# LIBMAGIC - Magic number recognition library - man(3) - [phpMan] [_LIBMAGIC_(3)](https://www.chedong.com/phpMan.php/man/LIBMAGIC/3/markdown) Library Functions Manual [_LIBMAGIC_(3)](https://www.chedong.com/phpMan.php/man/LIBMAGIC/3/markdown) ## 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 ### #include _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_(5)](https://www.chedong.com/phpMan.php/man/magic/5/markdown). 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)](https://www.chedong.com/phpMan.php/man/utime/3/markdown) or [_utimes_(2)](https://www.chedong.com/phpMan.php/man/utimes/2/markdown), 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_(5)](https://www.chedong.com/phpMan.php/man/magic/5/markdown) 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)](https://www.chedong.com/phpMan.php/man/errno/2/markdown)) that was encountered by a system call. The **magic_file**() function returns a textual description of the contents of the _filename_ argu‐ ment, 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_ argu‐ ment, or NULL if an error occurred. The **magic_buffer**() function returns a textual description of the contents of the _buffer_ argu‐ ment 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 sepa‐ rated 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)](https://www.chedong.com/phpMan.php/man/basename/1/markdown) of each file argu‐ ment 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 respec‐ tive 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 1048576 The MAGIC_PARAM_INDIR_RECURSION parameter controls how many levels of recursion will be fol‐ lowed for indirect magic entries. The MAGIC_PARAM_NAME_RECURSION parameter controls how many levels of recursion will be fol‐ lowed 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 **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**(), func‐ tions 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)](https://www.chedong.com/phpMan.php/man/utime/3/markdown), or [_utimes_(2)](https://www.chedong.com/phpMan.php/man/utimes/2/markdown) when MAGIC_PRESERVE_ATIME is set. ## FILES _/usr/share/misc/magic_ The non-compiled default magic database. _/usr/share/misc/magic.mgc_ The compiled default magic database. ## SEE ALSO [_file_(1)](https://www.chedong.com/phpMan.php/man/file/1/markdown), [_magic_(5)](https://www.chedong.com/phpMan.php/man/magic/5/markdown) ## 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)](https://www.chedong.com/phpMan.php/man/lseek/2/markdown) and [_stat_(2)](https://www.chedong.com/phpMan.php/man/stat/2/markdown) the file descriptor. ## AUTHORS Måns Rullgård Initial libmagic implementation, and configuration. Christos Zoulas API cleanup, error code and allocation handling. Debian June 16, 2023 [_LIBMAGIC_(3)](https://www.chedong.com/phpMan.php/man/LIBMAGIC/3/markdown)