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1 | \input texinfo |
2 | ||
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3 | @include gnus-overrides.texi |
4 | ||
db78a8cb | 5 | @setfilename ../../info/emacs-mime |
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6 | @settitle Emacs MIME Manual |
7 | @synindex fn cp | |
8 | @synindex vr cp | |
9 | @synindex pg cp | |
10 | ||
11 | @copying | |
12 | This file documents the Emacs MIME interface functionality. | |
13 | ||
acaf905b | 14 | Copyright @copyright{} 1998-2012 Free Software Foundation, Inc. |
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15 | |
16 | @quotation | |
17 | Permission is granted to copy, distribute and/or modify this document | |
6a2c4aec | 18 | under the terms of the GNU Free Documentation License, Version 1.3 or |
4009494e | 19 | any later version published by the Free Software Foundation; with no |
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20 | Invariant Sections, with the Front-Cover texts being ``A GNU Manual'', |
21 | and with the Back-Cover Texts as in (a) below. A copy of the license | |
22 | is included in the section entitled ``GNU Free Documentation License''. | |
4009494e | 23 | |
6f093307 GM |
24 | (a) The FSF's Back-Cover Text is: ``You have the freedom to copy and |
25 | modify this GNU manual. Buying copies from the FSF supports it in | |
26 | developing GNU and promoting software freedom.'' | |
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27 | @end quotation |
28 | @end copying | |
29 | ||
30 | @c Node ``Interface Functions'' uses Latin-1 characters | |
31 | @documentencoding ISO-8859-1 | |
32 | ||
0c973505 | 33 | @dircategory Emacs lisp libraries |
4009494e | 34 | @direntry |
62e034c2 | 35 | * Emacs MIME: (emacs-mime). Emacs MIME de/composition library. |
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36 | @end direntry |
37 | @iftex | |
38 | @finalout | |
39 | @end iftex | |
40 | @setchapternewpage odd | |
41 | ||
42 | @titlepage | |
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43 | @ifset WEBHACKDEVEL |
44 | @title Emacs MIME Manual (DEVELOPMENT VERSION) | |
45 | @end ifset | |
46 | @ifclear WEBHACKDEVEL | |
4009494e | 47 | @title Emacs MIME Manual |
7fbf7cae | 48 | @end ifclear |
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49 | |
50 | @author by Lars Magne Ingebrigtsen | |
51 | @page | |
52 | @vskip 0pt plus 1filll | |
53 | @insertcopying | |
54 | @end titlepage | |
55 | ||
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56 | @contents |
57 | ||
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58 | @node Top |
59 | @top Emacs MIME | |
60 | ||
61 | This manual documents the libraries used to compose and display | |
62 | @acronym{MIME} messages. | |
63 | ||
64 | This manual is directed at users who want to modify the behavior of | |
65 | the @acronym{MIME} encoding/decoding process or want a more detailed | |
66 | picture of how the Emacs @acronym{MIME} library works, and people who want | |
67 | to write functions and commands that manipulate @acronym{MIME} elements. | |
68 | ||
69 | @acronym{MIME} is short for @dfn{Multipurpose Internet Mail Extensions}. | |
70 | This standard is documented in a number of RFCs; mainly RFC2045 (Format | |
71 | of Internet Message Bodies), RFC2046 (Media Types), RFC2047 (Message | |
72 | Header Extensions for Non-@acronym{ASCII} Text), RFC2048 (Registration | |
73 | Procedures), RFC2049 (Conformance Criteria and Examples). It is highly | |
74 | recommended that anyone who intends writing @acronym{MIME}-compliant software | |
75 | read at least RFC2045 and RFC2047. | |
76 | ||
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77 | @ifnottex |
78 | @insertcopying | |
79 | @end ifnottex | |
80 | ||
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81 | @menu |
82 | * Decoding and Viewing:: A framework for decoding and viewing. | |
83 | * Composing:: @acronym{MML}; a language for describing @acronym{MIME} parts. | |
84 | * Interface Functions:: An abstraction over the basic functions. | |
85 | * Basic Functions:: Utility and basic parsing functions. | |
86 | * Standards:: A summary of RFCs and working documents used. | |
87 | * GNU Free Documentation License:: The license for this documentation. | |
88 | * Index:: Function and variable index. | |
89 | @end menu | |
90 | ||
91 | ||
92 | @node Decoding and Viewing | |
93 | @chapter Decoding and Viewing | |
94 | ||
95 | This chapter deals with decoding and viewing @acronym{MIME} messages on a | |
96 | higher level. | |
97 | ||
98 | The main idea is to first analyze a @acronym{MIME} article, and then allow | |
99 | other programs to do things based on the list of @dfn{handles} that are | |
100 | returned as a result of this analysis. | |
101 | ||
102 | @menu | |
103 | * Dissection:: Analyzing a @acronym{MIME} message. | |
104 | * Non-MIME:: Analyzing a non-@acronym{MIME} message. | |
105 | * Handles:: Handle manipulations. | |
106 | * Display:: Displaying handles. | |
107 | * Display Customization:: Variables that affect display. | |
108 | * Files and Directories:: Saving and naming attachments. | |
109 | * New Viewers:: How to write your own viewers. | |
110 | @end menu | |
111 | ||
112 | ||
113 | @node Dissection | |
114 | @section Dissection | |
115 | ||
116 | The @code{mm-dissect-buffer} is the function responsible for dissecting | |
117 | a @acronym{MIME} article. If given a multipart message, it will recursively | |
118 | descend the message, following the structure, and return a tree of | |
119 | @acronym{MIME} handles that describes the structure of the message. | |
120 | ||
121 | @node Non-MIME | |
122 | @section Non-MIME | |
123 | @vindex mm-uu-configure-list | |
124 | ||
125 | Gnus also understands some non-@acronym{MIME} attachments, such as | |
126 | postscript, uuencode, binhex, yenc, shar, forward, gnatsweb, pgp, | |
127 | diff. Each of these features can be disabled by add an item into | |
128 | @code{mm-uu-configure-list}. For example, | |
129 | ||
130 | @lisp | |
131 | (require 'mm-uu) | |
132 | (add-to-list 'mm-uu-configure-list '(pgp-signed . disabled)) | |
133 | @end lisp | |
134 | ||
135 | @table @code | |
136 | @item postscript | |
137 | @findex postscript | |
138 | PostScript file. | |
139 | ||
140 | @item uu | |
141 | @findex uu | |
142 | Uuencoded file. | |
143 | ||
144 | @item binhex | |
145 | @findex binhex | |
146 | Binhex encoded file. | |
147 | ||
148 | @item yenc | |
149 | @findex yenc | |
150 | Yenc encoded file. | |
151 | ||
152 | @item shar | |
153 | @findex shar | |
154 | Shar archive file. | |
155 | ||
156 | @item forward | |
157 | @findex forward | |
158 | Non-@acronym{MIME} forwarded message. | |
159 | ||
160 | @item gnatsweb | |
161 | @findex gnatsweb | |
162 | Gnatsweb attachment. | |
163 | ||
164 | @item pgp-signed | |
165 | @findex pgp-signed | |
166 | @acronym{PGP} signed clear text. | |
167 | ||
168 | @item pgp-encrypted | |
169 | @findex pgp-encrypted | |
170 | @acronym{PGP} encrypted clear text. | |
171 | ||
172 | @item pgp-key | |
173 | @findex pgp-key | |
174 | @acronym{PGP} public keys. | |
175 | ||
176 | @item emacs-sources | |
177 | @findex emacs-sources | |
178 | @vindex mm-uu-emacs-sources-regexp | |
179 | Emacs source code. This item works only in the groups matching | |
180 | @code{mm-uu-emacs-sources-regexp}. | |
181 | ||
182 | @item diff | |
183 | @vindex diff | |
184 | @vindex mm-uu-diff-groups-regexp | |
185 | Patches. This is intended for groups where diffs of committed files | |
186 | are automatically sent to. It only works in groups matching | |
187 | @code{mm-uu-diff-groups-regexp}. | |
188 | ||
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189 | @item verbatim-marks |
190 | @cindex verbatim-marks | |
191 | Slrn-style verbatim marks. | |
192 | ||
193 | @item LaTeX | |
194 | @cindex LaTeX | |
195 | LaTeX documents. It only works in groups matching | |
196 | @code{mm-uu-tex-groups-regexp}. | |
197 | ||
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198 | @end table |
199 | ||
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200 | @cindex text/x-verbatim |
201 | @c Is @vindex suitable for a face? | |
202 | @vindex mm-uu-extract | |
203 | Some inlined non-@acronym{MIME} attachments are displayed using the face | |
204 | @code{mm-uu-extract}. By default, no @acronym{MIME} button for these | |
205 | parts is displayed. You can force displaying a button using @kbd{K b} | |
206 | (@code{gnus-summary-display-buttonized}) or add @code{text/x-verbatim} | |
207 | to @code{gnus-buttonized-mime-types}, @xref{MIME Commands, ,MIME | |
208 | Commands, gnus, Gnus Manual}. | |
209 | ||
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210 | @node Handles |
211 | @section Handles | |
212 | ||
213 | A @acronym{MIME} handle is a list that fully describes a @acronym{MIME} | |
214 | component. | |
215 | ||
216 | The following macros can be used to access elements in a handle: | |
217 | ||
218 | @table @code | |
219 | @item mm-handle-buffer | |
220 | @findex mm-handle-buffer | |
221 | Return the buffer that holds the contents of the undecoded @acronym{MIME} | |
222 | part. | |
223 | ||
224 | @item mm-handle-type | |
225 | @findex mm-handle-type | |
226 | Return the parsed @code{Content-Type} of the part. | |
227 | ||
228 | @item mm-handle-encoding | |
229 | @findex mm-handle-encoding | |
230 | Return the @code{Content-Transfer-Encoding} of the part. | |
231 | ||
232 | @item mm-handle-undisplayer | |
233 | @findex mm-handle-undisplayer | |
234 | Return the object that can be used to remove the displayed part (if it | |
235 | has been displayed). | |
236 | ||
237 | @item mm-handle-set-undisplayer | |
238 | @findex mm-handle-set-undisplayer | |
239 | Set the undisplayer object. | |
240 | ||
241 | @item mm-handle-disposition | |
242 | @findex mm-handle-disposition | |
