @item charset | |
641 | The contents of the body of the part are to be encoded in the character | |
642 | set specified (@code{Content-Type}). @xref{Charset Translation}. | |
643 | ||
644 | @item name | |
645 | Might be used to suggest a file name if the part is to be saved | |
646 | to a file (@code{Content-Type}). | |
647 | ||
648 | @item disposition | |
649 | Valid values are @samp{inline} and @samp{attachment} | |
650 | (@code{Content-Disposition}). | |
651 | ||
652 | @item encoding | |
653 | Valid values are @samp{7bit}, @samp{8bit}, @samp{quoted-printable} and | |
654 | @samp{base64} (@code{Content-Transfer-Encoding}). @xref{Charset | |
655 | Translation}. | |
656 | ||
657 | @item description | |
658 | A description of the part (@code{Content-Description}). | |
659 | ||
660 | @item creation-date | |
661 | RFC822 date when the part was created (@code{Content-Disposition}). | |
662 | ||
663 | @item modification-date | |
664 | RFC822 date when the part was modified (@code{Content-Disposition}). | |
665 | ||
666 | @item read-date | |
667 | RFC822 date when the part was read (@code{Content-Disposition}). | |
668 | ||
669 | @item recipients | |
670 | Who to encrypt/sign the part to. This field is used to override any | |
671 | auto-detection based on the To/CC headers. | |
672 | ||
673 | @item sender | |
674 | Identity used to sign the part. This field is used to override the | |
675 | default key used. | |
676 | ||
677 | @item size | |
678 | The size (in octets) of the part (@code{Content-Disposition}). | |
679 | ||
680 | @item sign | |
681 | What technology to sign this @acronym{MML} part with (@code{smime}, @code{pgp} | |
682 | or @code{pgpmime}) | |
683 | ||
684 | @item encrypt | |
685 | What technology to encrypt this @acronym{MML} part with (@code{smime}, | |
686 | @code{pgp} or @code{pgpmime}) | |
687 | ||
688 | @end table | |
689 | ||
690 | Parameters for @samp{text/plain}: | |
691 | ||
692 | @table @samp | |
693 | @item format | |
694 | Formatting parameter for the text, valid values include @samp{fixed} | |
695 | (the default) and @samp{flowed}. Normally you do not specify this | |
696 | manually, since it requires the textual body to be formatted in a | |
697 | special way described in RFC 2646. @xref{Flowed text}. | |
698 | @end table | |
699 | ||
700 | Parameters for @samp{application/octet-stream}: | |
701 | ||
702 | @table @samp | |
703 | @item type | |
704 | Type of the part; informal---meant for human readers | |
705 | (@code{Content-Type}). | |
706 | @end table | |
707 | ||
708 | Parameters for @samp{message/external-body}: | |
709 | ||
710 | @table @samp | |
711 | @item access-type | |
712 | A word indicating the supported access mechanism by which the file may | |
713 | be obtained. Values include @samp{ftp}, @samp{anon-ftp}, @samp{tftp}, | |
714 | @samp{localfile}, and @samp{mailserver}. (@code{Content-Type}.) | |
715 | ||
716 | @item expiration | |
717 | The RFC822 date after which the file may no longer be fetched. | |
718 | (@code{Content-Type}.) | |
719 | ||
720 | @item size | |
721 | The size (in octets) of the file. (@code{Content-Type}.) | |
722 | ||
723 | @item permission | |
724 | Valid values are @samp{read} and @samp{read-write} | |
725 | (@code{Content-Type}). | |
726 | ||
727 | @end table | |
728 | ||
729 | Parameters for @samp{sign=smime}: | |
730 | ||
731 | @table @samp | |
732 | ||
733 | @item keyfile | |
734 | File containing key and certificate for signer. | |
735 | ||
736 | @end table | |
737 | ||
738 | Parameters for @samp{encrypt=smime}: | |
739 | ||
740 | @table @samp | |
741 | ||
742 | @item certfile | |
743 | File containing certificate for recipient. | |
744 | ||
745 | @end table | |
746 | ||
747 | ||
748 | @node Advanced MML Example | |
749 | @section Advanced MML Example | |
750 | ||
751 | Here's a complex multipart message. It's a @samp{multipart/mixed} that | |
752 | contains many parts, one of which is a @samp{multipart/alternative}. | |
753 | ||
754 | @example | |
755 | <#multipart type=mixed> | |
756 | <#part type=image/jpeg filename=~/rms.jpg disposition=inline> | |
757 | <#multipart type=alternative> | |
758 | This is a plain text part. | |
759 | <#part type=text/enriched name=enriched.txt> | |
760 | <center>This is a centered enriched part</center> | |
761 | <#/multipart> | |
762 | This is a new plain text part. | |
763 | <#part disposition=attachment> | |
764 | This plain text part is an attachment. | |
765 | <#/multipart> | |
766 | @end example | |
767 | ||
768 | And this is the resulting @acronym{MIME} message: | |
769 | ||
770 | @example | |
771 | Content-Type: multipart/mixed; boundary="=-=-=" | |
772 | ||
773 | ||
774 | --=-=-= | |
775 | ||
776 | ||
777 | ||
778 | --=-=-= | |
779 | Content-Type: image/jpeg; | |
780 | filename="~/rms.jpg" | |
781 | Content-Disposition: inline; | |
782 | filename="~/rms.jpg" | |
783 | Content-Transfer-Encoding: base64 | |
784 | ||
785 | /9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRof | |
786 | Hh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/wAALCAAwADABAREA/8QAHwAA | |
787 | AQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQAAAF9AQIDAAQR | |
788 | BRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3ODk6Q0RF | |
789 | RkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWmp6ip | |
790 | qrKztLW2t7i5usLDxMXGx8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/9oACAEB | |
791 | AAA/AO/rifFHjldNuGsrDa0qcSSHkA+gHrXKw+LtWLrMb+RgTyhbr+HSug07xNqV9fQtZrNI | |
792 | AyiaE/NuBPOOOP0rvRNE880KOC8TbXXGCv1FPqjrF4LDR7u5L7SkTFT/ALWOP1xXgTuXfc7E | |
793 | sx6nua6rwp4IvvEM8chCxWxOdzn7wz6V9AaB4S07w9p5itow0rDLSY5Pt9K43xO66P4xs71m | |
794 | 2QXiGCbA4yOVJ9+1aYORkdK434lyNH4ahCnG66VT9Nj15JFbPdX0MS43M4VQf5/yr2vSpLnw | |
795 | 5ZW8dlCZ8KFXjOPX0/mK6rSPEGt3Angu44fNEReHYNvIH3TzXDeKNO8RX+kSX2ouZkicTIOc | |
796 | L+g7E810ulFjpVtv3bwgB3HJyK5L4quY/C9sVxk3ij/xx6850u7t1mtp/wDlpEw3An3Jr3Dw | |
797 | 34gsbWza4nBlhC5LDsaW6+IFgupQyCF3iHH7gA7c9R9ay7zx6t7aX9jHC4smhfBkGCvHGfrm | |
798 | tLQ7hbnRrV1GPkAP1x1/Hr+Ncr8Vzjwrbf8AX6v/AKA9eQRyYlQk8Yx9K6XTNbkgia2ciSIn | |
799 | 7p5Ga9Atte0LTLKO6it4i7dVRFJDcZ4PvXN+JvEMF9bILVGXJLSZ4zkjivRPDaeX4b08HOTC | |
800 | pOffmua+KkbS+GLVUGT9tT/0B68eeIpIFYjB70+OOVXyoOM9+M1eaWeCLzHPyHGO/NVWvJJm | |
801 | jQ8KGH1NfQWhXSXmh2c8eArRLwO3HSv/2Q== | |
802 | ||
803 | --=-=-= | |
804 | Content-Type: multipart/alternative; boundary="==-=-=" | |
805 | ||
806 | ||
