Python ctypes.Structure() Examples

def windowsRam(self):
        """
        Uses Windows API to check RAM
        """
        kernel32 = ctypes.windll.kernel32
        c_ulong = ctypes.c_ulong

        class MEMORYSTATUS(ctypes.Structure):
            _fields_ = [
                ("dwLength", c_ulong),
                ("dwMemoryLoad", c_ulong),
                ("dwTotalPhys", c_ulong),
                ("dwAvailPhys", c_ulong),
                ("dwTotalPageFile", c_ulong),
                ("dwAvailPageFile", c_ulong),
                ("dwTotalVirtual", c_ulong),
                ("dwAvailVirtual", c_ulong)
            ]

        memoryStatus = MEMORYSTATUS()
        memoryStatus.dwLength = ctypes.sizeof(MEMORYSTATUS)
        kernel32.GlobalMemoryStatus(ctypes.byref(memoryStatus))

        return int(memoryStatus.dwTotalPhys / 1024 ** 2) 

def test_union_with_struct_packed(self):
        class Struct(ctypes.Structure):
            _pack_ = 1
            _fields_ = [
                ('one', ctypes.c_uint8),
                ('two', ctypes.c_uint32)
            ]

        class Union(ctypes.Union):
            _fields_ = [
                ('a', ctypes.c_uint8),
                ('b', ctypes.c_uint16),
                ('c', ctypes.c_uint32),
                ('d', Struct),
            ]
        expected = np.dtype(dict(
            names=['a', 'b', 'c', 'd'],
            formats=['u1', np.uint16, np.uint32, [('one', 'u1'), ('two', np.uint32)]],
            offsets=[0, 0, 0, 0],
            itemsize=ctypes.sizeof(Union)
        ))
        self.check(Union, expected) 

def _is_gui_available():
        UOI_FLAGS = 1
        WSF_VISIBLE = 0x0001
        class USEROBJECTFLAGS(ctypes.Structure):
            _fields_ = [("fInherit", ctypes.wintypes.BOOL),
                        ("fReserved", ctypes.wintypes.BOOL),
                        ("dwFlags", ctypes.wintypes.DWORD)]
        dll = ctypes.windll.user32
        h = dll.GetProcessWindowStation()
        if not h:
            raise ctypes.WinError()
        uof = USEROBJECTFLAGS()
        needed = ctypes.wintypes.DWORD()
        res = dll.GetUserObjectInformationW(h,
            UOI_FLAGS,
            ctypes.byref(uof),
            ctypes.sizeof(uof),
            ctypes.byref(needed))
        if not res:
            raise ctypes.WinError()
        return bool(uof.dwFlags & WSF_VISIBLE) 

def __init__(self, **kwargs):
        """
        Ctypes.Structure with integrated default values.
        https://stackoverflow.com/questions/7946519/default-values-in-a-ctypes-structure/25892189#25892189

        :param kwargs: values different to defaults
        :type kwargs: dict
        """

        # sanity checks
        defaults = type(self)._defaults_
        assert type(defaults) is types.DictionaryType

        # use defaults, but override with keyword arguments, if any
        values = defaults.copy()
        for (key, val) in kwargs.items():
            values[key] = val

        # appropriately initialize ctypes.Structure
        #super().__init__(**values)                     # Python 3 syntax
        return Structure.__init__(self, **values)       # Python 2 syntax

