Is it possible to tap into IDAPython from within a (C) plugin? ... or at least use that Python instance?

Question

I'm wondering whether it is possible to write a plugin for IDA and/or Hex-Rays which would use Python callbacks to perform certain tasks.

In particular I am wondering if there is an official way to reuse the loaded Python version and IDAPython in light of the Python GIL (global interpreter lock), because obviously attempting anything like that outside of the trodden path could easily to hard-to-debug deadlock situations.

So the question is: how would I go about to write a C/C++-based plugin for IDA, which is able to (re)use the Python interpreter used by IDA for IDAPython -- and if possible even tap into IDAPython?

Answer 1

You can register IDC functions from IDAPython plugins. See the %IDADIR%\python\examples\core\extend_idc.py for the following snippet:

from __future__ import print_function

import ida_expr

if ida_expr.add_idc_func(
        "pow",
        lambda n, e: n ** e,
        (ida_expr.VT_LONG, ida_expr.VT_LONG)):
    print("The pow() function is now available in IDC")
else:
    print("Failed to register pow() IDC function")

Next, your C/C++ plugin code can invoke IDC functions. See %IDASDK%\plugins\ex_debidc\ex_debidc.cpp for an example of how to use expr.hpp::exec_idc_script, whose prototype is as follows:

/// Compile and execute IDC function(s) from file.
/// \param result       ptr to idc_value_t to hold result of the function.
///                     If execution fails, this variable will contain
///                     the exception information.
///                     You may pass nullptr if you are not interested in the returned
///                     value.
/// \param path         text file containing text of IDC functions
/// \param func         function name to execute
/// \param args         array of parameters
/// \param argsnum      number of parameters to pass to 'fname'
///                     This number should be equal to number of parameters
///                     the function expects.
/// \param[out] errbuf  buffer for the error message
/// \retval true   ok
/// \retval false  error, see errbuf

THREAD_SAFE inline bool exec_idc_script(
        idc_value_t *result,
        const char *path,
        const char *func,
        const idc_value_t args[],
        size_t argsnum,
        qstring *errbuf=nullptr)