243 | Return the parsed @code{Content-Disposition} of the part. | |
244 | ||
245 | @item mm-get-content-id | |
246 | Returns the handle(s) referred to by @code{Content-ID}. | |
247 | ||
248 | @end table | |
249 | ||
250 | ||
251 | @node Display | |
252 | @section Display | |
253 | ||
254 | Functions for displaying, removing and saving. | |
255 | ||
256 | @table @code | |
257 | @item mm-display-part | |
258 | @findex mm-display-part | |
259 | Display the part. | |
260 | ||
261 | @item mm-remove-part | |
262 | @findex mm-remove-part | |
263 | Remove the part (if it has been displayed). | |
264 | ||
265 | @item mm-inlinable-p | |
266 | @findex mm-inlinable-p | |
267 | Say whether a @acronym{MIME} type can be displayed inline. | |
268 | ||
269 | @item mm-automatic-display-p | |
270 | @findex mm-automatic-display-p | |
271 | Say whether a @acronym{MIME} type should be displayed automatically. | |
272 | ||
273 | @item mm-destroy-part | |
274 | @findex mm-destroy-part | |
275 | Free all resources occupied by a part. | |
276 | ||
277 | @item mm-save-part | |
278 | @findex mm-save-part | |
279 | Offer to save the part in a file. | |
280 | ||
281 | @item mm-pipe-part | |
282 | @findex mm-pipe-part | |
283 | Offer to pipe the part to some process. | |
284 | ||
285 | @item mm-interactively-view-part | |
286 | @findex mm-interactively-view-part | |
287 | Prompt for a mailcap method to use to view the part. | |
288 | ||
289 | @end table | |
290 | ||
291 | ||
292 | @node Display Customization | |
293 | @section Display Customization | |
294 | ||
295 | @table @code | |
296 | ||
297 | @item mm-inline-media-tests | |
298 | @vindex mm-inline-media-tests | |
299 | This is an alist where the key is a @acronym{MIME} type, the second element | |
300 | is a function to display the part @dfn{inline} (i.e., inside Emacs), and | |
301 | the third element is a form to be @code{eval}ed to say whether the part | |
302 | can be displayed inline. | |
303 | ||
304 | This variable specifies whether a part @emph{can} be displayed inline, | |
305 | and, if so, how to do it. It does not say whether parts are | |
306 | @emph{actually} displayed inline. | |
307 | ||
308 | @item mm-inlined-types | |
309 | @vindex mm-inlined-types | |
310 | This, on the other hand, says what types are to be displayed inline, if | |
311 | they satisfy the conditions set by the variable above. It's a list of | |
312 | @acronym{MIME} media types. | |
313 | ||
314 | @item mm-automatic-display | |
315 | @vindex mm-automatic-display | |
316 | This is a list of types that are to be displayed ``automatically'', but | |
317 | only if the above variable allows it. That is, only inlinable parts can | |
318 | be displayed automatically. | |
319 | ||
320 | @item mm-automatic-external-display | |
321 | @vindex mm-automatic-external-display | |
322 | This is a list of types that will be displayed automatically in an | |
323 | external viewer. | |
324 | ||
325 | @item mm-keep-viewer-alive-types | |
326 | @vindex mm-keep-viewer-alive-types | |
327 | This is a list of media types for which the external viewer will not | |
328 | be killed when selecting a different article. | |
329 | ||
330 | @item mm-attachment-override-types | |
331 | @vindex mm-attachment-override-types | |
332 | Some @acronym{MIME} agents create parts that have a content-disposition of | |
333 | @samp{attachment}. This variable allows overriding that disposition and | |
334 | displaying the part inline. (Note that the disposition is only | |
335 | overridden if we are able to, and want to, display the part inline.) | |
336 | ||
337 | @item mm-discouraged-alternatives | |
338 | @vindex mm-discouraged-alternatives | |
339 | List of @acronym{MIME} types that are discouraged when viewing | |
340 | @samp{multipart/alternative}. Viewing agents are supposed to view the | |
341 | last possible part of a message, as that is supposed to be the richest. | |
342 | However, users may prefer other types instead, and this list says what | |
343 | types are most unwanted. If, for instance, @samp{text/html} parts are | |
344 | very unwanted, and @samp{text/richtext} parts are somewhat unwanted, | |
345 | you could say something like: | |
346 | ||
347 | @lisp | |
348 | (setq mm-discouraged-alternatives | |
349 | '("text/html" "text/richtext") | |
350 | mm-automatic-display | |
351 | (remove "text/html" mm-automatic-display)) | |
352 | @end lisp | |
353 | ||
354 | Adding @code{"image/.*"} might also be useful. Spammers use images as | |
355 | the preferred part of @samp{multipart/alternative} messages, so you might | |
356 | not notice there are other parts. See also | |
357 | @code{gnus-buttonized-mime-types}, @ref{MIME Commands, ,MIME Commands, | |
358 | gnus, Gnus Manual}. After adding @code{"multipart/alternative"} to | |
359 | @code{gnus-buttonized-mime-types} you can choose manually which | |
360 | alternative you'd like to view. For example, you can set those | |
361 | variables like: | |
362 | ||
363 | @lisp | |
364 | (setq gnus-buttonized-mime-types | |
365 | '("multipart/alternative" "multipart/signed") | |
366 | mm-discouraged-alternatives | |
367 | '("text/html" "image/.*")) | |
368 | @end lisp | |
369 | ||
370 | In this case, Gnus will display radio buttons for such a kind of spam | |
371 | message as follows: | |
372 | ||
373 | @example | |
374 | 1. (*) multipart/alternative ( ) image/gif | |
375 | ||
376 | 2. (*) text/plain ( ) text/html | |
377 | @end example | |
378 | ||
379 | @item mm-inline-large-images | |
380 | @vindex mm-inline-large-images | |
381 | When displaying inline images that are larger than the window, Emacs | |
382 | does not enable scrolling, which means that you cannot see the whole | |
a41c2e6d | 383 | image. To prevent this, the library tries to determine the image size |
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384 | before displaying it inline, and if it doesn't fit the window, the |
385 | library will display it externally (e.g. with @samp{ImageMagick} or | |
a41c2e6d | 386 | @samp{xv}). Setting this variable to @code{t} disables this check and |
4009494e | 387 | makes the library display all inline images as inline, regardless of |
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388 | their size. If you set this variable to @code{resize}, the image will |
389 | be displayed resized to fit in the window, if Emacs has the ability to | |
390 | resize images. | |
391 | ||
392 | @item mm-inline-large-images-proportion | |
393 | @vindex mm-inline-images-max-proportion | |
394 | The proportion used when resizing large images. | |
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395 | |
396 | @item mm-inline-override-types | |
397 | @vindex mm-inline-override-types | |
398 | @code{mm-inlined-types} may include regular expressions, for example to | |
399 | specify that all @samp{text/.*} parts be displayed inline. If a user | |
400 | prefers to have a type that matches such a regular expression be treated | |
401 | as an attachment, that can be accomplished by setting this variable to a | |
402 | list containing that type. For example assuming @code{mm-inlined-types} | |
403 | includes @samp{text/.*}, then including @samp{text/html} in this | |
404 | variable will cause @samp{text/html} parts to be treated as attachments. | |
405 | ||
406 | @item mm-text-html-renderer | |
407 | @vindex mm-text-html-renderer | |
408 | This selects the function used to render @acronym{HTML}. The predefined | |
85115796 | 409 | renderers are selected by the symbols @code{gnus-article-html}, @code{w3}, |
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410 | @code{w3m}@footnote{See @uref{http://emacs-w3m.namazu.org/} for more |
411 | information about emacs-w3m}, @code{links}, @code{lynx}, | |
412 | @code{w3m-standalone} or @code{html2text}. If @code{nil} use an | |
413 | external viewer. You can also specify a function, which will be | |
414 | called with a @acronym{MIME} handle as the argument. | |
415 | ||
416 | @item mm-inline-text-html-with-images | |
417 | @vindex mm-inline-text-html-with-images | |
418 | Some @acronym{HTML} mails might have the trick of spammers using | |
419 | @samp{<img>} tags. It is likely to be intended to verify whether you | |
333f9019 | 420 | have read the mail. You can prevent your personal information from |
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421 | leaking by setting this option to @code{nil} (which is the default). |
422 | It is currently ignored by Emacs/w3. For emacs-w3m, you may use the | |
423 | command @kbd{t} on the image anchor to show an image even if it is | |
424 | @code{nil}.@footnote{The command @kbd{T} will load all images. If you | |
425 | have set the option @code{w3m-key-binding} to @code{info}, use @kbd{i} | |
426 | or @kbd{I} instead.} | |
427 | ||
428 | @item mm-w3m-safe-url-regexp | |
429 | @vindex mm-w3m-safe-url-regexp | |
430 | A regular expression that matches safe URL names, i.e. URLs that are | |
431 | unlikely to leak personal information when rendering @acronym{HTML} | |
432 | email (the default value is @samp{\\`cid:}). If @code{nil} consider | |
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433 | all URLs safe. In Gnus, this will be overridden according to the value |
434 | of the variable @code{gnus-safe-html-newsgroups}, @xref{Various | |
435 | Various, ,Various Various, gnus, Gnus Manual}. | |
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436 | |
437 | @item mm-inline-text-html-with-w3m-keymap | |
438 | @vindex mm-inline-text-html-with-w3m-keymap | |
439 | You can use emacs-w3m command keys in the inlined text/html part by | |
440 | setting this option to non-@code{nil}. The default value is @code{t}. | |
441 | ||
442 | @item mm-external-terminal-program | |
443 | @vindex mm-external-terminal-program | |
444 | The program used to start an external terminal. | |
445 | ||
