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1826 lines
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Plaintext
1826 lines
55 KiB
Plaintext
\input texinfo
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@setfilename ../info/emacs-mime
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@settitle Emacs MIME Manual
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@synindex fn cp
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@synindex vr cp
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@synindex pg cp
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@copying
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This file documents the Emacs MIME interface functionality.
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Copyright @copyright{} 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
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2006 Free Software Foundation, Inc.
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@quotation
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.2 or
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any later version published by the Free Software Foundation; with no
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Invariant Sections, with the Front-Cover texts being ``A GNU
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||
Manual'', and with the Back-Cover Texts as in (a) below. A copy of the
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license is included in the section entitled ``GNU Free Documentation
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License'' in the Emacs manual.
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(a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
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this GNU Manual, like GNU software. Copies published by the Free
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Software Foundation raise funds for GNU development.''
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This document is part of a collection distributed under the GNU Free
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Documentation License. If you want to distribute this document
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separately from the collection, you can do so by adding a copy of the
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license to the document, as described in section 6 of the license.
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@end quotation
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@end copying
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@dircategory Emacs
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@direntry
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* Emacs MIME: (emacs-mime). Emacs MIME de/composition library.
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@end direntry
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@iftex
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@finalout
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@end iftex
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@setchapternewpage odd
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@titlepage
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@title Emacs MIME Manual
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@author by Lars Magne Ingebrigtsen
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@page
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@vskip 0pt plus 1filll
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@insertcopying
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@end titlepage
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@node Top
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@top Emacs MIME
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This manual documents the libraries used to compose and display
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@acronym{MIME} messages.
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This manual is directed at users who want to modify the behavior of
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the @acronym{MIME} encoding/decoding process or want a more detailed
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picture of how the Emacs @acronym{MIME} library works, and people who want
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to write functions and commands that manipulate @acronym{MIME} elements.
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@acronym{MIME} is short for @dfn{Multipurpose Internet Mail Extensions}.
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This standard is documented in a number of RFCs; mainly RFC2045 (Format
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of Internet Message Bodies), RFC2046 (Media Types), RFC2047 (Message
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Header Extensions for Non-@acronym{ASCII} Text), RFC2048 (Registration
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Procedures), RFC2049 (Conformance Criteria and Examples). It is highly
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recommended that anyone who intends writing @acronym{MIME}-compliant software
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read at least RFC2045 and RFC2047.
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@menu
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* Decoding and Viewing:: A framework for decoding and viewing.
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* Composing:: @acronym{MML}; a language for describing @acronym{MIME} parts.
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* Interface Functions:: An abstraction over the basic functions.
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* Basic Functions:: Utility and basic parsing functions.
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* Standards:: A summary of RFCs and working documents used.
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* Index:: Function and variable index.
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@end menu
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@node Decoding and Viewing
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@chapter Decoding and Viewing
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This chapter deals with decoding and viewing @acronym{MIME} messages on a
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higher level.
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The main idea is to first analyze a @acronym{MIME} article, and then allow
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other programs to do things based on the list of @dfn{handles} that are
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returned as a result of this analysis.
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@menu
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* Dissection:: Analyzing a @acronym{MIME} message.
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* Non-MIME:: Analyzing a non-@acronym{MIME} message.
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* Handles:: Handle manipulations.
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* Display:: Displaying handles.
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* Display Customization:: Variables that affect display.
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* Files and Directories:: Saving and naming attachments.
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* New Viewers:: How to write your own viewers.
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@end menu
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@node Dissection
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@section Dissection
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The @code{mm-dissect-buffer} is the function responsible for dissecting
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a @acronym{MIME} article. If given a multipart message, it will recursively
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descend the message, following the structure, and return a tree of
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@acronym{MIME} handles that describes the structure of the message.
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@node Non-MIME
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@section Non-MIME
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@vindex mm-uu-configure-list
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Gnus also understands some non-@acronym{MIME} attachments, such as
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postscript, uuencode, binhex, yenc, shar, forward, gnatsweb, pgp,
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diff. Each of these features can be disabled by add an item into
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@code{mm-uu-configure-list}. For example,
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@lisp
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(require 'mm-uu)
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(add-to-list 'mm-uu-configure-list '(pgp-signed . disabled))
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@end lisp
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@table @code
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@item postscript
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@findex postscript
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Postscript file.
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@item uu
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@findex uu
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Uuencoded file.
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@item binhex
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@findex binhex
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Binhex encoded file.
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@item yenc
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@findex yenc
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Yenc encoded file.
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@item shar
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@findex shar
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Shar archive file.
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@item forward
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@findex forward
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Non-@acronym{MIME} forwarded message.
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@item gnatsweb
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@findex gnatsweb
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Gnatsweb attachment.
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@item pgp-signed
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@findex pgp-signed
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@acronym{PGP} signed clear text.
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@item pgp-encrypted
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@findex pgp-encrypted
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@acronym{PGP} encrypted clear text.
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@item pgp-key
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@findex pgp-key
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@acronym{PGP} public keys.
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@item emacs-sources
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@findex emacs-sources
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@vindex mm-uu-emacs-sources-regexp
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Emacs source code. This item works only in the groups matching
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@code{mm-uu-emacs-sources-regexp}.
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@item diff
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@vindex diff
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@vindex mm-uu-diff-groups-regexp
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Patches. This is intended for groups where diffs of committed files
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are automatically sent to. It only works in groups matching
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@code{mm-uu-diff-groups-regexp}.
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@end table
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@node Handles
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@section Handles
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A @acronym{MIME} handle is a list that fully describes a @acronym{MIME}
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component.
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The following macros can be used to access elements in a handle:
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@table @code
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@item mm-handle-buffer
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@findex mm-handle-buffer
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Return the buffer that holds the contents of the undecoded @acronym{MIME}
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part.
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@item mm-handle-type
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@findex mm-handle-type
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Return the parsed @code{Content-Type} of the part.
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@item mm-handle-encoding
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@findex mm-handle-encoding
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Return the @code{Content-Transfer-Encoding} of the part.
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@item mm-handle-undisplayer
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@findex mm-handle-undisplayer
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Return the object that can be used to remove the displayed part (if it
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has been displayed).
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@item mm-handle-set-undisplayer
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@findex mm-handle-set-undisplayer
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Set the undisplayer object.
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@item mm-handle-disposition
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@findex mm-handle-disposition
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Return the parsed @code{Content-Disposition} of the part.
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@item mm-get-content-id
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Returns the handle(s) referred to by @code{Content-ID}.
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@end table
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@node Display
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@section Display
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Functions for displaying, removing and saving.
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@table @code
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@item mm-display-part
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@findex mm-display-part
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Display the part.
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@item mm-remove-part
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@findex mm-remove-part
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Remove the part (if it has been displayed).
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@item mm-inlinable-p
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@findex mm-inlinable-p
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Say whether a @acronym{MIME} type can be displayed inline.
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@item mm-automatic-display-p
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@findex mm-automatic-display-p
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Say whether a @acronym{MIME} type should be displayed automatically.
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@item mm-destroy-part
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@findex mm-destroy-part
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Free all resources occupied by a part.
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@item mm-save-part
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@findex mm-save-part
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Offer to save the part in a file.
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@item mm-pipe-part
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@findex mm-pipe-part
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Offer to pipe the part to some process.
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@item mm-interactively-view-part
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@findex mm-interactively-view-part
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Prompt for a mailcap method to use to view the part.
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@end table
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@node Display Customization
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@section Display Customization
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@table @code
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@item mm-inline-media-tests
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@vindex mm-inline-media-tests
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This is an alist where the key is a @acronym{MIME} type, the second element
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is a function to display the part @dfn{inline} (i.e., inside Emacs), and
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the third element is a form to be @code{eval}ed to say whether the part
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can be displayed inline.
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This variable specifies whether a part @emph{can} be displayed inline,
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and, if so, how to do it. It does not say whether parts are
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@emph{actually} displayed inline.
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@item mm-inlined-types
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@vindex mm-inlined-types
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This, on the other hand, says what types are to be displayed inline, if
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they satisfy the conditions set by the variable above. It's a list of
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@acronym{MIME} media types.
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@item mm-automatic-display
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@vindex mm-automatic-display
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This is a list of types that are to be displayed ``automatically'', but
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only if the above variable allows it. That is, only inlinable parts can
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be displayed automatically.
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@item mm-automatic-external-display
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@vindex mm-automatic-external-display
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This is a list of types that will be displayed automatically in an
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external viewer.
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@item mm-keep-viewer-alive-types
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@vindex mm-keep-viewer-alive-types
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This is a list of media types for which the external viewer will not
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be killed when selecting a different article.