    # http://stackoverflow.com/questions/1825715/how-to-pack-and-unpack-using-ctypes-structure-str/1827666#1827666
    # https://wiki.python.org/moin/ctypes 

def test_union_with_struct_packed(self):
        class Struct(ctypes.Structure):
            _pack_ = 1
            _fields_ = [
                ('one', ctypes.c_uint8),
                ('two', ctypes.c_uint32)
            ]

        class Union(ctypes.Union):
            _fields_ = [
                ('a', ctypes.c_uint8),
                ('b', ctypes.c_uint16),
                ('c', ctypes.c_uint32),
                ('d', Struct),
            ]
        expected = np.dtype(dict(
            names=['a', 'b', 'c', 'd'],
            formats=['u1', np.uint16, np.uint32, [('one', 'u1'), ('two', np.uint32)]],
            offsets=[0, 0, 0, 0],
            itemsize=ctypes.sizeof(Union)
        ))
        self.check(Union, expected) 

def test_union_packed(self):
        class Struct(ctypes.Structure):
            _fields_ = [
                ('one', ctypes.c_uint8),
                ('two', ctypes.c_uint32)
            ]
            _pack_ = 1
        class Union(ctypes.Union):
            _pack_ = 1
            _fields_ = [
                ('a', ctypes.c_uint8),
                ('b', ctypes.c_uint16),
                ('c', ctypes.c_uint32),
                ('d', Struct),
            ]
        expected = np.dtype(dict(
            names=['a', 'b', 'c', 'd'],
            formats=['u1', np.uint16, np.uint32, [('one', 'u1'), ('two', np.uint32)]],
            offsets=[0, 0, 0, 0],
            itemsize=ctypes.sizeof(Union)
        ))
        self.check(Union, expected) 

def MessageClass(length=DMX_LENGTH):
    assert 0 <= length <= DMX_LENGTH
    assert length % 2 == 0, 'artnet only takes messages of even length'

    Char, Int8, Int16 = ctypes.c_char, ctypes.c_ubyte, ctypes.c_ushort

    class DMXMessage(ctypes.Structure):
        # http://artisticlicence.com/WebSiteMaster/User%20Guides/art-net.pdf p47
        _fields_ = [
            ('id', Char * 8),
            ('opCode', Int16),
            ('protVerHi', Int8),
            ('protVerLo', Int8),
            ('sequence', Int8),
            ('physical', Int8),
            ('subUni', Int8),
            ('net', Int8),
            ('lengthHi', Int8),
            ('length', Int8),
            ('data', Int8 * length),  # At position 18
        ]

    return DMXMessage 

def test_union_packed(self):
        class Struct(ctypes.Structure):
            _fields_ = [
                ('one', ctypes.c_uint8),
                ('two', ctypes.c_uint32)
            ]
            _pack_ = 1
        class Union(ctypes.Union):
            _pack_ = 1
            _fields_ = [
                ('a', ctypes.c_uint8),
                ('b', ctypes.c_uint16),
                ('c', ctypes.c_uint32),
                ('d', Struct),
            ]
        expected = np.dtype(dict(
            names=['a', 'b', 'c', 'd'],
            formats=['u1', np.uint16, np.uint32, [('one', 'u1'), ('two', np.uint32)]],
            offsets=[0, 0, 0, 0],
            itemsize=ctypes.sizeof(Union)
        ))
        self.check(Union, expected) 

def create_remote_array(subtype, len):

    class RemoteArray(_ctypes.Array):
        _length_ = len
        _type_ = subtype

        def __init__(self, addr, target):
            self._base_addr = addr
            self.target = target

        def __getitem__(self, slice):
            if not isinstance(slice, (int, long)):
                raise NotImplementedError("RemoteArray slice __getitem__")
            if slice >= len:
                raise IndexError("Access to {0} for a RemoteArray of size {1}".format(slice, len))
            item_addr = self._base_addr + (ctypes.sizeof(subtype) * slice)

            # TODO: do better ?
            class TST(ctypes.Structure):
                _fields_ = [("TST", subtype)]
            return RemoteStructure.from_structure(TST)(item_addr, target=self.target).TST
    return RemoteArray