446 | @item mm-enable-external | |
447 | @vindex mm-enable-external | |
448 | Indicate whether external @acronym{MIME} handlers should be used. | |
449 | ||
450 | If @code{t}, all defined external @acronym{MIME} handlers are used. If | |
451 | @code{nil}, files are saved to disk (@code{mailcap-save-binary-file}). | |
452 | If it is the symbol @code{ask}, you are prompted before the external | |
453 | @acronym{MIME} handler is invoked. | |
454 | ||
455 | When you launch an attachment through mailcap (@pxref{mailcap}) an | |
456 | attempt is made to use a safe viewer with the safest options---this isn't | |
457 | the case if you save it to disk and launch it in a different way | |
458 | (command line or double-clicking). Anyhow, if you want to be sure not | |
459 | to launch any external programs, set this variable to @code{nil} or | |
460 | @code{ask}. | |
461 | ||
462 | @end table | |
463 | ||
464 | @node Files and Directories | |
465 | @section Files and Directories | |
466 | ||
467 | @table @code | |
468 | ||
469 | @item mm-default-directory | |
470 | @vindex mm-default-directory | |
471 | The default directory for saving attachments. If @code{nil} use | |
472 | @code{default-directory}. | |
473 | ||
474 | @item mm-tmp-directory | |
475 | @vindex mm-tmp-directory | |
476 | Directory for storing temporary files. | |
477 | ||
478 | @item mm-file-name-rewrite-functions | |
479 | @vindex mm-file-name-rewrite-functions | |
480 | A list of functions used for rewriting file names of @acronym{MIME} | |
481 | parts. Each function is applied successively to the file name. | |
482 | Ready-made functions include | |
483 | ||
484 | @table @code | |
485 | @item mm-file-name-delete-control | |
486 | @findex mm-file-name-delete-control | |
487 | Delete all control characters. | |
488 | ||
489 | @item mm-file-name-delete-gotchas | |
490 | @findex mm-file-name-delete-gotchas | |
491 | Delete characters that could have unintended consequences when used | |
492 | with flawed shell scripts, i.e. @samp{|}, @samp{>} and @samp{<}; and | |
493 | @samp{-}, @samp{.} as the first character. | |
494 | ||
495 | @item mm-file-name-delete-whitespace | |
496 | @findex mm-file-name-delete-whitespace | |
497 | Remove all whitespace. | |
498 | ||
499 | @item mm-file-name-trim-whitespace | |
500 | @findex mm-file-name-trim-whitespace | |
501 | Remove leading and trailing whitespace. | |
502 | ||
503 | @item mm-file-name-collapse-whitespace | |
504 | @findex mm-file-name-collapse-whitespace | |
505 | Collapse multiple whitespace characters. | |
506 | ||
507 | @item mm-file-name-replace-whitespace | |
508 | @findex mm-file-name-replace-whitespace | |
509 | @vindex mm-file-name-replace-whitespace | |
510 | Replace whitespace with underscores. Set the variable | |
511 | @code{mm-file-name-replace-whitespace} to any other string if you do | |
512 | not like underscores. | |
513 | @end table | |
514 | ||
515 | The standard Emacs functions @code{capitalize}, @code{downcase}, | |
516 | @code{upcase} and @code{upcase-initials} might also prove useful. | |
517 | ||
518 | @item mm-path-name-rewrite-functions | |
519 | @vindex mm-path-name-rewrite-functions | |
520 | List of functions used for rewriting the full file names of @acronym{MIME} | |
521 | parts. This is used when viewing parts externally, and is meant for | |
522 | transforming the absolute name so that non-compliant programs can find | |
523 | the file where it's saved. | |
524 | ||
525 | @end table | |
526 | ||
527 | @node New Viewers | |
528 | @section New Viewers | |
529 | ||
530 | Here's an example viewer for displaying @code{text/enriched} inline: | |
531 | ||
532 | @lisp | |
533 | (defun mm-display-enriched-inline (handle) | |
534 | (let (text) | |
535 | (with-temp-buffer | |
536 | (mm-insert-part handle) | |
537 | (save-window-excursion | |
538 | (enriched-decode (point-min) (point-max)) | |
539 | (setq text (buffer-string)))) | |
540 | (mm-insert-inline handle text))) | |
541 | @end lisp | |
542 | ||
543 | We see that the function takes a @acronym{MIME} handle as its parameter. It | |
544 | then goes to a temporary buffer, inserts the text of the part, does some | |
545 | work on the text, stores the result, goes back to the buffer it was | |
546 | called from and inserts the result. | |
547 | ||
548 | The two important helper functions here are @code{mm-insert-part} and | |
549 | @code{mm-insert-inline}. The first function inserts the text of the | |
550 | handle in the current buffer. It handles charset and/or content | |
551 | transfer decoding. The second function just inserts whatever text you | |
552 | tell it to insert, but it also sets things up so that the text can be | |
553 | ``undisplayed'' in a convenient manner. | |
554 | ||
555 | ||
556 | @node Composing | |
557 | @chapter Composing | |
558 | @cindex Composing | |
559 | @cindex MIME Composing | |
560 | @cindex MML | |
561 | @cindex MIME Meta Language | |
562 | ||
563 | Creating a @acronym{MIME} message is boring and non-trivial. Therefore, | |
564 | a library called @code{mml} has been defined that parses a language | |
565 | called @acronym{MML} (@acronym{MIME} Meta Language) and generates | |
566 | @acronym{MIME} messages. | |
567 | ||
568 | @findex mml-generate-mime | |
569 | The main interface function is @code{mml-generate-mime}. It will | |
570 | examine the contents of the current (narrowed-to) buffer and return a | |
571 | string containing the @acronym{MIME} message. | |
572 | ||
573 | @menu | |
574 | * Simple MML Example:: An example @acronym{MML} document. | |
575 | * MML Definition:: All valid @acronym{MML} elements. | |
576 | * Advanced MML Example:: Another example @acronym{MML} document. | |
577 | * Encoding Customization:: Variables that affect encoding. | |
578 | * Charset Translation:: How charsets are mapped from @sc{mule} to @acronym{MIME}. | |
579 | * Conversion:: Going from @acronym{MIME} to @acronym{MML} and vice versa. | |
580 | * Flowed text:: Soft and hard newlines. | |
581 | @end menu | |
582 | ||
583 | ||
584 | @node Simple MML Example | |
585 | @section Simple MML Example | |
586 | ||
587 | Here's a simple @samp{multipart/alternative}: | |
588 | ||
589 | @example | |
590 | <#multipart type=alternative> | |
591 | This is a plain text part. | |
592 | <#part type=text/enriched> | |
593 | <center>This is a centered enriched part</center> | |
594 | <#/multipart> | |
595 | @end example | |
596 | ||
597 | After running this through @code{mml-generate-mime}, we get this: | |
598 | ||
599 | @example | |
600 | Content-Type: multipart/alternative; boundary="=-=-=" | |
601 | ||
602 | ||
603 | --=-=-= | |
604 | ||
605 | ||
606 | This is a plain text part. | |
607 | ||
608 | --=-=-= | |
609 | Content-Type: text/enriched | |
610 | ||
611 | ||
612 | <center>This is a centered enriched part</center> | |
613 | ||
614 | --=-=-=-- | |
615 | @end example | |
616 | ||
617 | ||
618 | @node MML Definition | |
619 | @section MML Definition | |
620 | ||
621 | The @acronym{MML} language is very simple. It looks a bit like an SGML | |
622 | application, but it's not. | |
623 | ||
624 | The main concept of @acronym{MML} is the @dfn{part}. Each part can be of a | |
625 | different type or use a different charset. The way to delineate a part | |
626 | is with a @samp{<#part ...>} tag. Multipart parts can be introduced | |
627 | with the @samp{<#multipart ...>} tag. Parts are ended by the | |
628 | @samp{<#/part>} or @samp{<#/multipart>} tags. Parts started with the | |
629 | @samp{<#part ...>} tags are also closed by the next open tag. | |
630 | ||
631 | There's also the @samp{<#external ...>} tag. These introduce | |
632 | @samp{external/message-body} parts. | |
633 | ||
634 | Each tag can contain zero or more parameters on the form | |
635 | @samp{parameter=value}. The values may be enclosed in quotation marks, | |
636 | but that's not necessary unless the value contains white space. So | |
637 | @samp{filename=/home/user/#hello$^yes} is perfectly valid. | |
638 | ||
639 | The following parameters have meaning in @acronym{MML}; parameters that have no | |
640 | meaning are ignored. The @acronym{MML} parameter names are the same as the | |
641 | @acronym{MIME} parameter names; the things in the parentheses say which | |
642 | header it will be used in. | |
643 | ||
644 | @table @samp | |
645 | @item type | |
646 | The @acronym{MIME} type of the part (@code{Content-Type}). | |
647 | ||
648 | @item filename | |
649 | Use the contents of the file in the body of the part | |
650 | (@code{Content-Disposition}). | |
651 | ||
652 | @item charset | |
653 | The contents of the body of the part are to be encoded in the character | |
654 | set specified (@code{Content-Type}). @xref{Charset Translation}. | |
655 | ||
656 | @item name | |
657 | Might be used to suggest a file name if the part is to be saved | |
658 | to a file (@code{Content-Type}). | |
659 | ||
660 | @item disposition | |
661 | Valid values are @samp{inline} and @samp{attachment} | |
662 | (@code{Content-Disposition}). | |
663 | ||
664 | @item encoding | |
665 | Valid values are @samp{7bit}, @samp{8bit}, @samp{quoted-printable} and | |
666 | @samp{base64} (@code{Content-Transfer-Encoding}). @xref{Charset | |
667 | Translation}. | |
668 | ||
669 | @item description | |
670 | A description of the part (@code{Content-Description}). | |
671 | ||
672 | @item creation-date | |
673 | RFC822 date when the part was created (@code{Content-Disposition}). | |
674 | ||
675 | @item modification-date | |
676 | RFC822 date when the part was modified (@code{Content-Disposition}). | |
677 | ||
678 | @item read-date | |
679 | RFC822 date when the part was read (@code{Content-Disposition}). | |
680 | ||
681 | @item recipients | |
682 | Who to encrypt/sign the part to. This field is used to override any | |
683 | auto-detection based on the To/CC headers. | |