807 | --==-=-= | |
808 | ||
809 | ||
810 | This is a plain text part. | |
811 | ||
812 | --==-=-= | |
813 | Content-Type: text/enriched; | |
814 | name="enriched.txt" | |
815 | ||
816 | ||
817 | <center>This is a centered enriched part</center> | |
818 | ||
819 | --==-=-=-- | |
820 | ||
821 | --=-=-= | |
822 | ||
823 | This is a new plain text part. | |
824 | ||
825 | --=-=-= | |
826 | Content-Disposition: attachment | |
827 | ||
828 | ||
829 | This plain text part is an attachment. | |
830 | ||
831 | --=-=-=-- | |
832 | @end example | |
833 | ||
834 | @node Encoding Customization | |
835 | @section Encoding Customization | |
836 | ||
837 | @table @code | |
838 | ||
839 | @item mm-body-charset-encoding-alist | |
840 | @vindex mm-body-charset-encoding-alist | |
841 | Mapping from @acronym{MIME} charset to encoding to use. This variable is | |
842 | usually used except, e.g., when other requirements force a specific | |
843 | encoding (digitally signed messages require 7bit encodings). The | |
844 | default is | |
845 | ||
846 | @lisp | |
847 | ((iso-2022-jp . 7bit) | |
848 | (iso-2022-jp-2 . 7bit) | |
849 | (utf-16 . base64) | |
850 | (utf-16be . base64) | |
851 | (utf-16le . base64)) | |
852 | @end lisp | |
853 | ||
854 | As an example, if you do not want to have ISO-8859-1 characters | |
855 | quoted-printable encoded, you may add @code{(iso-8859-1 . 8bit)} to | |
856 | this variable. You can override this setting on a per-message basis | |
857 | by using the @code{encoding} @acronym{MML} tag (@pxref{MML Definition}). | |
858 | ||
859 | @item mm-coding-system-priorities | |
860 | @vindex mm-coding-system-priorities | |
861 | Prioritize coding systems to use for outgoing messages. The default | |
862 | is @code{nil}, which means to use the defaults in Emacs, but is | |
863 | @code{(iso-8859-1 iso-2022-jp iso-2022-jp-2 shift_jis utf-8)} when | |
864 | running Emacs in the Japanese language environment. It is a list of | |
865 | coding system symbols (aliases of coding systems are also allowed, use | |
866 | @kbd{M-x describe-coding-system} to make sure you are specifying correct | |
867 | coding system names). For example, if you have configured Emacs | |
868 | to prefer UTF-8, but wish that outgoing messages should be sent in | |
869 | ISO-8859-1 if possible, you can set this variable to | |
870 | @code{(iso-8859-1)}. You can override this setting on a per-message | |
871 | basis by using the @code{charset} @acronym{MML} tag (@pxref{MML Definition}). | |
872 | ||
01c52d31 MB |
873 | As different hierarchies prefer different charsets, you may want to set |
874 | @code{mm-coding-system-priorities} according to the hierarchy in Gnus. | |
875 | Here's an example: | |
876 | ||
877 | @c Corrections about preferred charsets are welcome. de, fr and fj | |
878 | @c should be correct, I don't know about the rest (so these are only | |
879 | @c examples): | |
880 | @lisp | |
881 | (add-to-list 'gnus-newsgroup-variables 'mm-coding-system-priorities) | |
882 | (setq gnus-parameters | |
883 | (nconc | |
884 | ;; Some charsets are just examples! | |
885 | '(("^cn\\." ;; Chinese | |
886 | (mm-coding-system-priorities | |
887 | '(iso-8859-1 cn-big5 chinese-iso-7bit utf-8))) | |
888 | ("^cz\\.\\|^pl\\." ;; Central and Eastern European | |
889 | (mm-coding-system-priorities '(iso-8859-2 utf-8))) | |
890 | ("^de\\." ;; German language | |
891 | (mm-coding-system-priorities '(iso-8859-1 iso-8859-15 utf-8))) | |
892 | ("^fr\\." ;; French | |
893 | (mm-coding-system-priorities '(iso-8859-15 iso-8859-1 utf-8))) | |
894 | ("^fj\\." ;; Japanese | |
895 | (mm-coding-system-priorities | |
896 | '(iso-8859-1 iso-2022-jp iso-2022-jp-2 shift_jis utf-8))) | |
897 | ("^ru\\." ;; Cyrillic | |
898 | (mm-coding-system-priorities | |
899 | '(koi8-r iso-8859-5 iso-8859-1 utf-8)))) | |
900 | gnus-parameters)) | |
901 | @end lisp | |
902 | ||
4009494e GM |
903 | @item mm-content-transfer-encoding-defaults |
904 | @vindex mm-content-transfer-encoding-defaults | |
905 | Mapping from @acronym{MIME} types to encoding to use. This variable is usually | |
906 | used except, e.g., when other requirements force a safer encoding | |
907 | (digitally signed messages require 7bit encoding). Besides the normal | |
908 | @acronym{MIME} encodings, @code{qp-or-base64} may be used to indicate that for | |
909 | each case the most efficient of quoted-printable and base64 should be | |
910 | used. | |
911 | ||
912 | @code{qp-or-base64} has another effect. It will fold long lines so that | |
913 | MIME parts may not be broken by MTA. So do @code{quoted-printable} and | |
914 | @code{base64}. | |
915 | ||
916 | Note that it affects body encoding only when a part is a raw forwarded | |
917 | message (which will be made by @code{gnus-summary-mail-forward} with the | |
918 | arg 2 for example) or is neither the @samp{text/*} type nor the | |
919 | @samp{message/*} type. Even though in those cases, you can override | |
920 | this setting on a per-message basis by using the @code{encoding} | |
921 | @acronym{MML} tag (@pxref{MML Definition}). | |
922 | ||
923 | @item mm-use-ultra-safe-encoding | |
924 | @vindex mm-use-ultra-safe-encoding | |
925 | When this is non-@code{nil}, it means that textual parts are encoded as | |
926 | quoted-printable if they contain lines longer than 76 characters or | |
927 | starting with "From " in the body. Non-7bit encodings (8bit, binary) | |
928 | are generally disallowed. This reduce the probability that a non-8bit | |
929 | clean MTA or MDA changes the message. This should never be set | |
930 | directly, but bound by other functions when necessary (e.g., when | |
931 | encoding messages that are to be digitally signed). | |
932 | ||
933 | @end table | |
934 | ||
935 | @node Charset Translation | |
936 | @section Charset Translation | |
937 | @cindex charsets | |
938 | ||
939 | During translation from @acronym{MML} to @acronym{MIME}, for each | |
940 | @acronym{MIME} part which has been composed inside Emacs, an appropriate | |
941 | charset has to be chosen. | |
942 | ||
943 | @vindex mail-parse-charset | |
944 | If you are running a non-@sc{mule} Emacs, this process is simple: If the | |
945 | part contains any non-@acronym{ASCII} (8-bit) characters, the @acronym{MIME} charset | |
946 | given by @code{mail-parse-charset} (a symbol) is used. (Never set this | |
