[PATCH] commandtest: Comply with FreeBSD poll()

[Martin Kletzander]

On Thu, Dec 01, 2022 at 04:58:07PM +0100, Michal Privoznik wrote:
>In one of recent commits I've introduced a new test case to
>commandtest. In the test case I'm using poll() to wait for data
>on a pipe (the write end is passed to commandhelper). However, on
>FreeBSD the POLLIN semantic is a bit different:
>
>  POLLIN        Data other than high priority data may be read
>                without blocking.
>
>Well, the pipe is non-blocking, so even if there's no data to be
>read the flag is set (and subsequent read() returns 0). On the

if the other end is closed and there is no data

Reviewed-by: Martin Kletzander <mkletzan at redhat.com>

>other hand, POLLHUP is set too, BUT, if the commandhelper manages
>to write everything into the pipe and die right after we'd get
>both POLLIN and POLLHUP after the very first time poll() returns.
>That's very unfortunate, but okay - we can just check whether
>read() returned zero and break from the reading loop.
>
>Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>---
> tests/commandtest.c | 3 +++
> 1 file changed, 3 insertions(+)
>
>diff --git a/tests/commandtest.c b/tests/commandtest.c
>index 62275ba96d..688cf59160 100644
>--- a/tests/commandtest.c
>+++ b/tests/commandtest.c
>@@ -1205,6 +1205,9 @@ test29(const void *unused G_GNUC_UNUSED)
>                 goto cleanup;
>             }
>
>+            if (rc == 0)
>+                break;
>+
>             outactual = g_renew(char, outactual, outactuallen + rc + 1);
>             memcpy(outactual + outactuallen, buf, rc);
>             outactuallen += rc;
>-- 
>2.37.4
>
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