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# coding: utf-8

"""

This module contains common `ctypes` utils.

"""

import ctypes

import logging

import sys

log = logging.getLogger("can.ctypesutil")

__all__ = ["CLibrary", "HANDLE", "PHANDLE", "HRESULT"]

try:

_LibBase = ctypes.WinDLL

except AttributeError:

_LibBase = ctypes.CDLL

class LibraryMixin:

def map_symbol(self, func_name, restype=None, argtypes=(), errcheck=None):

"""

Map and return a symbol (function) from a C library. A reference to the

mapped symbol is also held in the instance

:param str func_name:

symbol_name

:param ctypes.c_* restype:

function result type (i.e. ctypes.c_ulong...), defaults to void

:param tuple(ctypes.c_* ... ) argtypes:

argument types, defaults to no args

:param callable errcheck:

optional error checking function, see ctypes docs for _FuncPtr

"""

if argtypes:

prototype = self.function_type(restype, *argtypes)

else:

prototype = self.function_type(restype)

try:

symbol = prototype((func_name, self))

except AttributeError:

raise ImportError(

"Could not map function '{}' from library {}".format(

func_name, self._name

)

)

setattr(symbol, "_name", func_name)

log.debug(

f'Wrapped function "{func_name}", result type: {type(restype)}, error_check {errcheck}'

)

if errcheck:

symbol.errcheck = errcheck

setattr(self, func_name, symbol)

return symbol

class CLibrary_Win32(_LibBase, LibraryMixin):

" Basic ctypes.WinDLL derived class + LibraryMixin "

def __init__(self, library_or_path):

if isinstance(library_or_path, str):

super().__init__(library_or_path)

else:

super().__init__(library_or_path._name, library_or_path._handle)

@property

def function_type(self):

return ctypes.WINFUNCTYPE

class CLibrary_Unix(ctypes.CDLL, LibraryMixin):

" Basic ctypes.CDLL derived class + LibraryMixin "

def __init__(self, library_or_path):

if isinstance(library_or_path, str):

super().__init__(library_or_path)

else:

super().__init__(library_or_path._name, library_or_path._handle)

@property

def function_type(self):

return ctypes.CFUNCTYPE

if sys.platform == "win32":

CLibrary = CLibrary_Win32

HRESULT = ctypes.HRESULT

else:

CLibrary = CLibrary_Unix

if sys.platform == "cygwin":

# Define HRESULT for cygwin

class HRESULT(ctypes.c_long):

pass

# Common win32 definitions

class HANDLE(ctypes.c_void_p):

pass

PHANDLE = ctypes.POINTER(HANDLE)