684 | ||
685 | @item sender | |
686 | Identity used to sign the part. This field is used to override the | |
687 | default key used. | |
688 | ||
689 | @item size | |
690 | The size (in octets) of the part (@code{Content-Disposition}). | |
691 | ||
692 | @item sign | |
693 | What technology to sign this @acronym{MML} part with (@code{smime}, @code{pgp} | |
694 | or @code{pgpmime}) | |
695 | ||
696 | @item encrypt | |
697 | What technology to encrypt this @acronym{MML} part with (@code{smime}, | |
698 | @code{pgp} or @code{pgpmime}) | |
699 | ||
700 | @end table | |
701 | ||
702 | Parameters for @samp{text/plain}: | |
703 | ||
704 | @table @samp | |
705 | @item format | |
706 | Formatting parameter for the text, valid values include @samp{fixed} | |
707 | (the default) and @samp{flowed}. Normally you do not specify this | |
708 | manually, since it requires the textual body to be formatted in a | |
709 | special way described in RFC 2646. @xref{Flowed text}. | |
710 | @end table | |
711 | ||
712 | Parameters for @samp{application/octet-stream}: | |
713 | ||
714 | @table @samp | |
715 | @item type | |
716 | Type of the part; informal---meant for human readers | |
717 | (@code{Content-Type}). | |
718 | @end table | |
719 | ||
720 | Parameters for @samp{message/external-body}: | |
721 | ||
722 | @table @samp | |
723 | @item access-type | |
724 | A word indicating the supported access mechanism by which the file may | |
725 | be obtained. Values include @samp{ftp}, @samp{anon-ftp}, @samp{tftp}, | |
726 | @samp{localfile}, and @samp{mailserver}. (@code{Content-Type}.) | |
727 | ||
728 | @item expiration | |
729 | The RFC822 date after which the file may no longer be fetched. | |
730 | (@code{Content-Type}.) | |
731 | ||
732 | @item size | |
733 | The size (in octets) of the file. (@code{Content-Type}.) | |
734 | ||
735 | @item permission | |
736 | Valid values are @samp{read} and @samp{read-write} | |
737 | (@code{Content-Type}). | |
738 | ||
739 | @end table | |
740 | ||
741 | Parameters for @samp{sign=smime}: | |
742 | ||
743 | @table @samp | |
744 | ||
745 | @item keyfile | |
746 | File containing key and certificate for signer. | |
747 | ||
748 | @end table | |
749 | ||
750 | Parameters for @samp{encrypt=smime}: | |
751 | ||
752 | @table @samp | |
753 | ||
754 | @item certfile | |
755 | File containing certificate for recipient. | |
756 | ||
757 | @end table | |
758 | ||
759 | ||
760 | @node Advanced MML Example | |
761 | @section Advanced MML Example | |
762 | ||
763 | Here's a complex multipart message. It's a @samp{multipart/mixed} that | |
764 | contains many parts, one of which is a @samp{multipart/alternative}. | |
765 | ||
766 | @example | |
767 | <#multipart type=mixed> | |
768 | <#part type=image/jpeg filename=~/rms.jpg disposition=inline> | |
769 | <#multipart type=alternative> | |
770 | This is a plain text part. | |
771 | <#part type=text/enriched name=enriched.txt> | |
772 | <center>This is a centered enriched part</center> | |
773 | <#/multipart> | |
774 | This is a new plain text part. | |
775 | <#part disposition=attachment> | |
776 | This plain text part is an attachment. | |
777 | <#/multipart> | |
778 | @end example | |
779 | ||
780 | And this is the resulting @acronym{MIME} message: | |
781 | ||
782 | @example | |
783 | Content-Type: multipart/mixed; boundary="=-=-=" | |
784 | ||
785 | ||
786 | --=-=-= | |
787 | ||
788 | ||
789 | ||
790 | --=-=-= | |
791 | Content-Type: image/jpeg; | |
792 | filename="~/rms.jpg" | |
793 | Content-Disposition: inline; | |
794 | filename="~/rms.jpg" | |
795 | Content-Transfer-Encoding: base64 | |
796 | ||
797 | /9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRof | |
798 | Hh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/wAALCAAwADABAREA/8QAHwAA | |
799 | AQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQAAAF9AQIDAAQR | |
800 | BRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3ODk6Q0RF | |
801 | RkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWmp6ip | |
802 | qrKztLW2t7i5usLDxMXGx8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/9oACAEB | |
803 | AAA/AO/rifFHjldNuGsrDa0qcSSHkA+gHrXKw+LtWLrMb+RgTyhbr+HSug07xNqV9fQtZrNI | |
804 | AyiaE/NuBPOOOP0rvRNE880KOC8TbXXGCv1FPqjrF4LDR7u5L7SkTFT/ALWOP1xXgTuXfc7E | |
805 | sx6nua6rwp4IvvEM8chCxWxOdzn7wz6V9AaB4S07w9p5itow0rDLSY5Pt9K43xO66P4xs71m | |
806 | 2QXiGCbA4yOVJ9+1aYORkdK434lyNH4ahCnG66VT9Nj15JFbPdX0MS43M4VQf5/yr2vSpLnw | |
807 | 5ZW8dlCZ8KFXjOPX0/mK6rSPEGt3Angu44fNEReHYNvIH3TzXDeKNO8RX+kSX2ouZkicTIOc | |
808 | L+g7E810ulFjpVtv3bwgB3HJyK5L4quY/C9sVxk3ij/xx6850u7t1mtp/wDlpEw3An3Jr3Dw | |
809 | 34gsbWza4nBlhC5LDsaW6+IFgupQyCF3iHH7gA7c9R9ay7zx6t7aX9jHC4smhfBkGCvHGfrm | |
810 | tLQ7hbnRrV1GPkAP1x1/Hr+Ncr8Vzjwrbf8AX6v/AKA9eQRyYlQk8Yx9K6XTNbkgia2ciSIn | |
811 | 7p5Ga9Atte0LTLKO6it4i7dVRFJDcZ4PvXN+JvEMF9bILVGXJLSZ4zkjivRPDaeX4b08HOTC | |
812 | pOffmua+KkbS+GLVUGT9tT/0B68eeIpIFYjB70+OOVXyoOM9+M1eaWeCLzHPyHGO/NVWvJJm | |
813 | jQ8KGH1NfQWhXSXmh2c8eArRLwO3HSv/2Q== | |
814 | ||
815 | --=-=-= | |
816 | Content-Type: multipart/alternative; boundary="==-=-=" | |
817 | ||
818 | ||
819 | --==-=-= | |
820 | ||
821 | ||
822 | This is a plain text part. | |
823 | ||
824 | --==-=-= | |
825 | Content-Type: text/enriched; | |
826 | name="enriched.txt" | |
827 | ||
828 | ||
829 | <center>This is a centered enriched part</center> | |
830 | ||
831 | --==-=-=-- | |
832 | ||
833 | --=-=-= | |
834 | ||
835 | This is a new plain text part. | |
836 | ||
837 | --=-=-= | |
838 | Content-Disposition: attachment | |
839 | ||
840 | ||
841 | This plain text part is an attachment. | |
842 | ||
843 | --=-=-=-- | |
844 | @end example | |
845 | ||
846 | @node Encoding Customization | |
847 | @section Encoding Customization | |
848 | ||
849 | @table @code | |
850 | ||
851 | @item mm-body-charset-encoding-alist | |
852 | @vindex mm-body-charset-encoding-alist | |
853 | Mapping from @acronym{MIME} charset to encoding to use. This variable is | |
854 | usually used except, e.g., when other requirements force a specific | |
855 | encoding (digitally signed messages require 7bit encodings). The | |
856 | default is | |
857 | ||
858 | @lisp | |
859 | ((iso-2022-jp . 7bit) | |
860 | (iso-2022-jp-2 . 7bit) | |
861 | (utf-16 . base64) | |
862 | (utf-16be . base64) | |
863 | (utf-16le . base64)) | |
864 | @end lisp | |
865 | ||
866 | As an example, if you do not want to have ISO-8859-1 characters | |
867 | quoted-printable encoded, you may add @code{(iso-8859-1 . 8bit)} to | |
868 | this variable. You can override this setting on a per-message basis | |
869 | by using the @code{encoding} @acronym{MML} tag (@pxref{MML Definition}). | |
870 | ||
871 | @item mm-coding-system-priorities | |
872 | @vindex mm-coding-system-priorities | |
873 | Prioritize coding systems to use for outgoing messages. The default | |
874 | is @code{nil}, which means to use the defaults in Emacs, but is | |
875 | @code{(iso-8859-1 iso-2022-jp iso-2022-jp-2 shift_jis utf-8)} when | |
876 | running Emacs in the Japanese language environment. It is a list of | |
877 | coding system symbols (aliases of coding systems are also allowed, use | |
878 | @kbd{M-x describe-coding-system} to make sure you are specifying correct | |
879 | coding system names). For example, if you have configured Emacs | |
880 | to prefer UTF-8, but wish that outgoing messages should be sent in | |
881 | ISO-8859-1 if possible, you can set this variable to | |
882 | @code{(iso-8859-1)}. You can override this setting on a per-message | |
883 | basis by using the @code{charset} @acronym{MML} tag (@pxref{MML Definition}). | |
884 | ||
01c52d31 MB |
885 | As different hierarchies prefer different charsets, you may want to set |
886 | @code{mm-coding-system-priorities} according to the hierarchy in Gnus. | |
887 | Here's an example: | |
888 | ||
889 | @c Corrections about preferred charsets are welcome. de, fr and fj | |
890 | @c should be correct, I don't know about the rest (so these are only | |
891 | @c examples): | |
892 | @lisp | |
893 | (add-to-list 'gnus-newsgroup-variables 'mm-coding-system-priorities) | |
894 | (setq gnus-parameters | |
895 | (nconc | |
896 | ;; Some charsets are just examples! | |
897 | '(("^cn\\." ;; Chinese | |
898 | (mm-coding-system-priorities | |
899 | '(iso-8859-1 cn-big5 chinese-iso-7bit utf-8))) | |
900 | ("^cz\\.\\|^pl\\." ;; Central and Eastern European | |
901 | (mm-coding-system-priorities '(iso-8859-2 utf-8))) | |
902 | ("^de\\." ;; German language | |
903 | (mm-coding-system-priorities '(iso-8859-1 iso-8859-15 utf-8))) | |
904 | ("^fr\\." ;; French | |
905 | (mm-coding-system-priorities '(iso-8859-15 iso-8859-1 utf-8))) | |
906 | ("^fj\\." ;; Japanese | |
907 | (mm-coding-system-priorities | |
908 | '(iso-8859-1 iso-2022-jp iso-2022-jp-2 shift_jis utf-8))) | |
909 | ("^ru\\." ;; Cyrillic | |
910 | (mm-coding-system-priorities | |
911 | '(koi8-r iso-8859-5 iso-8859-1 utf-8)))) | |
912 | gnus-parameters)) | |
913 | @end lisp | |
914 | ||
4009494e GM |
915 | @item mm-content-transfer-encoding-defaults |
916 | @vindex mm-content-transfer-encoding-defaults | |
917 | Mapping from @acronym{MIME} types to encoding to use. This variable is usually | |
918 | used except, e.g., when other requirements force a safer encoding | |
919 | (digitally signed messages require 7bit encoding). Besides the normal | |
920 | @acronym{MIME} encodings, @code{qp-or-base64} may be used to indicate that for | |
921 | each case the most efficient of quoted-printable and base64 should be | |
922 | used. | |
923 | ||
924 | @code{qp-or-base64} has another effect. It will fold long lines so that | |
925 | MIME parts may not be broken by MTA. So do @code{quoted-printable} and | |
926 | @code{base64}. | |
927 | ||
928 | Note that it affects body encoding only when a part is a raw forwarded | |
929 | message (which will be made by @code{gnus-summary-mail-forward} with the | |
