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| <h1 align="CENTER">Module mod_mime_magic</h1> |
| |
| This module is an optional extension to the Apache HTTPD server. |
| The current version can be obtained from |
| <a href="http://www.employees.org/~ikluft/apache/mod_mime_magic/"> |
| http://www.employees.org/~ikluft/apache/mod_mime_magic/</a>. |
| |
| <h2>Summary</h2> |
| |
| 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. |
| In the case of this module, |
| it tries to figure out the MIME type of the file. |
| <p> |
| This module is only active if the magic file exists and |
| was successfully opened at server-configuration time. |
| The magic file can be named by the |
| <A HREF="#mimemagicfile"><code>MimeMagicFile</code></a> |
| directive or defaults to conf/magic. |
| <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 "#". |
| The remaining lines are parsed for the following columns: |
| <table border=1> |
| <tr valign=top> |
| <th>Column</th> |
| <th>Description</th> |
| </tr> |
| <tr valign=top> |
| <td>1</td> |
| <td>byte number to begin checking from |
| <br> |
| ">" indicates a dependency upon the previous non-">" line</td> |
| </tr><tr valign=top> |
| <td>2</td> |
| <td>type of data to match |
| <table border=1> |
| <tr><td>byte</td><td>single character</td></tr> |
| <tr><td>short</td><td>machine-order 16-bit integer</td></tr> |
| <tr><td>long</td><td>machine-order 32-bit integer</td></tr> |
| <tr><td>string</td><td>arbitrary-length string</td></tr> |
| <tr><td>date</td><td>long integer date |
| (seconds since Unix epoch/1970)</td></tr> |
| <tr><td>beshort</td><td>big-endian 16-bit integer</td></tr> |
| <tr><td>belong</td><td>big-endian 32-bit integer</td></tr> |
| <tr><td>bedate</td><td>big-endian 32-bit integer date</td></tr> |
| <tr><td>leshort</td><td>little-endian 16-bit integer</td></tr> |
| <tr><td>lelong</td><td>little-endian 32-bit integer</td></tr> |
| <tr><td>ledate</td><td>little-endian 32-bit integer date</td></tr> |
| </table> |
| </td> |
| </tr><tr valign=top> |
| <td>3</td> |
| <td>contents of data to match</td> |
| </tr><tr valign=top> |
| <td>4</td> |
| <td>MIME type if matched</td> |
| </tr><tr valign=top> |
| <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. |
| |
| <pre> |
| # Sun/NeXT audio data |
| 0 string .snd |
| >12 belong 1 audio/basic |
| >12 belong 2 audio/basic |
| >12 belong 3 audio/basic |
| >12 belong 4 audio/basic |
| >12 belong 5 audio/basic |
| >12 belong 6 audio/basic |
| >12 belong 7 audio/basic |
| >12 belong 23 audio/x-adpcm |
| </pre> |
| |
| Or these would recognize the difference between "*.doc" files containing |
| Microsoft Word or FrameMaker documents. (These are incompatible file |
| formats which use the same file suffix.) |
| |
| <pre> |
| # Frame |
| 0 string \<MakerFile application/x-frame |
| 0 string \<MIFFile application/x-frame |
| 0 string \<MakerDictionary application/x-frame |
| 0 string \<MakerScreenFon application/x-frame |
| 0 string \<MML application/x-frame |
| 0 string \<Book application/x-frame |
| 0 string \<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> |
| |
| An optional MIME encoding can be included as a fifth column. |
| For example, this can recognize gzipped files and set the encoding |
| for them. |
| |
| <pre> |
| # gzip (GNU zip, not to be confused with [Info-ZIP/PKWARE] zip archiver) |
| 0 string \037\213 application/octet-stream x-gzip |
| </pre> |
| |
| <h3>Performance Issues</h3> |
| |
| 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> |
| However, an effort was made to improve the performance of the original |
| file(1) 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> |
| When compiling an Apache server, this module should be at or near the |
| top of the list of modules in the Configuration file. The modules are |
| listed in increasing priority so that will mean this one is used only |
| as a last resort, just like it was designed to. |
| |
| <h2>Directives</h2> |
| <p> |
| <UL> |
| <LI><A HREF="#mimemagicfile">MimeMagicFile</A> |
| </LI> |
| </UL> |
| </P> |
| <HR> |
| <H2><A NAME="mimemagicfile"> |
| MimeMagicFile |
| </A></H2> |
| <P> |
| <STRONG>Syntax:</STRONG> MimeMagicFile <em>magic-file-name</em> |
| <BR> |
| <STRONG>Default:</STRONG> conf/magic |
| <BR> |
| <STRONG>Context:</STRONG> server config, virtual host |
| <BR> |
| <STRONG>Status:</STRONG> Extension |
| <BR> |
| <STRONG>Module:</STRONG> mod_mime_magic |
| <p> |
| |
| The MimeMagicFile directive can be used to change the location of the |
| magic file from its default location at <code>conf/magic</code>. |
| Non-rooted paths are relative to the ServerRoot. |
| <p> |
| <HR> |
| |
| <h2><a name="notes">Notes</a></h2> |
| |
| Patches and suggestions for mod_mime_magic should be sent to |
| Ian Kluft <ikluft<!--- comment inserted to discourage spam --->@cisco.com>. |
| Note that enhancements are done on a volunteer basis so no timetable can |
| be committed for any particular request. |
| Obviously, patches are given much higher priority over plain requests. |
| <p> |
| The following notes apply to the mod_mime_magic module and are |
| included here for compliance with contributors' copyright restrictions |
| that require their acknowledgement. |
| |
| <pre> |
| /* |
| * mod_mime_magic: MIME type lookup via file magic numbers |
| * Copyright (c) 1996-1997 Cisco Systems, Inc. |
| * |
| * 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. |
| * |
| * 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. |
| * --------------------------------------------------------------------------- |
| * - Copyright (c) Ian F. Darwin, 1987. Written by Ian F. Darwin. |
| * |
| * This software is not subject to any license of the American Telephone and |
| * Telegraph Company or of the Regents of the University of California. |
| * |
| * 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: |
| * |
| * 1. 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. |
| * |
| * 2. 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. |
| * |
| * 3. 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. |
| * |
| * 4. This notice may not be removed or altered. |
| * ------------------------------------------------------------------------- |
| * |
| * For complicance with Mr Darwin's terms: this has been very significantly |
| * modified from the free "file" command. |
| * - all-in-one file for compilation convenience when moving from one |
| * version of Apache to the next. |
| * - Memory allocation is done through the Apache API's pool structure. |
| * - All functions have had necessary Apache API request or server |
| * structures passed to them where necessary to call other Apache API |
| * routines. (i.e. usually for logging, files, or memory allocation in |
| * itself or a called function.) |
| * - 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 realloc(). |
| * - 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.) |
| * - 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. |
| * - Command-line flags have been removed since they will never be used here. |
| * |
| */ |
| </pre> |
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