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@item mm-attachment-override-types
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@vindex mm-attachment-override-types
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Some @acronym{MIME} agents create parts that have a content-disposition of
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@samp{attachment}. This variable allows overriding that disposition and
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displaying the part inline. (Note that the disposition is only
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overridden if we are able to, and want to, display the part inline.)
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@item mm-discouraged-alternatives
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@vindex mm-discouraged-alternatives
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List of @acronym{MIME} types that are discouraged when viewing
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@samp{multipart/alternative}. Viewing agents are supposed to view the
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last possible part of a message, as that is supposed to be the richest.
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However, users may prefer other types instead, and this list says what
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types are most unwanted. If, for instance, @samp{text/html} parts are
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very unwanted, and @samp{text/richtext} parts are somewhat unwanted,
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you could say something like:
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@lisp
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(setq mm-discouraged-alternatives
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'("text/html" "text/richtext")
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mm-automatic-display
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(remove "text/html" mm-automatic-display))
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@end lisp
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Adding @code{"image/.*"} might also be useful. Spammers use images as
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the prefered part of @samp{multipart/alternative} messages, so you might
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not notice there are other parts. See also
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@code{gnus-buttonized-mime-types}, @ref{MIME Commands, ,MIME Commands,
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gnus, Gnus Manual}. After adding @code{"multipart/alternative"} to
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@code{gnus-buttonized-mime-types} you can choose manually which
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alternative you'd like to view. For example, you can set those
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variables like:
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@lisp
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(setq gnus-buttonized-mime-types
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'("multipart/alternative" "multipart/signed")
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mm-discouraged-alternatives
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'("text/html" "image/.*"))
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@end lisp
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In this case, Gnus will display radio buttons for such a kind of spam
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message as follows:
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@example
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1. (*) multipart/alternative ( ) image/gif
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2. (*) text/plain ( ) text/html
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@end example
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@item mm-inline-large-images
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@vindex mm-inline-large-images
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When displaying inline images that are larger than the window, Emacs
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does not enable scrolling, which means that you cannot see the whole
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image. To prevent this, the library tries to determine the image size
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before displaying it inline, and if it doesn't fit the window, the
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library will display it externally (e.g. with @samp{ImageMagick} or
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@samp{xv}). Setting this variable to @code{t} disables this check and
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makes the library display all inline images as inline, regardless of
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their size.
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@item mm-inline-override-types
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@vindex mm-inline-override-types
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@code{mm-inlined-types} may include regular expressions, for example to
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specify that all @samp{text/.*} parts be displayed inline. If a user
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prefers to have a type that matches such a regular expression be treated
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as an attachment, that can be accomplished by setting this variable to a
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list containing that type. For example assuming @code{mm-inlined-types}
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includes @samp{text/.*}, then including @samp{text/html} in this
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variable will cause @samp{text/html} parts to be treated as attachments.
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@item mm-text-html-renderer
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@vindex mm-text-html-renderer
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This selects the function used to render @acronym{HTML}. The predefined
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renderers are selected by the symbols @code{w3},
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@code{w3m}@footnote{See @uref{http://emacs-w3m.namazu.org/} for more
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information about emacs-w3m}, @code{links}, @code{lynx},
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@code{w3m-standalone} or @code{html2text}. If @code{nil} use an
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external viewer. You can also specify a function, which will be
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called with a @acronym{MIME} handle as the argument.
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@item mm-inline-text-html-with-images
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@vindex mm-inline-text-html-with-images
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Some @acronym{HTML} mails might have the trick of spammers using
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@samp{<img>} tags. It is likely to be intended to verify whether you
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have read the mail. You can prevent your personal informations from
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leaking by setting this option to @code{nil} (which is the default).
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It is currently ignored by Emacs/w3. For emacs-w3m, you may use the
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command @kbd{t} on the image anchor to show an image even if it is
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@code{nil}.@footnote{The command @kbd{T} will load all images. If you
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have set the option @code{w3m-key-binding} to @code{info}, use @kbd{i}
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or @kbd{I} instead.}
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@item mm-w3m-safe-url-regexp
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@vindex mm-w3m-safe-url-regexp
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A regular expression that matches safe URL names, i.e. URLs that are
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unlikely to leak personal information when rendering @acronym{HTML}
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email (the default value is @samp{\\`cid:}). If @code{nil} consider
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all URLs safe.
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@item mm-inline-text-html-with-w3m-keymap
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@vindex mm-inline-text-html-with-w3m-keymap
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You can use emacs-w3m command keys in the inlined text/html part by
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setting this option to non-@code{nil}. The default value is @code{t}.
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@item mm-external-terminal-program
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@vindex mm-external-terminal-program
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The program used to start an external terminal.
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@item mm-enable-external
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@vindex mm-enable-external
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Indicate whether external @acronym{MIME} handlers should be used.
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If @code{t}, all defined external @acronym{MIME} handlers are used. If
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@code{nil}, files are saved to disk (@code{mailcap-save-binary-file}).
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If it is the symbol @code{ask}, you are prompted before the external
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@acronym{MIME} handler is invoked.
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When you launch an attachment through mailcap (@pxref{mailcap}) an
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attempt is made to use a safe viewer with the safest options---this isn't
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the case if you save it to disk and launch it in a different way
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(command line or double-clicking). Anyhow, if you want to be sure not
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to launch any external programs, set this variable to @code{nil} or
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@code{ask}.
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@end table
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@node Files and Directories
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@section Files and Directories
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@table @code
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@item mm-default-directory
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@vindex mm-default-directory
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The default directory for saving attachments. If @code{nil} use
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@code{default-directory}.
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@item mm-tmp-directory
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@vindex mm-tmp-directory
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Directory for storing temporary files.
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@item mm-file-name-rewrite-functions
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@vindex mm-file-name-rewrite-functions
|
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A list of functions used for rewriting file names of @acronym{MIME}
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parts. Each function is applied successively to the file name.
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Ready-made functions include
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@table @code
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@item mm-file-name-delete-control
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@findex mm-file-name-delete-control
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Delete all control characters.
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@item mm-file-name-delete-gotchas
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@findex mm-file-name-delete-gotchas
|
||
Delete characters that could have unintended consequences when used
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with flawed shell scripts, i.e. @samp{|}, @samp{>} and @samp{<}; and
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@samp{-}, @samp{.} as the first character.
|
||
|
||
@item mm-file-name-delete-whitespace
|
||
@findex mm-file-name-delete-whitespace
|
||
Remove all whitespace.
|
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|
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@item mm-file-name-trim-whitespace
|
||
@findex mm-file-name-trim-whitespace
|
||
Remove leading and trailing whitespace.
|
||
|
||
@item mm-file-name-collapse-whitespace
|
||
@findex mm-file-name-collapse-whitespace
|
||
Collapse multiple whitespace characters.
|
||
|
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@item mm-file-name-replace-whitespace
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||
@findex mm-file-name-replace-whitespace
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@vindex mm-file-name-replace-whitespace
|
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Replace whitespace with underscores. Set the variable
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@code{mm-file-name-replace-whitespace} to any other string if you do
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not like underscores.
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||
@end table
|
||
|
||
The standard Emacs functions @code{capitalize}, @code{downcase},
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||
@code{upcase} and @code{upcase-initials} might also prove useful.
|
||
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||
@item mm-path-name-rewrite-functions
|
||
@vindex mm-path-name-rewrite-functions
|
||
List of functions used for rewriting the full file names of @acronym{MIME}
|
||
parts. This is used when viewing parts externally, and is meant for
|
||
transforming the absolute name so that non-compliant programs can find
|
||
the file where it's saved.
|
||
|
||
@end table
|
||
|
||
@node New Viewers
|
||
@section New Viewers
|
||
|
||
Here's an example viewer for displaying @code{text/enriched} inline:
|
||
|
||
@lisp
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||
(defun mm-display-enriched-inline (handle)
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(let (text)
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||
(with-temp-buffer
|
||
(mm-insert-part handle)
|
||
(save-window-excursion
|
||
(enriched-decode (point-min) (point-max))
|
||
(setq text (buffer-string))))
|
||
(mm-insert-inline handle text)))
|
||
@end lisp
|
||
|
||
We see that the function takes a @acronym{MIME} handle as its parameter. It
|
||
then goes to a temporary buffer, inserts the text of the part, does some
|
||
work on the text, stores the result, goes back to the buffer it was
|
||
called from and inserts the result.
