#!/usr/bin/env python3

import errno
import fcntl
import os
import struct
import sys
import tempfile

from posix_parity import cleanup_dir
from posix_parity import compare_calls
from posix_parity import fail
from posix_parity import join
from posix_parity import temp_dir
from posix_parity import touch


FIBMAP = 1


def fibmap(fd, block=0):
    buf = struct.pack("i", block)
    out = fcntl.ioctl(fd, FIBMAP, buf)
    return struct.unpack("i", out)[0]


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

    mount = sys.argv[1]

    with tempfile.TemporaryDirectory() as native:
        merge_base = temp_dir(mount)
        try:
            native_base = join(native, os.path.basename(merge_base))
            os.makedirs(native_base, exist_ok=True)

            merge_file = join(merge_base, "file")
            native_file = join(native_base, "file")
            touch(merge_file, b"x" * 8192)
            touch(native_file, b"x" * 8192)

            mfd = os.open(merge_file, os.O_RDONLY)
            nfd = os.open(native_file, os.O_RDONLY)
            try:
                # FIBMAP often requires CAP_SYS_RAWIO; compare errno parity if denied.
                err = compare_calls(
                    "ioctl FIBMAP block0",
                    lambda: fibmap(mfd, 0),
                    lambda: fibmap(nfd, 0),
                    lambda a, b: (a >= 0) == (b >= 0),
                )
                if err:
                    # If both denied by privilege checks, compare_calls already passes.
                    return fail(err)
            finally:
                os.close(mfd)
                os.close(nfd)

            # EBADF parity on closed fds.
            err = compare_calls(
                "ioctl FIBMAP EBADF",
                lambda: fibmap(mfd, 0),
                lambda: fibmap(nfd, 0),
            )
            if err:
                return fail(err)

            return 0
        finally:
            cleanup_dir(merge_base)


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