947 | variable directly, though. If you want to change the default charset, | |
948 | please consult the documentation of the package which you use to process | |
949 | @acronym{MIME} messages. | |
950 | @xref{Various Message Variables, , Various Message Variables, message, | |
951 | Message Manual}, for example.) | |
952 | If there are only @acronym{ASCII} characters, the @acronym{MIME} charset US-ASCII is | |
953 | used, of course. | |
954 | ||
955 | @cindex MULE | |
956 | @cindex UTF-8 | |
957 | @cindex Unicode | |
958 | @vindex mm-mime-mule-charset-alist | |
959 | Things are slightly more complicated when running Emacs with @sc{mule} | |
960 | support. In this case, a list of the @sc{mule} charsets used in the | |
961 | part is obtained, and the @sc{mule} charsets are translated to | |
962 | @acronym{MIME} charsets by consulting the table provided by Emacs itself | |
963 | or the variable @code{mm-mime-mule-charset-alist} for XEmacs. | |
964 | If this results in a single @acronym{MIME} charset, this is used to encode | |
965 | the part. But if the resulting list of @acronym{MIME} charsets contains more | |
966 | than one element, two things can happen: If it is possible to encode the | |
967 | part via UTF-8, this charset is used. (For this, Emacs must support | |
968 | the @code{utf-8} coding system, and the part must consist entirely of | |
969 | characters which have Unicode counterparts.) If UTF-8 is not available | |
970 | for some reason, the part is split into several ones, so that each one | |
971 | can be encoded with a single @acronym{MIME} charset. The part can only be | |
972 | split at line boundaries, though---if more than one @acronym{MIME} charset is | |
973 | required to encode a single line, it is not possible to encode the part. | |
974 | ||
975 | When running Emacs with @sc{mule} support, the preferences for which | |
976 | coding system to use is inherited from Emacs itself. This means that | |
977 | if Emacs is set up to prefer UTF-8, it will be used when encoding | |
978 | messages. You can modify this by altering the | |
979 | @code{mm-coding-system-priorities} variable though (@pxref{Encoding | |
980 | Customization}). | |
981 | ||
982 | The charset to be used can be overridden by setting the @code{charset} | |
983 | @acronym{MML} tag (@pxref{MML Definition}) when composing the message. | |
984 | ||
985 | The encoding of characters (quoted-printable, 8bit etc) is orthogonal | |
986 | to the discussion here, and is controlled by the variables | |
987 | @code{mm-body-charset-encoding-alist} and | |
988 | @code{mm-content-transfer-encoding-defaults} (@pxref{Encoding | |
989 | Customization}). | |
990 | ||
991 | @node Conversion | |
992 | @section Conversion | |
993 | ||
994 | @findex mime-to-mml | |
995 | A (multipart) @acronym{MIME} message can be converted to @acronym{MML} | |
996 | with the @code{mime-to-mml} function. It works on the message in the | |
997 | current buffer, and substitutes @acronym{MML} markup for @acronym{MIME} | |
998 | boundaries. Non-textual parts do not have their contents in the buffer, | |
999 | but instead have the contents in separate buffers that are referred to | |
1000 | from the @acronym{MML} tags. | |
1001 | ||
1002 | @findex mml-to-mime | |
1003 | An @acronym{MML} message can be converted back to @acronym{MIME} by the | |
1004 | @code{mml-to-mime} function. | |
1005 | ||
1006 | These functions are in certain senses ``lossy''---you will not get back | |
1007 | an identical message if you run @code{mime-to-mml} and then | |
1008 | @code{mml-to-mime}. Not only will trivial things like the order of the | |
1009 | headers differ, but the contents of the headers may also be different. | |
1010 | For instance, the original message may use base64 encoding on text, | |
1011 | while @code{mml-to-mime} may decide to use quoted-printable encoding, and | |
1012 | so on. | |
1013 | ||
1014 | In essence, however, these two functions should be the inverse of each | |
1015 | other. The resulting contents of the message should remain equivalent, | |
1016 | if not identical. | |
1017 | ||
1018 | ||
1019 | @node Flowed text | |
1020 | @section Flowed text | |
1021 | @cindex format=flowed | |
1022 | ||
1023 | The Emacs @acronym{MIME} library will respect the @code{use-hard-newlines} | |
1024 | variable (@pxref{Hard and Soft Newlines, ,Hard and Soft Newlines, | |
1025 | emacs, Emacs Manual}) when encoding a message, and the | |
1026 | ``format=flowed'' Content-Type parameter when decoding a message. | |
1027 | ||
1028 | On encoding text, regardless of @code{use-hard-newlines}, lines | |
1029 | terminated by soft newline characters are filled together and wrapped | |
1030 | after the column decided by @code{fill-flowed-encode-column}. | |
1031 | Quotation marks (matching @samp{^>* ?}) are respected. The variable | |
1032 | controls how the text will look in a client that does not support | |
1033 | flowed text, the default is to wrap after 66 characters. If hard | |
1034 | newline characters are not present in the buffer, no flow encoding | |
1035 | occurs. | |
1036 | ||
1037 | On decoding flowed text, lines with soft newline characters are filled | |
1038 | together and wrapped after the column decided by | |
1039 | @code{fill-flowed-display-column}. The default is to wrap after | |
1040 | @code{fill-column}. | |
1041 | ||
1042 | @table @code | |
1043 | @item mm-fill-flowed | |
1044 | @vindex mm-fill-flowed | |
1045 | If non-@code{nil} a format=flowed article will be displayed flowed. | |
1046 | @end table | |
1047 | ||
1048 | ||
1049 | @node Interface Functions | |
1050 | @chapter Interface Functions | |
1051 | @cindex interface functions | |
1052 | @cindex mail-parse | |
1053 | ||
1054 | The @code{mail-parse} library is an abstraction over the actual | |
1055 | low-level libraries that are described in the next chapter. | |
1056 | ||
1057 | Standards change, and so programs have to change to fit in the new | |
1058 | mold. For instance, RFC2045 describes a syntax for the | |
1059 | @code{Content-Type} header that only allows @acronym{ASCII} characters in the | |
1060 | parameter list. RFC2231 expands on RFC2045 syntax to provide a scheme | |
1061 | for continuation headers and non-@acronym{ASCII} characters. | |
1062 | ||
1063 | The traditional way to deal with this is just to update the library | |
1064 | functions to parse the new syntax. However, this is sometimes the wrong | |