|
||
|
||
The two important helper functions here are @code{mm-insert-part} and
|
||
@code{mm-insert-inline}. The first function inserts the text of the
|
||
handle in the current buffer. It handles charset and/or content
|
||
transfer decoding. The second function just inserts whatever text you
|
||
tell it to insert, but it also sets things up so that the text can be
|
||
``undisplayed'' in a convenient manner.
|
||
|
||
|
||
@node Composing
|
||
@chapter Composing
|
||
@cindex Composing
|
||
@cindex MIME Composing
|
||
@cindex MML
|
||
@cindex MIME Meta Language
|
||
|
||
Creating a @acronym{MIME} message is boring and non-trivial. Therefore,
|
||
a library called @code{mml} has been defined that parses a language
|
||
called @acronym{MML} (@acronym{MIME} Meta Language) and generates
|
||
@acronym{MIME} messages.
|
||
|
||
@findex mml-generate-mime
|
||
The main interface function is @code{mml-generate-mime}. It will
|
||
examine the contents of the current (narrowed-to) buffer and return a
|
||
string containing the @acronym{MIME} message.
|
||
|
||
@menu
|
||
* Simple MML Example:: An example @acronym{MML} document.
|
||
* MML Definition:: All valid @acronym{MML} elements.
|
||
* Advanced MML Example:: Another example @acronym{MML} document.
|
||
* Encoding Customization:: Variables that affect encoding.
|
||
* Charset Translation:: How charsets are mapped from @sc{mule} to @acronym{MIME}.
|
||
* Conversion:: Going from @acronym{MIME} to @acronym{MML} and vice versa.
|
||
* Flowed text:: Soft and hard newlines.
|
||
@end menu
|
||
|
||
|
||
@node Simple MML Example
|
||
@section Simple MML Example
|
||
|
||
Here's a simple @samp{multipart/alternative}:
|
||
|
||
@example
|
||
<#multipart type=alternative>
|
||
This is a plain text part.
|
||
<#part type=text/enriched>
|
||
<center>This is a centered enriched part</center>
|
||
<#/multipart>
|
||
@end example
|
||
|
||
After running this through @code{mml-generate-mime}, we get this:
|
||
|
||
@example
|
||
Content-Type: multipart/alternative; boundary="=-=-="
|
||
|
||
|
||
--=-=-=
|
||
|
||
|
||
This is a plain text part.
|
||
|
||
--=-=-=
|
||
Content-Type: text/enriched
|
||
|
||
|
||
<center>This is a centered enriched part</center>
|
||
|
||
--=-=-=--
|
||
@end example
|
||
|
||
|
||
@node MML Definition
|
||
@section MML Definition
|
||
|
||
The @acronym{MML} language is very simple. It looks a bit like an SGML
|
||
application, but it's not.
|
||
|
||
The main concept of @acronym{MML} is the @dfn{part}. Each part can be of a
|
||
different type or use a different charset. The way to delineate a part
|
||
is with a @samp{<#part ...>} tag. Multipart parts can be introduced
|
||
with the @samp{<#multipart ...>} tag. Parts are ended by the
|
||
@samp{<#/part>} or @samp{<#/multipart>} tags. Parts started with the
|
||
@samp{<#part ...>} tags are also closed by the next open tag.
|
||
|
||
There's also the @samp{<#external ...>} tag. These introduce
|
||
@samp{external/message-body} parts.
|
||
|
||
Each tag can contain zero or more parameters on the form
|
||
@samp{parameter=value}. The values may be enclosed in quotation marks,
|
||
but that's not necessary unless the value contains white space. So
|
||
@samp{filename=/home/user/#hello$^yes} is perfectly valid.
|
||
|
||
The following parameters have meaning in @acronym{MML}; parameters that have no
|
||
meaning are ignored. The @acronym{MML} parameter names are the same as the
|
||
@acronym{MIME} parameter names; the things in the parentheses say which
|
||
header it will be used in.
|
||
|
||
@table @samp
|
||
@item type
|
||
The @acronym{MIME} type of the part (@code{Content-Type}).
|
||
|
||
@item filename
|
||
Use the contents of the file in the body of the part
|
||
(@code{Content-Disposition}).
|
||
|
||
@item charset
|
||
The contents of the body of the part are to be encoded in the character
|
||
set specified (@code{Content-Type}). @xref{Charset Translation}.
|
||
|
||
@item name
|
||
Might be used to suggest a file name if the part is to be saved
|
||
to a file (@code{Content-Type}).
|
||
|
||
@item disposition
|
||
Valid values are @samp{inline} and @samp{attachment}
|
||
(@code{Content-Disposition}).
|
||
|
||
@item encoding
|
||
Valid values are @samp{7bit}, @samp{8bit}, @samp{quoted-printable} and
|
||
@samp{base64} (@code{Content-Transfer-Encoding}). @xref{Charset
|
||
Translation}.
|
||
|
||
@item description
|
||
A description of the part (@code{Content-Description}).
|
||
|
||
@item creation-date
|
||
RFC822 date when the part was created (@code{Content-Disposition}).
|
||
|
||
@item modification-date
|
||
RFC822 date when the part was modified (@code{Content-Disposition}).
|
||
|
||
@item read-date
|
||
RFC822 date when the part was read (@code{Content-Disposition}).
|
||
|
||
@item recipients
|
||
Who to encrypt/sign the part to. This field is used to override any
|
||
auto-detection based on the To/CC headers.
|
||
|
||
@item sender
|
||
Identity used to sign the part. This field is used to override the
|
||
default key used.
|
||
|
||
@item size
|
||
The size (in octets) of the part (@code{Content-Disposition}).
|
||
|
||
@item sign
|
||
What technology to sign this @acronym{MML} part with (@code{smime}, @code{pgp}
|
||
or @code{pgpmime})
|
||
|
||
@item encrypt
|
||
What technology to encrypt this @acronym{MML} part with (@code{smime},
|
||
@code{pgp} or @code{pgpmime})
|
||
|
||
@end table
|
||
|
||
Parameters for @samp{text/plain}:
|
||
|
||
@table @samp
|
||
@item format
|
||
Formatting parameter for the text, valid values include @samp{fixed}
|
||
(the default) and @samp{flowed}. Normally you do not specify this
|
||
manually, since it requires the textual body to be formatted in a
|
||
special way described in RFC 2646. @xref{Flowed text}.
|
||
@end table
|
||
|
||
Parameters for @samp{application/octet-stream}:
|
||
|
||
@table @samp
|
||
@item type
|
||
Type of the part; informal---meant for human readers
|
||
(@code{Content-Type}).
|
||
@end table
|
||
|
||
Parameters for @samp{message/external-body}:
|
||
|
||
@table @samp
|
||
@item access-type
|
||
A word indicating the supported access mechanism by which the file may
|
||
be obtained. Values include @samp{ftp}, @samp{anon-ftp}, @samp{tftp},
|
||
@samp{localfile}, and @samp{mailserver}. (@code{Content-Type}.)
|
||
|
||
@item expiration
|
||
The RFC822 date after which the file may no longer be fetched.
|
||
(@code{Content-Type}.)
|
||
|
||
@item size
|
||
The size (in octets) of the file. (@code{Content-Type}.)
|
||
|
||
@item permission
|
||
Valid values are @samp{read} and @samp{read-write}
|
||
(@code{Content-Type}).
|
||
|
||
@end table
|
||
|
||
Parameters for @samp{sign=smime}:
|
||
|
||
@table @samp
|
||
|
||
@item keyfile
|
||
File containing key and certificate for signer.
|
||
|
||
@end table
|
||
|
||
Parameters for @samp{encrypt=smime}:
|
||
|
||
@table @samp
|
||
|
||
@item certfile
|
||
File containing certificate for recipient.
|
||
|
||
@end table
|
||
|
||
|
||
@node Advanced MML Example
|
||
@section Advanced MML Example
|
||
|
||
Here's a complex multipart message. It's a @samp{multipart/mixed} that
|
||
contains many parts, one of which is a @samp{multipart/alternative}.
|
||
|
||
@example
|
||
<#multipart type=mixed>
|
||
<#part type=image/jpeg filename=~/rms.jpg disposition=inline>
|
||
<#multipart type=alternative>
|
||
This is a plain text part.
|
||
<#part type=text/enriched name=enriched.txt>
|
||
<center>This is a centered enriched part</center>
|
||
<#/multipart>
|
||
This is a new plain text part.
|
||
<#part disposition=attachment>
|
||
This plain text part is an attachment.
