Re: [gentoo-portage-dev] [PATCH v2 3/3] Introduce a tiny init replacement for inside pid namespace

[Zac Medico]

On 11/18/18 12:53 AM, Michał Górny wrote:
> Signed-off-by: Michał Górny <mgorny@g.o>
> ---
>  bin/pid-ns-init        | 25 +++++++++++++++++++++++++
>  lib/portage/process.py | 11 ++++++-----
>  2 files changed, 31 insertions(+), 5 deletions(-)
>  create mode 100644 bin/pid-ns-init
>
> diff --git a/bin/pid-ns-init b/bin/pid-ns-init
> new file mode 100644
> index 000000000..90660571a
> --- /dev/null
> +++ b/bin/pid-ns-init
> @@ -0,0 +1,25 @@
> +#!/usr/bin/env python
> +# Copyright 2018 Gentoo Authors
> +# Distributed under the terms of the GNU General Public License v2
> +
> +import os
> +import sys
> +
> +
> +def main(argv):
> +	if len(argv) < 2:
> +		return 'Usage: {} <main-child-pid>'.format(argv[0])
> +	main_child_pid = int(argv[1])
> +
> +	# wait for child processes
> +	while True:
> +		pid, status = os.wait()
> +		if pid == main_child_pid:
> +			return os.WEXITSTATUS(status)

Technically, is not valid to call WEXITSTATUS unless WIFEXITED called
true. If the child process was killed by a signal, we have a couple of
options:

1) Kill the current process with the same signal, as suggested in
https://www.cons.org/cracauer/sigint.html.

2) Fake it by exiting with 128 + signum (this is what dumb-init does).

-- 
Thanks,
Zac