magic_open
, magic_close
,
magic_error
, magic_errno
,
magic_descriptor
,
magic_buffer
, magic_getflags
,
magic_setflags
, magic_check
,
magic_compile
, magic_list
,
magic_load
,
magic_load_buffers
,
magic_setparam
,
magic_getparam
, magic_version
—
Magic number recognition library
Magic Number Recognition Library (libmagic, -lmagic)
#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_descriptor
(magic_t
cookie, int
fd);
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_getflags
(magic_t
cookie);
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_list
(magic_t
cookie, const char
*filename);
int
magic_load
(magic_t
cookie, const char
*filename);
int
magic_load_buffers
(magic_t
cookie, void
**buffers, size_t
*sizes, size_t
nbuffers);
int
magic_getparam
(magic_t
cookie, int param,
void *value);
int
magic_setparam
(magic_t
cookie, int param,
const void *value);
int
magic_version
(void);
These functions operate on the magic database file which is described in
magic(5).
The function magic_open
() creates a magic
cookie pointer and returns it. It returns NULL
if
there was an error allocating the magic cookie. The
flags argument specifies how the other magic functions
should behave:
MAGIC_NONE
- No special handling.
MAGIC_DEBUG
- Print debugging messages to stderr.
MAGIC_SYMLINK
- If the file queried is a symlink, follow it.
MAGIC_COMPRESS
- If the file is compressed, unpack it and look at the contents.
MAGIC_DEVICES
- If the file is a block or character special device, then open the device
and try to look in its contents.
MAGIC_MIME_TYPE
- Return a MIME type string, instead of a textual description.
MAGIC_MIME_ENCODING
- Return a MIME encoding, instead of a textual description.
MAGIC_MIME
- A shorthand for MAGIC_MIME_TYPE | MAGIC_MIME_ENCODING.
MAGIC_CONTINUE
- Return all matches, not just the first.
MAGIC_CHECK
- Check the magic database for consistency and print warnings to
stderr.
MAGIC_PRESERVE_ATIME
- On systems that support
utime(3)
or
utimes(2),
attempt to preserve the access time of files analysed.
MAGIC_RAW
- Don't translate unprintable characters to a \ooo octal
representation.
MAGIC_ERROR
- Treat operating system errors while trying to open files and follow
symlinks as real errors, instead of printing them in the magic
buffer.
MAGIC_APPLE
- Return the Apple creator and type.
MAGIC_EXTENSION
- Return a slash-separated list of extensions for this file type.
MAGIC_COMPRESS_TRANSP
- Don't report on compression, only report about the uncompressed data.
MAGIC_NO_CHECK_APPTYPE
- Don't check for
EMX
application type (only on
EMX).
MAGIC_NO_CHECK_CDF
- Don't get extra information on MS Composite Document Files.
MAGIC_NO_CHECK_COMPRESS
- Don't look inside compressed files.
MAGIC_NO_CHECK_ELF
- Don't print ELF details.
MAGIC_NO_CHECK_ENCODING
- Don't check text encodings.
MAGIC_NO_CHECK_SOFT
- Don't consult magic files.
MAGIC_NO_CHECK_TAR
- Don't examine tar files.
MAGIC_NO_CHECK_TEXT
- Don't check for various types of text files.
MAGIC_NO_CHECK_TOKENS
- Don't look for known tokens inside ascii files.
MAGIC_NO_CHECK_JSON
- Don't examine JSON files.
MAGIC_NO_CHECK_CSV
- Don't examine CSV files.
The magic_close
() function closes the
magic(5)
database and deallocates any resources used.
The magic_error
() function returns a
textual explanation of the last error, or NULL
if
there was no error.
The magic_errno
() function returns the
last operating system error number
(errno(2))
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 an error occurred. If the
filename is NULL
, then stdin
is used.
The magic_descriptor
() function returns a
textual description of the contents of the fd
argument, or NULL
if an error occurred.
The magic_buffer
() function returns a
textual description of the contents of the buffer
argument with length bytes size.
The magic_getflags
() functions returns a
value representing current flags set.
The magic_setflags
() function sets the
flags described above. Note that using both MIME flags
together can also return extra information on the charset.
The magic_check
() function can be used to
check the validity of entries in the colon separated database files passed
in 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 colon separated list of database files passed in as
filename, or NULL
for the
default database. It returns 0 on success and -1 on failure. The compiled
files created are named from the
basename(1)
of each file argument with “.mgc” appended to it.
The magic_list
() function dumps all magic
entries in a human readable format, dumping first the entries that are
matched against binary files and then the ones that match text files. It
takes and optional filename argument which is a colon
separated list of database files, or NULL
for the
default database.
The magic_load
() function must be used to
load the colon separated list of database files passed in as
filename, or NULL
for the
default database file before any magic queries can performed.
The default database file is named by the MAGIC environment
variable. If that variable is not set, the default database file name is
/usr/share/misc/magic. magic_load
() adds
“.mgc” to the database filename as appropriate.
The magic_load_buffers
() function takes an
array of size nbuffers of
buffers with a respective size for each in the array
of sizes loaded with the contents of the magic
databases from the filesystem. This function can be used in environment
where the magic library does not have direct access to the filesystem, but
can access the magic database via shared memory or other IPC means.
The magic_getparam
() and
magic_setparam
() allow getting and setting various
limits related to the magic library.
The MAGIC_PARAM_INDIR_RECURSION
parameter
controls how many levels of recursion will be followed for indirect magic
entries.
The MAGIC_PARAM_NAME_RECURSION
parameter
controls how many levels of recursion will be followed for for name/use
calls.
The MAGIC_PARAM_NAME_MAX
parameter
controls the maximum number of calls for name/use.
The MAGIC_PARAM_NOTES_MAX
parameter
controls how many ELF notes will be processed.
The MAGIC_PARAM_PHNUM_MAX
parameter
controls how many ELF program sections will be processed.
The MAGIC_PARAM_SHNUM_MAX
parameter
controls how many ELF sections will be processed.
The magic_version
() command returns the
version number of this library which is compiled into the shared library
using the constant MAGIC_VERSION
from
<magic.h>
. This can be used
by client programs to verify that the version they compile against is the
same as the version that they run against.
The function magic_open
() returns a magic cookie on
success and NULL
on failure setting errno to an
appropriate value. It will set errno to EINVAL
if an
unsupported value for flags was given. The
magic_list
(), magic_load
(),
magic_compile
(), and
magic_check
() functions return 0 on success and -1 on
failure. The magic_buffer
(),
magic_getpath
(), and
magic_file
(), functions return a string on success and
NULL
on failure. The
magic_error
() function returns a textual description
of the errors of the above functions, or NULL
if there
was no error. The magic_version
() always returns the
version number of the library. Finally,
magic_setflags
() returns -1 on systems that don't
support
utime(3),
or
utimes(2)
when MAGIC_PRESERVE_ATIME
is set.
- /usr/share/misc/magic
- The non-compiled default magic database.
- /usr/share/misc/magic.mgc
- The compiled default magic database.
The results from magic_buffer
() and
magic_file
() where the buffer and the file contain the
same data can produce different results, because in the
magic_file
() case, the program can
lseek(2)
and stat(2)
the file descriptor.
Måns Rullgård Initial libmagic
implementation, and configuration.
Christos Zoulas API cleanup, error code and allocation
handling.