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magic.py
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# coding: utf-8 ''' Python bindings for libmagic ''' import ctypes import threading from collections import namedtuple from ctypes import * from ctypes.util import find_library def _init(): """ Loads the shared library through ctypes and returns a library L{ctypes.CDLL} instance """ return ctypes.cdll.LoadLibrary(find_library('magic')) _libraries = {} _libraries['magic'] = _init() # Flag constants for open and setflags MAGIC_NONE = NONE = 0 MAGIC_DEBUG = DEBUG = 1 MAGIC_SYMLINK = SYMLINK = 2 MAGIC_COMPRESS = COMPRESS = 4 MAGIC_DEVICES = DEVICES = 8 MAGIC_MIME_TYPE = MIME_TYPE = 16 MAGIC_CONTINUE = CONTINUE = 32 MAGIC_CHECK = CHECK = 64 MAGIC_PRESERVE_ATIME = PRESERVE_ATIME = 128 MAGIC_RAW = RAW = 256 MAGIC_ERROR = ERROR = 512 MAGIC_MIME_ENCODING = MIME_ENCODING = 1024 MAGIC_MIME = MIME = 1040 # MIME_TYPE + MIME_ENCODING MAGIC_APPLE = APPLE = 2048 MAGIC_NO_CHECK_COMPRESS = NO_CHECK_COMPRESS = 4096 MAGIC_NO_CHECK_TAR = NO_CHECK_TAR = 8192 MAGIC_NO_CHECK_SOFT = NO_CHECK_SOFT = 16384 MAGIC_NO_CHECK_APPTYPE = NO_CHECK_APPTYPE = 32768 MAGIC_NO_CHECK_ELF = NO_CHECK_ELF = 65536 MAGIC_NO_CHECK_TEXT = NO_CHECK_TEXT = 131072 MAGIC_NO_CHECK_CDF = NO_CHECK_CDF = 262144 MAGIC_NO_CHECK_TOKENS = NO_CHECK_TOKENS = 1048576 MAGIC_NO_CHECK_ENCODING = NO_CHECK_ENCODING = 2097152 MAGIC_NO_CHECK_BUILTIN = NO_CHECK_BUILTIN = 4173824 FileMagic = namedtuple('FileMagic', ('mime_type', 'encoding', 'name')) class magic_set(Structure): pass magic_set._fields_ = [] magic_t = POINTER(magic_set) _open = _libraries['magic'].magic_open _open.restype = magic_t _open.argtypes = [c_int] _close = _libraries['magic'].magic_close _close.restype = None _close.argtypes = [magic_t] _file = _libraries['magic'].magic_file _file.restype = c_char_p _file.argtypes = [magic_t, c_char_p] _descriptor = _libraries['magic'].magic_descriptor _descriptor.restype = c_char_p _descriptor.argtypes = [magic_t, c_int] _buffer = _libraries['magic'].magic_buffer _buffer.restype = c_char_p _buffer.argtypes = [magic_t, c_void_p, c_size_t] _error = _libraries['magic'].magic_error _error.restype = c_char_p _error.argtypes = [magic_t] _setflags = _libraries['magic'].magic_setflags _setflags.restype = c_int _setflags.argtypes = [magic_t, c_int] _load = _libraries['magic'].magic_load _load.restype = c_int _load.argtypes = [magic_t, c_char_p] _compile = _libraries['magic'].magic_compile _compile.restype = c_int _compile.argtypes = [magic_t, c_char_p] _check = _libraries['magic'].magic_check _check.restype = c_int _check.argtypes = [magic_t, c_char_p] _list = _libraries['magic'].magic_list _list.restype = c_int _list.argtypes = [magic_t, c_char_p] _errno = _libraries['magic'].magic_errno _errno.restype = c_int _errno.argtypes = [magic_t] class Magic(object): def __init__(self, ms): self._magic_t = ms def close(self): """ Closes the magic database and deallocates any resources used. """ _close(self._magic_t) @staticmethod def __tostr(s): if s is None: return None if isinstance(s, str): return s try: # keep Python 2 compatibility return str(s, 'utf-8') except TypeError: return str(s) @staticmethod def __tobytes(b): if b is None: return None if isinstance(b, bytes): return b try: # keep Python 2 compatibility return bytes(b, 'utf-8') except TypeError: return bytes(b) def file(self, filename): """ Returns a textual description of the contents of the argument passed as a filename or None if an error occurred and the MAGIC_ERROR flag is set. A call to errno() will return the numeric error code. """ return Magic.__tostr(_file(self._magic_t, Magic.__tobytes(filename))) def descriptor(self, fd): """ Returns a textual description of the contents of the argument passed as a file descriptor or None if an error occurred and the MAGIC_ERROR flag is set. A call to errno() will return the numeric error code. """ return Magic.