1065 | thing to do. In some instances it may be vital to be able to understand | |
1066 | both the old syntax as well as the new syntax, and if there is only one | |
1067 | library, one must choose between the old version of the library and the | |
1068 | new version of the library. | |
1069 | ||
1070 | The Emacs @acronym{MIME} library takes a different tack. It defines a | |
1071 | series of low-level libraries (@file{rfc2047.el}, @file{rfc2231.el} | |
1072 | and so on) that parses strictly according to the corresponding | |
1073 | standard. However, normal programs would not use the functions | |
1074 | provided by these libraries directly, but instead use the functions | |
1075 | provided by the @code{mail-parse} library. The functions in this | |
1076 | library are just aliases to the corresponding functions in the latest | |
1077 | low-level libraries. Using this scheme, programs get a consistent | |
1078 | interface they can use, and library developers are free to create | |
1079 | write code that handles new standards. | |
1080 | ||
1081 | The following functions are defined by this library: | |
1082 | ||
1083 | @table @code | |
1084 | @item mail-header-parse-content-type | |
1085 | @findex mail-header-parse-content-type | |
1086 | Parse a @code{Content-Type} header and return a list on the following | |
1087 | format: | |
1088 | ||
1089 | @lisp | |
1090 | ("type/subtype" | |
1091 | (attribute1 . value1) | |
1092 | (attribute2 . value2) | |
1093 | ...) | |
1094 | @end lisp | |
1095 | ||
1096 | Here's an example: | |
1097 | ||
1098 | @example | |
1099 | (mail-header-parse-content-type | |
1100 | "image/gif; name=\"b980912.gif\"") | |
1101 | @result{} ("image/gif" (name . "b980912.gif")) | |
1102 | @end example | |
1103 | ||
1104 | @item mail-header-parse-content-disposition | |
1105 | @findex mail-header-parse-content-disposition | |
1106 | Parse a @code{Content-Disposition} header and return a list on the same | |
1107 | format as the function above. | |
1108 | ||
1109 | @item mail-content-type-get | |
1110 | @findex mail-content-type-get | |
1111 | Takes two parameters---a list on the format above, and an attribute. | |
1112 | Returns the value of the attribute. | |
1113 | ||
1114 | @example | |
1115 | (mail-content-type-get | |
1116 | '("image/gif" (name . "b980912.gif")) 'name) | |
1117 | @result{} "b980912.gif" | |
1118 | @end example | |
1119 | ||
1120 | @item mail-header-encode-parameter | |
1121 | @findex mail-header-encode-parameter | |
1122 | Takes a parameter string and returns an encoded version of the string. | |
1123 | This is used for parameters in headers like @code{Content-Type} and | |
1124 | @code{Content-Disposition}. | |
1125 | ||
1126 | @item mail-header-remove-comments | |
1127 | @findex mail-header-remove-comments | |
1128 | Return a comment-free version of a header. | |
1129 | ||
1130 | @example | |
1131 | (mail-header-remove-comments | |
1132 | "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)") | |
1133 | @result{} "Gnus/5.070027 " | |
1134 | @end example | |
1135 | ||
1136 | @item mail-header-remove-whitespace | |
1137 | @findex mail-header-remove-whitespace | |
1138 | Remove linear white space from a header. Space inside quoted strings | |
1139 | and comments is preserved. | |
1140 | ||
1141 | @example | |
1142 | (mail-header-remove-whitespace | |
1143 | "image/gif; name=\"Name with spaces\"") | |
1144 | @result{} "image/gif;name=\"Name with spaces\"" | |
1145 | @end example | |
1146 | ||
1147 | @item mail-header-get-comment | |
1148 | @findex mail-header-get-comment | |
1149 | Return the last comment in a header. | |
1150 | ||
1151 | @example | |
1152 | (mail-header-get-comment | |
1153 | "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)") | |
1154 | @result{} "Finnish Landrace" | |
1155 | @end example | |
1156 | ||
1157 | @item mail-header-parse-address | |
1158 | @findex mail-header-parse-address | |
1159 | Parse an address and return a list containing the mailbox and the | |
1160 | plaintext name. | |
1161 | ||
1162 | @example | |
1163 | (mail-header-parse-address | |
1164 | "Hrvoje Niksic <hniksic@@srce.hr>") | |
1165 | @result{} ("hniksic@@srce.hr" . "Hrvoje Niksic") | |
1166 | @end example | |
1167 | ||
1168 | @item mail-header-parse-addresses | |
1169 | @findex mail-header-parse-addresses | |
1170 | Parse a string with list of addresses and return a list of elements like | |
1171 | the one described above. | |
1172 | ||
1173 | @example | |
1174 | (mail-header-parse-addresses | |
1175 | "Hrvoje Niksic <hniksic@@srce.hr>, Steinar Bang <sb@@metis.no>") | |
1176 | @result{} (("hniksic@@srce.hr" . "Hrvoje Niksic") | |
1177 | ("sb@@metis.no" . "Steinar Bang")) | |
1178 | @end example | |
1179 | ||
1180 | @item mail-header-parse-date | |
1181 | @findex mail-header-parse-date | |
1182 | Parse a date string and return an Emacs time structure. | |
1183 | ||
1184 | @item mail-narrow-to-head | |
1185 | @findex mail-narrow-to-head | |
1186 | Narrow the buffer to the header section of the buffer. Point is placed | |
1187 | at the beginning of the narrowed buffer. | |
1188 | ||
1189 | @item mail-header-narrow-to-field | |
1190 | @findex mail-header-narrow-to-field | |
1191 | Narrow the buffer to the header under point. Understands continuation | |
1192 | headers. | |
1193 | ||
1194 | @item mail-header-fold-field | |
1195 | @findex mail-header-fold-field | |
1196 | Fold the header under point. | |
1197 | ||
1198 | @item mail-header-unfold-field | |
1199 | @findex mail-header-unfold-field | |
1200 | Unfold the header under point. | |
1201 | ||
1202 | @item mail-header-field-value | |
1203 | @findex mail-header-field-value | |
1204 | Return the value of the field under point. | |
1205 | ||
1206 | @item mail-encode-encoded-word-region | |
1207 | @findex mail-encode-encoded-word-region | |
1208 | Encode the non-@acronym{ASCII} words in the region. For instance, | |
01c52d31 | 1209 | @samp{Na@"{@dotless{i}}ve} is encoded as @samp{=?iso-8859-1?q?Na=EFve?=}. |
4009494e GM |
1210 | |
1211 | @item mail-encode-encoded-word-buffer | |
1212 | @findex mail-encode-encoded-word-buffer | |
1213 | Encode the non-@acronym{ASCII} words in the current buffer. This function is | |
1214 | meant to be called narrowed to the headers of a message. | |
1215 | ||
1216 | @item mail-encode-encoded-word-string | |
