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.
>
> 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.
> + }
> +
> + if (!hwclock_available) {
> + error_setg(errp, QERR_UNSUPPORTED);
> + return;
> + }
>
> /* If user has passed a time, validate and set it. */
> if (has_time) {
> @@ -195,7 +213,7 @@ 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",
> NULL, environ);
> _exit(EXIT_FAILURE);
> } else if (pid < 0) {
> --
> 2.21.0
>
>
Regards,
Daniel
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