|
||
<#/multipart>
|
||
@end example
|
||
|
||
And this is the resulting @acronym{MIME} message:
|
||
|
||
@example
|
||
Content-Type: multipart/mixed; boundary="=-=-="
|
||
|
||
|
||
--=-=-=
|
||
|
||
|
||
|
||
--=-=-=
|
||
Content-Type: image/jpeg;
|
||
filename="~/rms.jpg"
|
||
Content-Disposition: inline;
|
||
filename="~/rms.jpg"
|
||
Content-Transfer-Encoding: base64
|
||
|
||
/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRof
|
||
Hh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/wAALCAAwADABAREA/8QAHwAA
|
||
AQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQAAAF9AQIDAAQR
|
||
BRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3ODk6Q0RF
|
||
RkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWmp6ip
|
||
qrKztLW2t7i5usLDxMXGx8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/9oACAEB
|
||
AAA/AO/rifFHjldNuGsrDa0qcSSHkA+gHrXKw+LtWLrMb+RgTyhbr+HSug07xNqV9fQtZrNI
|
||
AyiaE/NuBPOOOP0rvRNE880KOC8TbXXGCv1FPqjrF4LDR7u5L7SkTFT/ALWOP1xXgTuXfc7E
|
||
sx6nua6rwp4IvvEM8chCxWxOdzn7wz6V9AaB4S07w9p5itow0rDLSY5Pt9K43xO66P4xs71m
|
||
2QXiGCbA4yOVJ9+1aYORkdK434lyNH4ahCnG66VT9Nj15JFbPdX0MS43M4VQf5/yr2vSpLnw
|
||
5ZW8dlCZ8KFXjOPX0/mK6rSPEGt3Angu44fNEReHYNvIH3TzXDeKNO8RX+kSX2ouZkicTIOc
|
||
L+g7E810ulFjpVtv3bwgB3HJyK5L4quY/C9sVxk3ij/xx6850u7t1mtp/wDlpEw3An3Jr3Dw
|
||
34gsbWza4nBlhC5LDsaW6+IFgupQyCF3iHH7gA7c9R9ay7zx6t7aX9jHC4smhfBkGCvHGfrm
|
||
tLQ7hbnRrV1GPkAP1x1/Hr+Ncr8Vzjwrbf8AX6v/AKA9eQRyYlQk8Yx9K6XTNbkgia2ciSIn
|
||
7p5Ga9Atte0LTLKO6it4i7dVRFJDcZ4PvXN+JvEMF9bILVGXJLSZ4zkjivRPDaeX4b08HOTC
|
||
pOffmua+KkbS+GLVUGT9tT/0B68eeIpIFYjB70+OOVXyoOM9+M1eaWeCLzHPyHGO/NVWvJJm
|
||
jQ8KGH1NfQWhXSXmh2c8eArRLwO3HSv/2Q==
|
||
|
||
--=-=-=
|
||
Content-Type: multipart/alternative; boundary="==-=-="
|
||
|
||
|
||
--==-=-=
|
||
|
||
|
||
This is a plain text part.
|
||
|
||
--==-=-=
|
||
Content-Type: text/enriched;
|
||
name="enriched.txt"
|
||
|
||
|
||
<center>This is a centered enriched part</center>
|
||
|
||
--==-=-=--
|
||
|
||
--=-=-=
|
||
|
||
This is a new plain text part.
|
||
|
||
--=-=-=
|
||
Content-Disposition: attachment
|
||
|
||
|
||
This plain text part is an attachment.
|
||
|
||
--=-=-=--
|
||
@end example
|
||
|
||
@node Encoding Customization
|
||
@section Encoding Customization
|
||
|
||
@table @code
|
||
|
||
@item mm-body-charset-encoding-alist
|
||
@vindex mm-body-charset-encoding-alist
|
||
Mapping from @acronym{MIME} charset to encoding to use. This variable is
|
||
usually used except, e.g., when other requirements force a specific
|
||
encoding (digitally signed messages require 7bit encodings). The
|
||
default is
|
||
|
||
@lisp
|
||
((iso-2022-jp . 7bit)
|
||
(iso-2022-jp-2 . 7bit)
|
||
(utf-16 . base64)
|
||
(utf-16be . base64)
|
||
(utf-16le . base64))
|
||
@end lisp
|
||
|
||
As an example, if you do not want to have ISO-8859-1 characters
|
||
quoted-printable encoded, you may add @code{(iso-8859-1 . 8bit)} to
|
||
this variable. You can override this setting on a per-message basis
|
||
by using the @code{encoding} @acronym{MML} tag (@pxref{MML Definition}).
|
||
|
||
@item mm-coding-system-priorities
|
||
@vindex mm-coding-system-priorities
|
||
Prioritize coding systems to use for outgoing messages. The default
|
||
is @code{nil}, which means to use the defaults in Emacs, but is
|
||
@code{(iso-8859-1 iso-2022-jp iso-2022-jp-2 shift_jis utf-8)} when
|
||
running Emacs in the Japanese language environment. It is a list of
|
||
coding system symbols (aliases of coding systems are also allowed, use
|
||
@kbd{M-x describe-coding-system} to make sure you are specifying correct
|
||
coding system names). For example, if you have configured Emacs
|
||
to prefer UTF-8, but wish that outgoing messages should be sent in
|
||
ISO-8859-1 if possible, you can set this variable to
|
||
@code{(iso-8859-1)}. You can override this setting on a per-message
|
||
basis by using the @code{charset} @acronym{MML} tag (@pxref{MML Definition}).
|
||
|
||
@item mm-content-transfer-encoding-defaults
|
||
@vindex mm-content-transfer-encoding-defaults
|
||
Mapping from @acronym{MIME} types to encoding to use. This variable is usually
|
||
used except, e.g., when other requirements force a safer encoding
|
||
(digitally signed messages require 7bit encoding). Besides the normal
|
||
@acronym{MIME} encodings, @code{qp-or-base64} may be used to indicate that for
|
||
each case the most efficient of quoted-printable and base64 should be
|
||
used.
|
||
|
||
@code{qp-or-base64} has another effect. It will fold long lines so that
|
||
MIME parts may not be broken by MTA. So do @code{quoted-printable} and
|
||
@code{base64}.
|
||
|
||
Note that it affects body encoding only when a part is a raw forwarded
|
||
message (which will be made by @code{gnus-summary-mail-forward} with the
|
||
arg 2 for example) or is neither the @samp{text/*} type nor the
|
||
@samp{message/*} type. Even though in those cases, you can override
|
||
this setting on a per-message basis by using the @code{encoding}
|
||
@acronym{MML} tag (@pxref{MML Definition}).
|
||
|
||
@item mm-use-ultra-safe-encoding
|
||
@vindex mm-use-ultra-safe-encoding
|
||
When this is non-@code{nil}, it means that textual parts are encoded as
|
||
quoted-printable if they contain lines longer than 76 characters or
|
||
starting with "From " in the body. Non-7bit encodings (8bit, binary)
|
||
are generally disallowed. This reduce the probability that a non-8bit
|
||
clean MTA or MDA changes the message. This should never be set
|
||
directly, but bound by other functions when necessary (e.g., when
|
||
encoding messages that are to be digitally signed).
|
||
|
||
@end table
|
||
|
||
@node Charset Translation
|
||
@section Charset Translation
|
||
@cindex charsets
|
||
|
||
During translation from @acronym{MML} to @acronym{MIME}, for each
|
||
@acronym{MIME} part which has been composed inside Emacs, an appropriate
|
||
charset has to be chosen.
|
||
|
||
@vindex mail-parse-charset
|
||
If you are running a non-@sc{mule} Emacs, this process is simple: If the
|
||
part contains any non-@acronym{ASCII} (8-bit) characters, the @acronym{MIME} charset
|
||
given by @code{mail-parse-charset} (a symbol) is used. (Never set this
|
||
variable directly, though. If you want to change the default charset,
|
||
please consult the documentation of the package which you use to process
|
||
@acronym{MIME} messages.
|
||
@xref{Various Message Variables, , Various Message Variables, message,
|
||
Message Manual}, for example.)
|
||
If there are only @acronym{ASCII} characters, the @acronym{MIME} charset US-ASCII is
|
||
used, of course.
|
||
|
||
@cindex MULE
|
||
@cindex UTF-8
|
||
@cindex Unicode
|
||
@vindex mm-mime-mule-charset-alist
|
||
Things are slightly more complicated when running Emacs with @sc{mule}
|
||
support. In this case, a list of the @sc{mule} charsets used in the
|
||
part is obtained, and the @sc{mule} charsets are translated to
|
||
@acronym{MIME} charsets by consulting the table provided by Emacs itself
|
||
or the variable @code{mm-mime-mule-charset-alist} for XEmacs.
