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

[Lei Li <lilei@linux.vnet.ibm.com>]

On 01/09/2013 09:40 PM, Luiz Capitulino wrote:
> 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.

ok.

>> +            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.

Sure.

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

>> +        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?
>
I have thought about implementing this ourselves, and I did take a look
at the source code of hwclock. But looks like the implement ofthe synchronization
for hardware clock and system clock is a little complicated, so I am not
sure if it's worth to have a try here.

  

>> +        _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.
>


-- 
Lei