On Thu, Nov 28, 2019 at 01:49:32PM +0100, Cornelia Huck wrote:
> On Thu, 28 Nov 2019 12:45:32 +0000
> Daniel P. Berrangé <berra...@redhat.com> wrote:
>
> > On Thu, Nov 28, 2019 at 01:36:58PM +0100, Cornelia Huck wrote:
> > > The Posix implementation of guest-set-time invokes hwclock to
> > > set/retrieve the time to/from the hardware clock. If hwclock
> > > is not available, the user is currently informed that "hwclock
> > > failed to set hardware clock to system time", which is quite
> > > misleading. This may happen e.g. on s390x, which has a different
> > > timekeeping concept anyway.
> > >
> > > Let's check for the availability of the hwclock command and
> > > return QERR_UNSUPPORTED for guest-set-time if it is not available.
> > >
> > > Signed-off-by: Cornelia Huck <coh...@redhat.com>
> > > ---
> > >
> > > Not sure if that is the correct approach, but the current error
> > > message is really quite confusing.
> >
> > I guess the alternative is to just #ifndef __s390x__ the whole
> > impl of the qmp_guest_set_time method, but I don't have a
> > strong opinion on which is best.
>
> This hardcodes this as a s390x specialty, though, and I'm not sure that
> assumption is and will stay correct.
>
> >
> > >
> > > Gave it a quick test with an s390x and an x86_64 guest; invoking
> > > 'virsh domtime <value>' now fails with 'not currently supported'
> > > on s390x and continues to work as before on x86_64.
> > >
> > > ---
> > > qga/commands-posix.c | 20 +++++++++++++++++++-
> > > 1 file changed, 19 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/qga/commands-posix.c b/qga/commands-posix.c
> > > index 1c1a165daed8..bd298a38b716 100644
> > > --- a/qga/commands-posix.c
> > > +++ b/qga/commands-posix.c
> > > @@ -149,6 +149,13 @@ int64_t qmp_guest_get_time(Error **errp)
> > > return tq.tv_sec * 1000000000LL + tq.tv_usec * 1000;
> > > }
> > >
> > > +static int check_hwclock_available(const char *path)
> > > +{
> > > + struct stat st;
> > > +
> > > + return (stat(path, &st) < 0) ? 0 : 1;
> > > +}
> > > +
> > > void qmp_guest_set_time(bool has_time, int64_t time_ns, Error **errp)
> > > {
> > > int ret;
> > > @@ -156,6 +163,17 @@ void qmp_guest_set_time(bool has_time, int64_t
> > > time_ns, Error **errp)
> > > pid_t pid;
> > > Error *local_err = NULL;
> > > struct timeval tv;
> > > + const char *hwclock_path = "/sbin/hwclock";
> > > + static int hwclock_available = -1;
> > > +
> > > + if (hwclock_available < 0) {
> > > + hwclock_available = check_hwclock_available(hwclock_path);
> >
> > Could do this inline with:
> >
> > hwclock_available = (access(hwclock_available, X_OK) == 0);
> >
> > getting a slightly better result as this check for it being
> > executable as well as existing.
>
> Yes, that looks better. Can do if we agree on this approach.
I'm fine with this
Regards,
Daniel
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