<?xml version="1.0"?>

<!DOCTYPE modulesynopsis SYSTEM "/style/modulesynopsis.dtd">

<?xml-stylesheet type="text/xsl" href="/style/manual.en.xsl"?>

<modulesynopsis metafile="mod_mime_magic.xml.meta">

<name>mod_mime_magic</name>

<description>Determines the MIME type of a file

by looking at a few bytes of its contents</description>

<status>Extension</status>

<sourcefile>mod_mime_magic.c</sourcefile>

<identifier>mime_magic_module</identifier>

<summary>

<p>This module determines the <glossary ref="mime-type">MIME

type</glossary> of files in the same way the Unix

<code>file(1)</code> command works: it looks at the first few

bytes of the file. It is intended as a "second line of defense"

for cases that <module>mod_mime</module> can't resolve.</p>

<p>This module is derived from a free version of the

<code>file(1)</code> command for Unix, which uses "magic

numbers" and other hints from a file's contents to figure out

what the contents are. This module is active only if the magic

file is specified by the <directive module="mod_mime_magic"

>MimeMagicFile</directive> directive.</p>

</summary>

<section id="format"><title>Format of the Magic File</title>

<p>The contents of the file are plain ASCII text in 4-5

columns. Blank lines are allowed but ignored. Commented lines

use a hash mark (<code>#</code>). The remaining lines are parsed for

the following columns:</p>

<table style="zebra" border="1">

<columnspec><column width=".15"/><column width=".8"/></columnspec>

<tr><th>Column</th><th>Description</th></tr>

<tr><td>1</td>

<td>byte number to begin checking from<br />

"<code>&gt;</code>" indicates a dependency upon the previous

non-"<code>&gt;</code>" line</td></tr>

<tr><td>2</td>

<td><p>type of data to match</p>

<table border="1">

<columnspec><column width=".2"/><column width=".7"/></columnspec>

<tr><td><code>byte</code></td>

<td>single character</td></tr>

<tr><td><code>short</code></td>

<td>machine-order 16-bit integer</td></tr>

<tr><td><code>long</code></td>

<td>machine-order 32-bit integer</td></tr>

<tr><td><code>string</code></td>

<td>arbitrary-length string</td></tr>

<tr><td><code>date</code></td>

<td>long integer date (seconds since Unix epoch/1970)</td></tr>

<tr><td><code>beshort</code></td>

<td>big-endian 16-bit integer</td></tr>

<tr><td><code>belong</code></td>

<td>big-endian 32-bit integer</td></tr>

<tr><td><code>bedate</code></td>

<td>big-endian 32-bit integer date</td></tr>

<tr><td><code>leshort</code></td>

<td>little-endian 16-bit integer</td></tr>

<tr><td><code>lelong</code></td>

<td>little-endian 32-bit integer</td></tr>

<tr><td><code>ledate</code></td>

<td>little-endian 32-bit integer date</td></tr>

</table></td></tr>

<tr><td>3</td>

<td>contents of data to match</td></tr>

<tr><td>4</td>

<td>MIME type if matched</td></tr>

<tr><td>5</td>

<td>MIME encoding if matched (optional)</td></tr>

</table>

<p>For example, the following magic file lines would recognize

some audio formats:</p>

<example>

<pre># Sun/NeXT audio data

0 string .snd

&gt;12 belong 1 audio/basic

&gt;12 belong 2 audio/basic

&gt;12 belong 3 audio/basic

&gt;12 belong 4 audio/basic

&gt;12 belong 5 audio/basic

&gt;12 belong 6 audio/basic

&gt;12 belong 7 audio/basic

&gt;12 belong 23 audio/x-adpcm</pre>

</example>

<p>Or these would recognize the difference between <code>*.doc</code>

files containing Microsoft Word or FrameMaker documents. (These are

incompatible file formats which use the same file suffix.)</p>

<example>

<pre># Frame

0 string \&lt;MakerFile application/x-frame

0 string \&lt;MIFFile application/x-frame

0 string \&lt;MakerDictionary application/x-frame

0 string \&lt;MakerScreenFon application/x-frame

0 string \&lt;MML application/x-frame

0 string \&lt;Book application/x-frame

0 string \&lt;Maker application/x-frame

# MS-Word

0 string \376\067\0\043 application/msword

0 string \320\317\021\340\241\261 application/msword

0 string \333\245-\0\0\0 application/msword</pre>

</example>

<p>An optional MIME encoding can be included as a fifth column.

