# Copyright 2014 The ChromiumOS Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Process related utilities."""

import errno
import os
import signal
import sys
import time


def GetExitStatus(status):
    """Get the exit status of a child from an os.waitpid call.

    Args:
        status: The return value of os.waitpid(pid, 0)[1]

    Returns:
        The exit status of the process. If the process exited with a signal,
        the return value will be 128 plus the signal number.
    """
    if os.WIFSIGNALED(status):
        return 128 + os.WTERMSIG(status)
    else:
        assert os.WIFEXITED(status), "Unexpected exit status %r" % status
        return os.WEXITSTATUS(status)


def ExitAsStatus(status):
    """Exit the same way as |status|.

    If the status field says it was killed by a signal, then we'll do that to
    ourselves.  Otherwise we'll exit with the exit code.

    See http://www.cons.org/cracauer/sigint.html for more details.

    Args:
        status: A status as returned by os.wait type funcs.
    """
    exit_status = os.WEXITSTATUS(status)

    if os.WIFSIGNALED(status):
        # Kill ourselves with the same signal.
        sig_status = os.WTERMSIG(status)
        pid = os.getpid()
        os.kill(pid, sig_status)
        time.sleep(0.1)

        # Still here?  Maybe the signal was ignored, so set the handler to the
        # default and try again.
        # TODO(vapier): Should unmask the signal too (pthread_sigmask).
        try:
            signal.signal(sig_status, signal.SIG_DFL)
        except OSError as e:
            if e.errno != errno.EINVAL:
                raise
        os.kill(pid, sig_status)
        time.sleep(0.1)

        # Still here?  Just exit.
        exit_status = 127

    # Exit with the code we want.
    sys.exit(exit_status)