Re: [Qemu-devel] [PATCH 2/2] qga: add windows implementation for guest-set-time

[Eric Blake <eblake@redhat.com>]

[-- Attachment #1: Type: text/plain, Size: 2226 bytes --]

On 03/06/2013 06:45 AM, Lei Li wrote:
> Signed-off-by: Lei Li <lilei@linux.vnet.ibm.com>
> ---
>  qga/commands-win32.c |   35 +++++++++++++++++++++++++++++++++++
>  1 files changed, 35 insertions(+), 0 deletions(-)
> 
> diff --git a/qga/commands-win32.c b/qga/commands-win32.c
> index 4febec7..1a90aa7 100644
> --- a/qga/commands-win32.c
> +++ b/qga/commands-win32.c
> @@ -136,6 +136,41 @@ int64_t qmp_guest_get_time(Error **errp)
>     return time_ns;
>  }
>  
> +void qmp_guest_set_time(int64_t time_ns, Error **errp)
> +{
> +    SYSTEMTIME ts;
> +    FILETIME tf;
> +    LONGLONG time;
> +
> +    /* 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);
> +        return;
> +    }

Do you really need this?  That is, don't you already know what size
time_t is on windows; not to mention that on Windows, you aren't going
through time_t, but directly to tf.dwHighDateTime.

> +
> +    acquire_privilege(SE_SYSTEMTIME_NAME, errp);
> +    if (error_is_set(errp)) {
> +        error_setg(errp, "Failed to acquire privilege");
> +        return;
> +    }
> +
> +    time = time_ns / 100 + _W32_FT_OFFSET;

On the other hand, _this_ operation can overflow, so you should be
checking that time_ns doesn't result in an unexpected time value.

> +
> +    tf.dwLowDateTime = (DWORD) time;
> +    tf.dwHighDateTime = (DWORD) (time >> 32);
> +
> +    if (!FileTimeToSystemTime(&tf, &ts)) {
> +        error_setg(errp, "Failed to convert system time");
> +        return;
> +    }
> +
> +    if (!SetSystemTime(&ts)) {
> +        slog("guest-set-time failed: %d", GetLastError());
> +        error_setg_errno(errp, errno, "Failed to set time to guest");
> +        return;
> +    }   

Trailing whitespace.  Run your submission through scripts/checkpatch.pl.

Should you relinquish the SE_SYSTEMTIME_NAME privilege when exiting this
function, instead of leaving it always enabled for the remaining life of
the agent service?

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 621 bytes --]