From: Michael Roth <mdroth@linux.vnet.ibm.com>
To: Cornelia Huck <cohuck@redhat.com>
Cc: "Laszlo Ersek" <lersek@redhat.com>,
"Cornelia Huck" <cohuck@redhat.com>,
"Daniel P . Berrangé" <berrange@redhat.com>,
qemu-devel@nongnu.org
Subject: Re: [PATCH v2] qga: fence guest-set-time if hwclock not available
Date: Wed, 04 Dec 2019 09:05:16 -0600 [thread overview]
Message-ID: <157547191693.3810.11857712694339556499@sif> (raw)
In-Reply-To: <20191128181100.23187-1-cohuck@redhat.com>
Quoting Cornelia Huck (2019-11-28 12:11:00)
> 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 <cohuck@redhat.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.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";
> + 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",
> NULL, environ);
> _exit(EXIT_FAILURE);
> } else if (pid < 0) {
> --
> 2.21.0
>
prev parent reply other threads:[~2019-12-04 15:06 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-28 18:11 [PATCH v2] qga: fence guest-set-time if hwclock not available Cornelia Huck
2019-11-28 18:38 ` Laszlo Ersek
2019-11-29 7:56 ` Cornelia Huck
2019-11-29 9:35 ` Daniel P. Berrangé
2019-12-04 14:12 ` Cornelia Huck
2019-12-04 15:05 ` Michael Roth [this message]
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