Re: [Qemu-devel] [PATCH 3/3] qga: add guest-set-time command

[Luiz Capitulino <lcapitulino@redhat.com>]

On Sun,  6 Jan 2013 18:07:00 +0800
Lei Li <lilei@linux.vnet.ibm.com> wrote:

> Signed-off-by: Lei Li <lilei@linux.vnet.ibm.com>
> ---
>  qga/commands-posix.c |   57 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  qga/qapi-schema.json |   32 ++++++++++++++++++++++++++++
>  2 files changed, 89 insertions(+), 0 deletions(-)
> 
> diff --git a/qga/commands-posix.c b/qga/commands-posix.c
> index 190199d..7fff49a 100644
> --- a/qga/commands-posix.c
> +++ b/qga/commands-posix.c
> @@ -121,6 +121,63 @@ struct HostTimeInfo *qmp_guest_get_time(Error **errp)
>      return host_time;
>  }
>  
> +void qmp_guest_set_time(bool has_seconds, int64_t seconds,
> +                        bool has_microseconds, int64_t microseconds,
> +                        bool has_utc_offset, int64_t utc_offset, Error **errp)
> +{
> +    int ret;
> +    int status;
> +    pid_t pid, rpid;
> +    struct timeval tv;
> +    HostTimeInfo *host_time;
> +
> +    if ((!has_seconds) && (!has_microseconds) && (!has_utc_offset)) {
> +        host_time = get_host_time();
> +        if (!host_time) {
> +            error_set(errp, QERR_QGA_COMMAND_FAILED, "Failed to set guest time");

If you change get_host_time() to take an Error * argument, you can drop this.

> +            return;
> +        }
> +        tv.tv_sec = host_time->seconds;
> +        tv.tv_usec = host_time->microseconds;
> +    } else if (has_seconds && has_microseconds && has_utc_offset) {
> +        tv.tv_sec = (time_t) seconds + utc_offset;
> +        tv.tv_usec = (time_t) microseconds;
> +    } else {
> +        error_set(errp, QERR_INVALID_PARAMETER, "parameter missing");

Please, use error_setg() instead.

> +        return;
> +    }
> +
> +    ret = settimeofday(&tv, NULL);
> +    if (ret < 0) {
> +        error_set(errp, QERR_QGA_COMMAND_FAILED, strerror(errno));

Please, use error_setg_errno().

> +        return;
> +    }
> +
> +    /* Set the Hardware Clock to the current System Time. */
> +    pid = fork();
> +    if (pid == 0) {
> +        setsid();
> +        reopen_fd_to_null(0);
> +        reopen_fd_to_null(1);
> +        reopen_fd_to_null(2);
> +
> +        execle("/sbin/hwclock", "hwclock", "-w", NULL, environ);

Honest question: is this really necessary? Can't we do whatever hwclock does?

> +        _exit(EXIT_FAILURE);
> +    } else if (pid < 0) {
> +        goto exit_err;
> +    }
> +
> +    do {
> +        rpid = waitpid(pid, &status, 0);
> +    } while (rpid == -1 && errno == EINTR);
> +    if (rpid == pid && WIFEXITED(status) && !WEXITSTATUS(status)) {
> +        return;
> +    }
> +
> +exit_err:
> +    error_set(errp, QERR_UNDEFINED_ERROR);
> +}
> +
>  typedef struct GuestFileHandle {
>      uint64_t id;
>      FILE *fh;
> diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
> index 4a8b93c..4649b55 100644
> --- a/qga/qapi-schema.json
> +++ b/qga/qapi-schema.json
> @@ -117,6 +117,38 @@
>    'returns': 'HostTimeInfo' }
>  
>  ##
> +# @guest-set-time:
> +#
> +# Set guest time. If none arguments were given, will set
> +# host time to guest.
> +#
> +# Right now, when a guest is paused or migrated to a file
> +# then loaded from that file, the guest OS has no idea that
> +# there was a big gap in the time. Depending on how long
> +# the gap was, NTP might not be able to resynchronize the
> +# guest.
> +#
> +# This command tries to set guest time based on the information
> +# from host or an absolute value given by management app, and
> +# set the Hardware Clock to the current System Time. This
> +# will make it easier for a guest to resynchronize without
> +# waiting for NTP.
> +#
> +# @seconds: #optional "seconds" time.
> +#
> +# @microseconds: #optional "microseconds" time.
> +#
> +# @utc-offset: #optional utc offset.
> +#
> +# Returns: Nothing on success.
> +#
> +# Since: 1.4
> +##
> +{ 'command': 'guest-set-time',
> +  'data': { '*seconds': 'int', '*microseconds': 'int',
> +            '*utc-offset': 'int' } }
> +
> +##
>  # @GuestAgentCommandInfo:
>  #
>  # Information about guest agent commands.