fdshare.py

import array
import os
import socket
import mmap

import time


def send_fds(sock, msg, fds):  # not yet used
    return sock.sendmsg(
        [msg], [(socket.SOL_SOCKET, socket.SCM_RIGHTS, array.array("i", fds))]
    )


def main():
    size = 1024
    path = "/tmp/fd-test"
    fd = os.open(path, flags=os.O_EXCL | os.O_RDWR | os.O_CREAT, mode=0o600)
    os.ftruncate(fd, size)
    os.unlink(path)

    child = os.fork()
    if child == 0:
        time.sleep(2)

        mm = mmap.mmap(fd, 0)
        print("child read", mm.readline())

        return

    mm = mmap.mmap(fd, 0, prot=mmap.PROT_READ | mmap.PROT_WRITE, flags=mmap.MAP_SHARED)
    mm.write(b"oh yes")


if __name__ == "__main__":
    main()