2 <!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd">
3 <?xml-stylesheet type="text/xsl" href="../style/manual.en.xsl"?>
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7 Licensed to the Apache Software Foundation (ASF) under one or more
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9 this work for additional information regarding copyright ownership.
10 The ASF licenses this file to You under the Apache License, Version 2.0
11 (the "License"); you may not use this file except in compliance with
12 the License. You may obtain a copy of the License at
14 http://www.apache.org/licenses/LICENSE-2.0
16 Unless required by applicable law or agreed to in writing, software
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23 <modulesynopsis metafile="mod_mime_magic.xml.meta">
25 <name>mod_mime_magic</name>
26 <description>Determines the MIME type of a file
27 by looking at a few bytes of its contents</description>
28 <status>Extension</status>
29 <sourcefile>mod_mime_magic.c</sourcefile>
30 <identifier>mime_magic_module</identifier>
33 <p>This module determines the <glossary ref="mime-type">MIME
34 type</glossary> of files in the same way the Unix
35 <code>file(1)</code> command works: it looks at the first few
36 bytes of the file. It is intended as a "second line of defense"
37 for cases that <module>mod_mime</module> can't resolve.</p>
39 <p>This module is derived from a free version of the
40 <code>file(1)</code> command for Unix, which uses "magic
41 numbers" and other hints from a file's contents to figure out
42 what the contents are. This module is active only if the magic
43 file is specified by the <directive module="mod_mime_magic"
44 >MimeMagicFile</directive> directive.</p>
47 <section id="format"><title>Format of the Magic File</title>
49 <p>The contents of the file are plain ASCII text in 4-5
50 columns. Blank lines are allowed but ignored. Commented lines
51 use a hash mark (<code>#</code>). The remaining lines are parsed for
52 the following columns:</p>
54 <table style="zebra" border="1">
55 <columnspec><column width=".15"/><column width=".8"/></columnspec>
56 <tr><th>Column</th><th>Description</th></tr>
58 <td>byte number to begin checking from<br />
59 "<code>></code>" indicates a dependency upon the previous
60 non-"<code>></code>" line</td></tr>
63 <td><p>type of data to match</p>
65 <columnspec><column width=".2"/><column width=".7"/></columnspec>
66 <tr><td><code>byte</code></td>
67 <td>single character</td></tr>
68 <tr><td><code>short</code></td>
69 <td>machine-order 16-bit integer</td></tr>
70 <tr><td><code>long</code></td>
71 <td>machine-order 32-bit integer</td></tr>
72 <tr><td><code>string</code></td>
73 <td>arbitrary-length string</td></tr>
74 <tr><td><code>date</code></td>
75 <td>long integer date (seconds since Unix epoch/1970)</td></tr>
76 <tr><td><code>beshort</code></td>
77 <td>big-endian 16-bit integer</td></tr>
78 <tr><td><code>belong</code></td>
79 <td>big-endian 32-bit integer</td></tr>
80 <tr><td><code>bedate</code></td>
81 <td>big-endian 32-bit integer date</td></tr>
82 <tr><td><code>leshort</code></td>
83 <td>little-endian 16-bit integer</td></tr>
84 <tr><td><code>lelong</code></td>
85 <td>little-endian 32-bit integer</td></tr>
86 <tr><td><code>ledate</code></td>
87 <td>little-endian 32-bit integer date</td></tr>
91 <td>contents of data to match</td></tr>
94 <td>MIME type if matched</td></tr>
97 <td>MIME encoding if matched (optional)</td></tr>
100 <p>For example, the following magic file lines would recognize
101 some audio formats:</p>
104 <pre># Sun/NeXT audio data
106 >12 belong 1 audio/basic
107 >12 belong 2 audio/basic
108 >12 belong 3 audio/basic
109 >12 belong 4 audio/basic
110 >12 belong 5 audio/basic
111 >12 belong 6 audio/basic
112 >12 belong 7 audio/basic
113 >12 belong 23 audio/x-adpcm</pre>
116 <p>Or these would recognize the difference between <code>*.doc</code>
117 files containing Microsoft Word or FrameMaker documents. (These are
118 incompatible file formats which use the same file suffix.)</p>
122 0 string \<MakerFile application/x-frame
123 0 string \<MIFFile application/x-frame
124 0 string \<MakerDictionary application/x-frame
125 0 string \<MakerScreenFon application/x-frame
126 0 string \<MML application/x-frame
127 0 string \<Book application/x-frame
128 0 string \<Maker application/x-frame
131 0 string \376\067\0\043 application/msword
132 0 string \320\317\021\340\241\261 application/msword
133 0 string \333\245-\0\0\0 application/msword</pre>
136 <p>An optional MIME encoding can be included as a fifth column.
