Re: Why does localtime() call tzset() but localtime_r() not?

Jan. 11, 2008


      "Jonathan Leffler" <jonathan.leffler@gmail.com> writes:
...
Actually, the subject pretty much says it all.
In tzcode2007k (also in 2007h), the code in localtime.c is:
struct tm *
localtime(const time_t *const timep)
{
    tzset();
    return localsub(timep, 0L, &tm);
}
struct tm *
localtime_r(const time_t *const timep, struct tm *tmp)
{
    return localsub(timep, 0L, tmp);
}
I can't immediately see a justification for the asymmetry in the POSIX
specification of these functions, but I could be missing something.
My guess is it's because tzset() sets global variables and hence isn't
threadsafe.

-- 
Russ Allbery (rra@stanford.edu)             <http://www.eyrie.org/~eagle/>