How to call idc function with idapython

Question

I want to script a x86Emu plugin (an IDA emulator) with IdaPython. It's registered idc functions. Below is function names from the plugin source code.

/* add IDC functions for interacting with the emulator
EmuRun();
EmuTrace();
EmuStepOne();
EmuTraceOne();
EmuSync();
EmuGetReg(regno);
EmuSetReg(regno, value);
EmuAddBpt(addr);
*/

This functions works well in idc. I found a class calling idc function in idaapi.py.

class _IdcFunction(object):
"""
Internal class that calls pyw_call_idc_func() with a context
"""
def \_\_init\_\_(self, ctxptr):
    self.ctxptr = ctxptr
    # Take a reference to the ctypes callback
    # (note: this will create a circular reference)
    self.cb   = _IDCFUNC_CB_T(self)
fp_ptr = property(lambda self: ctypes.cast(self.cb, ctypes.c_void_p).value)
def \_\_call\_\_(self, args, res):
    return call_idc_func__(self.ctxptr, args, res)

When I type this:

import ctypes
idaapi._IdcFuntion( ctypes ).\_\_call\_\_( 'EmuStepOne', ctypes.c_voidp ) 

I get the following error:

ctypes.ArgumentError: argument 1: <type 'exceptions.TypeError'>: Don't know how to convert parameter 1

I don't know why I get this error, has anyone an idea ?

Answer 1

You get these errors because you're trying to use ctypes, which calls native functions from python using conversions from python objects to low-level C-like types.

Obviously, a python exception is not something ctypes can convert to native representation, so it fails.

There's a really simple way to call IDC code from within IDAPython, using idc.Eval, like the following:

idc.Eval("EmuStepOne();")