# 64bits pointers 

def _handle_field_getattr(self, ftype, fosset, fsize):
        s = self._target.read_memory(self._base_addr + fosset, fsize)
        if ftype in self._field_type_to_remote_type:
            return self._field_type_to_remote_type[ftype].from_buffer_with_target(bytearray(s), target=self._target).value
        if issubclass(ftype, _ctypes._Pointer):  # Pointer
            return RemoteStructurePointer.from_buffer_with_target_and_ptr_type(bytearray(s), target=self._target, ptr_type=ftype)
        if issubclass(ftype, RemotePtr64):  # Pointer to remote64 bits process
            return RemoteStructurePointer64.from_buffer_with_target_and_ptr_type(bytearray(s), target=self._target, ptr_type=ftype)
        if issubclass(ftype, RemoteStructureUnion):  # Structure|Union already transfomed in remote
            return ftype(self._base_addr + fosset, self._target)
        if issubclass(ftype, ctypes.Structure):  # Structure that must be transfomed
            return RemoteStructure.from_structure(ftype)(self._base_addr + fosset, self._target)
        if issubclass(ftype, ctypes.Union):  # Union that must be transfomed
            return RemoteUnion.from_structure(ftype)(self._base_addr + fosset, self._target)
        if issubclass(ftype, _ctypes.Array):  # Arrays
            return create_remote_array(ftype._type_, ftype._length_)(self._base_addr + fosset, self._target)
        # Normal types
        # Follow the ctypes usage: if it's not directly inherited from _SimpleCData
        # We do not apply the .value
        # Seems weird but it's mandatory AND useful :D (in pe_parse)
        if _SimpleCData not in ftype.__bases__:
            return ftype.from_buffer(bytearray(s))
        return ftype.from_buffer(bytearray(s)).value 

def write_physical_memory(self, addr, data):
        """Write data to a given physical address

           :param addr: The Symbol to write to
           :type addr: Symbol
           :param size: The Data to write
           :type size: str or ctypes.Structure
           :returns: the size written -- :class:`int`
        """
        try:
            # ctypes structure
            size = ctypes.sizeof(data)
            buffer = ctypes.byref(data)
        except TypeError:
            # buffer
            size = len(data)
            buffer = data
        written = ULONG(0)
        self.DebugDataSpaces.WritePhysical(c_uint64(addr), buffer, size, byref(written))
        return written.value 

def create_vtable(cls, **implem_overwrite):
        vtables_names = [x[0] for x in cls._funcs_]
        non_expected_args = [func_name for func_name in implem_overwrite if func_name not in vtables_names]
        if non_expected_args:
            raise ValueError("Non expected function : {0}".format(non_expected_args))

        implems = []
        for name, types, func_implem in cls._funcs_:
            func_implem = implem_overwrite.get(name, func_implem)
            if func_implem is None:
                raise ValueError("Missing implementation for function <{0}>".format(name))
            implems.append(create_c_callable(func_implem, types))

        class Vtable(ctypes.Structure):
            _fields_ = [(name, ctypes.c_void_p) for name in vtables_names]

        return Vtable(*implems) 

def _is_gui_available():
        UOI_FLAGS = 1
        WSF_VISIBLE = 0x0001
        class USEROBJECTFLAGS(ctypes.Structure):
            _fields_ = [("fInherit", ctypes.wintypes.BOOL),
                        ("fReserved", ctypes.wintypes.BOOL),
                        ("dwFlags", ctypes.wintypes.DWORD)]
        dll = ctypes.windll.user32
        h = dll.GetProcessWindowStation()
        if not h:
            raise ctypes.WinError()
        uof = USEROBJECTFLAGS()
        needed = ctypes.wintypes.DWORD()
        res = dll.GetUserObjectInformationW(h,
            UOI_FLAGS,
            ctypes.byref(uof),
            ctypes.sizeof(uof),
            ctypes.byref(needed))
        if not res:
            raise ctypes.WinError()
        return bool(uof.dwFlags & WSF_VISIBLE) 

