#!/usr/bin/env python3

import fcntl
import os
import struct
import sys
import tempfile

from posix_parity import compare_calls
from posix_parity import fail
from posix_parity import join
from posix_parity import touch


def pack_flock(l_type, l_whence=0, l_start=0, l_len=0, l_pid=0):
    # struct flock (common glibc x86_64 layout)
    return struct.pack("hhqqi", l_type, l_whence, l_start, l_len, l_pid)


def main():
    if len(sys.argv) != 2:
        print("usage: TEST_posix_locking <mountpoint>", file=sys.stderr)
        return 1

    mount = sys.argv[1]

    with tempfile.TemporaryDirectory() as native:
        merge_file = join(mount, "posix-locking/file")
        native_file = join(native, "posix-locking/file")
        touch(merge_file, b"x")
        touch(native_file, b"x")

        mfd1 = os.open(merge_file, os.O_RDWR)
        mfd2 = os.open(merge_file, os.O_RDWR)
        nfd1 = os.open(native_file, os.O_RDWR)
        nfd2 = os.open(native_file, os.O_RDWR)

        try:
            err = compare_calls(
                "flock EX nonblock",
                lambda: fcntl.flock(mfd1, fcntl.LOCK_EX | fcntl.LOCK_NB),
                lambda: fcntl.flock(nfd1, fcntl.LOCK_EX | fcntl.LOCK_NB),
            )
            if err:
                return fail(err)

            err = compare_calls(
                "flock SH nonblock second fd",
                lambda: fcntl.flock(mfd2, fcntl.LOCK_SH | fcntl.LOCK_NB),
                lambda: fcntl.flock(nfd2, fcntl.LOCK_SH | fcntl.LOCK_NB),
            )
            if err:
                return fail(err)

            err = compare_calls("flock unlock", lambda: fcntl.flock(mfd1, fcntl.LOCK_UN), lambda: fcntl.flock(nfd1, fcntl.LOCK_UN))
            if err:
                return fail(err)
            err = compare_calls("flock unlock second fd", lambda: fcntl.flock(mfd2, fcntl.LOCK_UN), lambda: fcntl.flock(nfd2, fcntl.LOCK_UN))
            if err:
                return fail(err)

            # POSIX record lock via fcntl
            wrlk = pack_flock(fcntl.F_WRLCK)
            unlck = pack_flock(fcntl.F_UNLCK)

            err = compare_calls("fcntl F_SETLK write lock", lambda: fcntl.fcntl(mfd1, fcntl.F_SETLK, wrlk), lambda: fcntl.fcntl(nfd1, fcntl.F_SETLK, wrlk))
            if err:
                return fail(err)

            err = compare_calls("fcntl F_SETLK write lock second fd", lambda: fcntl.fcntl(mfd2, fcntl.F_SETLK, wrlk), lambda: fcntl.fcntl(nfd2, fcntl.F_SETLK, wrlk))
            if err:
                return fail(err)

            err = compare_calls("fcntl F_SETLK unlock", lambda: fcntl.fcntl(mfd1, fcntl.F_SETLK, unlck), lambda: fcntl.fcntl(nfd1, fcntl.F_SETLK, unlck))
            if err:
                return fail(err)

            bad_m = os.open(merge_file, os.O_RDONLY)
            bad_n = os.open(native_file, os.O_RDONLY)
            os.close(bad_m)
            os.close(bad_n)
            err = compare_calls(
                "fcntl EBADF",
                lambda: fcntl.fcntl(bad_m, fcntl.F_SETLK, wrlk),
                lambda: fcntl.fcntl(bad_n, fcntl.F_SETLK, wrlk),
            )
            if err:
                return fail(err)
        finally:
            os.close(mfd1)
            os.close(mfd2)
            os.close(nfd1)
            os.close(nfd2)

        return 0


if __name__ == "__main__":
    raise SystemExit(main())