Apache HTTP Server Version 2.5
Apache HTTP Server Version 2.5
Available Languages: en
| Description: | Determines the MIME type of a file from its contents using libmagic |
|---|---|
| Status: | Extension |
| Module Identifier: | mime_libmagic_module |
| Source File: | mod_mime_libmagic.c |
| Compatibility: | Available in Apache 2.5.1 and later |
This module determines the MIME
type of a file by examining its contents, in the same
way the file(1) command does. It is intended as a
"second line of defense" for files which
mod_mime cannot type from their extension: it
runs after mod_mime and does nothing if a type
has already been set.
Unlike mod_mime_magic, which has its own
copy of the file(1) engine and its own magic
database, this module uses the system's libmagic(3)
library and magic database from the file package,
so the types it reports are those which file --mime-type
would report. The module is built only if libmagic is found at
configure time, and is only active in a server or virtual host
where MimeLibmagic
is On.
Where libmagic reports application/octet-stream
the module sets no type, leaving the response without a
Content-Type header, as mod_mime_magic
does for unrecognised content. Directories are typed as
httpd/unix-directory and empty files as
text/plain.
The module does not look inside compressed files and never
sets a Content-Encoding: a gzip file is reported as
application/gzip. This differs from
mod_mime_magic, which reports the compressed
file's encoding.
A libmagic handle is created, loaded with the magic database
and destroyed for every request examined. Loading a compiled database
(magic.mgc) maps the file into memory rather than
parsing it, and the mapped pages are shared between all server
processes, so this is inexpensive. If the configured database
is a text file rather than a compiled one, it is parsed on every
request.
Only the first MimeLibmagicBytes bytes of a file are read and
examined, whatever its size.
Examining text content in particular can allocate a few megabytes of memory temporarily. With a threaded MPM and a C library which keeps a separate heap per thread, each server thread retains its peak allocation, so the resident size of a busy child process can grow by that much per thread before levelling off. This is not a leak.
| Description: | Enable MIME type determination from file contents |
|---|---|
| Syntax: | MimeLibmagic On|Off |
| Default: | MimeLibmagic Off |
| Context: | server config, virtual host |
| Status: | Extension |
| Module: | mod_mime_libmagic |
The MimeLibmagic directive enables the
module for a server or virtual host. Files which
mod_mime leaves untyped, typically those without
a recognised extension, then have their contents examined by
libmagic.
MimeLibmagic On
| Description: | Number of bytes of a file examined |
|---|---|
| Syntax: | MimeLibmagicBytes bytes |
| Default: | MimeLibmagicBytes 16384 |
| Context: | server config, virtual host |
| Status: | Extension |
| Module: | mod_mime_libmagic |
The MimeLibmagicBytes directive sets
how many bytes from the start of a file are read and examined.
Larger values allow magic rules which look deeper into a file to
match, at the cost of reading more of every examined file. The
maximum is 1048576.
| Description: | Add a charset parameter to text types |
|---|---|
| Syntax: | MimeLibmagicCharset On|Off |
| Default: | MimeLibmagicCharset Off |
| Context: | server config, virtual host |
| Status: | Extension |
| Module: | mod_mime_libmagic |
When MimeLibmagicCharset is
On, the character encoding libmagic detects (such
as us-ascii, utf-8 or
iso-8859-1) is added as a charset
parameter to text/* types, giving for example
text/plain; charset=utf-8. Other types are not
affected. As with AddDefaultCharset, the detected charset should be
trusted only where the content is known to be encoded
consistently.
| Description: | The magic database to use |
|---|---|
| Syntax: | MimeLibmagicFile file-path |
| Default: | The default database of the installed libmagic |
| Context: | server config, virtual host |
| Status: | Extension |
| Module: | mod_mime_libmagic |
The MimeLibmagicFile directive names
the magic database, in place of the default compiled into
libmagic (typically /usr/share/misc/magic, for which
the compiled magic.mgc alongside it is loaded).
The database must be in the format described in
magic(5); the file distributed with
mod_mime_magic is not suitable. A relative path
is taken relative to the ServerRoot. If the database cannot be loaded, an
error is logged for each request examined and the file is left
untyped.
Note that the MAGIC environment variable, if set
when the server is started, overrides the library default, but
not a database given with this directive.
MimeLibmagicFile /usr/share/misc/magic.mgc
Available Languages: en