For example, this can recognize gzipped files and set the

encoding for them.</p>

<example>

<pre># gzip (GNU zip, not to be confused with

# [Info-ZIP/PKWARE] zip archiver)

0 string \037\213 application/octet-stream x-gzip</pre>

</example>

</section>

<section id="performance"><title>Performance Issues</title>

<p>This module is not for every system. If your system is barely

keeping up with its load or if you're performing a web server

benchmark, you may not want to enable this because the

processing is not free.</p>

<p>However, an effort was made to improve the performance of

the original <code>file(1)</code> code to make it fit in a busy web

server. It was designed for a server where there are thousands of users

who publish their own documents. This is probably very common

on intranets. Many times, it's helpful if the server can make

more intelligent decisions about a file's contents than the

file name allows ...even if just to reduce the "why doesn't my

page work" calls when users improperly name their own files.

You have to decide if the extra work suits your

environment.</p>

</section>

<section id="notes"><title>Notes</title>

<p>The following notes apply to the <module>mod_mime_magic</module>

module and are included here for compliance with contributors'

copyright restrictions that require their acknowledgment.</p>

<note>

<p>mod_mime_magic: MIME type lookup via file magic numbers<br />

Copyright (c) 1996-1997 Cisco Systems, Inc.</p>

<p>This software was submitted by Cisco Systems to the Apache Group

in July 1997. Future revisions and derivatives of this source code

must acknowledge Cisco Systems as the original contributor of this

module. All other licensing and usage conditions are those of the

Apache Group.</p>

<p>Some of this code is derived from the free version of the file

command originally posted to comp.sources.unix. Copyright info for

that program is included below as required.</p>

</note>

<note>

<p> - Copyright (c) Ian F. Darwin, 1987. Written by Ian F. Darwin.</p>

<p>This software is not subject to any license of the American

Telephone and Telegraph Company or of the Regents of the University

of California.</p>

<p>Permission is granted to anyone to use this software for any

purpose on any computer system, and to alter it and redistribute it

freely, subject to the following restrictions:</p>

<ol>

<li>The author is not responsible for the consequences of use of

this software, no matter how awful, even if they arise from flaws

in it.</li>

<li>The origin of this software must not be misrepresented, either

by explicit claim or by omission. Since few users ever read

sources, credits must appear in the documentation.</li>

<li>Altered versions must be plainly marked as such, and must not

be misrepresented as being the original software. Since few users

ever read sources, credits must appear in the documentation.</li>

<li>This notice may not be removed or altered.</li>

</ol>

</note>

<note>

<p>For compliance with Mr Darwin's terms: this has been very

significantly modified from the free "file" command.</p>

<ul>

<li>all-in-one file for compilation convenience when moving from

one version of Apache to the next.</li>

<li>Memory allocation is done through the Apache API's pool

structure.</li>

<li>All functions have had necessary Apache API request or server

structures passed to them where necessary to call other Apache API

routines. (<em>i.e.</em>, usually for logging, files, or memory

allocation in itself or a called function.)</li>

<li>struct magic has been converted from an array to a single-ended

linked list because it only grows one record at a time, it's only

accessed sequentially, and the Apache API has no equivalent of

<code>realloc()</code>.</li>

<li>Functions have been changed to get their parameters from the

server configuration instead of globals. (It should be reentrant

now but has not been tested in a threaded environment.)</li>

<li>Places where it used to print results to stdout now saves them

in a list where they're used to set the MIME type in the Apache

request record.</li>

<li>Command-line flags have been removed since they will never be

used here.</li>

</ul>

</note>

</section>

<directivesynopsis>

<name>MimeMagicFile</name>

<description>Enable MIME-type determination based on file contents

using the specified magic file</description>

<syntax>MimeMagicFile <var>file-path</var></syntax>

<contextlist><context>server config</context><context>virtual host</context>

</contextlist>

<usage>

<p>The <directive>MimeMagicFile</directive> directive can be used to

enable this module, the default file is distributed at

<code>conf/magic</code>. Non-rooted paths are relative to the

<directive module="core">ServerRoot</directive>. Virtual hosts will use

the same file as the main server unless a more specific setting is

used, in which case the more specific setting overrides the main

server's file.</p>

<example><title>Example</title>

<highlight language="config">

MimeMagicFile conf/magic

</highlight>

</example>

</usage>

</directivesynopsis>

</modulesynopsis>