1217 | @findex mail-encode-encoded-word-string | |
1218 | Encode the words that need encoding in a string, and return the result. | |
1219 | ||
1220 | @example | |
1221 | (mail-encode-encoded-word-string | |
01c52d31 | 1222 | "This is na@"{@dotless{i}}ve, baby") |
4009494e GM |
1223 | @result{} "This is =?iso-8859-1?q?na=EFve,?= baby" |
1224 | @end example | |
1225 | ||
1226 | @item mail-decode-encoded-word-region | |
1227 | @findex mail-decode-encoded-word-region | |
1228 | Decode the encoded words in the region. | |
1229 | ||
1230 | @item mail-decode-encoded-word-string | |
1231 | @findex mail-decode-encoded-word-string | |
1232 | Decode the encoded words in the string and return the result. | |
1233 | ||
1234 | @example | |
1235 | (mail-decode-encoded-word-string | |
1236 | "This is =?iso-8859-1?q?na=EFve,?= baby") | |
01c52d31 | 1237 | @result{} "This is na@"{@dotless{i}}ve, baby" |
4009494e GM |
1238 | @end example |
1239 | ||
1240 | @end table | |
1241 | ||
1242 | Currently, @code{mail-parse} is an abstraction over @code{ietf-drums}, | |
1243 | @code{rfc2047}, @code{rfc2045} and @code{rfc2231}. These are documented | |
1244 | in the subsequent sections. | |
1245 | ||
1246 | ||
1247 | ||
1248 | @node Basic Functions | |
1249 | @chapter Basic Functions | |
1250 | ||
1251 | This chapter describes the basic, ground-level functions for parsing and | |
1252 | handling. Covered here is parsing @code{From} lines, removing comments | |
1253 | from header lines, decoding encoded words, parsing date headers and so | |
1254 | on. High-level functionality is dealt with in the first chapter | |
1255 | (@pxref{Decoding and Viewing}). | |
1256 | ||
1257 | @menu | |
1258 | * rfc2045:: Encoding @code{Content-Type} headers. | |
1259 | * rfc2231:: Parsing @code{Content-Type} headers. | |
1260 | * ietf-drums:: Handling mail headers defined by RFC822bis. | |
1261 | * rfc2047:: En/decoding encoded words in headers. | |
1262 | * time-date:: Functions for parsing dates and manipulating time. | |
1263 | * qp:: Quoted-Printable en/decoding. | |
1264 | * base64:: Base64 en/decoding. | |
1265 | * binhex:: Binhex decoding. | |
1266 | * uudecode:: Uuencode decoding. | |
1267 | * yenc:: Yenc decoding. | |
1268 | * rfc1843:: Decoding HZ-encoded text. | |
1269 | * mailcap:: How parts are displayed is specified by the @file{.mailcap} file | |
1270 | @end menu | |
1271 | ||
1272 | ||
1273 | @node rfc2045 | |
1274 | @section rfc2045 | |
1275 | ||
1276 | RFC2045 is the ``main'' @acronym{MIME} document, and as such, one would | |
1277 | imagine that there would be a lot to implement. But there isn't, since | |
1278 | most of the implementation details are delegated to the subsequent | |
1279 | RFCs. | |
1280 | ||
1281 | So @file{rfc2045.el} has only a single function: | |
1282 | ||
1283 | @table @code | |
1284 | @item rfc2045-encode-string | |
1285 | @findex rfc2045-encode-string | |
1286 | Takes a parameter and a value and returns a @samp{PARAM=VALUE} string. | |
1287 | @var{value} will be quoted if there are non-safe characters in it. | |
1288 | @end table | |
1289 | ||
1290 | ||
1291 | @node rfc2231 | |
1292 | @section rfc2231 | |
1293 | ||
1294 | RFC2231 defines a syntax for the @code{Content-Type} and | |
1295 | @code{Content-Disposition} headers. Its snappy name is @dfn{MIME | |
1296 | Parameter Value and Encoded Word Extensions: Character Sets, Languages, | |
1297 | and Continuations}. | |
1298 | ||
1299 | In short, these headers look something like this: | |
1300 | ||
1301 | @example | |
1302 | Content-Type: application/x-stuff; | |
1303 | title*0*=us-ascii'en'This%20is%20even%20more%20; | |
1304 | title*1*=%2A%2A%2Afun%2A%2A%2A%20; | |
1305 | title*2="isn't it!" | |
1306 | @end example | |
1307 | ||
1308 | They usually aren't this bad, though. | |
1309 | ||
1310 | The following functions are defined by this library: | |
1311 | ||
1312 | @table @code | |
1313 | @item rfc2231-parse-string | |
1314 | @findex rfc2231-parse-string | |
1315 | Parse a @code{Content-Type} header and return a list describing its | |
1316 | elements. | |
1317 | ||
1318 | @example | |
1319 | (rfc2231-parse-string | |
1320 | "application/x-stuff; | |
1321 | title*0*=us-ascii'en'This%20is%20even%20more%20; | |
1322 | title*1*=%2A%2A%2Afun%2A%2A%2A%20; | |
1323 | title*2=\"isn't it!\"") | |
1324 | @result{} ("application/x-stuff" | |
1325 | (title . "This is even more ***fun*** isn't it!")) | |
1326 | @end example | |
1327 | ||
1328 | @item rfc2231-get-value | |
1329 | @findex rfc2231-get-value | |
1330 | Takes one of the lists on the format above and returns | |
1331 | the value of the specified attribute. | |
1332 | ||
1333 | @item rfc2231-encode-string | |
1334 | @findex rfc2231-encode-string | |
1335 | Encode a parameter in headers likes @code{Content-Type} and | |
1336 | @code{Content-Disposition}. | |
1337 | ||
1338 | @end table | |
1339 | ||
1340 | ||
1341 | @node ietf-drums | |
1342 | @section ietf-drums | |
1343 | ||
1344 | @dfn{drums} is an IETF working group that is working on the replacement | |
1345 | for RFC822. | |
1346 | ||
1347 | The functions provided by this library include: | |
1348 | ||
1349 | @table @code | |
1350 | @item ietf-drums-remove-comments | |
1351 | @findex ietf-drums-remove-comments | |
1352 | Remove the comments from the argument and return the results. | |
1353 | ||
1354 | @item ietf-drums-remove-whitespace | |
1355 | @findex ietf-drums-remove-whitespace | |
1356 | Remove linear white space from the string and return the results. | |
1357 | Spaces inside quoted strings and comments are left untouched. | |
1358 | ||
1359 | @item ietf-drums-get-comment | |
1360 | @findex ietf-drums-get-comment | |
1361 | Return the last most comment from the string. | |
1362 | ||
1363 | @item ietf-drums-parse-address | |
1364 | @findex ietf-drums-parse-address | |
1365 | Parse an address string and return a list that contains the mailbox and | |
1366 | the plain text name. | |
1367 | ||
1368 | @item ietf-drums-parse-addresses | |
1369 | @findex ietf-drums-parse-addresses | |
1370 | Parse a string that contains any number of comma-separated addresses and | |
1371 | return a list that contains mailbox/plain text pairs. | |
1372 | ||
1373 | @item ietf-drums-parse-date | |
1374 | @findex ietf-drums-parse-date | |
1375 | Parse a date string and return an Emacs time structure. | |
1376 | ||
