Merge in compatability mode with libmagic

The libmagic distribution uses the same package name `magic` as
python-magic, but has an incompatible API.  This change merges in a
copy of libmagic's bindings, wrapped to give deprecation warnings.

This is intended to a) mitigate the short-term pain to users and
packagers who need to figure out which to use, and b) give us a path
to merging the two sets of bindings.

I'd be happy for libmagic to take over this package if we could find a
path to it.

2 files changed, 331 insertions, 1 deletions

diff --git a/magic/__init__.py b/magic/__init__.py
index fae6620..6ccc8d9 100644
--- a/magic/__init__.py
+++ b/magic/__init__.py
@@ -21,6 +21,7 @@ import glob
 import ctypes
 import ctypes.util
 import threading
+import logging
 
 from ctypes import c_char_p, c_int, c_size_t, c_void_p, byref, POINTER
 
@@ -113,8 +114,10 @@ class Magic:
 
     def from_file(self, filename):
         # raise FileNotFoundException or IOError if the file does not exist
-        with open(filename):
+        # use __builtins__ because the compat stuff at the bottom shadows the builtin open
+        with __builtins__['open'](filename):
             pass
+
         with self.lock:
             try:
                 return maybe_decode(magic_file(self.cookie, filename))
@@ -435,3 +438,45 @@ MAGIC_PARAM_ELF_SHNUM_MAX = 3 # Max ELF program sections processed
 MAGIC_PARAM_ELF_NOTES_MAX = 4 # # Max ELF sections processed
 MAGIC_PARAM_REGEX_MAX = 5 # Length limit for regex searches
 MAGIC_PARAM_BYTES_MAX = 6 # Max number of bytes to read from file
+
+# This package name conflicts with the one provided by upstream
+# libmagic.  This is a common source of confusion for users.  To
+# resolve, We ship a copy of that module, and expose it's functions
+# wrapped in deprecation warnings.
+def add_compat(to_module):
+
+    import warnings, re
+    from magic import compat
+
+    def deprecation_wrapper(compat, fn, alternate):
+        def _(*args, **kwargs):
+            warnings.warn(
+                "Using compatability mode with libmagic's python binding",
+                DeprecationWarning)
+
+            return compat[fn](*args, **kwargs)
+        return _
+
+    fn = [('detect_from_filename', 'magic.from_file'),
+          ('detect_from_content', 'magic.from_buffer'),
+          ('detect_from_fobj', 'magic.Magic.from_open_file'),
+          ('open', 'magic.Magic')]
+    for (fname, alternate) in fn:
+        to_module[fname] = deprecation_wrapper(compat.__dict__, fname, alternate)
+
+    # copy constants over, ensuring there's no conflicts
+    is_const_re = re.compile("^[A-Z_]+$")
+    allowed_inconsistent = set(['MAGIC_MIME'])
+    for name, value in compat.__dict__.items():
+        if is_const_re.match(name):
+            if name in to_module:
+                if name in allowed_inconsistent:
+                    continue
+                if to_module[name] != value:
+                    raise Exception("inconsistent value for " + name)
+                else:
+                    continue
+            else:
+                to_module[name] = value
+
+add_compat(globals())
diff --git a/magic/compat.py b/magic/compat.py
new file mode 100644
index 0000000..662569e
--- /dev/null
+++ b/magic/compat.py
@@ -0,0 +1,285 @@
+# coding: utf-8
+
+'''
+Python bindings for libmagic
+'''
+
+import ctypes
+
+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
+mime_magic = Magic(_open(MAGIC_MIME))
+mime_magic.load()
+none_magic = Magic(_open(MAGIC_NONE))
+none_magic.load()
+
+
+def _create_filemagic(mime_detected, type_detected):
+    mime_type, mime_encoding = mime_detected.split('; ')
+
+    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.
+    '''
+
+    return _create_filemagic(mime_magic.file(filename),
+                             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()
+    return _create_filemagic(mime_magic.descriptor(file_descriptor),
+                             none_magic.descriptor(file_descriptor))
+
+
+def detect_from_content(byte_content):
+    '''Detect mime type, encoding and file type from bytes
+
+    Returns a `FileMagic` namedtuple.
+    '''
+
+    return _create_filemagic(mime_magic.buffer(byte_content),
+                             none_magic.buffer(byte_content))