137 For example, this can recognize gzipped files and set the
138 encoding for them.</p>
141 <pre># gzip (GNU zip, not to be confused with
142 # [Info-ZIP/PKWARE] zip archiver)
144 0 string \037\213 application/octet-stream x-gzip</pre>
148 <section id="performance"><title>Performance Issues</title>
149 <p>This module is not for every system. If your system is barely
150 keeping up with its load or if you're performing a web server
151 benchmark, you may not want to enable this because the
152 processing is not free.</p>
154 <p>However, an effort was made to improve the performance of
155 the original <code>file(1)</code> code to make it fit in a busy web
156 server. It was designed for a server where there are thousands of users
157 who publish their own documents. This is probably very common
158 on intranets. Many times, it's helpful if the server can make
159 more intelligent decisions about a file's contents than the
160 file name allows ...even if just to reduce the "why doesn't my
161 page work" calls when users improperly name their own files.
162 You have to decide if the extra work suits your
166 <section id="notes"><title>Notes</title>
167 <p>The following notes apply to the <module>mod_mime_magic</module>
168 module and are included here for compliance with contributors'
169 copyright restrictions that require their acknowledgment.</p>
172 <p>mod_mime_magic: MIME type lookup via file magic numbers<br />
173 Copyright (c) 1996-1997 Cisco Systems, Inc.</p>
175 <p>This software was submitted by Cisco Systems to the Apache Group
176 in July 1997. Future revisions and derivatives of this source code
177 must acknowledge Cisco Systems as the original contributor of this
178 module. All other licensing and usage conditions are those of the
181 <p>Some of this code is derived from the free version of the file
182 command originally posted to comp.sources.unix. Copyright info for
183 that program is included below as required.</p>
187 <p> - Copyright (c) Ian F. Darwin, 1987. Written by Ian F. Darwin.</p>
189 <p>This software is not subject to any license of the American
190 Telephone and Telegraph Company or of the Regents of the University
193 <p>Permission is granted to anyone to use this software for any
194 purpose on any computer system, and to alter it and redistribute it
195 freely, subject to the following restrictions:</p>
198 <li>The author is not responsible for the consequences of use of
199 this software, no matter how awful, even if they arise from flaws
202 <li>The origin of this software must not be misrepresented, either
203 by explicit claim or by omission. Since few users ever read
204 sources, credits must appear in the documentation.</li>
206 <li>Altered versions must be plainly marked as such, and must not
207 be misrepresented as being the original software. Since few users
208 ever read sources, credits must appear in the documentation.</li>
210 <li>This notice may not be removed or altered.</li>
215 <p>For compliance with Mr Darwin's terms: this has been very
216 significantly modified from the free "file" command.</p>
219 <li>all-in-one file for compilation convenience when moving from
220 one version of Apache to the next.</li>
222 <li>Memory allocation is done through the Apache API's pool
225 <li>All functions have had necessary Apache API request or server
226 structures passed to them where necessary to call other Apache API
227 routines. (<em>i.e.</em>, usually for logging, files, or memory
228 allocation in itself or a called function.)</li>
230 <li>struct magic has been converted from an array to a single-ended
231 linked list because it only grows one record at a time, it's only
232 accessed sequentially, and the Apache API has no equivalent of
233 <code>realloc()</code>.</li>
235 <li>Functions have been changed to get their parameters from the
236 server configuration instead of globals. (It should be reentrant
237 now but has not been tested in a threaded environment.)</li>
239 <li>Places where it used to print results to stdout now saves them
240 in a list where they're used to set the MIME type in the Apache
243 <li>Command-line flags have been removed since they will never be
250 <name>MimeMagicFile</name>
251 <description>Enable MIME-type determination based on file contents
252 using the specified magic file</description>
253 <syntax>MimeMagicFile <var>file-path</var></syntax>
254 <contextlist><context>server config</context><context>virtual host</context>
258 <p>The <directive>MimeMagicFile</directive> directive can be used to
259 enable this module, the default file is distributed at
260 <code>conf/magic</code>. Non-rooted paths are relative to the
261 <directive module="core">ServerRoot</directive>. Virtual hosts will use
262 the same file as the main server unless a more specific setting is
263 used, in which case the more specific setting overrides the main
266 <example><title>Example</title>
267 <highlight language="config">
268 MimeMagicFile conf/magic