ctypesを使う際の(個人的な)ポイント ref: http://qiita.com/FGtatsuro/items/019d56287366e5f7016d

interface.py

from ctypes import *

test.func1.restype = c_int
test.func2.argtypes = (None)

test.func2.restype = c_char_p
test.func2.argtypes = (c_char_p, c_char_p, c_char_p)

ポインタのポインタ型(元々ポインタを表す型)

from ctypes import *

test.func4.restype = c_char_p
test.func4.argtypes = (c_void_p, c_char_p, c_char_p, c_char_p, POINTER(c_void_p), POINTER(c_char_p))

ポインタのポインタ型の引数を扱う

from ctypes import *

test.func4.restype = c_char_p
test.func4.argtypes = (c_void_p, c_char_p, c_char_p, c_char_p, POINTER(c_void_p), POINTER(c_char_p))

# arg1は既に定義済みとする
arg2 = 'str2'
arg3 = 'str3'
arg4 = 'str4'
void_p_p = c_void_p(None)
char_p_p = c_char_p(None)
# 以下だとポインタのポインタにNULLが代入されるためダメ
# void_p_p = None
# char_p_p = None

test.func4(arg1, arg2, arg3, arg4, byref(void_p_p), byref(char_p_p))

型の指定

from ctypes import *

# 実行時に指定
ret = test.func2(c_char_p("test"), c_char_p("test2"), c_char_p("test3"))

# restype/argtypesにより指定
test.func2.restype = c_char_p
test.func2.argtypes = (c_char_p, c_char_p, c_char_p)
ret = test.func2("test", "test2", "test3")

構造体と対応するクラス

from ctypes import *

class JSON_T(Structure):
    __fields__ = [('type', c_int), ('refcount', c_size_t)]

構造体のポインタ型

from ctypes import *

class JSON_T(Structure):
    __fields__ = [('type', c_int), ('refcount', c_size_t)]

test.func3.restype = c_char_p
test.func3.argtypes = (c_void_p, c_char_p, c_char_p, c_char_p, POINTER(JSON_T))