Re: [PATCH 1/7] qemu-common: Briefly document qemu_timedate_diff() unit

[Philippe Mathieu-Daudé]

On 6/18/20 7:47 AM, Markus Armbruster wrote:
> Philippe Mathieu-Daudé <f4bug@amsat.org> writes:
> 
>> It is not obvious that the qemu_timedate_diff() and
>> qemu_ref_timedate() functions return seconds. Briefly
>> document it.
>>
>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> ---
>>  include/qemu-common.h | 1 +
>>  softmmu/vl.c          | 2 +-
>>  2 files changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/qemu-common.h b/include/qemu-common.h
>> index d0142f29ac..e97644710c 100644
>> --- a/include/qemu-common.h
>> +++ b/include/qemu-common.h
>> @@ -27,6 +27,7 @@ int qemu_main(int argc, char **argv, char **envp);
>>  #endif
>>  
>>  void qemu_get_timedate(struct tm *tm, int offset);
>> +/* Returns difference with RTC reference time (in seconds) */
>>  int qemu_timedate_diff(struct tm *tm);
> 
> Not this patch's problem: use of int here smells; is it wide enough?

I'll add a /* FIXME */ comment.

> 
>>  
>>  void *qemu_oom_check(void *ptr);
>> diff --git a/softmmu/vl.c b/softmmu/vl.c
>> index f669c06ede..215459c7b5 100644
>> --- a/softmmu/vl.c
>> +++ b/softmmu/vl.c
>> @@ -737,7 +737,7 @@ void qemu_system_vmstop_request(RunState state)
>>  }
>>  
>>  /***********************************************************/
>> -/* RTC reference time/date access */
>> +/* RTC reference time/date access (in seconds) */
>>  static time_t qemu_ref_timedate(QEMUClockType clock)
>>  {
>>      time_t value = qemu_clock_get_ms(clock) / 1000;
> 
> time_t is seconds on all systems we support.  Using it for something
> other than seconds would be wrong.  The comment feels redundant to me.
> But if it helps someone else...

Ah, TIL 'time_t' is the arithmetic time type to represent
the number of seconds since the epoch.

I guess I almost never used it ... (Not something real time
embedded systems care much) :)

So scratch that comment.

> 
>