930 | arg 2 for example) or is neither the @samp{text/*} type nor the | |
931 | @samp{message/*} type. Even though in those cases, you can override | |
932 | this setting on a per-message basis by using the @code{encoding} | |
933 | @acronym{MML} tag (@pxref{MML Definition}). | |
934 | ||
935 | @item mm-use-ultra-safe-encoding | |
936 | @vindex mm-use-ultra-safe-encoding | |
937 | When this is non-@code{nil}, it means that textual parts are encoded as | |
938 | quoted-printable if they contain lines longer than 76 characters or | |
939 | starting with "From " in the body. Non-7bit encodings (8bit, binary) | |
940 | are generally disallowed. This reduce the probability that a non-8bit | |
941 | clean MTA or MDA changes the message. This should never be set | |
942 | directly, but bound by other functions when necessary (e.g., when | |
943 | encoding messages that are to be digitally signed). | |
944 | ||
945 | @end table | |
946 | ||
947 | @node Charset Translation | |
948 | @section Charset Translation | |
949 | @cindex charsets | |
950 | ||
951 | During translation from @acronym{MML} to @acronym{MIME}, for each | |
952 | @acronym{MIME} part which has been composed inside Emacs, an appropriate | |
953 | charset has to be chosen. | |
954 | ||
955 | @vindex mail-parse-charset | |
956 | If you are running a non-@sc{mule} Emacs, this process is simple: If the | |
957 | part contains any non-@acronym{ASCII} (8-bit) characters, the @acronym{MIME} charset | |
958 | given by @code{mail-parse-charset} (a symbol) is used. (Never set this | |
959 | variable directly, though. If you want to change the default charset, | |
960 | please consult the documentation of the package which you use to process | |
961 | @acronym{MIME} messages. | |
962 | @xref{Various Message Variables, , Various Message Variables, message, | |
963 | Message Manual}, for example.) | |
964 | If there are only @acronym{ASCII} characters, the @acronym{MIME} charset US-ASCII is | |
965 | used, of course. | |
966 | ||
967 | @cindex MULE | |
968 | @cindex UTF-8 | |
969 | @cindex Unicode | |
970 | @vindex mm-mime-mule-charset-alist | |
971 | Things are slightly more complicated when running Emacs with @sc{mule} | |
972 | support. In this case, a list of the @sc{mule} charsets used in the | |
973 | part is obtained, and the @sc{mule} charsets are translated to | |
974 | @acronym{MIME} charsets by consulting the table provided by Emacs itself | |
975 | or the variable @code{mm-mime-mule-charset-alist} for XEmacs. | |
976 | If this results in a single @acronym{MIME} charset, this is used to encode | |
977 | the part. But if the resulting list of @acronym{MIME} charsets contains more | |
978 | than one element, two things can happen: If it is possible to encode the | |
979 | part via UTF-8, this charset is used. (For this, Emacs must support | |
980 | the @code{utf-8} coding system, and the part must consist entirely of | |
981 | characters which have Unicode counterparts.) If UTF-8 is not available | |
982 | for some reason, the part is split into several ones, so that each one | |
983 | can be encoded with a single @acronym{MIME} charset. The part can only be | |
984 | split at line boundaries, though---if more than one @acronym{MIME} charset is | |
985 | required to encode a single line, it is not possible to encode the part. | |
986 | ||
987 | When running Emacs with @sc{mule} support, the preferences for which | |
988 | coding system to use is inherited from Emacs itself. This means that | |
989 | if Emacs is set up to prefer UTF-8, it will be used when encoding | |
990 | messages. You can modify this by altering the | |
991 | @code{mm-coding-system-priorities} variable though (@pxref{Encoding | |
992 | Customization}). | |
993 | ||
994 | The charset to be used can be overridden by setting the @code{charset} | |
995 | @acronym{MML} tag (@pxref{MML Definition}) when composing the message. | |
996 | ||
997 | The encoding of characters (quoted-printable, 8bit etc) is orthogonal | |
998 | to the discussion here, and is controlled by the variables | |
999 | @code{mm-body-charset-encoding-alist} and | |
1000 | @code{mm-content-transfer-encoding-defaults} (@pxref{Encoding | |
1001 | Customization}). | |
1002 | ||
1003 | @node Conversion | |
1004 | @section Conversion | |
1005 | ||
1006 | @findex mime-to-mml | |
1007 | A (multipart) @acronym{MIME} message can be converted to @acronym{MML} | |
1008 | with the @code{mime-to-mml} function. It works on the message in the | |
1009 | current buffer, and substitutes @acronym{MML} markup for @acronym{MIME} | |
1010 | boundaries. Non-textual parts do not have their contents in the buffer, | |
1011 | but instead have the contents in separate buffers that are referred to | |
1012 | from the @acronym{MML} tags. | |
1013 | ||
1014 | @findex mml-to-mime | |
1015 | An @acronym{MML} message can be converted back to @acronym{MIME} by the | |
1016 | @code{mml-to-mime} function. | |
1017 | ||
1018 | These functions are in certain senses ``lossy''---you will not get back | |
1019 | an identical message if you run @code{mime-to-mml} and then | |
1020 | @code{mml-to-mime}. Not only will trivial things like the order of the | |
1021 | headers differ, but the contents of the headers may also be different. | |
1022 | For instance, the original message may use base64 encoding on text, | |
1023 | while @code{mml-to-mime} may decide to use quoted-printable encoding, and | |
1024 | so on. | |
1025 | ||
1026 | In essence, however, these two functions should be the inverse of each | |
1027 | other. The resulting contents of the message should remain equivalent, | |
1028 | if not identical. | |
1029 | ||
1030 | ||
1031 | @node Flowed text | |
1032 | @section Flowed text | |
1033 | @cindex format=flowed | |
1034 | ||
1035 | The Emacs @acronym{MIME} library will respect the @code{use-hard-newlines} | |
1036 | variable (@pxref{Hard and Soft Newlines, ,Hard and Soft Newlines, | |
1037 | emacs, Emacs Manual}) when encoding a message, and the | |
1038 | ``format=flowed'' Content-Type parameter when decoding a message. | |
1039 | ||
1040 | On encoding text, regardless of @code{use-hard-newlines}, lines | |
1041 | terminated by soft newline characters are filled together and wrapped | |
1042 | after the column decided by @code{fill-flowed-encode-column}. | |
1043 | Quotation marks (matching @samp{^>* ?}) are respected. The variable | |
1044 | controls how the text will look in a client that does not support | |
1045 | flowed text, the default is to wrap after 66 characters. If hard | |
1046 | newline characters are not present in the buffer, no flow encoding | |
1047 | occurs. | |
1048 | ||
ba91f05d G |
1049 | You can customize the value of the @code{mml-enable-flowed} variable |
1050 | to enable or disable the flowed encoding usage when newline | |
da6062e6 | 1051 | characters are present in the buffer. |
ba91f05d | 1052 | |
4009494e GM |
1053 | On decoding flowed text, lines with soft newline characters are filled |
1054 | together and wrapped after the column decided by | |
1055 | @code{fill-flowed-display-column}. The default is to wrap after | |
1056 | @code{fill-column}. | |
1057 | ||
1058 | @table @code | |
1059 | @item mm-fill-flowed | |
1060 | @vindex mm-fill-flowed | |
1061 | If non-@code{nil} a format=flowed article will be displayed flowed. | |
1062 | @end table | |
1063 | ||
1064 | ||
1065 | @node Interface Functions | |
1066 | @chapter Interface Functions | |
1067 | @cindex interface functions | |
1068 | @cindex mail-parse | |
1069 | ||
1070 | The @code{mail-parse} library is an abstraction over the actual | |
1071 | low-level libraries that are described in the next chapter. | |
1072 | ||
1073 | Standards change, and so programs have to change to fit in the new | |
1074 | mold. For instance, RFC2045 describes a syntax for the | |
1075 | @code{Content-Type} header that only allows @acronym{ASCII} characters in the | |
1076 | parameter list. RFC2231 expands on RFC2045 syntax to provide a scheme | |
1077 | for continuation headers and non-@acronym{ASCII} characters. | |
1078 | ||
1079 | The traditional way to deal with this is just to update the library | |
1080 | functions to parse the new syntax. However, this is sometimes the wrong | |
1081 | thing to do. In some instances it may be vital to be able to understand | |
1082 | both the old syntax as well as the new syntax, and if there is only one | |
1083 | library, one must choose between the old version of the library and the | |
1084 | new version of the library. | |
1085 | ||
1086 | The Emacs @acronym{MIME} library takes a different tack. It defines a | |
1087 | series of low-level libraries (@file{rfc2047.el}, @file{rfc2231.el} | |
1088 | and so on) that parses strictly according to the corresponding | |
1089 | standard. However, normal programs would not use the functions | |
1090 | provided by these libraries directly, but instead use the functions | |
1091 | provided by the @code{mail-parse} library. The functions in this | |
1092 | library are just aliases to the corresponding functions in the latest | |
1093 | low-level libraries. Using this scheme, programs get a consistent | |
1094 | interface they can use, and library developers are free to create | |
1095 | write code that handles new standards. | |
1096 | ||
1097 | The following functions are defined by this library: | |
1098 | ||
1099 | @table @code | |
1100 | @item mail-header-parse-content-type | |
1101 | @findex mail-header-parse-content-type | |
1102 | Parse a @code{Content-Type} header and return a list on the following | |
1103 | format: | |
1104 | ||
1105 | @lisp | |
1106 | ("type/subtype" | |
1107 | (attribute1 . value1) | |
1108 | (attribute2 . value2) | |
1109 | ...) | |
1110 | @end lisp | |
1111 | ||
1112 | Here's an example: | |
1113 | ||
