lib/gettimeofday.c

   1 /* Work around the bug in some systems whereby gettimeofday clobbers the
   2    static buffer that localtime uses for it's return value.  The gettimeofday
   3    function from Mac OS X 10.0.4, i.e. Darwin 1.3.7 has this problem.
   4    Copyright (C) 2001, 2002 Free Software Foundation, Inc.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software Foundation,
  18    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  19
  20 /* written by Jim Meyering */
  21
  22 #include <config.h>
  23
  24 /* Disable the definitions of gettimeofday and localtime (from config.h)
  25    so we can use the library versions here.  */
  26 #undef gettimeofday
  27 #undef localtime
  28
  29 #include <sys/types.h>
  30
  31 #if TIME_WITH_SYS_TIME
  32 # include <sys/time.h>
  33 # include <time.h>
  34 #else
  35 # if HAVE_SYS_TIME_H
  36 #  include <sys/time.h>
  37 # else
  38 #  include <time.h>
  39 # endif
  40 #endif
  41
  42 #include <stdlib.h>
  43
  44 static struct tm *localtime_buffer_addr;
  45
  46 /* This is a wrapper for localtime.  It is used only on systems for which
  47    gettimeofday clobbers the static buffer used for localtime's result.
  48
  49    On the first call, record the address of the static buffer that
  50    localtime uses for its result.  */
  51
  52 struct tm *
  53 rpl_localtime (const time_t *timep)
  54 {
  55   struct tm *tm = localtime (timep);
  56
  57   if (! localtime_buffer_addr)
  58     localtime_buffer_addr = tm;
  59
  60   return tm;
  61 }
  62
  63 /* This is a wrapper for gettimeofday.  It is used only on systems for which
  64    gettimeofday clobbers the static buffer used for localtime's result.
  65
  66    Save and restore the contents of the buffer used for localtime's result
  67    around the call to gettimeofday.  */
  68
  69 int
  70 rpl_gettimeofday (struct timeval *tv, struct timezone *tz)
  71 {
  72   struct tm save;
  73   int result;
  74
  75   if (! localtime_buffer_addr)
  76     {
  77       time_t t = 0;
  78       localtime_buffer_addr = localtime (&t);
  79     }
  80
  81   save = *localtime_buffer_addr;
  82   result = gettimeofday (tv, tz);
  83   *localtime_buffer_addr = save;
  84
  85   return result;
  86 }