don't spoil errno in sig handler (#411)

reported by thread-sanitizer.

the sighandler's spoiled `errno` was causing xlib to incorrectly assume some
error occurred and thus causing the crash described in #391.

to reproduce:

* Open an nsxiv window
* Open another terminal and run the following:

	var=$(pidof nsxiv); while :; do kill -s SIGCHLD $var; done

putting the `pid` into a variable is actually important because doing
`$(pidof nsxiv)` inside the loop makes it really hard to reproduce the
issue, I presume because of the extra process invocation it was sending
less SIGCHLD and so putting it into a variable avoids that overhead and
is able to generate more signals.

instead of reaping the zombies manually, we now pass the
`SA_NOCLDSTOP|SA_NOCLDWAIT` for SIGCHLD instead so that the zombies are
reaped automatically.

Closes: https://codeberg.org/nsxiv/nsxiv/issues/391
Reviewed-on: https://codeberg.org/nsxiv/nsxiv/pulls/411
Reviewed-by: explosion-mental <explosion-mental@noreply.codeberg.org>

0 files changed, 0 insertions, 0 deletions