__tostr(_descriptor(self._magic_t, fd)) def buffer(self, buf): """ Returns a textual description of the contents of the argument passed as a buffer or None if an error occurred and the MAGIC_ERROR flag is set. A call to errno() will return the numeric error code. """ return Magic.__tostr(_buffer(self._magic_t, buf, len(buf))) def error(self): """ Returns a textual explanation of the last error or None if there was no error. """ return Magic.__tostr(_error(self._magic_t)) def setflags(self, flags): """ Set flags on the magic object which determine how magic checking behaves; a bitwise OR of the flags described in libmagic(3), but without the MAGIC_ prefix. Returns -1 on systems that don't support utime(2) or utimes(2) when PRESERVE_ATIME is set. """ return _setflags(self._magic_t, flags) def load(self, filename=None): """ Must be called to load entries in the colon separated list of database files passed as argument or the default database file if no argument before any magic queries can be performed. Returns 0 on success and -1 on failure. """ return _load(self._magic_t, Magic.__tobytes(filename)) def compile(self, dbs): """ Compile entries in the colon separated list of database files passed as argument or the default database file if no argument. The compiled files created are named from the basename(1) of each file argument with ".mgc" appended to it. Returns 0 on success and -1 on failure. """ return _compile(self._magic_t, Magic.__tobytes(dbs)) def check(self, dbs): """ Check the validity of entries in the colon separated list of database files passed as argument or the default database file if no argument. Returns 0 on success and -1 on failure. """ return _check(self._magic_t, Magic.__tobytes(dbs)) def list(self, dbs): """ Check the validity of entries in the colon separated list of database files passed as argument or the default database file if no argument. Returns 0 on success and -1 on failure. """ return _list(self._magic_t, Magic.__tobytes(dbs)) def errno(self): """ Returns a numeric error code. If return value is 0, an internal magic error occurred. If return value is non-zero, the value is an OS error code. Use the errno module or os.strerror() can be used to provide detailed error information. """ return _errno(self._magic_t) def open(flags): """ Returns a magic object on success and None on failure. Flags argument as for setflags. """ return Magic(_open(flags)) # Objects used by `detect_from_` functions class MagicDetect(object): def __init__(self): self.mime_magic = Magic(_open(MAGIC_MIME)) self.mime_magic.load() self.none_magic = Magic(_open(MAGIC_NONE)) self.none_magic.load() def __del__(self): self.mime_magic.close() self.none_magic.close() threadlocal = threading.local() def _detect_make(): v = getattr(threadlocal, "magic_instance", None) if v is None: v = MagicDetect() setattr(threadlocal, "magic_instance", v) return v def _create_filemagic(mime_detected, type_detected): try: mime_type, mime_encoding = mime_detected.split('; ') except ValueError: raise ValueError(mime_detected) return FileMagic(name=type_detected, mime_type=mime_type, encoding=mime_encoding.replace('charset=', '')) def detect_from_filename(filename): '''Detect mime type, encoding and file type from a filename Returns a `FileMagic` namedtuple. ''' x = _detect_make() return _create_filemagic(x.mime_magic.file(filename), x.none_magic.file(filename)) def detect_from_fobj(fobj): '''Detect mime type, encoding and file type from file-like object Returns a `FileMagic` namedtuple. ''' file_descriptor = fobj.fileno() x = _detect_make() return _create_filemagic(x.mime_magic.descriptor(file_descriptor), x.none_magic.descriptor(file_descriptor)) def detect_from_content(byte_content): '''Detect mime type, encoding and file type from bytes Returns a `FileMagic` namedtuple. ''' x = _detect_make() return _create_filemagic(x.mime_magic.buffer(byte_content), x.none_magic.buffer(byte_content))