ctypes variable length structures

Question

Ever since I read Dave Beazley\'s post on binary I/O handling (http://dabeaz.blogspot.com/2009/08/python-binary-io-handling.html) I\'ve wanted to create a Python library for

Answer 1

You could use ctypes pointers to do this.

C struct

struct some_struct {
    uint  length;
    uchar data[1];
};

Python code

from ctypes import *

class SomeStruct(Structure):
    _fields_ = [('length', c_uint), ('data', c_ubyte)]

#read data into SomeStruct
s = SomeStruct()
ptr_data = pointer(s.data)
for i in range(s.length):
    print ptr_data[i]