1377 | @item ietf-drums-narrow-to-header | |
1378 | @findex ietf-drums-narrow-to-header | |
1379 | Narrow the buffer to the header section of the current buffer. | |
1380 | ||
1381 | @end table | |
1382 | ||
1383 | ||
1384 | @node rfc2047 | |
1385 | @section rfc2047 | |
1386 | ||
1387 | RFC2047 (Message Header Extensions for Non-@acronym{ASCII} Text) specifies how | |
1388 | non-@acronym{ASCII} text in headers are to be encoded. This is actually rather | |
1389 | complicated, so a number of variables are necessary to tweak what this | |
1390 | library does. | |
1391 | ||
1392 | The following variables are tweakable: | |
1393 | ||
1394 | @table @code | |
1395 | @item rfc2047-header-encoding-alist | |
1396 | @vindex rfc2047-header-encoding-alist | |
1397 | This is an alist of header / encoding-type pairs. Its main purpose is | |
1398 | to prevent encoding of certain headers. | |
1399 | ||
1400 | The keys can either be header regexps, or @code{t}. | |
1401 | ||
1402 | The values can be @code{nil}, in which case the header(s) in question | |
1403 | won't be encoded, @code{mime}, which means that they will be encoded, or | |
1404 | @code{address-mime}, which means the header(s) will be encoded carefully | |
1405 | assuming they contain addresses. | |
1406 | ||
1407 | @item rfc2047-charset-encoding-alist | |
1408 | @vindex rfc2047-charset-encoding-alist | |
1409 | RFC2047 specifies two forms of encoding---@code{Q} (a | |
1410 | Quoted-Printable-like encoding) and @code{B} (base64). This alist | |
1411 | specifies which charset should use which encoding. | |
1412 | ||
1413 | @item rfc2047-encode-function-alist | |
1414 | @vindex rfc2047-encode-function-alist | |
1415 | This is an alist of encoding / function pairs. The encodings are | |
1416 | @code{Q}, @code{B} and @code{nil}. | |
1417 | ||
1418 | @item rfc2047-encoded-word-regexp | |
1419 | @vindex rfc2047-encoded-word-regexp | |
1420 | When decoding words, this library looks for matches to this regexp. | |
1421 | ||
b890d447 MB |
1422 | @item rfc2047-encoded-word-regexp-loose |
1423 | @vindex rfc2047-encoded-word-regexp-loose | |
1424 | This is a version from which the regexp for the Q encoding pattern of | |
1425 | @code{rfc2047-encoded-word-regexp} is made loose. | |
1426 | ||
4009494e GM |
1427 | @item rfc2047-encode-encoded-words |
1428 | @vindex rfc2047-encode-encoded-words | |
1429 | The boolean variable specifies whether encoded words | |
b890d447 MB |
1430 | (e.g. @samp{=?us-ascii?q?hello?=}) should be encoded again. |
1431 | @code{rfc2047-encoded-word-regexp} is used to look for such words. | |
1432 | ||
1433 | @item rfc2047-allow-irregular-q-encoded-words | |
1434 | @vindex rfc2047-allow-irregular-q-encoded-words | |
1435 | The boolean variable specifies whether irregular Q encoded words | |
1436 | (e.g. @samp{=?us-ascii?q?hello??=}) should be decoded. If it is | |
1437 | non-@code{nil}, @code{rfc2047-encoded-word-regexp-loose} is used instead | |
1438 | of @code{rfc2047-encoded-word-regexp} to look for encoded words. | |
4009494e GM |
1439 | |
1440 | @end table | |
1441 | ||
1442 | Those were the variables, and these are this functions: | |
1443 | ||
1444 | @table @code | |
1445 | @item rfc2047-narrow-to-field | |
1446 | @findex rfc2047-narrow-to-field | |
1447 | Narrow the buffer to the header on the current line. | |
1448 | ||
1449 | @item rfc2047-encode-message-header | |
1450 | @findex rfc2047-encode-message-header | |
1451 | Should be called narrowed to the header of a message. Encodes according | |
1452 | to @code{rfc2047-header-encoding-alist}. | |
1453 | ||
1454 | @item rfc2047-encode-region | |
1455 | @findex rfc2047-encode-region | |
1456 | Encodes all encodable words in the region specified. | |
1457 | ||
1458 | @item rfc2047-encode-string | |
1459 | @findex rfc2047-encode-string | |
1460 | Encode a string and return the results. | |
1461 | ||
1462 | @item rfc2047-decode-region | |
1463 | @findex rfc2047-decode-region | |
1464 | Decode the encoded words in the region. | |
1465 | ||
1466 | @item rfc2047-decode-string | |
1467 | @findex rfc2047-decode-string | |
1468 | Decode a string and return the results. | |
1469 | ||
1470 | @item rfc2047-encode-parameter | |
1471 | @findex rfc2047-encode-parameter | |
1472 | Encode a parameter in the RFC2047-like style. This is a replacement for | |
1473 | the @code{rfc2231-encode-string} function. @xref{rfc2231}. | |
1474 | ||
1475 | When attaching files as @acronym{MIME} parts, we should use the RFC2231 | |
1476 | encoding to specify the file names containing non-@acronym{ASCII} | |
1477 | characters. However, many mail softwares don't support it in practice | |
1478 | and recipients won't be able to extract files with correct names. | |
1479 | Instead, the RFC2047-like encoding is acceptable generally. This | |
1480 | function provides the very RFC2047-like encoding, resigning to such a | |
1481 | regrettable trend. To use it, put the following line in your | |
1482 | @file{~/.gnus.el} file: | |
1483 | ||
1484 | @lisp | |
1485 | (defalias 'mail-header-encode-parameter 'rfc2047-encode-parameter) | |
1486 | @end lisp | |
1487 | ||
1488 | @end table | |
1489 | ||
1490 | ||
1491 | @node time-date | |
1492 | @section time-date | |
1493 | ||
1494 | While not really a part of the @acronym{MIME} library, it is convenient to | |
1495 | document this library here. It deals with parsing @code{Date} headers | |
1496 | and manipulating time. (Not by using tesseracts, though, I'm sorry to | |
1497 | say.) | |
1498 | ||
1499 | These functions convert between five formats: A date string, an Emacs | |
1500 | time structure, a decoded time list, a second number, and a day number. | |
1501 | ||
1502 | Here's a bunch of time/date/second/day examples: | |
1503 | ||
1504 | @example | |
1505 | (parse-time-string "Sat Sep 12 12:21:54 1998 +0200") | |
1506 | @result{} (54 21 12 12 9 1998 6 nil 7200) | |
1507 | ||
1508 | (date-to-time "Sat Sep 12 12:21:54 1998 +0200") | |
1509 | @result{} (13818 19266) | |
1510 | ||
1511 | (time-to-seconds '(13818 19266)) | |
1512 | @result{} 905595714.0 | |
1513 | ||
1514 | (seconds-to-time 905595714.0) | |
1515 | @result{} (13818 19266 0) | |
1516 | ||
1517 | (time-to-days '(13818 19266)) | |
1518 | @result{} 729644 | |
1519 | ||
1520 | (days-to-time 729644) | |
1521 | @result{} (961933 65536) | |
1522 | ||
1523 | (time-since '(13818 19266)) | |
1524 | @result{} (0 430) | |
