Fix: MdsShr->LibTimeToVMSTime: Avoid separate calls for current seconds and microseconds (#2467)

[merlea]

See #2467.

In MdsShr->LibTimeToVMSTime, if time_in is not provided in input, then the current time is fetched using a single call to gettimeofday.

[joshStillerman]

I am reviewing this now. Seems odd to me that the input to this routine is a time_t but I guess that is the way we wrote it, or I am confused about what a time_t is. Do you have time to discuss?

[joshStillerman]

retest this please

[merlea]

I am not an expert at all about compilation on Windows and I don't know what is your build setup but my guess is that since gettimeofday is a POSIX extension, it might have to be added in an ad-hoc way on Windows systems.

Otherwise as the tv argument is a timeval and its tv_sec member is declared as a time_t, there should be no problem when passing that to get_tz_offset. So I suppose on your Windows build timeval.tv_sec is not declared as a time_t.

I then see 2 options:

• we can introduce an intermediate variable which casts explicitely the tv.tv_sec value to time_t and pass its address to get_tz_offset (this is quite easy but does feel like a workaround only).
• Fix the definitions of timeval and gettimeofday in the Windows build (this feels like a better option but I don't know how to do it).

[merlea]

I have looked further and it seems the definition of timeval and gettimeofday come from mingw directly. And according to this ticket, they will not change it. So we must accept and take into account that for Windows, timeval is [long,long] and not [time_t,suseconds_t].