1114 | @example | |
1115 | (mail-header-parse-content-type | |
1116 | "image/gif; name=\"b980912.gif\"") | |
1117 | @result{} ("image/gif" (name . "b980912.gif")) | |
1118 | @end example | |
1119 | ||
1120 | @item mail-header-parse-content-disposition | |
1121 | @findex mail-header-parse-content-disposition | |
1122 | Parse a @code{Content-Disposition} header and return a list on the same | |
1123 | format as the function above. | |
1124 | ||
1125 | @item mail-content-type-get | |
1126 | @findex mail-content-type-get | |
1127 | Takes two parameters---a list on the format above, and an attribute. | |
1128 | Returns the value of the attribute. | |
1129 | ||
1130 | @example | |
1131 | (mail-content-type-get | |
1132 | '("image/gif" (name . "b980912.gif")) 'name) | |
1133 | @result{} "b980912.gif" | |
1134 | @end example | |
1135 | ||
1136 | @item mail-header-encode-parameter | |
1137 | @findex mail-header-encode-parameter | |
1138 | Takes a parameter string and returns an encoded version of the string. | |
1139 | This is used for parameters in headers like @code{Content-Type} and | |
1140 | @code{Content-Disposition}. | |
1141 | ||
1142 | @item mail-header-remove-comments | |
1143 | @findex mail-header-remove-comments | |
1144 | Return a comment-free version of a header. | |
1145 | ||
1146 | @example | |
1147 | (mail-header-remove-comments | |
1148 | "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)") | |
1149 | @result{} "Gnus/5.070027 " | |
1150 | @end example | |
1151 | ||
1152 | @item mail-header-remove-whitespace | |
1153 | @findex mail-header-remove-whitespace | |
1154 | Remove linear white space from a header. Space inside quoted strings | |
1155 | and comments is preserved. | |
1156 | ||
1157 | @example | |
1158 | (mail-header-remove-whitespace | |
1159 | "image/gif; name=\"Name with spaces\"") | |
1160 | @result{} "image/gif;name=\"Name with spaces\"" | |
1161 | @end example | |
1162 | ||
1163 | @item mail-header-get-comment | |
1164 | @findex mail-header-get-comment | |
1165 | Return the last comment in a header. | |
1166 | ||
1167 | @example | |
1168 | (mail-header-get-comment | |
1169 | "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)") | |
1170 | @result{} "Finnish Landrace" | |
1171 | @end example | |
1172 | ||
1173 | @item mail-header-parse-address | |
1174 | @findex mail-header-parse-address | |
1175 | Parse an address and return a list containing the mailbox and the | |
1176 | plaintext name. | |
1177 | ||
1178 | @example | |
1179 | (mail-header-parse-address | |
1180 | "Hrvoje Niksic <hniksic@@srce.hr>") | |
1181 | @result{} ("hniksic@@srce.hr" . "Hrvoje Niksic") | |
1182 | @end example | |
1183 | ||
1184 | @item mail-header-parse-addresses | |
1185 | @findex mail-header-parse-addresses | |
1186 | Parse a string with list of addresses and return a list of elements like | |
1187 | the one described above. | |
1188 | ||
1189 | @example | |
1190 | (mail-header-parse-addresses | |
1191 | "Hrvoje Niksic <hniksic@@srce.hr>, Steinar Bang <sb@@metis.no>") | |
1192 | @result{} (("hniksic@@srce.hr" . "Hrvoje Niksic") | |
1193 | ("sb@@metis.no" . "Steinar Bang")) | |
1194 | @end example | |
1195 | ||
1196 | @item mail-header-parse-date | |
1197 | @findex mail-header-parse-date | |
1198 | Parse a date string and return an Emacs time structure. | |
1199 | ||
1200 | @item mail-narrow-to-head | |
1201 | @findex mail-narrow-to-head | |
1202 | Narrow the buffer to the header section of the buffer. Point is placed | |
1203 | at the beginning of the narrowed buffer. | |
1204 | ||
1205 | @item mail-header-narrow-to-field | |
1206 | @findex mail-header-narrow-to-field | |
1207 | Narrow the buffer to the header under point. Understands continuation | |
1208 | headers. | |
1209 | ||
1210 | @item mail-header-fold-field | |
1211 | @findex mail-header-fold-field | |
1212 | Fold the header under point. | |
1213 | ||
1214 | @item mail-header-unfold-field | |
1215 | @findex mail-header-unfold-field | |
1216 | Unfold the header under point. | |
1217 | ||
1218 | @item mail-header-field-value | |
1219 | @findex mail-header-field-value | |
1220 | Return the value of the field under point. | |
1221 | ||
1222 | @item mail-encode-encoded-word-region | |
1223 | @findex mail-encode-encoded-word-region | |
1224 | Encode the non-@acronym{ASCII} words in the region. For instance, | |
01c52d31 | 1225 | @samp{Na@"{@dotless{i}}ve} is encoded as @samp{=?iso-8859-1?q?Na=EFve?=}. |
4009494e GM |
1226 | |
1227 | @item mail-encode-encoded-word-buffer | |
1228 | @findex mail-encode-encoded-word-buffer | |
1229 | Encode the non-@acronym{ASCII} words in the current buffer. This function is | |
1230 | meant to be called narrowed to the headers of a message. | |
1231 | ||
1232 | @item mail-encode-encoded-word-string | |
1233 | @findex mail-encode-encoded-word-string | |
1234 | Encode the words that need encoding in a string, and return the result. | |
1235 | ||
1236 | @example | |
1237 | (mail-encode-encoded-word-string | |
01c52d31 | 1238 | "This is na@"{@dotless{i}}ve, baby") |
4009494e GM |
1239 | @result{} "This is =?iso-8859-1?q?na=EFve,?= baby" |
1240 | @end example | |
1241 | ||
1242 | @item mail-decode-encoded-word-region | |
1243 | @findex mail-decode-encoded-word-region | |
1244 | Decode the encoded words in the region. | |
1245 | ||
1246 | @item mail-decode-encoded-word-string | |
1247 | @findex mail-decode-encoded-word-string | |
1248 | Decode the encoded words in the string and return the result. | |
1249 | ||
1250 | @example | |
1251 | (mail-decode-encoded-word-string | |
1252 | "This is =?iso-8859-1?q?na=EFve,?= baby") | |
01c52d31 | 1253 | @result{} "This is na@"{@dotless{i}}ve, baby" |
4009494e GM |
1254 | @end example |
1255 | ||
1256 | @end table | |
1257 | ||
1258 | Currently, @code{mail-parse} is an abstraction over @code{ietf-drums}, | |
1259 | @code{rfc2047}, @code{rfc2045} and @code{rfc2231}. These are documented | |
1260 | in the subsequent sections. | |
1261 | ||
1262 | ||
1263 | ||
1264 | @node Basic Functions | |
1265 | @chapter Basic Functions | |
1266 | ||
1267 | This chapter describes the basic, ground-level functions for parsing and | |
1268 | handling. Covered here is parsing @code{From} lines, removing comments | |
1269 | from header lines, decoding encoded words, parsing date headers and so | |
1270 | on. High-level functionality is dealt with in the first chapter | |
1271 | (@pxref{Decoding and Viewing}). | |
1272 | ||
1273 | @menu | |
1274 | * rfc2045:: Encoding @code{Content-Type} headers. | |
1275 | * rfc2231:: Parsing @code{Content-Type} headers. | |
1276 | * ietf-drums:: Handling mail headers defined by RFC822bis. | |
1277 | * rfc2047:: En/decoding encoded words in headers. | |
1278 | * time-date:: Functions for parsing dates and manipulating time. | |
1279 | * qp:: Quoted-Printable en/decoding. | |
1280 | * base64:: Base64 en/decoding. | |
1281 | * binhex:: Binhex decoding. | |
1282 | * uudecode:: Uuencode decoding. | |
1283 | * yenc:: Yenc decoding. | |
1284 | * rfc1843:: Decoding HZ-encoded text. | |
1285 | * mailcap:: How parts are displayed is specified by the @file{.mailcap} file | |
1286 | @end menu | |
1287 | ||
1288 | ||
1289 | @node rfc2045 | |
1290 | @section rfc2045 | |
1291 | ||
1292 | RFC2045 is the ``main'' @acronym{MIME} document, and as such, one would | |
1293 | imagine that there would be a lot to implement. But there isn't, since | |
1294 | most of the implementation details are delegated to the subsequent | |
1295 | RFCs. | |
1296 | ||
1297 | So @file{rfc2045.el} has only a single function: | |
1298 | ||
1299 | @table @code | |
1300 | @item rfc2045-encode-string | |
1301 | @findex rfc2045-encode-string | |
1302 | Takes a parameter and a value and returns a @samp{PARAM=VALUE} string. | |
1303 | @var{value} will be quoted if there are non-safe characters in it. | |
1304 | @end table | |
1305 | ||
1306 | ||
1307 | @node rfc2231 | |
1308 | @section rfc2231 | |
1309 | ||
1310 | RFC2231 defines a syntax for the @code{Content-Type} and | |
1311 | @code{Content-Disposition} headers. Its snappy name is @dfn{MIME | |
1312 | Parameter Value and Encoded Word Extensions: Character Sets, Languages, | |
1313 | and Continuations}. | |
1314 | ||
1315 | In short, these headers look something like this: | |
1316 | ||
1317 | @example | |
1318 | Content-Type: application/x-stuff; | |
1319 | title*0*=us-ascii'en'This%20is%20even%20more%20; | |
1320 | title*1*=%2A%2A%2Afun%2A%2A%2A%20; | |
1321 | title*2="isn't it!" | |
1322 | @end example | |
1323 | ||
1324 | They usually aren't this bad, though. | |
1325 | ||
1326 | The following functions are defined by this library: | |
1327 | ||
1328 | @table @code | |
1329 | @item rfc2231-parse-string | |
1330 | @findex rfc2231-parse-string | |
1331 | Parse a @code{Content-Type} header and return a list describing its | |
1332 | elements. | |
1333 | ||
1334 | @example | |
1335 | (rfc2231-parse-string | |
1336 | "application/x-stuff; | |
1337 | title*0*=us-ascii'en'This%20is%20even%20more%20; | |
1338 | title*1*=%2A%2A%2Afun%2A%2A%2A%20; | |
1339 | title*2=\"isn't it!\"") | |
1340 | @result{} ("application/x-stuff" | |
1341 | (title . "This is even more ***fun*** isn't it!")) | |
1342 | @end example | |
1343 | ||
1344 | @item rfc2231-get-value | |
1345 | @findex rfc2231-get-value | |
1346 | Takes one of the lists on the format above and returns | |
1347 | the value of the specified attribute. | |
1348 | ||
1349 | @item rfc2231-encode-string | |
1350 | @findex rfc2231-encode-string | |
1351 | Encode a parameter in headers likes @code{Content-Type} and | |
1352 | @code{Content-Disposition}. | |
1353 | ||
1354 | @end table | |
1355 | ||
1356 | ||
1357 | @node ietf-drums | |
1358 | @section ietf-drums | |
1359 | ||
1360 | @dfn{drums} is an IETF working group that is working on the replacement | |
1361 | for RFC822. | |
1362 | ||