1525 | ||
1526 | (time-less-p '(13818 19266) '(13818 19145)) | |
1527 | @result{} nil | |
1528 | ||
1529 | (subtract-time '(13818 19266) '(13818 19145)) | |
1530 | @result{} (0 121) | |
1531 | ||
1532 | (days-between "Sat Sep 12 12:21:54 1998 +0200" | |
1533 | "Sat Sep 07 12:21:54 1998 +0200") | |
1534 | @result{} 5 | |
1535 | ||
1536 | (date-leap-year-p 2000) | |
1537 | @result{} t | |
1538 | ||
1539 | (time-to-day-in-year '(13818 19266)) | |
1540 | @result{} 255 | |
1541 | ||
1542 | (time-to-number-of-days | |
1543 | (time-since | |
1544 | (date-to-time "Mon, 01 Jan 2001 02:22:26 GMT"))) | |
1545 | @result{} 4.146122685185185 | |
1546 | @end example | |
1547 | ||
1548 | And finally, we have @code{safe-date-to-time}, which does the same as | |
1549 | @code{date-to-time}, but returns a zero time if the date is | |
1550 | syntactically malformed. | |
1551 | ||
1552 | The five data representations used are the following: | |
1553 | ||
1554 | @table @var | |
1555 | @item date | |
1556 | An RFC822 (or similar) date string. For instance: @code{"Sat Sep 12 | |
1557 | 12:21:54 1998 +0200"}. | |
1558 | ||
1559 | @item time | |
1560 | An internal Emacs time. For instance: @code{(13818 26466)}. | |
1561 | ||
1562 | @item seconds | |
1563 | A floating point representation of the internal Emacs time. For | |
1564 | instance: @code{905595714.0}. | |
1565 | ||
1566 | @item days | |
1567 | An integer number representing the number of days since 00000101. For | |
1568 | instance: @code{729644}. | |
1569 | ||
1570 | @item decoded time | |
1571 | A list of decoded time. For instance: @code{(54 21 12 12 9 1998 6 t | |
1572 | 7200)}. | |
1573 | @end table | |
1574 | ||
1575 | All the examples above represent the same moment. | |
1576 | ||
1577 | These are the functions available: | |
1578 | ||
1579 | @table @code | |
1580 | @item date-to-time | |
1581 | Take a date and return a time. | |
1582 | ||
1583 | @item time-to-seconds | |
e402f452 GM |
1584 | Take a time and return seconds. Note that Emacs has a built-in |
1585 | function, @code{float-time}, that does this. | |
4009494e GM |
1586 | |
1587 | @item seconds-to-time | |
1588 | Take seconds and return a time. | |
1589 | ||
1590 | @item time-to-days | |
1591 | Take a time and return days. | |
1592 | ||
1593 | @item days-to-time | |
1594 | Take days and return a time. | |
1595 | ||
1596 | @item date-to-day | |
1597 | Take a date and return days. | |
1598 | ||
1599 | @item time-to-number-of-days | |
1600 | Take a time and return the number of days that represents. | |
1601 | ||
1602 | @item safe-date-to-time | |
1603 | Take a date and return a time. If the date is not syntactically valid, | |
1604 | return a ``zero'' time. | |
1605 | ||
1606 | @item time-less-p | |
1607 | Take two times and say whether the first time is less (i. e., earlier) | |
1608 | than the second time. | |
1609 | ||
1610 | @item time-since | |
1611 | Take a time and return a time saying how long it was since that time. | |
1612 | ||
1613 | @item subtract-time | |
1614 | Take two times and subtract the second from the first. I. e., return | |
1615 | the time between the two times. | |
1616 | ||
1617 | @item days-between | |
1618 | Take two days and return the number of days between those two days. | |
1619 | ||
1620 | @item date-leap-year-p | |
1621 | Take a year number and say whether it's a leap year. | |
1622 | ||
1623 | @item time-to-day-in-year | |
1624 | Take a time and return the day number within the year that the time is | |
1625 | in. | |
1626 | ||
1627 | @end table | |
1628 | ||
1629 | ||
1630 | @node qp | |
1631 | @section qp | |
1632 | ||
1633 | This library deals with decoding and encoding Quoted-Printable text. | |
1634 | ||
1635 | Very briefly explained, qp encoding means translating all 8-bit | |
1636 | characters (and lots of control characters) into things that look like | |
1637 | @samp{=EF}; that is, an equal sign followed by the byte encoded as a hex | |
1638 | string. | |
1639 | ||
1640 | The following functions are defined by the library: | |
1641 | ||
1642 | @table @code | |
1643 | @item quoted-printable-decode-region | |
1644 | @findex quoted-printable-decode-region | |
1645 | QP-decode all the encoded text in the specified region. | |
1646 | ||
1647 | @item quoted-printable-decode-string | |
1648 | @findex quoted-printable-decode-string | |
1649 | Decode the QP-encoded text in a string and return the results. | |
1650 | ||
1651 | @item quoted-printable-encode-region | |
1652 | @findex quoted-printable-encode-region | |
1653 | QP-encode all the encodable characters in the specified region. The third | |
1654 | optional parameter @var{fold} specifies whether to fold long lines. | |
1655 | (Long here means 72.) | |
1656 | ||
1657 | @item quoted-printable-encode-string | |
1658 | @findex quoted-printable-encode-string | |
1659 | QP-encode all the encodable characters in a string and return the | |
1660 | results. | |
1661 | ||
1662 | @end table | |
1663 | ||
1664 | ||
1665 | @node base64 | |
1666 | @section base64 | |
1667 | @cindex base64 | |
1668 | ||
1669 | Base64 is an encoding that encodes three bytes into four characters, | |
1670 | thereby increasing the size by about 33%. The alphabet used for | |
1671 | encoding is very resistant to mangling during transit. | |
1672 | ||
1673 | The following functions are defined by this library: | |
1674 | ||
1675 | @table @code | |
1676 | @item base64-encode-region | |
1677 | @findex base64-encode-region | |
1678 | base64 encode the selected region. Return the length of the encoded | |
1679 | text. Optional third argument @var{no-line-break} means do not break | |
1680 | long lines into shorter lines. | |
1681 | ||
1682 | @item base64-encode-string | |
1683 | @findex base64-encode-string | |
1684 | base64 encode a string and return the result. | |
1685 | ||
1686 | @item base64-decode-region | |
1687 | @findex base64-decode-region | |
1688 | base64 decode the selected region. Return the length of the decoded | |
1689 | text. If the region can't be decoded, return @code{nil} and don't | |
1690 | modify the buffer. | |
1691 | ||
1692 | @item base64-decode-string | |
1693 | @findex base64-decode-string | |
1694 | base64 decode a string and return the result. If the string can't be | |
1695 | decoded, @code{nil} is returned. | |
1696 | ||
1697 | @end table | |
1698 | ||
1699 | ||