|
||
If this results in a single @acronym{MIME} charset, this is used to encode
|
||
the part. But if the resulting list of @acronym{MIME} charsets contains more
|
||
than one element, two things can happen: If it is possible to encode the
|
||
part via UTF-8, this charset is used. (For this, Emacs must support
|
||
the @code{utf-8} coding system, and the part must consist entirely of
|
||
characters which have Unicode counterparts.) If UTF-8 is not available
|
||
for some reason, the part is split into several ones, so that each one
|
||
can be encoded with a single @acronym{MIME} charset. The part can only be
|
||
split at line boundaries, though---if more than one @acronym{MIME} charset is
|
||
required to encode a single line, it is not possible to encode the part.
|
||
|
||
When running Emacs with @sc{mule} support, the preferences for which
|
||
coding system to use is inherited from Emacs itself. This means that
|
||
if Emacs is set up to prefer UTF-8, it will be used when encoding
|
||
messages. You can modify this by altering the
|
||
@code{mm-coding-system-priorities} variable though (@pxref{Encoding
|
||
Customization}).
|
||
|
||
The charset to be used can be overridden by setting the @code{charset}
|
||
@acronym{MML} tag (@pxref{MML Definition}) when composing the message.
|
||
|
||
The encoding of characters (quoted-printable, 8bit etc) is orthogonal
|
||
to the discussion here, and is controlled by the variables
|
||
@code{mm-body-charset-encoding-alist} and
|
||
@code{mm-content-transfer-encoding-defaults} (@pxref{Encoding
|
||
Customization}).
|
||
|
||
@node Conversion
|
||
@section Conversion
|
||
|
||
@findex mime-to-mml
|
||
A (multipart) @acronym{MIME} message can be converted to @acronym{MML}
|
||
with the @code{mime-to-mml} function. It works on the message in the
|
||
current buffer, and substitutes @acronym{MML} markup for @acronym{MIME}
|
||
boundaries. Non-textual parts do not have their contents in the buffer,
|
||
but instead have the contents in separate buffers that are referred to
|
||
from the @acronym{MML} tags.
|
||
|
||
@findex mml-to-mime
|
||
An @acronym{MML} message can be converted back to @acronym{MIME} by the
|
||
@code{mml-to-mime} function.
|
||
|
||
These functions are in certain senses ``lossy''---you will not get back
|
||
an identical message if you run @code{mime-to-mml} and then
|
||
@code{mml-to-mime}. Not only will trivial things like the order of the
|
||
headers differ, but the contents of the headers may also be different.
|
||
For instance, the original message may use base64 encoding on text,
|
||
while @code{mml-to-mime} may decide to use quoted-printable encoding, and
|
||
so on.
|
||
|
||
In essence, however, these two functions should be the inverse of each
|
||
other. The resulting contents of the message should remain equivalent,
|
||
if not identical.
|
||
|
||
|
||
@node Flowed text
|
||
@section Flowed text
|
||
@cindex format=flowed
|
||
|
||
The Emacs @acronym{MIME} library will respect the @code{use-hard-newlines}
|
||
variable (@pxref{Hard and Soft Newlines, ,Hard and Soft Newlines,
|
||
emacs, Emacs Manual}) when encoding a message, and the
|
||
``format=flowed'' Content-Type parameter when decoding a message.
|
||
|
||
On encoding text, regardless of @code{use-hard-newlines}, lines
|
||
terminated by soft newline characters are filled together and wrapped
|
||
after the column decided by @code{fill-flowed-encode-column}.
|
||
Quotation marks (matching @samp{^>* ?}) are respected. The variable
|
||
controls how the text will look in a client that does not support
|
||
flowed text, the default is to wrap after 66 characters. If hard
|
||
newline characters are not present in the buffer, no flow encoding
|
||
occurs.
|
||
|
||
On decoding flowed text, lines with soft newline characters are filled
|
||
together and wrapped after the column decided by
|
||
@code{fill-flowed-display-column}. The default is to wrap after
|
||
@code{fill-column}.
|
||
|
||
@table @code
|
||
@item mm-fill-flowed
|
||
@vindex mm-fill-flowed
|
||
If non-@code{nil} a format=flowed article will be displayed flowed.
|
||
@end table
|
||
|
||
|
||
@node Interface Functions
|
||
@chapter Interface Functions
|
||
@cindex interface functions
|
||
@cindex mail-parse
|
||
|
||
The @code{mail-parse} library is an abstraction over the actual
|
||
low-level libraries that are described in the next chapter.
|
||
|
||
Standards change, and so programs have to change to fit in the new
|
||
mold. For instance, RFC2045 describes a syntax for the
|
||
@code{Content-Type} header that only allows @acronym{ASCII} characters in the
|
||
parameter list. RFC2231 expands on RFC2045 syntax to provide a scheme
|
||
for continuation headers and non-@acronym{ASCII} characters.
|
||
|
||
The traditional way to deal with this is just to update the library
|
||
functions to parse the new syntax. However, this is sometimes the wrong
|
||
thing to do. In some instances it may be vital to be able to understand
|
||
both the old syntax as well as the new syntax, and if there is only one
|
||
library, one must choose between the old version of the library and the
|
||
new version of the library.
|
||
|
||
The Emacs @acronym{MIME} library takes a different tack. It defines a
|
||
series of low-level libraries (@file{rfc2047.el}, @file{rfc2231.el}
|
||
and so on) that parses strictly according to the corresponding
|
||
standard. However, normal programs would not use the functions
|
||
provided by these libraries directly, but instead use the functions
|
||
provided by the @code{mail-parse} library. The functions in this
|
||
library are just aliases to the corresponding functions in the latest
|
||
low-level libraries. Using this scheme, programs get a consistent
|
||
interface they can use, and library developers are free to create
|
||
write code that handles new standards.
|
||
|
||
The following functions are defined by this library:
|
||
|
||
@table @code
|
||
@item mail-header-parse-content-type
|
||
@findex mail-header-parse-content-type
|
||
Parse a @code{Content-Type} header and return a list on the following
|
||
format:
|
||
|
||
@lisp
|
||
("type/subtype"
|
||
(attribute1 . value1)
|
||
(attribute2 . value2)
|
||
...)
|
||
@end lisp
|
||
|
||
Here's an example:
|
||
|
||
@example
|
||
(mail-header-parse-content-type
|
||
"image/gif; name=\"b980912.gif\"")
|
||
@result{} ("image/gif" (name . "b980912.gif"))
|
||
@end example
|
||
|
||
@item mail-header-parse-content-disposition
|
||
@findex mail-header-parse-content-disposition
|
||
Parse a @code{Content-Disposition} header and return a list on the same
|
||
format as the function above.
|
||
|
||
@item mail-content-type-get
|
||
@findex mail-content-type-get
|
||
Takes two parameters---a list on the format above, and an attribute.
|
||
Returns the value of the attribute.
|
||
|
||
@example
|
||
(mail-content-type-get
|
||
'("image/gif" (name . "b980912.gif")) 'name)
|
||
@result{} "b980912.gif"
|
||
@end example
|
||
|
||
@item mail-header-encode-parameter
|
||
@findex mail-header-encode-parameter
|
||
Takes a parameter string and returns an encoded version of the string.
|
||
This is used for parameters in headers like @code{Content-Type} and
|
||
@code{Content-Disposition}.
|
||
|
||
@item mail-header-remove-comments
|
||
@findex mail-header-remove-comments
|
||
Return a comment-free version of a header.
|
||
|
||
@example
|
||
(mail-header-remove-comments
|
||
"Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
|
||
@result{} "Gnus/5.070027 "
|
||
@end example
|
||
|
||
@item mail-header-remove-whitespace
|
||
@findex mail-header-remove-whitespace
|
||
Remove linear white space from a header. Space inside quoted strings
|
||
and comments is preserved.
|
||
|
||
@example
|
||
(mail-header-remove-whitespace
|
||
"image/gif; name=\"Name with spaces\"")
|
||
@result{} "image/gif;name=\"Name with spaces\""
|
||
@end example
|
||
|
||
@item mail-header-get-comment
|
||
@findex mail-header-get-comment
|
||
Return the last comment in a header.
|
||
|
||
@example
|
||
(mail-header-get-comment
|
||
"Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
|
||
@result{} "Finnish Landrace"
|
||
@end example
|
||
|
||
@item mail-header-parse-address
|
||
@findex mail-header-parse-address
|
||
Parse an address and return a list containing the mailbox and the
|
||
plaintext name.
|
||
|
||
@example
|
||
(mail-header-parse-address
|
||
"Hrvoje Niksic <hniksic@@srce.hr>")
|
||
@result{} ("hniksic@@srce.hr" . "Hrvoje Niksic")
|
||
@end example
|
||
|
||
@item mail-header-parse-addresses
|
||
@findex mail-header-parse-addresses
|
||
Parse a string with list of addresses and return a list of elements like
|
||
the one described above.