def _is_gui_available():
        UOI_FLAGS = 1
        WSF_VISIBLE = 0x0001
        class USEROBJECTFLAGS(ctypes.Structure):
            _fields_ = [("fInherit", ctypes.wintypes.BOOL),
                        ("fReserved", ctypes.wintypes.BOOL),
                        ("dwFlags", ctypes.wintypes.DWORD)]
        dll = ctypes.windll.user32
        h = dll.GetProcessWindowStation()
        if not h:
            raise ctypes.WinError()
        uof = USEROBJECTFLAGS()
        needed = ctypes.wintypes.DWORD()
        res = dll.GetUserObjectInformationW(h,
            UOI_FLAGS,
            ctypes.byref(uof),
            ctypes.sizeof(uof),
            ctypes.byref(needed))
        if not res:
            raise ctypes.WinError()
        return bool(uof.dwFlags & WSF_VISIBLE) 

def write_virtual_memory(self, addr, data):
        """Write data to a given virtual address

           :param addr: The Symbol to write to
           :type addr: Symbol
           :param size: The Data to write
           :type size: str or ctypes.Structure
           :returns: the size written -- :class:`int`
        """
        try:
            # ctypes structure
            size = ctypes.sizeof(data)
            buffer = ctypes.byref(data)
        except TypeError:
            # buffer
            size = len(data)
            buffer = data
        written = ULONG(0)
        addr = self.resolve_symbol(addr)
        self.DebugDataSpaces.WriteVirtual(c_uint64(addr), buffer, size, byref(written))
        return written.value 

def compile(self, structure):
        source = self.gen_struct_class(structure)
        c = compile(source, '<compiled>', 'exec')

        env = {
            'OrderedDict': OrderedDict,
            'Structure': Structure,
            'Instance': Instance,
            'Expression': Expression,
            'EnumInstance': EnumInstance,
            'PointerInstance': PointerInstance,
            'BytesInteger': BytesInteger,
            'BitBuffer': BitBuffer,
            'struct': struct,
            'xrange': xrange,
        }

        exec(c, env)
        sc = env[structure.name](self.cstruct, structure, source)

        return sc 

def as_ctypes_type(dtype):
        r"""
        Convert a dtype into a ctypes type.

        Parameters
        ----------
        dtype : dtype
            The dtype to convert

        Returns
        -------
        ctype
            A ctype scalar, union, array, or struct

        Raises
        ------
        NotImplementedError
            If the conversion is not possible

        Notes
        -----
        This function does not losslessly round-trip in either direction.

        ``np.dtype(as_ctypes_type(dt))`` will:

         - insert padding fields
         - reorder fields to be sorted by offset
         - discard field titles

        ``as_ctypes_type(np.dtype(ctype))`` will:

         - discard the class names of `ctypes.Structure`\ s and
           `ctypes.Union`\ s
         - convert single-element `ctypes.Union`\ s into single-element
           `ctypes.Structure`\ s
         - insert padding fields

        """
        return _ctype_from_dtype(_dtype(dtype)) 

def __init__(self, cstruct, name, fields=None):
        self.name = name
        self.size = None
        self.lookup = OrderedDict()
        self.fields = fields if fields else []

        for f in self.fields:
            self.lookup[f.name] = f

        self._calc_offsets()
        super(Structure, self).__init__(cstruct) 

def _structs(self, data):
        compiler = Compiler(self.cstruct)
        r = re.finditer(
            r'(#(?P<flags>(?:compile))\s+)?((?P<typedef>typedef)\s+)?(?P<type>[^\s]+)\s+(?P<name>[^\s]+)?(?P<fields>\s*\{[^}]+\}(?P<defs>\s+[^;\n]+)?)?\s*;',
            data,
        )
        for t in r:
            d = t.groupdict()

            if d['name']:
                name = d['name']
            elif d['defs']:
                name = d['defs'].strip().split(',')[0].strip()
            else:
                raise ParserError("No name for struct")

            if d['type'] == 'struct':
                data = self._parse_fields(d['fields'][1:-1].strip())
                st = Structure(self.cstruct, name, data)
                if d['flags'] == 'compile' or self.compiled:
                    st = compiler.compile(st)
            elif d['typedef'] == 'typedef':
                st = d['type']
            else:
                continue

            if d['name']:
                self.cstruct.addtype(d['name'], st)

            if d['defs']:
                for td in d['defs'].strip().split(','):
                    td = td.strip()
                    self.cstruct.addtype(td, st) 

def struct_unpack(structure, raw_data):
	"""
	Convert *raw_data* to an instance of *structure*.