1363 | The functions provided by this library include: | |
1364 | ||
1365 | @table @code | |
1366 | @item ietf-drums-remove-comments | |
1367 | @findex ietf-drums-remove-comments | |
1368 | Remove the comments from the argument and return the results. | |
1369 | ||
1370 | @item ietf-drums-remove-whitespace | |
1371 | @findex ietf-drums-remove-whitespace | |
1372 | Remove linear white space from the string and return the results. | |
1373 | Spaces inside quoted strings and comments are left untouched. | |
1374 | ||
1375 | @item ietf-drums-get-comment | |
1376 | @findex ietf-drums-get-comment | |
1377 | Return the last most comment from the string. | |
1378 | ||
1379 | @item ietf-drums-parse-address | |
1380 | @findex ietf-drums-parse-address | |
1381 | Parse an address string and return a list that contains the mailbox and | |
1382 | the plain text name. | |
1383 | ||
1384 | @item ietf-drums-parse-addresses | |
1385 | @findex ietf-drums-parse-addresses | |
1386 | Parse a string that contains any number of comma-separated addresses and | |
1387 | return a list that contains mailbox/plain text pairs. | |
1388 | ||
1389 | @item ietf-drums-parse-date | |
1390 | @findex ietf-drums-parse-date | |
1391 | Parse a date string and return an Emacs time structure. | |
1392 | ||
1393 | @item ietf-drums-narrow-to-header | |
1394 | @findex ietf-drums-narrow-to-header | |
1395 | Narrow the buffer to the header section of the current buffer. | |
1396 | ||
1397 | @end table | |
1398 | ||
1399 | ||
1400 | @node rfc2047 | |
1401 | @section rfc2047 | |
1402 | ||
1403 | RFC2047 (Message Header Extensions for Non-@acronym{ASCII} Text) specifies how | |
1404 | non-@acronym{ASCII} text in headers are to be encoded. This is actually rather | |
1405 | complicated, so a number of variables are necessary to tweak what this | |
1406 | library does. | |
1407 | ||
1408 | The following variables are tweakable: | |
1409 | ||
1410 | @table @code | |
1411 | @item rfc2047-header-encoding-alist | |
1412 | @vindex rfc2047-header-encoding-alist | |
1413 | This is an alist of header / encoding-type pairs. Its main purpose is | |
1414 | to prevent encoding of certain headers. | |
1415 | ||
1416 | The keys can either be header regexps, or @code{t}. | |
1417 | ||
1418 | The values can be @code{nil}, in which case the header(s) in question | |
1419 | won't be encoded, @code{mime}, which means that they will be encoded, or | |
1420 | @code{address-mime}, which means the header(s) will be encoded carefully | |
1421 | assuming they contain addresses. | |
1422 | ||
1423 | @item rfc2047-charset-encoding-alist | |
1424 | @vindex rfc2047-charset-encoding-alist | |
1425 | RFC2047 specifies two forms of encoding---@code{Q} (a | |
1426 | Quoted-Printable-like encoding) and @code{B} (base64). This alist | |
1427 | specifies which charset should use which encoding. | |
1428 | ||
1429 | @item rfc2047-encode-function-alist | |
1430 | @vindex rfc2047-encode-function-alist | |
1431 | This is an alist of encoding / function pairs. The encodings are | |
1432 | @code{Q}, @code{B} and @code{nil}. | |
1433 | ||
1434 | @item rfc2047-encoded-word-regexp | |
1435 | @vindex rfc2047-encoded-word-regexp | |
1436 | When decoding words, this library looks for matches to this regexp. | |
1437 | ||
b890d447 MB |
1438 | @item rfc2047-encoded-word-regexp-loose |
1439 | @vindex rfc2047-encoded-word-regexp-loose | |
1440 | This is a version from which the regexp for the Q encoding pattern of | |
1441 | @code{rfc2047-encoded-word-regexp} is made loose. | |
1442 | ||
4009494e GM |
1443 | @item rfc2047-encode-encoded-words |
1444 | @vindex rfc2047-encode-encoded-words | |
1445 | The boolean variable specifies whether encoded words | |
b890d447 MB |
1446 | (e.g. @samp{=?us-ascii?q?hello?=}) should be encoded again. |
1447 | @code{rfc2047-encoded-word-regexp} is used to look for such words. | |
1448 | ||
1449 | @item rfc2047-allow-irregular-q-encoded-words | |
1450 | @vindex rfc2047-allow-irregular-q-encoded-words | |
1451 | The boolean variable specifies whether irregular Q encoded words | |
1452 | (e.g. @samp{=?us-ascii?q?hello??=}) should be decoded. If it is | |
1453 | non-@code{nil}, @code{rfc2047-encoded-word-regexp-loose} is used instead | |
1454 | of @code{rfc2047-encoded-word-regexp} to look for encoded words. | |
4009494e GM |
1455 | |
1456 | @end table | |
1457 | ||
1458 | Those were the variables, and these are this functions: | |
1459 | ||
1460 | @table @code | |
1461 | @item rfc2047-narrow-to-field | |
1462 | @findex rfc2047-narrow-to-field | |
1463 | Narrow the buffer to the header on the current line. | |
1464 | ||
1465 | @item rfc2047-encode-message-header | |
1466 | @findex rfc2047-encode-message-header | |
1467 | Should be called narrowed to the header of a message. Encodes according | |
1468 | to @code{rfc2047-header-encoding-alist}. | |
1469 | ||
1470 | @item rfc2047-encode-region | |
1471 | @findex rfc2047-encode-region | |
1472 | Encodes all encodable words in the region specified. | |
1473 | ||
1474 | @item rfc2047-encode-string | |
1475 | @findex rfc2047-encode-string | |
1476 | Encode a string and return the results. | |
1477 | ||
1478 | @item rfc2047-decode-region | |
1479 | @findex rfc2047-decode-region | |
1480 | Decode the encoded words in the region. | |
1481 | ||
1482 | @item rfc2047-decode-string | |
1483 | @findex rfc2047-decode-string | |
1484 | Decode a string and return the results. | |
1485 | ||
1486 | @item rfc2047-encode-parameter | |
1487 | @findex rfc2047-encode-parameter | |
e4e22d29 KY |
1488 | Encode a parameter in the RFC2047-like style. This is a substitution |
1489 | for the @code{rfc2231-encode-string} function, that is the standard but | |
1490 | many mailers don't support it. @xref{rfc2231}. | |
4009494e GM |
1491 | |
1492 | @end table | |
1493 | ||
1494 | ||
1495 | @node time-date | |
1496 | @section time-date | |
1497 | ||
1498 | While not really a part of the @acronym{MIME} library, it is convenient to | |
1499 | document this library here. It deals with parsing @code{Date} headers | |
1500 | and manipulating time. (Not by using tesseracts, though, I'm sorry to | |
1501 | say.) | |
1502 | ||
1503 | These functions convert between five formats: A date string, an Emacs | |
1504 | time structure, a decoded time list, a second number, and a day number. | |
1505 | ||
1506 | Here's a bunch of time/date/second/day examples: | |
1507 | ||
1508 | @example | |
1509 | (parse-time-string "Sat Sep 12 12:21:54 1998 +0200") | |
1510 | @result{} (54 21 12 12 9 1998 6 nil 7200) | |
1511 | ||
1512 | (date-to-time "Sat Sep 12 12:21:54 1998 +0200") | |
1513 | @result{} (13818 19266) | |
1514 | ||
1515 | (time-to-seconds '(13818 19266)) | |
1516 | @result{} 905595714.0 | |
1517 | ||
1518 | (seconds-to-time 905595714.0) | |
1519 | @result{} (13818 19266 0) | |
1520 | ||
1521 | (time-to-days '(13818 19266)) | |
1522 | @result{} 729644 | |
1523 | ||
1524 | (days-to-time 729644) | |
1525 | @result{} (961933 65536) | |
1526 | ||
1527 | (time-since '(13818 19266)) | |
1528 | @result{} (0 430) | |
1529 | ||
1530 | (time-less-p '(13818 19266) '(13818 19145)) | |
1531 | @result{} nil | |
1532 | ||
1533 | (subtract-time '(13818 19266) '(13818 19145)) | |
1534 | @result{} (0 121) | |
1535 | ||
1536 | (days-between "Sat Sep 12 12:21:54 1998 +0200" | |
1537 | "Sat Sep 07 12:21:54 1998 +0200") | |
1538 | @result{} 5 | |
1539 | ||
1540 | (date-leap-year-p 2000) | |
1541 | @result{} t | |
1542 | ||
1543 | (time-to-day-in-year '(13818 19266)) | |
1544 | @result{} 255 | |
1545 | ||
1546 | (time-to-number-of-days | |
1547 | (time-since | |
1548 | (date-to-time "Mon, 01 Jan 2001 02:22:26 GMT"))) | |
1549 | @result{} 4.146122685185185 | |
1550 | @end example | |
1551 | ||
1552 | And finally, we have @code{safe-date-to-time}, which does the same as | |
1553 | @code{date-to-time}, but returns a zero time if the date is | |
1554 | syntactically malformed. | |
1555 | ||
1556 | The five data representations used are the following: | |
1557 | ||
1558 | @table @var | |
1559 | @item date | |
1560 | An RFC822 (or similar) date string. For instance: @code{"Sat Sep 12 | |
1561 | 12:21:54 1998 +0200"}. | |
1562 | ||
1563 | @item time | |
1564 | An internal Emacs time. For instance: @code{(13818 26466)}. | |
1565 | ||
1566 | @item seconds | |
1567 | A floating point representation of the internal Emacs time. For | |
1568 | instance: @code{905595714.0}. | |
1569 | ||
1570 | @item days | |
1571 | An integer number representing the number of days since 00000101. For | |
1572 | instance: @code{729644}. | |
1573 | ||
1574 | @item decoded time | |
1575 | A list of decoded time. For instance: @code{(54 21 12 12 9 1998 6 t | |
1576 | 7200)}. | |
1577 | @end table | |
1578 | ||
1579 | All the examples above represent the same moment. | |
1580 | ||
1581 | These are the functions available: | |
1582 | ||
1583 | @table @code | |
1584 | @item date-to-time | |
1585 | Take a date and return a time. | |
1586 | ||
1587 | @item time-to-seconds | |
e402f452 GM |
1588 | Take a time and return seconds. Note that Emacs has a built-in |
1589 | function, @code{float-time}, that does this. | |
4009494e GM |
1590 | |
1591 | @item seconds-to-time | |
1592 | Take seconds and return a time. | |
1593 | ||
1594 | @item time-to-days | |
1595 | Take a time and return days. | |
1596 | ||
1597 | @item days-to-time | |
1598 | Take days and return a time. | |
1599 | ||
1600 | @item date-to-day | |
1601 | Take a date and return days. | |
1602 | ||
1603 | @item time-to-number-of-days | |
1604 | Take a time and return the number of days that represents. | |
1605 | ||
1606 | @item safe-date-to-time | |
1607 | Take a date and return a time. If the date is not syntactically valid, | |
1608 | return a ``zero'' time. | |
1609 | ||
1610 | @item time-less-p | |
