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Re: bin/47524: make(1) loops in Job_CatchOutput()
The following reply was made to PR bin/47524; it has been noted by GNATS.
From: David Laight <david%l8s.co.uk@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost
Subject: Re: bin/47524: make(1) loops in Job_CatchOutput()
Date: Sat, 2 Feb 2013 19:10:56 +0000
On Sat, Feb 02, 2013 at 02:15:01PM +0000, Andreas Gustafsson wrote:
> >Number: 47524
> >Category: bin
> >Synopsis: make(1) loops in Job_CatchOutput()
...
> @@ -2046,7 +2050,8 @@
> if (nready < 0 || readyfd(&childExitJob)) {
> char token = 0;
> nready -= 1;
> - (void)read(childExitJob.inPipe, &token, 1);
> + while (read(childExitJob.inPipe, &token, 1) == -1 && errno == EAGAIN)
> + continue;
> if (token == DO_JOB_RESUME[0])
> /* Complete relay requested from our SIGCONT handler */
> JobRestartJobs();
>
> I believe the "while" loop added by this change is where make is now
> looping.
I'd guess that fd in non-blocking so EAGAIN would just mean that the
pipe is empty.
The purpose of the read() is to empty the pipe, If it is already empty
it won't matter.
I think you'll find the sigchild handler writes into it, possibly
with some check of nready (not looked) to wake things up.
Most likely two children finishing at once only write 1 character,
or some path comes in with nready < 0 ...
David
--
David Laight: david%l8s.co.uk@localhost
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