| 1 | \input texinfo |
| 2 | |
| 3 | @setfilename ../../info/emacs-mime |
| 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, |
| 13 | 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc. |
| 14 | |
| 15 | @quotation |
| 16 | Permission is granted to copy, distribute and/or modify this document |
| 17 | under the terms of the GNU Free Documentation License, Version 1.3 or |
| 18 | any later version published by the Free Software Foundation; with no |
| 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''. |
| 22 | |
| 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.'' |
| 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 lisp libraries |
| 33 | @direntry |
| 34 | * Emacs MIME: (emacs-mime). Emacs MIME de/composition library. |
| 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 | |
| 50 | @contents |
| 51 | |
| 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 | |
| 71 | @ifnottex |
| 72 | @insertcopying |
| 73 | @end ifnottex |
| 74 | |
| 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 | |
| 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 | |
| 192 | @end table |
| 193 | |
| 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 | |
| 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 |
| 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}. |
| 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 | |
| 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 | |
| 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, |
| 1209 | @samp{Na@"{@dotless{i}}ve} is encoded as @samp{=?iso-8859-1?q?Na=EFve?=}. |
| 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 |
| 1222 | "This is na@"{@dotless{i}}ve, baby") |
| 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") |
| 1237 | @result{} "This is na@"{@dotless{i}}ve, baby" |
| 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 | |
| 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 | |
| 1427 | @item rfc2047-encode-encoded-words |
| 1428 | @vindex rfc2047-encode-encoded-words |
| 1429 | The boolean variable specifies whether encoded words |
| 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. |
| 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 |
| 1584 | Take a time and return seconds. Note that Emacs has a built-in |
| 1585 | function, @code{float-time}, that does this. |
| 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 | |
| 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 |