|
||
|
||
@example
|
||
(mail-header-parse-addresses
|
||
"Hrvoje Niksic <hniksic@@srce.hr>, Steinar Bang <sb@@metis.no>")
|
||
@result{} (("hniksic@@srce.hr" . "Hrvoje Niksic")
|
||
("sb@@metis.no" . "Steinar Bang"))
|
||
@end example
|
||
|
||
@item mail-header-parse-date
|
||
@findex mail-header-parse-date
|
||
Parse a date string and return an Emacs time structure.
|
||
|
||
@item mail-narrow-to-head
|
||
@findex mail-narrow-to-head
|
||
Narrow the buffer to the header section of the buffer. Point is placed
|
||
at the beginning of the narrowed buffer.
|
||
|
||
@item mail-header-narrow-to-field
|
||
@findex mail-header-narrow-to-field
|
||
Narrow the buffer to the header under point. Understands continuation
|
||
headers.
|
||
|
||
@item mail-header-fold-field
|
||
@findex mail-header-fold-field
|
||
Fold the header under point.
|
||
|
||
@item mail-header-unfold-field
|
||
@findex mail-header-unfold-field
|
||
Unfold the header under point.
|
||
|
||
@item mail-header-field-value
|
||
@findex mail-header-field-value
|
||
Return the value of the field under point.
|
||
|
||
@item mail-encode-encoded-word-region
|
||
@findex mail-encode-encoded-word-region
|
||
Encode the non-@acronym{ASCII} words in the region. For instance,
|
||
@samp{Na<4E>ve} is encoded as @samp{=?iso-8859-1?q?Na=EFve?=}.
|
||
|
||
@item mail-encode-encoded-word-buffer
|
||
@findex mail-encode-encoded-word-buffer
|
||
Encode the non-@acronym{ASCII} words in the current buffer. This function is
|
||
meant to be called narrowed to the headers of a message.
|
||
|
||
@item mail-encode-encoded-word-string
|
||
@findex mail-encode-encoded-word-string
|
||
Encode the words that need encoding in a string, and return the result.
|
||
|
||
@example
|
||
(mail-encode-encoded-word-string
|
||
"This is na<6E>ve, baby")
|
||
@result{} "This is =?iso-8859-1?q?na=EFve,?= baby"
|
||
@end example
|
||
|
||
@item mail-decode-encoded-word-region
|
||
@findex mail-decode-encoded-word-region
|
||
Decode the encoded words in the region.
|
||
|
||
@item mail-decode-encoded-word-string
|
||
@findex mail-decode-encoded-word-string
|
||
Decode the encoded words in the string and return the result.
|
||
|
||
@example
|
||
(mail-decode-encoded-word-string
|
||
"This is =?iso-8859-1?q?na=EFve,?= baby")
|
||
@result{} "This is na<6E>ve, baby"
|
||
@end example
|
||
|
||
@end table
|
||
|
||
Currently, @code{mail-parse} is an abstraction over @code{ietf-drums},
|
||
@code{rfc2047}, @code{rfc2045} and @code{rfc2231}. These are documented
|
||
in the subsequent sections.
|
||
|
||
|
||
|
||
@node Basic Functions
|
||
@chapter Basic Functions
|
||
|
||
This chapter describes the basic, ground-level functions for parsing and
|
||
handling. Covered here is parsing @code{From} lines, removing comments
|
||
from header lines, decoding encoded words, parsing date headers and so
|
||
on. High-level functionality is dealt with in the first chapter
|
||
(@pxref{Decoding and Viewing}).
|
||
|
||
@menu
|
||
* rfc2045:: Encoding @code{Content-Type} headers.
|
||
* rfc2231:: Parsing @code{Content-Type} headers.
|
||
* ietf-drums:: Handling mail headers defined by RFC822bis.
|
||
* rfc2047:: En/decoding encoded words in headers.
|
||
* time-date:: Functions for parsing dates and manipulating time.
|
||
* qp:: Quoted-Printable en/decoding.
|
||
* base64:: Base64 en/decoding.
|
||
* binhex:: Binhex decoding.
|
||
* uudecode:: Uuencode decoding.
|
||
* yenc:: Yenc decoding.
|
||
* rfc1843:: Decoding HZ-encoded text.
|
||
* mailcap:: How parts are displayed is specified by the @file{.mailcap} file
|
||
@end menu
|
||
|
||
|
||
@node rfc2045
|
||
@section rfc2045
|
||
|
||
RFC2045 is the ``main'' @acronym{MIME} document, and as such, one would
|
||
imagine that there would be a lot to implement. But there isn't, since
|
||
most of the implementation details are delegated to the subsequent
|
||
RFCs.
|
||
|
||
So @file{rfc2045.el} has only a single function:
|
||
|
||
@table @code
|
||
@item rfc2045-encode-string
|
||
@findex rfc2045-encode-string
|
||
Takes a parameter and a value and returns a @samp{PARAM=VALUE} string.
|
||
@var{value} will be quoted if there are non-safe characters in it.
|
||
@end table
|
||
|
||
|
||
@node rfc2231
|
||
@section rfc2231
|
||
|
||
RFC2231 defines a syntax for the @code{Content-Type} and
|
||
@code{Content-Disposition} headers. Its snappy name is @dfn{MIME
|
||
Parameter Value and Encoded Word Extensions: Character Sets, Languages,
|
||
and Continuations}.
|
||
|
||
In short, these headers look something like this:
|
||
|
||
@example
|
||
Content-Type: application/x-stuff;
|
||
title*0*=us-ascii'en'This%20is%20even%20more%20;
|
||
title*1*=%2A%2A%2Afun%2A%2A%2A%20;
|
||
title*2="isn't it!"
|
||
@end example
|
||
|
||
They usually aren't this bad, though.
|
||
|
||
The following functions are defined by this library:
|
||
|
||
@table @code
|
||
@item rfc2231-parse-string
|
||
@findex rfc2231-parse-string
|
||
Parse a @code{Content-Type} header and return a list describing its
|
||
elements.
|
||
|
||
@example
|
||
(rfc2231-parse-string
|
||
"application/x-stuff;
|
||
title*0*=us-ascii'en'This%20is%20even%20more%20;
|
||
title*1*=%2A%2A%2Afun%2A%2A%2A%20;
|
||
title*2=\"isn't it!\"")
|
||
@result{} ("application/x-stuff"
|
||
(title . "This is even more ***fun*** isn't it!"))
|
||
@end example
|
||
|
||
@item rfc2231-get-value
|
||
@findex rfc2231-get-value
|
||
Takes one of the lists on the format above and returns
|
||
the value of the specified attribute.
|
||
|
||
@item rfc2231-encode-string
|
||
@findex rfc2231-encode-string
|
||
Encode a parameter in headers likes @code{Content-Type} and
|
||
@code{Content-Disposition}.
|
||
|
||
@end table
|
||
|
||
|
||
@node ietf-drums
|
||
@section ietf-drums
|
||
|
||
@dfn{drums} is an IETF working group that is working on the replacement
|
||
for RFC822.
|
||
|
||
The functions provided by this library include:
|
||
|
||
@table @code
|
||
@item ietf-drums-remove-comments
|
||
@findex ietf-drums-remove-comments
|
||
Remove the comments from the argument and return the results.
|
||
|
||
@item ietf-drums-remove-whitespace
|
||
@findex ietf-drums-remove-whitespace
|
||
Remove linear white space from the string and return the results.
|
||
Spaces inside quoted strings and comments are left untouched.
|
||
|
||
@item ietf-drums-get-comment
|
||
@findex ietf-drums-get-comment
|
||
Return the last most comment from the string.
|
||
|
||
@item ietf-drums-parse-address
|
||
@findex ietf-drums-parse-address
|
||
Parse an address string and return a list that contains the mailbox and
|
||
the plain text name.
|
||
|
||
@item ietf-drums-parse-addresses
|
||
@findex ietf-drums-parse-addresses
|
||
Parse a string that contains any number of comma-separated addresses and
|
||
return a list that contains mailbox/plain text pairs.
|
||
|
||
@item ietf-drums-parse-date
|
||
@findex ietf-drums-parse-date
|
||
Parse a date string and return an Emacs time structure.
|
||
|
||
@item ietf-drums-narrow-to-header
|
||
@findex ietf-drums-narrow-to-header
|
||
Narrow the buffer to the header section of the current buffer.
