add raw version of this.. will have magic_wrap embedded in next commit

ui/medashare/magic.py

@@ -0,0 +1,390 @@
+# coding: utf-8
+
+# from: https://github.com/file/file/raw/master/python/magic.py
+
+# LICENSE:
+# Copyright (c) Ian F. Darwin 1986-1995.
+# Software written by Ian F. Darwin and others;
+# maintained 1995-present by Christos Zoulas and others.
+# 
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice immediately at the beginning of the file, without modification,
+#    this list of conditions, and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+# 
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
+# ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+
+'''
+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
+
+MAGIC_PARAM_INDIR_MAX = PARAM_INDIR_MAX = 0
+MAGIC_PARAM_NAME_MAX = PARAM_NAME_MAX = 1
+MAGIC_PARAM_ELF_PHNUM_MAX = PARAM_ELF_PHNUM_MAX = 2
+MAGIC_PARAM_ELF_SHNUM_MAX = PARAM_ELF_SHNUM_MAX = 3
+MAGIC_PARAM_ELF_NOTES_MAX = PARAM_ELF_NOTES_MAX = 4
+MAGIC_PARAM_REGEX_MAX = PARAM_REGEX_MAX = 5
+MAGIC_PARAM_BYTES_MAX = PARAM_BYTES_MAX = 6
+
+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]
+
+_getparam = _libraries['magic'].magic_getparam
+_getparam.restype = c_int
+_getparam.argtypes = [magic_t, c_int, c_void_p]
+
+_setparam = _libraries['magic'].magic_setparam
+_setparam.restype = c_int
+_setparam.argtypes = [magic_t, c_int, c_void_p]
+
+
+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 getparam(self, param):
+        """
+        Returns the param value if successful and -1 if the parameter
+        was unknown.
+        """
+        v = c_int()
+        i = _getparam(self._magic_t, param, byref(v))
+        if i == -1:
+            return -1
+        return v.value
+
+    def setparam(self, param, value):
+        """
+        Returns 0 if successful and -1 if the parameter was unknown.
+        """
+        v = c_int(value)
+        return _setparam(self._magic_t, param, byref(v))
+
+
+def open(flags):
+    """
+    Returns a magic object on success and None on failure.
+    Flags argument as for setflags.
+    """
+    magic_t = _open(flags)
+    if magic_t is None:
+        return None
+    return Magic(magic_t)
+
+
+# Objects used by `detect_from_` functions
+class error(Exception):
+    pass
+
+class MagicDetect(object):
+    def __init__(self):
+        self.mime_magic = open(MAGIC_MIME)
+        if self.mime_magic is None:
+            raise error
+        if self.mime_magic.load() == -1:
+            self.mime_magic.close()
+            self.mime_magic = None
+            raise error
+        self.none_magic = open(MAGIC_NONE)
+        if self.none_magic is None:
+            self.mime_magic.close()
+            self.mime_magic = None
+            raise error
+        if self.none_magic.load() == -1:
+            self.none_magic.close()
+            self.none_magic = None
+            self.mime_magic.close()
+            self.mime_magic = None
+            raise error
+
+    def __del__(self):
+        if self.mime_magic is not None:
+            self.mime_magic.close()
+        if self.none_magic is not None:
+            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))