Expert: Ralph McArdell - 5/10/2010

Question
Hi,
I need the equivalent API for SystemTimeToFileTime() in QNX. This is necessary for me to convert the system time into File time.

Please tell me how to do the same.


Regards,
Amol

Answer
Well you do not state _what_ sort of FILETIME Win32 struct equivalent you want to use on QNX,  - which I take to be a POSIX/UN*X like system nor for that matter what you intend to do with such a time value.

Assuming you wish to set the access and/or modification times of a file the easiest thing to do is to set up one or two C/C++ standard library tm struct objects and use the C/C++ standard library function mktime to convert them to time_t values (include <ctime> or <time.h> for C) which you use to set the actime and modtime members of a POSIX/UN*X utimbuf struct and use it to pass to utime together with the pathname of the file who's times you wish to update (include <sys/types.h> and <utime.h> - see http://www.qnx.com/developers/docs/6.4.0/neutrino/lib_ref/u/utime.html for more information).

The above will generally allow an accuracy to 1 second - depending on the resolution of time_t values for QNX - which as an operating system I have never used and not explicitly mentioned in the documentation for time_t for <time.h> (see http://www.qnx.com/developers/docs/6.3.0SP3/dinkum_en/c99/time.html) I cannot comment on further - sorry. However the tm struct does not allow times less than a second anyway.

If you require further accuracy then you will have to think of something else - e.g. getting the time using gettimeofday and using a timeval struct object with utimes (include <sys/time.h>) (see http://www.qnx.com/developers/docs/6.3.0SP3/neutrino/lib_ref/g/gettimeofday.html and http://www.qnx.net/developers/docs/6.3.0SP3/neutrino/lib_ref/u/utimes.html).

Now I located the above information from a standing start in about 10 to 15 minutes using nothing more than a web browser and some queries to Google (well two browsers as the MSDN Library site requires MSIE and it seems I require an updated plug in for Firefox to handle such situations). In the future please do likewise and do not use me as an unpaid research assistant.

If this is not what you were looking for then I suggest you start making use of Google or other search facilities and the available documentation for QNX - you should of course get a good grasp of what the existing Win32 code is doing if you are trying to convert some existing Windows specific code - why is it using SystemTimetoFileTime - where is it getting the system time from, what does it need the file time for etc.