fix: faulty zombie reaping

issues with the current signal handler:

1. die() isn't async-signal-safe
2. there's a race-window during reinstating the signal handler allowing
   zombies to be produced (should be rare in practice).
3. if waitpid fails, it will clobber the errno which can lead to
   undesired codepath being taken on the resuming code (this one can
   actually occur in practice).

to reproduce the 3rd issue:

	~> ./tabbed &
	[1] 20644
	0x1800003
	~> while :; do kill -s SIGCHLD 20644; done >&2 2>/dev/null
	XIO:  fatal IO error 10 (No child processes) on X server ":0"
	      after 47 requests (47 known processed) with 0 events remaining.
	[1]  + exit 1     ./tabbed

set the signal handler to SIG_IGN to reap zombies automatically
(according to POSIX.1-2001).

NOTE: this patch follows dwm's commit 712d663. according to the manpage,
none of the sa_flags being set are meaningful since we're using SIG_IGN.
they used to be meaningful on earlier version of the patch where it was
using SIG_DFL, i've kept them here just in case.

0 files changed, 0 insertions, 0 deletions