|
||
|
||
@end table
|
||
|
||
|
||
@node rfc2047
|
||
@section rfc2047
|
||
|
||
RFC2047 (Message Header Extensions for Non-@acronym{ASCII} Text) specifies how
|
||
non-@acronym{ASCII} text in headers are to be encoded. This is actually rather
|
||
complicated, so a number of variables are necessary to tweak what this
|
||
library does.
|
||
|
||
The following variables are tweakable:
|
||
|
||
@table @code
|
||
@item rfc2047-header-encoding-alist
|
||
@vindex rfc2047-header-encoding-alist
|
||
This is an alist of header / encoding-type pairs. Its main purpose is
|
||
to prevent encoding of certain headers.
|
||
|
||
The keys can either be header regexps, or @code{t}.
|
||
|
||
The values can be @code{nil}, in which case the header(s) in question
|
||
won't be encoded, @code{mime}, which means that they will be encoded, or
|
||
@code{address-mime}, which means the header(s) will be encoded carefully
|
||
assuming they contain addresses.
|
||
|
||
@item rfc2047-charset-encoding-alist
|
||
@vindex rfc2047-charset-encoding-alist
|
||
RFC2047 specifies two forms of encoding---@code{Q} (a
|
||
Quoted-Printable-like encoding) and @code{B} (base64). This alist
|
||
specifies which charset should use which encoding.
|
||
|
||
@item rfc2047-encode-function-alist
|
||
@vindex rfc2047-encode-function-alist
|
||
This is an alist of encoding / function pairs. The encodings are
|
||
@code{Q}, @code{B} and @code{nil}.
|
||
|
||
@item rfc2047-encoded-word-regexp
|
||
@vindex rfc2047-encoded-word-regexp
|
||
When decoding words, this library looks for matches to this regexp.
|
||
|
||
@item rfc2047-encode-encoded-words
|
||
@vindex rfc2047-encode-encoded-words
|
||
The boolean variable specifies whether encoded words
|
||
(e.g. @samp{=?hello?=}) should be encoded again.
|
||
|
||
@end table
|
||
|
||
Those were the variables, and these are this functions:
|
||
|
||
@table @code
|
||
@item rfc2047-narrow-to-field
|
||
@findex rfc2047-narrow-to-field
|
||
Narrow the buffer to the header on the current line.
|
||
|
||
@item rfc2047-encode-message-header
|
||
@findex rfc2047-encode-message-header
|
||
Should be called narrowed to the header of a message. Encodes according
|
||
to @code{rfc2047-header-encoding-alist}.
|
||
|
||
@item rfc2047-encode-region
|
||
@findex rfc2047-encode-region
|
||
Encodes all encodable words in the region specified.
|
||
|
||
@item rfc2047-encode-string
|
||
@findex rfc2047-encode-string
|
||
Encode a string and return the results.
|
||
|
||
@item rfc2047-decode-region
|
||
@findex rfc2047-decode-region
|
||
Decode the encoded words in the region.
|
||
|
||
@item rfc2047-decode-string
|
||
@findex rfc2047-decode-string
|
||
Decode a string and return the results.
|
||
|
||
@item rfc2047-encode-parameter
|
||
@findex rfc2047-encode-parameter
|
||
Encode a parameter in the RFC2047-like style. This is a replacement for
|
||
the @code{rfc2231-encode-string} function. @xref{rfc2231}.
|
||
|
||
When attaching files as @acronym{MIME} parts, we should use the RFC2231
|
||
encoding to specify the file names containing non-@acronym{ASCII}
|
||
characters. However, many mail softwares don't support it in practice
|
||
and recipients won't be able to extract files with correct names.
|
||
Instead, the RFC2047-like encoding is acceptable generally. This
|
||
function provides the very RFC2047-like encoding, resigning to such a
|
||
regrettable trend. To use it, put the following line in your
|
||
@file{~/.gnus.el} file:
|
||
|
||
@lisp
|
||
(defalias 'mail-header-encode-parameter 'rfc2047-encode-parameter)
|
||
@end lisp
|
||
|
||
@end table
|
||
|
||
|
||
@node time-date
|
||
@section time-date
|
||
|
||
While not really a part of the @acronym{MIME} library, it is convenient to
|
||
document this library here. It deals with parsing @code{Date} headers
|
||
and manipulating time. (Not by using tesseracts, though, I'm sorry to
|
||
say.)
|
||
|
||
These functions convert between five formats: A date string, an Emacs
|
||
time structure, a decoded time list, a second number, and a day number.
|
||
|
||
Here's a bunch of time/date/second/day examples:
|
||
|
||
@example
|
||
(parse-time-string "Sat Sep 12 12:21:54 1998 +0200")
|
||
@result{} (54 21 12 12 9 1998 6 nil 7200)
|
||
|
||
(date-to-time "Sat Sep 12 12:21:54 1998 +0200")
|
||
@result{} (13818 19266)
|
||
|
||
(time-to-seconds '(13818 19266))
|
||
@result{} 905595714.0
|
||
|
||
(seconds-to-time 905595714.0)
|
||
@result{} (13818 19266 0)
|
||
|
||
(time-to-days '(13818 19266))
|
||
@result{} 729644
|
||
|
||
(days-to-time 729644)
|
||
@result{} (961933 65536)
|
||
|
||
(time-since '(13818 19266))
|
||
@result{} (0 430)
|
||
|
||
(time-less-p '(13818 19266) '(13818 19145))
|
||
@result{} nil
|
||
|
||
(subtract-time '(13818 19266) '(13818 19145))
|
||
@result{} (0 121)
|
||
|
||
(days-between "Sat Sep 12 12:21:54 1998 +0200"
|
||
"Sat Sep 07 12:21:54 1998 +0200")
|
||
@result{} 5
|
||
|
||
(date-leap-year-p 2000)
|
||
@result{} t
|
||
|
||
(time-to-day-in-year '(13818 19266))
|
||
@result{} 255
|
||
|
||
(time-to-number-of-days
|
||
(time-since
|
||
(date-to-time "Mon, 01 Jan 2001 02:22:26 GMT")))
|
||
@result{} 4.146122685185185
|
||
@end example
|
||
|
||
And finally, we have @code{safe-date-to-time}, which does the same as
|
||
@code{date-to-time}, but returns a zero time if the date is
|
||
syntactically malformed.
|
||
|
||
The five data representations used are the following:
|
||
|
||
@table @var
|
||
@item date
|
||
An RFC822 (or similar) date string. For instance: @code{"Sat Sep 12
|
||
12:21:54 1998 +0200"}.
|
||
|
||
@item time
|
||
An internal Emacs time. For instance: @code{(13818 26466)}.
|
||
|
||
@item seconds
|
||
A floating point representation of the internal Emacs time. For
|
||
instance: @code{905595714.0}.
|
||
|
||
@item days
|
||
An integer number representing the number of days since 00000101. For
|
||
instance: @code{729644}.
|
||
|
||
@item decoded time
|
||
A list of decoded time. For instance: @code{(54 21 12 12 9 1998 6 t
|
||
7200)}.
|
||
@end table
|
||
|
||
All the examples above represent the same moment.
|
||
|
||
These are the functions available:
|
||
|
||
@table @code
|
||
@item date-to-time
|
||
Take a date and return a time.
|
||
|
||
@item time-to-seconds
|
||
Take a time and return seconds.
|
||
|
||
@item seconds-to-time
|
||
Take seconds and return a time.
|
||
|
||
@item time-to-days
|
||
Take a time and return days.
|
||
|
||
@item days-to-time
|
||
Take days and return a time.
|
||
|
||
@item date-to-day
|
||
Take a date and return days.
|
||
|
||
@item time-to-number-of-days
|
||
Take a time and return the number of days that represents.
|
||
|
||
@item safe-date-to-time
|
||
Take a date and return a time. If the date is not syntactically valid,
|
||
return a ``zero'' time.
|
||
|
||
@item time-less-p
|
||
Take two times and say whether the first time is less (i. e., earlier)
|
||
than the second time.
|
||
|
||
@item time-since
|
||
Take a time and return a time saying how long it was since that time.
|
||
|
||
@item subtract-time
|
||
Take two times and subtract the second from the first. I. e., return
|
||
the time between the two times.
|
||
|
||
@item days-between
|
||
Take two days and return the number of days between those two days.
|
||
|
||
@item date-leap-year-p
|
||
Take a year number and say whether it's a leap year.
|
||
|
||
@item time-to-day-in-year
|
||
Take a time and return the day number within the year that the time is
|
||
in.
|
||
|
||
@end table
|
||
|
||
|
||
@node qp
|
||
@section qp
|
||
|
||
This library deals with decoding and encoding Quoted-Printable text.
