magic.py revision 299236 
1#!/usr/bin/env python
2'''
3Python bindings for libmagic
4'''
5
6import ctypes
7
8from ctypes import *
9from ctypes.util import find_library
10
11
12def _init():
13    """
14    Loads the shared library through ctypes and returns a library
15    L{ctypes.CDLL} instance
16    """
17    return ctypes.cdll.LoadLibrary(find_library('magic'))
18
19_libraries = {}
20_libraries['magic'] = _init()
21
22# Flag constants for open and setflags
23MAGIC_NONE = NONE = 0
24MAGIC_DEBUG = DEBUG = 1
25MAGIC_SYMLINK = SYMLINK = 2
26MAGIC_COMPRESS = COMPRESS = 4
27MAGIC_DEVICES = DEVICES = 8
28MAGIC_MIME_TYPE = MIME_TYPE = 16
29MAGIC_CONTINUE = CONTINUE = 32
30MAGIC_CHECK = CHECK = 64
31MAGIC_PRESERVE_ATIME = PRESERVE_ATIME = 128
32MAGIC_RAW = RAW = 256
33MAGIC_ERROR = ERROR = 512
34MAGIC_MIME_ENCODING = MIME_ENCODING = 1024
35MAGIC_MIME = MIME = 1040
36MAGIC_APPLE = APPLE = 2048
37
38MAGIC_NO_CHECK_COMPRESS = NO_CHECK_COMPRESS = 4096
39MAGIC_NO_CHECK_TAR = NO_CHECK_TAR = 8192
40MAGIC_NO_CHECK_SOFT = NO_CHECK_SOFT = 16384
41MAGIC_NO_CHECK_APPTYPE = NO_CHECK_APPTYPE = 32768
42MAGIC_NO_CHECK_ELF = NO_CHECK_ELF = 65536
43MAGIC_NO_CHECK_TEXT = NO_CHECK_TEXT = 131072
44MAGIC_NO_CHECK_CDF = NO_CHECK_CDF = 262144
45MAGIC_NO_CHECK_TOKENS = NO_CHECK_TOKENS = 1048576
46MAGIC_NO_CHECK_ENCODING = NO_CHECK_ENCODING = 2097152
47
48MAGIC_NO_CHECK_BUILTIN = NO_CHECK_BUILTIN = 4173824
49
50
51class magic_set(Structure):
52    pass
53magic_set._fields_ = []
54magic_t = POINTER(magic_set)
55
56_open = _libraries['magic'].magic_open
57_open.restype = magic_t
58_open.argtypes = [c_int]
59
60_close = _libraries['magic'].magic_close
61_close.restype = None
62_close.argtypes = [magic_t]
63
64_file = _libraries['magic'].magic_file
65_file.restype = c_char_p
66_file.argtypes = [magic_t, c_char_p]
67
68_descriptor = _libraries['magic'].magic_descriptor
69_descriptor.restype = c_char_p
70_descriptor.argtypes = [magic_t, c_int]
71
72_buffer = _libraries['magic'].magic_buffer
73_buffer.restype = c_char_p
74_buffer.argtypes = [magic_t, c_void_p, c_size_t]
75
76_error = _libraries['magic'].magic_error
77_error.restype = c_char_p
78_error.argtypes = [magic_t]
79
80_setflags = _libraries['magic'].magic_setflags
81_setflags.restype = c_int
82_setflags.argtypes = [magic_t, c_int]
83
84_load = _libraries['magic'].magic_load
85_load.restype = c_int
86_load.argtypes = [magic_t, c_char_p]
87
88_compile = _libraries['magic'].magic_compile
89_compile.restype = c_int
90_compile.argtypes = [magic_t, c_char_p]
91
92_check = _libraries['magic'].magic_check
93_check.restype = c_int
94_check.argtypes = [magic_t, c_char_p]
95
96_list = _libraries['magic'].magic_list
97_list.restype = c_int
98_list.argtypes = [magic_t, c_char_p]
99
100_errno = _libraries['magic'].magic_errno
101_errno.restype = c_int
102_errno.argtypes = [magic_t]
103
104
105class Magic(object):
106    def __init__(self, ms):
107        self._magic_t = ms
108
109    def close(self):
110        """
111        Closes the magic database and deallocates any resources used.
112        """
113        _close(self._magic_t)
114
115    def file(self, filename):
116        """
117        Returns a textual description of the contents of the argument passed
118        as a filename or None if an error occurred and the MAGIC_ERROR flag
119        is set.  A call to errno() will return the numeric error code.
120        """
121        try:  # attempt python3 approach first
122            if isinstance(filename, bytes):
123                bi = filename
124            else:
125                bi = bytes(filename, 'utf-8')
126            return str(_file(self._magic_t, bi), 'utf-8')
127        except:
128            return _file(self._magic_t, filename.encode('utf-8'))
129
130    def descriptor(self, fd):
131        """
132        Like the file method, but the argument is a file descriptor.
133        """
134        return _descriptor(self._magic_t, fd)
135
136    def buffer(self, buf):
137        """
138        Returns a textual description of the contents of the argument passed
139        as a buffer or None if an error occurred and the MAGIC_ERROR flag
140        is set. A call to errno() will return the numeric error code.
141        """
142        try:  # attempt python3 approach first
143            return str(_buffer(self._magic_t, buf, len(buf)), 'utf-8')
144        except:
145            return _buffer(self._magic_t, buf, len(buf))
146
147    def error(self):
148        """
149        Returns a textual explanation of the last error or None
150        if there was no error.
151        """
152        try:  # attempt python3 approach first
153            return str(_error(self._magic_t), 'utf-8')
154        except:
155            return _error(self._magic_t)
156
157    def setflags(self, flags):
158        """
159        Set flags on the magic object which determine how magic checking
160        behaves; a bitwise OR of the flags described in libmagic(3), but
161        without the MAGIC_ prefix.
162
163        Returns -1 on systems that don't support utime(2) or utimes(2)
164        when PRESERVE_ATIME is set.
165        """
166        return _setflags(self._magic_t, flags)
167
168    def load(self, filename=None):
169        """
170        Must be called to load entries in the colon separated list of database
171        files passed as argument or the default database file if no argument
172        before any magic queries can be performed.
173
174        Returns 0 on success and -1 on failure.
175        """
176        return _load(self._magic_t, filename)
177
178    def compile(self, dbs):
179        """
180        Compile entries in the colon separated list of database files
181        passed as argument or the default database file if no argument.
182        Returns 0 on success and -1 on failure.
183        The compiled files created are named from the basename(1) of each file
184        argument with ".mgc" appended to it.
185        """
186        return _compile(self._magic_t, dbs)
187
188    def check(self, dbs):
189        """
190        Check the validity of entries in the colon separated list of
191        database files passed as argument or the default database file
192        if no argument.
193        Returns 0 on success and -1 on failure.
194        """
195        return _check(self._magic_t, dbs)
196
197    def list(self, dbs):
198        """
199        Check the validity of entries in the colon separated list of
200        database files passed as argument or the default database file
201        if no argument.
202        Returns 0 on success and -1 on failure.
203        """
204        return _list(self._magic_t, dbs)
205
206    def errno(self):
207        """
208        Returns a numeric error code. If return value is 0, an internal
209        magic error occurred. If return value is non-zero, the value is
210        an OS error code. Use the errno module or os.strerror() can be used
211        to provide detailed error information.
212        """
213        return _errno(self._magic_t)
214
215
216def open(flags):
217    """
218    Returns a magic object on success and None on failure.
219    Flags argument as for setflags.
220    """
221    return Magic(_open(flags))
222