gmtime

/*
 *  call-seq:
 *     time.gmtime    => time
 *     time.utc       => time
 *  
 *  Converts <i>time</i> to UTC (GMT), modifying the receiver.
 *     
 *     t = Time.now   #=> Wed Apr 09 08:56:03 CDT 2003
 *     t.gmt?         #=> false
 *     t.gmtime       #=> Wed Apr 09 13:56:03 UTC 2003
 *     t.gmt?         #=> true
 *
 *     t = Time.now   #=> Wed Apr 09 08:56:04 CDT 2003
 *     t.utc?         #=> false
 *     t.utc          #=> Wed Apr 09 13:56:04 UTC 2003
 *     t.utc?         #=> true
 */

static VALUE
time_gmtime(time)
    VALUE time;
{
    struct time_object *tobj;
    struct tm *tm_tmp;
    time_t t;

    GetTimeval(time, tobj);
    if (tobj->gmt) {
        if (tobj->tm_got)
            return time;
    }
    else {
        time_modify(time);
    }
    t = tobj->tv.tv_sec;
    tm_tmp = gmtime(&t);
    if (!tm_tmp)
        rb_raise(rb_eArgError, "gmtime error");
    tobj->tm = *tm_tmp;
    tobj->tm_got = 1;
    tobj->gmt = 1;
    return time;
}