Function gkfs::log::detail::mini_gmtime_r

Function Documentation

static inline struct tm *gkfs::log::detail::mini_gmtime_r(const time_t *timep, struct tm *tm)

convert a time_t to a tm It is not POSIX compliant, but it dows not uses any syscall or timezone Converts a Unix timestamp (number of seconds since the beginning of 1970 CE) to a Gregorian civil date-time tuple in GMT (UTC) time zone.

This conforms to C89 (and C99…) and POSIX.

This implementation works, and doesn’t overflow for any sizeof(time_t). It doesn’t check for overflow/underflow in tm->tm_year output. Other than that, it never overflows or underflows. It assumes that that time_t is signed.

This implements the inverse of the POSIX formula (http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_15) for all time_t values, no matter the size, as long as tm->tm_year doesn’t overflow or underflow. The formula is: tm_sec + tm_min*60 + tm_hour*3600

  • tm_yday*86400 + (tm_year-70)*31536000 + ((tm_year-69)/4)*86400 - ((tm_year-1)/100)*86400 + ((tm_year+299)/400)*86400.

License : GNU General Public License v2.0 from https://github.com/pts/minilibc686/

Parameters:

time_t –

Returns:

tm