1611 | Take two times and say whether the first time is less (i. e., earlier) | |
1612 | than the second time. | |
1613 | ||
1614 | @item time-since | |
1615 | Take a time and return a time saying how long it was since that time. | |
1616 | ||
1617 | @item subtract-time | |
1618 | Take two times and subtract the second from the first. I. e., return | |
1619 | the time between the two times. | |
1620 | ||
1621 | @item days-between | |
1622 | Take two days and return the number of days between those two days. | |
1623 | ||
1624 | @item date-leap-year-p | |
1625 | Take a year number and say whether it's a leap year. | |
1626 | ||
1627 | @item time-to-day-in-year | |
1628 | Take a time and return the day number within the year that the time is | |
1629 | in. | |
1630 | ||
1631 | @end table | |
1632 | ||
1633 | ||
1634 | @node qp | |
1635 | @section qp | |
1636 | ||
1637 | This library deals with decoding and encoding Quoted-Printable text. | |
1638 | ||
1639 | Very briefly explained, qp encoding means translating all 8-bit | |
1640 | characters (and lots of control characters) into things that look like | |
1641 | @samp{=EF}; that is, an equal sign followed by the byte encoded as a hex | |
1642 | string. | |
1643 | ||
1644 | The following functions are defined by the library: | |
1645 | ||
1646 | @table @code | |
1647 | @item quoted-printable-decode-region | |
1648 | @findex quoted-printable-decode-region | |
1649 | QP-decode all the encoded text in the specified region. | |
1650 | ||
1651 | @item quoted-printable-decode-string | |
1652 | @findex quoted-printable-decode-string | |
1653 | Decode the QP-encoded text in a string and return the results. | |
1654 | ||
1655 | @item quoted-printable-encode-region | |
1656 | @findex quoted-printable-encode-region | |
1657 | QP-encode all the encodable characters in the specified region. The third | |
1658 | optional parameter @var{fold} specifies whether to fold long lines. | |
1659 | (Long here means 72.) | |
1660 | ||
1661 | @item quoted-printable-encode-string | |
1662 | @findex quoted-printable-encode-string | |
1663 | QP-encode all the encodable characters in a string and return the | |
1664 | results. | |
1665 | ||
1666 | @end table | |
1667 | ||
1668 | ||
1669 | @node base64 | |
1670 | @section base64 | |
1671 | @cindex base64 | |
1672 | ||
1673 | Base64 is an encoding that encodes three bytes into four characters, | |
1674 | thereby increasing the size by about 33%. The alphabet used for | |
1675 | encoding is very resistant to mangling during transit. | |
1676 | ||
1677 | The following functions are defined by this library: | |
1678 | ||
1679 | @table @code | |
1680 | @item base64-encode-region | |
1681 | @findex base64-encode-region | |
1682 | base64 encode the selected region. Return the length of the encoded | |
1683 | text. Optional third argument @var{no-line-break} means do not break | |
1684 | long lines into shorter lines. | |
1685 | ||
1686 | @item base64-encode-string | |
1687 | @findex base64-encode-string | |
1688 | base64 encode a string and return the result. | |
1689 | ||
1690 | @item base64-decode-region | |
1691 | @findex base64-decode-region | |
1692 | base64 decode the selected region. Return the length of the decoded | |
1693 | text. If the region can't be decoded, return @code{nil} and don't | |
1694 | modify the buffer. | |
1695 | ||
1696 | @item base64-decode-string | |
1697 | @findex base64-decode-string | |
1698 | base64 decode a string and return the result. If the string can't be | |
1699 | decoded, @code{nil} is returned. | |
1700 | ||
1701 | @end table | |
1702 | ||
1703 | ||
1704 | @node binhex | |
1705 | @section binhex | |
1706 | @cindex binhex | |
1707 | @cindex Apple | |
1708 | @cindex Macintosh | |
1709 | ||
1710 | @code{binhex} is an encoding that originated in Macintosh environments. | |
1711 | The following function is supplied to deal with these: | |
1712 | ||
1713 | @table @code | |
1714 | @item binhex-decode-region | |
1715 | @findex binhex-decode-region | |
1716 | Decode the encoded text in the region. If given a third parameter, only | |
1717 | decode the @code{binhex} header and return the filename. | |
1718 | ||
1719 | @end table | |
1720 | ||
1721 | @node uudecode | |
1722 | @section uudecode | |
1723 | @cindex uuencode | |
1724 | @cindex uudecode | |
1725 | ||
1726 | @code{uuencode} is probably still the most popular encoding of binaries | |
1727 | used on Usenet, although @code{base64} rules the mail world. | |
1728 | ||
1729 | The following function is supplied by this package: | |
1730 | ||
1731 | @table @code | |
1732 | @item uudecode-decode-region | |
1733 | @findex uudecode-decode-region | |
1734 | Decode the text in the region. | |
1735 | @end table | |
1736 | ||
1737 | ||
1738 | @node yenc | |
1739 | @section yenc | |
1740 | @cindex yenc | |
1741 | ||
1742 | @code{yenc} is used for encoding binaries on Usenet. The following | |
1743 | function is supplied by this package: | |
1744 | ||
1745 | @table @code | |
1746 | @item yenc-decode-region | |
1747 | @findex yenc-decode-region | |
1748 | Decode the encoded text in the region. | |
1749 | ||
1750 | @end table | |
1751 | ||
1752 | ||
1753 | @node rfc1843 | |
1754 | @section rfc1843 | |
1755 | @cindex rfc1843 | |
1756 | @cindex HZ | |
1757 | @cindex Chinese | |
1758 | ||
1759 | RFC1843 deals with mixing Chinese and @acronym{ASCII} characters in messages. In | |
1760 | essence, RFC1843 switches between @acronym{ASCII} and Chinese by doing this: | |
1761 | ||
1762 | @example | |
1763 | This sentence is in @acronym{ASCII}. | |
1764 | The next sentence is in GB.~@{<:Ky2;S@{#,NpJ)l6HK!#~@}Bye. | |
1765 | @end example | |
1766 | ||
1767 | Simple enough, and widely used in China. | |
1768 | ||
1769 | The following functions are available to handle this encoding: | |
1770 | ||
1771 | @table @code | |
1772 | @item rfc1843-decode-region | |
1773 | Decode HZ-encoded text in the region. | |
1774 | ||
1775 | @item rfc1843-decode-string | |
1776 | Decode a HZ-encoded string and return the result. | |
1777 | ||
1778 | @end table | |
1779 | ||
1780 | ||
1781 | @node mailcap | |
1782 | @section mailcap | |
1783 | ||
1784 | The @file{~/.mailcap} file is parsed by most @acronym{MIME}-aware message | |
1785 | handlers and describes how elements are supposed to be displayed. | |
1786 | Here's an example file: | |
1787 | ||
1788 | @example | |
1789 | image/*; gimp -8 %s | |
1790 | audio/wav; wavplayer %s | |
1791 | application/msword; catdoc %s ; copiousoutput ; nametemplate=%s.doc | |
1792 | @end example | |
1793 | ||
1794 | This says that all image files should be displayed with @code{gimp}, | |
1795 | that WAVE audio files should be played by @code{wavplayer}, and that | |
1796 | MS-WORD files should be inlined by @code{catdoc}. | |
1797 | ||
1798 | The @code{mailcap} library parses this file, and provides functions for | |
1799 | matching types. | |
1800 | ||
1801 | @table @code | |
1802 | @item mailcap-mime-data | |
1803 | @vindex mailcap-mime-data | |
1804 | This variable is an alist of alists containing backup viewing rules. | |
1805 | ||
1806 | @end table | |
1807 | ||
1808 | Interface functions: | |
1809 | ||
1810 | @table @code | |
1811 | @item mailcap-parse-mailcaps | |
1812 | @findex mailcap-parse-mailcaps | |
1813 | Parse the @file{~/.mailcap} file. | |
1814 | ||
1815 | @item mailcap-mime-info | |
1816 | Takes a @acronym{MIME} type as its argument and returns the matching viewer. | |
1817 | ||
1818 | @end table | |
1819 | ||
1820 | ||
1821 | ||
1822 | ||
1823 | @node Standards | |
1824 | @chapter Standards | |
1825 | ||
1826 | The Emacs @acronym{MIME} library implements handling of various elements | |
1827 | according to a (somewhat) large number of RFCs, drafts and standards | |
1828 | documents. This chapter lists the relevant ones. They can all be | |
1829 | fetched from @uref{http://quimby.gnus.org/notes/}. | |
1830 | ||
1831 | @table @dfn | |
1832 | @item RFC822 | |
1833 | @itemx STD11 | |
1834 | Standard for the Format of ARPA Internet Text Messages. | |
1835 | ||
1836 | @item RFC1036 | |
1837 | Standard for Interchange of USENET Messages | |
1838 | ||
1839 | @item RFC2045 | |
1840 | Format of Internet Message Bodies | |
1841 | ||
1842 | @item RFC2046 | |
1843 | Media Types | |
1844 | ||
1845 | @item RFC2047 | |
1846 | Message Header Extensions for Non-@acronym{ASCII} Text | |
1847 | ||
1848 | @item RFC2048 | |
1849 | Registration Procedures | |
1850 | ||
1851 | @item RFC2049 | |
1852 | Conformance Criteria and Examples | |
1853 | ||
1854 | @item RFC2231 | |
1855 | @acronym{MIME} Parameter Value and Encoded Word Extensions: Character Sets, | |
1856 | Languages, and Continuations | |
1857 | ||
1858 | @item RFC1843 | |
1859 | HZ - A Data Format for Exchanging Files of Arbitrarily Mixed Chinese and | |
1860 | @acronym{ASCII} characters | |
1861 | ||
1862 | @item draft-ietf-drums-msg-fmt-05.txt | |
1863 | Draft for the successor of RFC822 | |
1864 | ||
1865 | @item RFC2112 | |
1866 | The @acronym{MIME} Multipart/Related Content-type | |
1867 | ||
1868 | @item RFC1892 | |
1869 | The Multipart/Report Content Type for the Reporting of Mail System | |
1870 | Administrative Messages | |
1871 | ||
1872 | @item RFC2183 | |
1873 | Communicating Presentation Information in Internet Messages: The | |
1874 | Content-Disposition Header Field | |
1875 | ||
1876 | @item RFC2646 | |
1877 | Documentation of the text/plain format parameter for flowed text. | |
1878 | ||
1879 | @end table | |
1880 | ||
1881 | @node GNU Free Documentation License | |
1882 | @chapter GNU Free Documentation License | |
1883 | @include doclicense.texi | |
1884 | ||
1885 | @node Index | |
1886 | @chapter Index | |
1887 | @printindex cp | |
1888 | ||
4009494e GM |
1889 | @bye |
1890 | ||
1891 | \f | |
1892 | @c Local Variables: | |
1893 | @c mode: texinfo | |
1894 | @c coding: iso-8859-1 | |
1895 | @c End: |