Get input event device name via ioctl by CPython extension module

eviocgmodule.c

#include <Python.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/mtio.h>
#include <stdio.h>
#include <stdlib.h>
#include <linux/input.h>

char* getDeviceName(char* device, char* name, size_t len)
{
    int fd = -1;
    int result = 0;

    fd = open(device, O_RDONLY);
    
    // EVIOCGNAME(len) _IOC(_IOC_READ, 'E', 0x06, len) (linux/input.h)
    int request = EVIOCGNAME(len);
    
    result = ioctl(fd, request, name);

    close(fd);
}

static PyObject * get_device_name(PyObject *self, PyObject *args) {
    // parse input
    const char *device;
    if (!PyArg_ParseTuple(args, "s", &device))
        return NULL;

    char name[256] = "Unknown";
    getDeviceName(device, name, 256);

    // return name
    return Py_BuildValue("s", name);
}

static PyMethodDef EVIOCG_Methods[] = {
    {"get_device_name",  get_device_name, METH_VARARGS,
     "Get device name."},
    {NULL, NULL, 0, NULL}        /* Sentinel */
};

static struct PyModuleDef EVIOCG_MODULE = {
    PyModuleDef_HEAD_INIT,
    "eviocg",   /* name of module */
    NULL, /* module documentation, may be NULL */
    -1,       /* size of per-interpreter state of the module,
                 or -1 if the module keeps state in global variables. */
    EVIOCG_Methods
};

PyMODINIT_FUNC PyInit_eviocg(void) {
    PyObject* m = PyModule_Create(&EVIOCG_MODULE);
    if (m == NULL) {
        return NULL;
    }
    return m;
}

fcntl_example.py

"""
courtesy of https://github.com/vpelletier/python-ioctl-opt/blob/master/README.rst
"""

# -*- coding: utf-8 -*-
from ioctl_opt import IOC, IOC_READ

# porting from linux/input.h
EVIOCGNAME = lambda length: IOC(IOC_READ, ord('E'), 0x06, length)

import fcntl


def get_device_name(fd, length=1024):
    name = bytearray(length)
    actual_length = fcntl.ioctl(fd, EVIOCGNAME(length), name, True)
    return name[:actual_length - 1].decode('UTF-8')


if __name__ == '__main__':
    for i in range(7):
        with open('/dev/input/event' + str(i)) as fd:
            print(get_device_name(fd))

  

setup.py

from setuptools import setup, Extension

module = Extension('eviocg', sources=['eviocgmodule.c'])

setup(name='eviocg', ext_modules=[module])

test.log

In [1]: import eviocg

In [2]: eviocg.get_device_name('/dev/input/event3')
Name : Video Bus
Out[2]: 'Video Bus'