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

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

On 03/12/2013 11:05 PM, Eric Blake wrote:
> On 03/12/2013 03:08 AM, Lei Li wrote:
>> Signed-off-by: Lei Li <lilei@linux.vnet.ibm.com>
>> ---
>>   qga/commands-win32.c | 34 ++++++++++++++++++++++++++++++++++
>>   1 file changed, 34 insertions(+)
>>
>> +void qmp_guest_set_time(int64_t time_ns, Error **errp)
>> +{
>> +    SYSTEMTIME ts;
>> +    FILETIME tf;
>> +    LONGLONG time;
>> +
>> +    acquire_privilege(SE_SYSTEMTIME_NAME, errp);
>> +    if (error_is_set(errp)) {
>> +        error_setg(errp, "Failed to acquire privilege");
>> +        return;
>> +    }
> Earlier, you told me that acquire_privilege is auto-dropped after a
> successful SetSystemTime.  But here, you acquire the privilege...
>
>> +
>> +    if (time_ns < 0 || time_ns / 100 > INT64_MAX - W32_FT_OFFSET) {
>> +        error_setg(errp, "Time %" PRId64 "is invalid", time_ns);
>> +        return;
> ...then return early without ever relinquishing it.
>
>> +    }
>> +
>> +    time = time_ns / 100 + W32_FT_OFFSET;
>> +
>> +    tf.dwLowDateTime = (DWORD) time;
>> +    tf.dwHighDateTime = (DWORD) (time >> 32);
>> +
>> +    if (!FileTimeToSystemTime(&tf, &ts)) {
>> +        error_setg(errp, "Failed to convert system time");
>> +        return;
>> +    }
> I would reorder the acquire_privilege to here, to give us the best
> possible chance of avoiding a leak of privileges when the user passes
> bogus data.

It make sense, I should thought about this, thank you!

>> +
>> +    if (!SetSystemTime(&ts)) {
>> +        slog("guest-set-time failed: %d", GetLastError());
>> +        error_setg_errno(errp, errno, "Failed to set time to guest");
>> +        return;
>> +    }
>> +}
>> +
>>   int64_t qmp_guest_file_open(const char *path, bool has_mode, const char *mode, Error **err)
>>   {
>>       error_set(err, QERR_UNSUPPORTED);
>>


-- 
Lei