Zone time

time_t my_timegm (struct tm *tm) {
time_t ret;
char *tz;
tz = getenv("TZ");
setenv("TZ", "", 1); // reinitial
tzset();
ret = mktime(tm);
if (tz)
setenv("TZ", tz, 1);
else
unsetenv("TZ");
tzset();
return ret;
}