	:param structure: The structure that describes *raw_data*.
	:type structure: :py:class:`ctypes.Structure`
	:param bytes raw_data: The binary string which contains the structures data.
	:return: A new instance of *structure*.
	:rtype: :py:class:`ctypes.Structure`
	"""
	if not isinstance(structure, ctypes.Structure):
		structure = structure()
	ctypes.memmove(ctypes.byref(structure), raw_data, ctypes.sizeof(structure))
	return structure 

def test_structure_aligned(self):
        dt = np.dtype([
            ('a', np.uint16),
            ('b', np.uint32),
        ], align=True)

        ct = np.ctypeslib.as_ctypes_type(dt)
        assert_(issubclass(ct, ctypes.Structure))
        assert_equal(ctypes.sizeof(ct), dt.itemsize)
        assert_equal(ct._fields_, [
            ('a', ctypes.c_uint16),
            ('', ctypes.c_char * 2),  # padding
            ('b', ctypes.c_uint32),
        ]) 

def test_structure(self):
        dt = np.dtype([
            ('a', np.uint16),
            ('b', np.uint32),
        ])

        ct = np.ctypeslib.as_ctypes_type(dt)
        assert_(issubclass(ct, ctypes.Structure))
        assert_equal(ctypes.sizeof(ct), dt.itemsize)
        assert_equal(ct._fields_, [
            ('a', ctypes.c_uint16),
            ('b', ctypes.c_uint32),
        ]) 

def test_struct_array_pointer(self):
        from ctypes import c_int16, Structure, pointer

        class Struct(Structure):
            _fields_ = [('a', c_int16)]

        Struct3 = 3 * Struct

        c_array = (2 * Struct3)(
            Struct3(Struct(a=1), Struct(a=2), Struct(a=3)),
            Struct3(Struct(a=4), Struct(a=5), Struct(a=6))
        )

        expected = np.array([
            [(1,), (2,), (3,)],
            [(4,), (5,), (6,)],
        ], dtype=[('a', np.int16)])

        def check(x):
            assert_equal(x.dtype, expected.dtype)
            assert_equal(x, expected)

        # all of these should be equivalent
        check(as_array(c_array))
        check(as_array(pointer(c_array), shape=()))
        check(as_array(pointer(c_array[0]), shape=(2,)))
        check(as_array(pointer(c_array[0][0]), shape=(2, 3))) 

def _calc_signature(self, signature):
        self._cast_signature_pointers_to_void(signature)
        class Arguments (ctypes.Structure):
            _fields_ = [ ("arg_%s" % i, signature[i]) \
                         for i in compat.xrange(len(signature) - 1, -1, -1) ]
        return Arguments 

def _list_ppid_and_pid():
    _TH32CS_SNAPPROCESS = 0x00000002

    class PROCESSENTRY32(ctypes.Structure):
        _fields_ = [("dwSize", ctypes.c_uint32),
                    ("cntUsage", ctypes.c_uint32),
                    ("th32ProcessID", ctypes.c_uint32),
                    ("th32DefaultHeapID", ctypes.c_size_t),
                    ("th32ModuleID", ctypes.c_uint32),
                    ("cntThreads", ctypes.c_uint32),
                    ("th32ParentProcessID", ctypes.c_uint32),
                    ("pcPriClassBase", ctypes.c_long),
                    ("dwFlags", ctypes.c_uint32),
                    ("szExeFile", ctypes.c_char * 260)]

