sys.subproj/gettimeofday.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved
  24  *
  25  *      File:   libc/sys/gettimeofday.c
  26  */
  27
  28 #include <time.h>
  29 #include <tzfile.h>
  30 #include <sys/time.h>
  31 #include <errno.h>
  32 #include <sys/syscall.h>
  33 #include <unistd.h>
  34
  35 int gettimeofday (struct timeval *tp, struct timezone *tzp)
  36 {
  37         static int validtz = 0;
  38         static struct timezone cached_tz = {0};
  39
  40         if (syscall (SYS_gettimeofday, tp, tzp) < 0) {
  41                 return (-1);
  42         }
  43         if (validtz == 0)  {
  44                 struct tm *localtm = localtime ((time_t *)&tp->tv_sec);
  45                 cached_tz.tz_dsttime = localtm->tm_isdst;
  46                 cached_tz.tz_minuteswest =
  47                         (-localtm->tm_gmtoff / SECSPERMIN) +
  48                         (localtm->tm_isdst * MINSPERHOUR);
  49                 validtz = 1;
  50         }
  51         if (tzp) {
  52           tzp->tz_dsttime = cached_tz.tz_dsttime;
  53           tzp->tz_minuteswest = cached_tz.tz_minuteswest;
  54         }
  55         return (0);
  56 }