[libvirt] [PATCH] vircommand: fix polling in virCommandProcessIO

[Martin Kletzander]

On Tue, Apr 21, 2015 at 08:19:45PM +0300, Roman Bogorodskiy wrote:
>When running on FreeBSD, there's a bug in virCommandProcessIO
>polling that is triggered by the commandtest.
>
>A test that triggers EPIPE in commandtest (named "test20") hungs
>forever on FreeBSD.
>
>Apparently, this happens because FreeBSD sets POLLHUP flag on revents
>when stdin in closed. And as the current implementation only checks for
>POLLOUT and POLLERR, it ends up looping forever inside
>virCommandProcessIO and not trying to do one more write() that would
>trigger EPIPE.
>
>To fix that check for the POLLHUP flag along with POLLOUT and POLLERR.

We're already checking that for the pipe heading the other way and
according to information I found it makes sense to do this, even
though it seems that according to documentation this shouldn't happen.

ACK

>---
> src/util/vircommand.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/src/util/vircommand.c b/src/util/vircommand.c
>index 648f5ed..f9b3c3f 100644
>--- a/src/util/vircommand.c
>+++ b/src/util/vircommand.c
>@@ -2097,7 +2097,7 @@ virCommandProcessIO(virCommandPtr cmd)
>                 }
>             }
>
>-            if (fds[i].revents & (POLLOUT | POLLERR) &&
>+            if (fds[i].revents & (POLLOUT | POLLHUP | POLLERR) &&
>                 fds[i].fd == cmd->inpipe) {
>                 int done;
>
>--
>2.3.5
>
>--
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