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Re: [Qemu-devel] [PATCH 2/2] qga: add guest-set-time command
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] qga: add guest-set-time command |
Date: |
Mon, 04 Mar 2013 12:01:43 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130219 Thunderbird/17.0.3 |
On 03/04/2013 02:16 AM, Lei Li wrote:
> Signed-off-by: Lei Li <address@hidden>
> ---
> qga/commands-posix.c | 54
> ++++++++++++++++++++++++++++++++++++++++++++++++++++
> qga/qapi-schema.json | 27 ++++++++++++++++++++++++++
> 2 files changed, 81 insertions(+)
>
> diff --git a/qga/commands-posix.c b/qga/commands-posix.c
> index 6fc6003..0515f5f 100644
> --- a/qga/commands-posix.c
> +++ b/qga/commands-posix.c
> @@ -135,6 +135,60 @@ int64_t qmp_guest_get_time(Error **errp)
> return time_ns;
> }
>
> +void qmp_guest_set_time(int64_t time_ns, Error **errp)
> +{
> + int ret;
> + int status;
> + pid_t pid;
> + Error *local_err = NULL;
> + struct timeval tv;
> +
> + /* year-2038 will overflow in case time_t is 32bit */
> + if (time_ns / 1000000000 != (time_t)(time_ns / 1000000000)) {
> + error_setg(errp, "Time %" PRId64 " is too large", time_ns);
You set the error, but then fall through...
> + }
> +
> + tv.tv_sec = time_ns / 1000000000;
> + tv.tv_usec = (time_ns % 1000000000) / 1000;
> +
> + ret = settimeofday(&tv, NULL);
...and change the guest time to an invalid value anyways. This could
cause the guest to severely misbehave.
> + if (ret < 0) {
> + error_setg_errno(errp, errno, "Failed to set time to guest");
> + return;
You should have done an early exit on the other error, like you did here.
> +#
> +# This command tries to set guest time based on the information
> +# from host or an absolute value given by management app, and
The absolute value given by the management app _is_ information from the
host. I'd simplify this to just:
This command tries to set guest time to the given value, then
> +# set the Hardware Clock to the current System Time. This
s/set/sets/
> +# will make it easier for a guest to resynchronize without
> +# waiting for NTP.
> +#
> +# @time: time of nanoseconds, relative to the Epoch of
> +# 1970-01-01 in UTC.
> +#
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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