2 <!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd">
3 <?xml-stylesheet type="text/xsl" href="../style/manual.en.xsl"?>
4 <!-- $LastChangedRevision$ -->
7 Copyright 2002-2005 The Apache Software Foundation or its licensors,
10 Licensed under the Apache License, Version 2.0 (the "License");
11 you may not use this file except in compliance with the License.
12 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
17 distributed under the License is distributed on an "AS IS" BASIS,
18 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
19 See the License for the specific language governing permissions and
20 limitations under the License.
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 MIME type of files in the same
34 way the Unix <code>file(1)</code> command works: it looks at the first
35 few bytes of the file. It is intended as a "second line of defense"
36 for cases that <module>mod_mime</module> can't resolve.</p>
38 <p>This module is derived from a free version of the
39 <code>file(1)</code> command for Unix, which uses "magic
40 numbers" and other hints from a file's contents to figure out
41 what the contents are. This module is active only if the magic
42 file is specified by the <directive module="mod_mime_magic"
43 >MimeMagicFile</directive> directive.</p>
46 <section id="format"><title>Format of the Magic File</title>
48 <p>The contents of the file are plain ASCII text in 4-5
49 columns. Blank lines are allowed but ignored. Commented lines
50 use a hash mark (<code>#</code>). The remaining lines are parsed for
51 the following columns:</p>
53 <table style="zebra" border="1">
54 <columnspec><column width=".15"/><column width=".8"/></columnspec>
55 <tr><th>Column</th><th>Description</th></tr>
57 <td>byte number to begin checking from<br />
58 "<code>></code>" indicates a dependency upon the previous
59 non-"<code>></code>" line</td></tr>
62 <td><p>type of data to match</p>
64 <columnspec><column width=".2"/><column width=".7"/></columnspec>
65 <tr><td><code>byte</code></td>
66 <td>single character</td></tr>
67 <tr><td><code>short</code></td>
68 <td>machine-order 16-bit integer</td></tr>
69 <tr><td><code>long</code></td>
70 <td>machine-order 32-bit integer</td></tr>
71 <tr><td><code>string</code></td>
72 <td>arbitrary-length string</td></tr>
73 <tr><td><code>date</code></td>
74 <td>long integer date (seconds since Unix epoch/1970)</td></tr>
75 <tr><td><code>beshort</code></td>
76 <td>big-endian 16-bit integer</td></tr>
77 <tr><td><code>belong</code></td>
78 <td>big-endian 32-bit integer</td></tr>
79 <tr><td><code>bedate</code></td>
80 <td>big-endian 32-bit integer date</td></tr>
81 <tr><td><code>leshort</code></td>
82 <td>little-endian 16-bit integer</td></tr>
83 <tr><td><code>lelong</code></td>
84 <td>little-endian 32-bit integer</td></tr>
85 <tr><td><code>ledate</code></td>
86 <td>little-endian 32-bit integer date</td></tr>
90 <td>contents of data to match</td></tr>
93 <td>MIME type if matched</td></tr>
96 <td>MIME encoding if matched (optional)</td></tr>
99 <p>For example, the following magic file lines would recognize
100 some audio formats:</p>
103 <pre># Sun/NeXT audio data
105 >12 belong 1 audio/basic
106 >12 belong 2 audio/basic
107 >12 belong 3 audio/basic
108 >12 belong 4 audio/basic
109 >12 belong 5 audio/basic
110 >12 belong 6 audio/basic
111 >12 belong 7 audio/basic
112 >12 belong 23 audio/x-adpcm</pre>
115 <p>Or these would recognize the difference between <code>*.doc</code>
116 files containing Microsoft Word or FrameMaker documents. (These are
117 incompatible file formats which use the same file suffix.)</p>
121 0 string \<MakerFile application/x-frame
122 0 string \<MIFFile application/x-frame
123 0 string \<MakerDictionary application/x-frame
124 0 string \<MakerScreenFon application/x-frame
125 0 string \<MML application/x-frame
126 0 string \<Book application/x-frame
127 0 string \<Maker application/x-frame
130 0 string \376\067\0\043 application/msword
131 0 string \320\317\021\340\241\261 application/msword
132 0 string \333\245-\0\0\0 application/msword</pre>
135 <p>An optional MIME encoding can be included as a fifth column.
