Path: utzoo!mnetor!uunet!husc6!rutgers!ames!sdcsvax!ucsdhub!hp-sdd!hplabs!hpcea!hpfcdc!rml
From: rml@hpfcdc.HP.COM (Bob Lenk)
Newsgroups: comp.unix.wizards
Subject: Re: Wait, Select, and a SIGCHLD Race Condition
Message-ID: <5980016@hpfcdc.HP.COM>
Date: 17 Dec 87 22:12:18 GMT
References: <5105@sol.ARPA>
Organization: HP Ft. Collins, Co.
Lines: 19

> In summary:
> 
> 	FASYNC
> 	select timeout
> 	longjmp

A fourth (not necessarily better) alternative is to have an extra pipe
or socket that the signal handler writes to, and select on it for
reading.  One reply alluded to this general type of mechanism, but
didn't tie it into specific BSD features.

One warning about the longjmp() method is that it can be troblesome in
the presence of other signals.  If SIGCHLD happens to interrupt another
signal handler, that handler can be aborted.  This can be avoided by
setting the SIGCHLD bit in sv_mask for all other handlers that might be
invoked, further complicating things.

		Bob Lenk
		{ihnp4, hplabs}!hpfcla!rml