|
||
|
||
Very briefly explained, qp encoding means translating all 8-bit
|
||
characters (and lots of control characters) into things that look like
|
||
@samp{=EF}; that is, an equal sign followed by the byte encoded as a hex
|
||
string.
|
||
|
||
The following functions are defined by the library:
|
||
|
||
@table @code
|
||
@item quoted-printable-decode-region
|
||
@findex quoted-printable-decode-region
|
||
QP-decode all the encoded text in the specified region.
|
||
|
||
@item quoted-printable-decode-string
|
||
@findex quoted-printable-decode-string
|
||
Decode the QP-encoded text in a string and return the results.
|
||
|
||
@item quoted-printable-encode-region
|
||
@findex quoted-printable-encode-region
|
||
QP-encode all the encodable characters in the specified region. The third
|
||
optional parameter @var{fold} specifies whether to fold long lines.
|
||
(Long here means 72.)
|
||
|
||
@item quoted-printable-encode-string
|
||
@findex quoted-printable-encode-string
|
||
QP-encode all the encodable characters in a string and return the
|
||
results.
|
||
|
||
@end table
|
||
|
||
|
||
@node base64
|
||
@section base64
|
||
@cindex base64
|
||
|
||
Base64 is an encoding that encodes three bytes into four characters,
|
||
thereby increasing the size by about 33%. The alphabet used for
|
||
encoding is very resistant to mangling during transit.
|
||
|
||
The following functions are defined by this library:
|
||
|
||
@table @code
|
||
@item base64-encode-region
|
||
@findex base64-encode-region
|
||
base64 encode the selected region. Return the length of the encoded
|
||
text. Optional third argument @var{no-line-break} means do not break
|
||
long lines into shorter lines.
|
||
|
||
@item base64-encode-string
|
||
@findex base64-encode-string
|
||
base64 encode a string and return the result.
|
||
|
||
@item base64-decode-region
|
||
@findex base64-decode-region
|
||
base64 decode the selected region. Return the length of the decoded
|
||
text. If the region can't be decoded, return @code{nil} and don't
|
||
modify the buffer.
|
||
|
||
@item base64-decode-string
|
||
@findex base64-decode-string
|
||
base64 decode a string and return the result. If the string can't be
|
||
decoded, @code{nil} is returned.
|
||
|
||
@end table
|
||
|
||
|
||
@node binhex
|
||
@section binhex
|
||
@cindex binhex
|
||
@cindex Apple
|
||
@cindex Macintosh
|
||
|
||
@code{binhex} is an encoding that originated in Macintosh environments.
|
||
The following function is supplied to deal with these:
|
||
|
||
@table @code
|
||
@item binhex-decode-region
|
||
@findex binhex-decode-region
|
||
Decode the encoded text in the region. If given a third parameter, only
|
||
decode the @code{binhex} header and return the filename.
|
||
|
||
@end table
|
||
|
||
@node uudecode
|
||
@section uudecode
|
||
@cindex uuencode
|
||
@cindex uudecode
|
||
|
||
@code{uuencode} is probably still the most popular encoding of binaries
|
||
used on Usenet, although @code{base64} rules the mail world.
|
||
|
||
The following function is supplied by this package:
|
||
|
||
@table @code
|
||
@item uudecode-decode-region
|
||
@findex uudecode-decode-region
|
||
Decode the text in the region.
|
||
@end table
|
||
|
||
|
||
@node yenc
|
||
@section yenc
|
||
@cindex yenc
|
||
|
||
@code{yenc} is used for encoding binaries on Usenet. The following
|
||
function is supplied by this package:
|
||
|
||
@table @code
|
||
@item yenc-decode-region
|
||
@findex yenc-decode-region
|
||
Decode the encoded text in the region.
|
||
|
||
@end table
|
||
|
||
|
||
@node rfc1843
|
||
@section rfc1843
|
||
@cindex rfc1843
|
||
@cindex HZ
|
||
@cindex Chinese
|
||
|
||
RFC1843 deals with mixing Chinese and @acronym{ASCII} characters in messages. In
|
||
essence, RFC1843 switches between @acronym{ASCII} and Chinese by doing this:
|
||
|
||
@example
|
||
This sentence is in @acronym{ASCII}.
|
||
The next sentence is in GB.~@{<:Ky2;S@{#,NpJ)l6HK!#~@}Bye.
|
||
@end example
|
||
|
||
Simple enough, and widely used in China.
|
||
|
||
The following functions are available to handle this encoding:
|
||
|
||
@table @code
|
||
@item rfc1843-decode-region
|
||
Decode HZ-encoded text in the region.
|
||
|
||
@item rfc1843-decode-string
|
||
Decode a HZ-encoded string and return the result.
|
||
|
||
@end table
|
||
|
||
|
||
@node mailcap
|
||
@section mailcap
|
||
|
||
The @file{~/.mailcap} file is parsed by most @acronym{MIME}-aware message
|
||
handlers and describes how elements are supposed to be displayed.
|
||
Here's an example file:
|
||
|
||
@example
|
||
image/*; gimp -8 %s
|
||
audio/wav; wavplayer %s
|
||
application/msword; catdoc %s ; copiousoutput ; nametemplate=%s.doc
|
||
@end example
|
||
|
||
This says that all image files should be displayed with @code{gimp},
|
||
that WAVE audio files should be played by @code{wavplayer}, and that
|
||
MS-WORD files should be inlined by @code{catdoc}.
|
||
|
||
The @code{mailcap} library parses this file, and provides functions for
|
||
matching types.
|
||
|
||
@table @code
|
||
@item mailcap-mime-data
|
||
@vindex mailcap-mime-data
|
||
This variable is an alist of alists containing backup viewing rules.
|
||
|
||
@end table
|
||
|
||
Interface functions:
|
||
|
||
@table @code
|
||
@item mailcap-parse-mailcaps
|
||
@findex mailcap-parse-mailcaps
|
||
Parse the @file{~/.mailcap} file.
|
||
|
||
@item mailcap-mime-info
|
||
Takes a @acronym{MIME} type as its argument and returns the matching viewer.
|
||
|
||
@end table
|
||
|
||
|
||
|
||
|
||
@node Standards
|
||
@chapter Standards
|
||
|
||
The Emacs @acronym{MIME} library implements handling of various elements
|
||
according to a (somewhat) large number of RFCs, drafts and standards
|
||
documents. This chapter lists the relevant ones. They can all be
|
||
fetched from @uref{http://quimby.gnus.org/notes/}.
|
||
|
||
@table @dfn
|
||
@item RFC822
|
||
@itemx STD11
|
||
Standard for the Format of ARPA Internet Text Messages.
|
||
|
||
@item RFC1036
|
||
Standard for Interchange of USENET Messages
|
||
|
||
@item RFC2045
|
||
Format of Internet Message Bodies
|
||
|
||
@item RFC2046
|
||
Media Types
|
||
|
||
@item RFC2047
|
||
Message Header Extensions for Non-@acronym{ASCII} Text
|
||
|
||
@item RFC2048
|
||
Registration Procedures
|
||
|
||
@item RFC2049
|
||
Conformance Criteria and Examples
|
||
|
||
@item RFC2231
|
||
@acronym{MIME} Parameter Value and Encoded Word Extensions: Character Sets,
|
||
Languages, and Continuations
|
||
|
||
@item RFC1843
|
||
HZ - A Data Format for Exchanging Files of Arbitrarily Mixed Chinese and
|
||
@acronym{ASCII} characters
|
||
|
||
@item draft-ietf-drums-msg-fmt-05.txt
|
||
Draft for the successor of RFC822
|
||
|
||
@item RFC2112
|
||
The @acronym{MIME} Multipart/Related Content-type
|
||
|
||
@item RFC1892
|
||
The Multipart/Report Content Type for the Reporting of Mail System
|
||
Administrative Messages
|
||
|
||
@item RFC2183
|
||
Communicating Presentation Information in Internet Messages: The
|
||
Content-Disposition Header Field
|
||
|
||
@item RFC2646
|
||
Documentation of the text/plain format parameter for flowed text.
|
||
|
||
@end table
|
||
|
||
|
||
@node Index
|
||
@chapter Index
|
||
@printindex cp
|
||
|
||
@summarycontents
|
||
@contents
|
||
@bye
|
||
|
||
|
||
@c Local Variables:
|
||
@c mode: texinfo
|
||
@c coding: iso-8859-1
|
||
@c End:
|
||
|
||
@ignore
|
||
arch-tag: c7ef2fd0-a91c-4e10-aa52-c1a2b11b1a8d
|
||
@end ignore
|