Passing a string to a char* argument

[iamkisly]

I'm trying to emulate a function call
int __cdecl sub_46F8B0(int a1, char *a2)
The function I want to invoke is a wrapper over sprintf (a2, template, ... ).

In IDA 6.6, I call this:

from idaemu import  * 
a = Emu ( UC_ARCH_X86 , UC_MODE_32 )
print a.eFunc(0x0046F8B0, None, [0x4105C0, ?])

How to pass the second argument? The most reasonable would be to use ctypes.create_string_buffer(%) (because the return type is ctypes.c_char_Array_%). But an integer argument is required.

Python>s2=ctypes.create_string_buffer(50)
Python>print a.eFunc(0x454AB0, None, [0x4105C0, s2])
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "C:/Program Files (x86)/IDA 6.6/plugins\idaemu.py", line 371, in eFunc
    self._emulate(func.startEA, retAddr, args)
  File "C:/Program Files (x86)/IDA 6.6/plugins\idaemu.py", line 285, in _emulate
    self._initStackAndArgs(uc, stopAddr, args)
  File "C:/Program Files (x86)/IDA 6.6/plugins\idaemu.py", line 177, in _initStackAndArgs
    uc.mem_write(sp, pack(self.pack_fmt, args[i]))
struct.error: cannot convert argument to integer

I'm not strong at python and ctypes. How to be in this situation?