# libmagic

## NAME



           **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
    


## LIBRARY



           Magic Number Recognition Library (libmagic, -lmagic)
    


## SYNOPSIS



           <_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_) _const char *_
           **magic_getpath**(_const char *magicfile_ , _int action_)
    


## DESCRIPTION



           These functions operate on the magic database file which is
           described in _magic_(4).
    
           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_COMPRESS_FORK
                           Don't allow decompressors that use fork.
    
           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.
    
           MAGIC_NO_CHECK_SIMH
                           Don't examine SIMH tape files.
    
           The **magic_close**() function closes the _magic_(4) 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/local/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.
    
                 **Parameter                    Type      Default**
                 **MAGIC_PARAM_INDIR_MAX** size_t    15
                 **MAGIC_PARAM_NAME_MAX** size_t    30
                 **MAGIC_PARAM_ELF_NOTES_MAX** size_t    256
                 **MAGIC_PARAM_ELF_PHNUM_MAX** size_t    128
                 **MAGIC_PARAM_ELF_SHNUM_MAX** size_t    32768
                 **MAGIC_PARAM_REGEX_MAX** size_t    8192
                 **MAGIC_PARAM_BYTES_MAX** size_t    7340032
                 **MAGIC_PARAM_ENCODING_MAX** size_t    1048576
                 **MAGIC_PARAM_ELF_SHSIZE_MAX** size_t    134217728
                 **MAGIC_PARAM_MAGWARN_MAX** size_t    64
    
           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_PARAM_REGEX_MAX parameter controls the maximum length
           for regex searches.
    
           The MAGIC_PARAM_BYTES_MAX parameter controls the maximum number of
           bytes to look inside a file.
    
           The MAGIC_PARAM_ENCODING_MAX parameter controls the maximum number
           of bytes to scan for encoding detection.
    
           The MAGIC_PARAM_ELF_SHSIZE_MAX parameter controls the maximum
           number of bytes in an elf section.
    
           The MAGIC_PARAM_MAGWARN_MAX parameter controls the maximum number
           of warnings to tolerate in a magic file.
    
           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 **magic_getpath**() command returns the colon separated list of
           magic database locations.  If the _filename_ is non-NULL, then it is
           returned.  Otherwise, if the MAGIC environment variable is
           defined, then it is returned.  Otherwise, if _action_ is 0 (meaning
           "file load"), then any user-specific magic database file is
           included.  Otherwise, only the system default magic database path
           is included.
    


## RETURN VALUES



           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.
    


## FILES



           _/usr/local/share/misc/magic_      The non-compiled default magic
                                            database.
           _/usr/local/share/misc/magic.mgc_  The compiled default magic
                                            database.
    


## BUGS



           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.
    


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