MAGIC(3) BSD Library Functions Manual MAGIC(3)
NAME
magic_open, magic_close, magic_error, magic_file, magic_buffer,
magic_setflags, magic_check, magic_compile, magic_load -- Magic number
recognition library.
LIBRARY
Magic Number Recognition Library (libmagic, -lmagic)
SYNOPSIS
#include <magic.h>
magic_t
magic_open(int flags);
void
magic_close(magic_t cookie);
const char *
magic_error(magic_t cookie);
int
magic_errno(magic_t cookie);
const char *
magic_file(magic_t cookie, const char *filename);
const char *
magic_buffer(magic_t cookie, const void *buffer, size_t length);
int
magic_setflags(magic_t cookie, int flags);
int
magic_check(magic_t cookie, const char *filename);
int
magic_compile(magic_t cookie, const char *filename);
int
magic_load(magic_t cookie, const char *filename);
DESCRIPTION
These functions operate on the magic(4,5) database file(1,n) which is described in(1,8)
magic(4,5)(4).
The function magic_open() creates a magic(4,5) cookie pointer and returns it.
It returns NULL if(3,n) there was an error(8,n) allocating the magic(4,5) cookie. The
flags argument specifies how the other magic(4,5) functions should behave:
MAGIC_NONE No special handling.
MAGIC_DEBUG Print debugging messages to stderr.
MAGIC_SYMLINK If the file(1,n) queried is a symlink, follow it.
MAGIC_COMPRESS If the file(1,n) is compressed, unpack it and look(1,8,3 Search::Dict) at the con-
tents.
MAGIC_DEVICES If the file(1,n) is a block or character special device, then
open(2,3,n) the device and try to look(1,8,3 Search::Dict) in(1,8) its contents.
MAGIC_MIME Return a mime string(3,n), instead of a textual description.
MAGIC_CONTINUE Return all matches, not just the first.
MAGIC_CHECK Check the magic(4,5) database for consistency and print warn-
ings to stderr.
MAGIC_PRESERVE_ATIME
On systems that support utime(2) or utimes(2), attempt to
preserve the access(2,5) time(1,2,n) of files analyzed.
MAGIC_RAW Don't translate unprintable characters to a \ooo octal
representation.
MAGIC_ERROR Treat operating system errors while trying to open(2,3,n) files
and follow symlinks as real errors, instead of printing
them in(1,8) the magic(4,5) buffer.
The magic_close() function closes the magic(4,5)(4) database and deallocates
any resources used.
The magic_error() function returns a textual explanation of the last
error(8,n), or NULL if(3,n) there was no error.
The magic_errno() function returns the last operating system error(8,n) number
( errno(3)) that was encountered by a system call.
The magic_file() function returns a textual description of the contents
of the filename argument, or NULL if(3,n) an error(8,n) occurred. If the filename
is NULL, then stdin is used.
The magic_buffer() function returns a textual description of the contents
of the buffer argument with length bytes size.
The magic_setflags() function, sets the flags described above.
The magic_check() function can be used to check the validity of entries
in(1,8) the colon separated database files passed in(1,8) as filename, or NULL for
the default database. It returns 0 on success and -1 on failure.
The magic_compile() function can be used to compile the the colon sepa-
rated list of database files passed in(1,8) as filename, or NULL for the
default database. It returns 0 on success and -1 on failure. The compiled
files created are named(5,8) from the basename(1,3,3 File::Basename)(1) of each file(1,n) argument with
".mgc" appended to it.
The magic_load() function must be used to load(7,n) the the colon separated
list of database files passed in(1,8) as filename, or NULL for the default
database file(1,n) before any magic(4,5) queries can performed.
The default database file(1,n) is named(5,8) by the MAGIC environment variable. If
that variable is not set(7,n,1 builtins), the default database file(1,n) name is
/usr/share/misc/file(1,n)/magic.
magic_load() adds ".mime" and/or ".mgc" to the database filename as
appropriate.
RETURN VALUES
The function magic_open() returns a magic(4,5) cookie on success and NULL on
failure setting errno to an appropriate value. It will set(7,n,1 builtins) errno to EIN-
VAL if(3,n) an unsupported value for flags was given. The magic_load(),
magic_compile(), and magic_check() functions return 0 on success and -1
on failure. The magic_file(), and magic_buffer() functions return a
string(3,n) on success and NULL on failure. The magic_error() function returns
a textual description of the errors of the above functions, or NULL if(3,n)
there was no error. Finally, magic_setflags() returns -1 on systems that
don't support utime(2), or utimes(2) when MAGIC_PRESERVE_ATIME is set.
FILES
/usr/share/misc/file(1,n)/magic.mime The non-compiled default magic(4,5) mime
database.
/usr/share/misc/file(1,n)/magic.mime.mgc The compiled default magic(4,5) mime
database.
/usr/share/misc/file(1,n)/magic(4,5) The non-compiled default magic(4,5) data-
base.
/usr/share/misc/file(1,n)/magic.mgc The compiled default magic(4,5) database.
SEE ALSO
file(1,n)(1), magic(4,5)(4)
AUTHORS
Mns Rullgrd Initial libmagic implementation, and configuration. Chris-
tos Zoulas API cleanup, error(8,n) code and allocation handling.
BSD March 22, 2003 BSD