    kernel32 = ctypes.windll.kernel32
    snapshot = kernel32.CreateToolhelp32Snapshot(_TH32CS_SNAPPROCESS, 0)
    ppid_and_pids = []
    try:
        process_entry = PROCESSENTRY32()
        process_entry.dwSize = ctypes.sizeof(PROCESSENTRY32)
        if not kernel32.Process32First(snapshot, ctypes.byref(process_entry)):
            pydev_log.critical('Process32First failed (getting process from CreateToolhelp32Snapshot).')
        else:
            while True:
                ppid_and_pids.append((process_entry.th32ParentProcessID, process_entry.th32ProcessID))
                if not kernel32.Process32Next(snapshot, ctypes.byref(process_entry)):
                    break
    finally:
        kernel32.CloseHandle(snapshot)

    return ppid_and_pids 

def leak_inner():
    class POINT(Structure):
        _fields_ = [("x", c_int)]
    class RECT(Structure):
        _fields_ = [("a", POINTER(POINT))] 

def new_struct_type(self, name):
        return self._new_struct_or_union('struct', name, ctypes.Structure) 

def check_tk_availability():
    """Check that Tk is installed and available."""
    global _tk_unavailable

    if _tk_unavailable is None:
        _tk_unavailable = False
        if sys.platform == 'darwin':
            # The Aqua Tk implementations on OS X can abort the process if
            # being called in an environment where a window server connection
            # cannot be made, for instance when invoked by a buildbot or ssh
            # process not running under the same user id as the current console
            # user.  To avoid that, raise an exception if the window manager
            # connection is not available.
            from ctypes import cdll, c_int, pointer, Structure
            from ctypes.util import find_library

            app_services = cdll.LoadLibrary(find_library("ApplicationServices"))

            if app_services.CGMainDisplayID() == 0:
                _tk_unavailable = "cannot run without OS X window manager"
            else:
                class ProcessSerialNumber(Structure):
                    _fields_ = [("highLongOfPSN", c_int),
                                ("lowLongOfPSN", c_int)]
                psn = ProcessSerialNumber()
                psn_p = pointer(psn)
                if (  (app_services.GetCurrentProcess(psn_p) < 0) or
                      (app_services.SetFrontProcess(psn_p) < 0) ):
                    _tk_unavailable = "cannot run without OS X gui process"
        else:   # not OS X
            import Tkinter
            try:
                Tkinter.Button()
            except Tkinter.TclError as msg:
                # assuming tk is not available
                _tk_unavailable = "tk not available: %s" % msg

    if _tk_unavailable:
        raise unittest.SkipTest(_tk_unavailable)
    return 

def create_interrupt_event():
        """ Create an interrupt event handle.

        The parent process should use this static method for creating the
        interrupt event that is passed to the child process. It should store
        this handle and use it with ``send_interrupt`` to interrupt the child
        process.
        """
        # Create a security attributes struct that permits inheritance of the
        # handle by new processes.
        # FIXME: We can clean up this mess by requiring pywin32 for IPython.
        class SECURITY_ATTRIBUTES(ctypes.Structure):
            _fields_ = [ ("nLength", ctypes.c_int),
                         ("lpSecurityDescriptor", ctypes.c_void_p),
                         ("bInheritHandle", ctypes.c_int) ]
        sa = SECURITY_ATTRIBUTES()
        sa_p = ctypes.pointer(sa)
        sa.nLength = ctypes.sizeof(SECURITY_ATTRIBUTES)
        sa.lpSecurityDescriptor = 0
        sa.bInheritHandle = 1

        return ctypes.windll.kernel32.CreateEventA(
            sa_p,  # lpEventAttributes
            False, # bManualReset
            False, # bInitialState
            '')    # lpName 

def new_struct_type(self, name):
        return self._new_struct_or_union('struct', name, ctypes.Structure)