Return clock_gettime in python by invoking librt system call

clock_gettime.py

#!/usr/bin/python
import ctypes, os

class timespec(ctypes.Structure):
    _fields_ = [
            ('tv_sec', ctypes.c_long),
            ('tv_nsec', ctypes.c_long)
    ]

librt = ctypes.CDLL('librt.so.1', use_errno=True)
clock_gettime = librt.clock_gettime
clock_gettime.argtypes = [ctypes.c_int, ctypes.POINTER(timespec)]

def realtime():
    t = timespec()
    if clock_gettime(0, ctypes.pointer(t)) != 0:
        errno_ = ctypes.get_errno()
        raise OSError(errno_, os.strerror(errno_))
    print t.tv_nsec
    #return str(t.tv_sec) + "." +  str(t.tv_nsec)

if __name__ == "__main__":
    for i in range(0, 100):
        realtime()