From: Zoltan Hidvegi <hzoli@ny.frontiercomm.net>
To: zsh-workers@math.gatech.edu (Zsh hacking and development)
Subject: Re: stopping "wait" in (sub)script ?
Date: Thu, 15 May 1997 11:47:16 -0400 (EDT) [thread overview]
Message-ID: <199705151547.LAA00880@hzoli.home> (raw)
In-Reply-To: <970515035240.ZM381@candle.brasslantern.com> from Bart Schaefer at "May 15, 97 03:52:39 am"
> On May 15, 11:07am, Peter Stephenson wrote:
> } This doesn't seem to fix this particular bug here, it's still
> } uninterruptible. On the other hand, replacing `cat ss` with $(<ss)
> } has always worked. That doesn't leave much code in getoutput() to
> } make the difference.
>
> I think the problem must be in signal_suspend(). The only difference
> between the two cases in getoutput() is that $(<ss) does an explicit
> child_unblock(), whereas `cat ss` does it implicitly via child_suspend(0).
>
> If you go look at signal_suspend(), you'll find a lot of #ifdefs for the
> assorted signal handling variations. I'll bet this problem is specific
> to one or more of those variations.
No. The problem is that $(...) does not enter the new process to the
process table. $(<...) does not fork, so it is not surprising that it
works. The problem is that `cat ss` forks, and does an entersubsh after
the fork(). When a process terminates the SIGCHLD handler calls
update_job, which should reattach the terminal, but it does not do that
since the terminated job was not in the process table so update_job() is
not even called :-(. I'll try to figure out a better solution tonight
(by that time it'll be tomorrow in Europe).
Zoltan
next prev parent reply other threads:[~1997-05-15 16:05 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <33797750.316A@ptc.com>
1997-05-14 9:00 ` Peter Stephenson
1997-05-15 7:27 ` Zoltan Hidvegi
1997-05-15 9:07 ` Peter Stephenson
1997-05-15 10:52 ` Bart Schaefer
1997-05-15 15:47 ` Zoltan Hidvegi [this message]
1997-05-16 7:11 ` Zoltan Hidvegi
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