Hi Cornelia, On 11/28/19 19:11, 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> > --- > > v1 (RFC) -> v2: > - use hwclock_path[] > - use access() instead of stat() > > --- > qga/commands-posix.c | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) > > diff --git a/qga/commands-posix.c b/qga/commands-posix.c > index 1c1a165daed8..ffb6420fa9cd 100644 > --- a/qga/commands-posix.c > +++ b/qga/commands-posix.c > @@ -156,6 +156,17 @@ 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";
Did you drop the "static" storage-class specifier on purpose? > + static int hwclock_available = -1; > + > + if (hwclock_available < 0) { > + hwclock_available = (access(hwclock_path, X_OK) == 0); > + } > + > + if (!hwclock_available) { > + error_setg(errp, QERR_UNSUPPORTED); > + return; > + } > > /* If user has passed a time, validate and set it. */ > if (has_time) { > @@ -195,7 +206,7 @@ void qmp_guest_set_time(bool has_time, int64_t time_ns, > Error **errp) > > /* Use '/sbin/hwclock -w' to set RTC from the system time, > * or '/sbin/hwclock -s' to set the system time from RTC. */ > - execle("/sbin/hwclock", "hwclock", has_time ? "-w" : "-s", > + execle(hwclock_path, "hwclock", has_time ? "-w" : "-s", I think it's somewhat obscure now that arg="hwclock" is supposed to match the last pathname component in hwclock_path="/sbin/hwclock". There are multiple ways to compute "arg" like that, of course. But I think they all look uglier than the above. So I'm fine if we just keep this. If you purposely dropped the "static", then: Reviewed-by: Laszlo Ersek <ler...@redhat.com> If you just missed the "static" and now intend to add it back, then for v3: Reviewed-by: Laszlo Ersek <ler...@redhat.com> Thanks Laszlo > NULL, environ); > _exit(EXIT_FAILURE); > } else if (pid < 0) { >