136 For example, this can recognize gzipped files and set the
137 encoding for them.</p>
140 <pre># gzip (GNU zip, not to be confused with
141 # [Info-ZIP/PKWARE] zip archiver)
143 0 string \037\213 application/octet-stream x-gzip</pre>
147 <section id="performance"><title>Performance Issues</title>
148 <p>This module is not for every system. If your system is barely
149 keeping up with its load or if you're performing a web server
150 benchmark, you may not want to enable this because the
151 processing is not free.</p>
153 <p>However, an effort was made to improve the performance of
154 the original <code>file(1)</code> code to make it fit in a busy web
155 server. It was designed for a server where there are thousands of users
156 who publish their own documents. This is probably very common
157 on intranets. Many times, it's helpful if the server can make
158 more intelligent decisions about a file's contents than the
159 file name allows ...even if just to reduce the "why doesn't my
160 page work" calls when users improperly name their own files.
161 You have to decide if the extra work suits your
165 <section id="notes"><title>Notes</title>
166 <p>The following notes apply to the <module>mod_mime_magic</module>
167 module and are included here for compliance with contributors'
168 copyright restrictions that require their acknowledgment.</p>
171 <p>mod_mime_magic: MIME type lookup via file magic numbers<br />
172 Copyright (c) 1996-1997 Cisco Systems, Inc.</p>
174 <p>This software was submitted by Cisco Systems to the Apache Group
175 in July 1997. Future revisions and derivatives of this source code
176 must acknowledge Cisco Systems as the original contributor of this
177 module. All other licensing and usage conditions are those of the
180 <p>Some of this code is derived from the free version of the file
181 command originally posted to comp.sources.unix. Copyright info for
182 that program is included below as required.</p>
186 <p> - Copyright (c) Ian F. Darwin, 1987. Written by Ian F. Darwin.</p>
188 <p>This software is not subject to any license of the American
189 Telephone and Telegraph Company or of the Regents of the University
192 <p>Permission is granted to anyone to use this software for any
193 purpose on any computer system, and to alter it and redistribute it
194 freely, subject to the following restrictions:</p>
197 <li>The author is not responsible for the consequences of use of
198 this software, no matter how awful, even if they arise from flaws
201 <li>The origin of this software must not be misrepresented, either
202 by explicit claim or by omission. Since few users ever read
203 sources, credits must appear in the documentation.</li>
205 <li>Altered versions must be plainly marked as such, and must not
206 be misrepresented as being the original software. Since few users
207 ever read sources, credits must appear in the documentation.</li>
209 <li>This notice may not be removed or altered.</li>
214 <p>For compliance with Mr Darwin's terms: this has been very
215 significantly modified from the free "file" command.</p>
218 <li>all-in-one file for compilation convenience when moving from
219 one version of Apache to the next.</li>
221 <li>Memory allocation is done through the Apache API's pool
224 <li>All functions have had necessary Apache API request or server
225 structures passed to them where necessary to call other Apache API
226 routines. (<em>i.e.</em>, usually for logging, files, or memory
227 allocation in itself or a called function.)</li>
229 <li>struct magic has been converted from an array to a single-ended
230 linked list because it only grows one record at a time, it's only
231 accessed sequentially, and the Apache API has no equivalent of
232 <code>realloc()</code>.</li>
234 <li>Functions have been changed to get their parameters from the
235 server configuration instead of globals. (It should be reentrant
236 now but has not been tested in a threaded environment.)</li>
238 <li>Places where it used to print results to stdout now saves them
239 in a list where they're used to set the MIME type in the Apache
242 <li>Command-line flags have been removed since they will never be
249 <name>MimeMagicFile</name>
250 <description>Enable MIME-type determination based on file contents
251 using the specified magic file</description>
252 <syntax>MimeMagicFile <var>file-path</var></syntax>
253 <contextlist><context>server config</context><context>virtual host</context>
257 <p>The <directive>MimeMagicFile</directive> directive can be used to
258 enable this module, the default file is distributed at
259 <code>conf/magic</code>. Non-rooted paths are relative to the
260 <directive module="core">ServerRoot</directive>. Virtual hosts will use
261 the same file as the main server unless a more specific setting is
262 used, in which case the more specific setting overrides the main
265 <example><title>Example</title>
266 MimeMagicFile conf/magic