Function gmtime_r 

pub unsafe extern "C" fn gmtime_r(
    timep: *const TimeT,
    tmp: *mut Tm,
) -> *mut Tm

Convert system time to a UTC Tm.

Rust interface for the C function:

struct tm *gmtime_r(time_t const *restrict, struct tm *restrict);

The gmtime_r function converts to Coordinated Universal Time, returning a pointer to Tm structures, described below. The storage for the returned Tm should be passed in as the 2nd argument. If it encounters an error, it will return a NULL and set errno (see std::io::Error::last_os_error).