A Python module written in C that checks if a file is a valid PE using Windows API used to illustrate the idea on how to write a Python module in C because Hello words' are boring! Post: https://tahadraidia.com/lets-build-a-python-module-in-c.html

pevalidator.c

#include <Python.h>
#include <windows.h>

#pragma comment(lib,"kernel32.lib")

static PyObject* isValidPE(PyObject *self, PyObject* args)
{
	LPSTR pfile =  NULL;

	if(!PyArg_ParseTuple(args, "s", &pfile))
	{
      		return Py_None;
	}

	// Get file handler.
	HANDLE hFile = CreateFileA(
		pfile,
		GENERIC_READ,
		FILE_SHARE_READ,
		NULL,
		OPEN_EXISTING,
		FILE_ATTRIBUTE_NORMAL,
		NULL
	);

	// Error check.
	if(hFile == INVALID_HANDLE_VALUE)
	{
		PyErr_SetString(PyExc_ValueError, "CreateFileA retuned INVALID_HANDLE_VALUE.");
		return Py_None;
	}

	// Map the EXE file.
	HANDLE hMapFile = CreateFileMapping(
		hFile,
		NULL,
		PAGE_READONLY,
		0,
		0,
		NULL
	);

	// Error check.
	if(hMapFile == NULL)
	{
		PyErr_SetString(PyExc_ValueError, "CreateFileMapping retuned NULL.");
		return Py_None;
	}

	// Get the base address.
	LPVOID lpBase = MapViewOfFile(
		hMapFile,
		FILE_MAP_READ,
		0, 0, 0);

	// Error check.
	if(lpBase == NULL)
	{
		PyErr_SetString(PyExc_ValueError, "MapViewOfFile retuned NULL.");
		return Py_None;
	}

	PIMAGE_DOS_HEADER dosHeader = (PIMAGE_DOS_HEADER)lpBase;

	// Clean up. 
	UnmapViewOfFile(hMapFile);
	CloseHandle(hMapFile);
	CloseHandle(hFile);
	
	// Either True or False.
	return dosHeader->e_magic == IMAGE_DOS_SIGNATURE ? Py_True : Py_False;
}

static PyMethodDef pevalidator_module_methods[] = {
    {"isValidPE", (PyCFunction)isValidPE, METH_VARARGS, "This method checks if a file is  a valid PE."},
    {NULL, NULL, 0, NULL}
};

static struct PyModuleDef pevalidator_module = {
    PyModuleDef_HEAD_INIT,
    "pevalidator",
    "This module checks if a file is PE file.",
    -1,
    pevalidator_module_methods
};

PyMODINIT_FUNC PyInit_pevalidator(void)
{
    return PyModule_Create(&pevalidator_module);
}

setup.py

from distutils.core import setup, Extension

setup(name="pevalidator", version="1.0", ext_modules=[Extension('pevalidator',
    ['pevalidator.c'])])