1700 | @node binhex | |
1701 | @section binhex | |
1702 | @cindex binhex | |
1703 | @cindex Apple | |
1704 | @cindex Macintosh | |
1705 | ||
1706 | @code{binhex} is an encoding that originated in Macintosh environments. | |
1707 | The following function is supplied to deal with these: | |
1708 | ||
1709 | @table @code | |
1710 | @item binhex-decode-region | |
1711 | @findex binhex-decode-region | |
1712 | Decode the encoded text in the region. If given a third parameter, only | |
1713 | decode the @code{binhex} header and return the filename. | |
1714 | ||
1715 | @end table | |
1716 | ||
1717 | @node uudecode | |
1718 | @section uudecode | |
1719 | @cindex uuencode | |
1720 | @cindex uudecode | |
1721 | ||
1722 | @code{uuencode} is probably still the most popular encoding of binaries | |
1723 | used on Usenet, although @code{base64} rules the mail world. | |
1724 | ||
1725 | The following function is supplied by this package: | |
1726 | ||
1727 | @table @code | |
1728 | @item uudecode-decode-region | |
1729 | @findex uudecode-decode-region | |
1730 | Decode the text in the region. | |
1731 | @end table | |
1732 | ||
1733 | ||
1734 | @node yenc | |
1735 | @section yenc | |
1736 | @cindex yenc | |
1737 | ||
1738 | @code{yenc} is used for encoding binaries on Usenet. The following | |
1739 | function is supplied by this package: | |
1740 | ||
1741 | @table @code | |
1742 | @item yenc-decode-region | |
1743 | @findex yenc-decode-region | |
1744 | Decode the encoded text in the region. | |
1745 | ||
1746 | @end table | |
1747 | ||
1748 | ||
1749 | @node rfc1843 | |
1750 | @section rfc1843 | |
1751 | @cindex rfc1843 | |
1752 | @cindex HZ | |
1753 | @cindex Chinese | |
1754 | ||
1755 | RFC1843 deals with mixing Chinese and @acronym{ASCII} characters in messages. In | |
1756 | essence, RFC1843 switches between @acronym{ASCII} and Chinese by doing this: | |
1757 | ||
1758 | @example | |
1759 | This sentence is in @acronym{ASCII}. | |
1760 | The next sentence is in GB.~@{<:Ky2;S@{#,NpJ)l6HK!#~@}Bye. | |
1761 | @end example | |
1762 | ||
1763 | Simple enough, and widely used in China. | |
1764 | ||
1765 | The following functions are available to handle this encoding: | |
1766 | ||
1767 | @table @code | |
1768 | @item rfc1843-decode-region | |
1769 | Decode HZ-encoded text in the region. | |
1770 | ||
1771 | @item rfc1843-decode-string | |
1772 | Decode a HZ-encoded string and return the result. | |
1773 | ||
1774 | @end table | |
1775 | ||
1776 | ||
1777 | @node mailcap | |
1778 | @section mailcap | |
1779 | ||
1780 | The @file{~/.mailcap} file is parsed by most @acronym{MIME}-aware message | |
1781 | handlers and describes how elements are supposed to be displayed. | |
1782 | Here's an example file: | |
1783 | ||
1784 | @example | |
1785 | image/*; gimp -8 %s | |
1786 | audio/wav; wavplayer %s | |
1787 | application/msword; catdoc %s ; copiousoutput ; nametemplate=%s.doc | |
1788 | @end example | |
1789 | ||
1790 | This says that all image files should be displayed with @code{gimp}, | |
1791 | that WAVE audio files should be played by @code{wavplayer}, and that | |
1792 | MS-WORD files should be inlined by @code{catdoc}. | |
1793 | ||
1794 | The @code{mailcap} library parses this file, and provides functions for | |
1795 | matching types. | |
1796 | ||
1797 | @table @code | |
1798 | @item mailcap-mime-data | |
1799 | @vindex mailcap-mime-data | |
1800 | This variable is an alist of alists containing backup viewing rules. | |
1801 | ||
1802 | @end table | |
1803 | ||
1804 | Interface functions: | |
1805 | ||
1806 | @table @code | |
1807 | @item mailcap-parse-mailcaps | |
1808 | @findex mailcap-parse-mailcaps | |
1809 | Parse the @file{~/.mailcap} file. | |
1810 | ||
1811 | @item mailcap-mime-info | |
1812 | Takes a @acronym{MIME} type as its argument and returns the matching viewer. | |
1813 | ||
1814 | @end table | |
1815 | ||
1816 | ||
1817 | ||
1818 | ||
1819 | @node Standards | |
1820 | @chapter Standards | |
1821 | ||
1822 | The Emacs @acronym{MIME} library implements handling of various elements | |
1823 | according to a (somewhat) large number of RFCs, drafts and standards | |
1824 | documents. This chapter lists the relevant ones. They can all be | |
1825 | fetched from @uref{http://quimby.gnus.org/notes/}. | |
1826 | ||
1827 | @table @dfn | |
1828 | @item RFC822 | |
1829 | @itemx STD11 | |
1830 | Standard for the Format of ARPA Internet Text Messages. | |
1831 | ||
1832 | @item RFC1036 | |
1833 | Standard for Interchange of USENET Messages | |
1834 | ||
1835 | @item RFC2045 | |
1836 | Format of Internet Message Bodies | |
1837 | ||
1838 | @item RFC2046 | |
1839 | Media Types | |
1840 | ||
1841 | @item RFC2047 | |
1842 | Message Header Extensions for Non-@acronym{ASCII} Text | |
1843 | ||
1844 | @item RFC2048 | |
1845 | Registration Procedures | |
1846 | ||
1847 | @item RFC2049 | |
1848 | Conformance Criteria and Examples | |
1849 | ||
1850 | @item RFC2231 | |
1851 | @acronym{MIME} Parameter Value and Encoded Word Extensions: Character Sets, | |
1852 | Languages, and Continuations | |
1853 | ||
1854 | @item RFC1843 | |
1855 | HZ - A Data Format for Exchanging Files of Arbitrarily Mixed Chinese and | |
1856 | @acronym{ASCII} characters | |
1857 | ||
1858 | @item draft-ietf-drums-msg-fmt-05.txt | |
1859 | Draft for the successor of RFC822 | |
1860 | ||
1861 | @item RFC2112 | |
1862 | The @acronym{MIME} Multipart/Related Content-type | |
1863 | ||
1864 | @item RFC1892 | |
1865 | The Multipart/Report Content Type for the Reporting of Mail System | |
1866 | Administrative Messages | |
1867 | ||
1868 | @item RFC2183 | |
1869 | Communicating Presentation Information in Internet Messages: The | |
1870 | Content-Disposition Header Field | |
1871 | ||
1872 | @item RFC2646 | |
1873 | Documentation of the text/plain format parameter for flowed text. | |
1874 | ||
1875 | @end table | |
1876 | ||
1877 | @node GNU Free Documentation License | |
1878 | @chapter GNU Free Documentation License | |
1879 | @include doclicense.texi | |
1880 | ||
1881 | @node Index | |
1882 | @chapter Index | |
1883 | @printindex cp | |
1884 | ||
4009494e GM |
1885 | @bye |
1886 | ||
1887 | \f | |
1888 | @c Local Variables: | |
1889 | @c mode: texinfo | |
1890 | @c coding: iso-8859-1 | |
1891 | @c End: | |
1892 | ||
1893 | @ignore | |
1894 | arch-tag: c7ef2fd0-a91c-4e10-aa52-c1a2b11b1a8d | |
1895 | @end ignore |