lib/gettimeofday.c

   1 /* Provide gettimeofday for systems that don't have it or for which it's broken.
   2
   3    Copyright (C) 2001-2003, 2005-2007, 2009-2015 Free Software
   4    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 3, 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, see <http://www.gnu.org/licenses/>.  */
  18
  19 /* written by Jim Meyering */
  20
  21 #include <config.h>
  22
  23 /* Specification.  */
  24 #include <sys/time.h>
  25
  26 #include <time.h>
  27
  28 #if HAVE_SYS_TIMEB_H
  29 # include <sys/timeb.h>
  30 #endif
  31
  32 #if GETTIMEOFDAY_CLOBBERS_LOCALTIME || TZSET_CLOBBERS_LOCALTIME
  33
  34 /* Work around the bug in some systems whereby gettimeofday clobbers
  35    the static buffer that localtime uses for its return value.  The
  36    gettimeofday function from Mac OS X 10.0.4 (i.e., Darwin 1.3.7) has
  37    this problem.  The tzset replacement is necessary for at least
  38    Solaris 2.5, 2.5.1, and 2.6.  */
  39
  40 static struct tm tm_zero_buffer;
  41 static struct tm *localtime_buffer_addr = &tm_zero_buffer;
  42
  43 # undef localtime
  44 extern struct tm *localtime (time_t const *);
  45
  46 # undef gmtime
  47 extern struct tm *gmtime (time_t const *);
  48
  49 /* This is a wrapper for localtime.  It is used only on systems for which
  50    gettimeofday clobbers the static buffer used for localtime's result.
  51
  52    On the first call, record the address of the static buffer that
  53    localtime uses for its result.  */
  54
  55 struct tm *
  56 rpl_localtime (time_t const *timep)
  57 {
  58   struct tm *tm = localtime (timep);
  59
  60   if (localtime_buffer_addr == &tm_zero_buffer)
  61     localtime_buffer_addr = tm;
  62
  63   return tm;
  64 }
  65
  66 /* Same as above, since gmtime and localtime use the same buffer.  */
  67 struct tm *
  68 rpl_gmtime (time_t const *timep)
  69 {
  70   struct tm *tm = gmtime (timep);
  71
  72   if (localtime_buffer_addr == &tm_zero_buffer)
  73     localtime_buffer_addr = tm;
  74
  75   return tm;
  76 }
  77
  78 #endif /* GETTIMEOFDAY_CLOBBERS_LOCALTIME || TZSET_CLOBBERS_LOCALTIME */
  79
  80 #if TZSET_CLOBBERS_LOCALTIME
  81
  82 # undef tzset
  83 extern void tzset (void);
  84
  85 /* This is a wrapper for tzset, for systems on which tzset may clobber
  86    the static buffer used for localtime's result.  */
  87 void
  88 rpl_tzset (void)
  89 {
  90   /* Save and restore the contents of the buffer used for localtime's
  91      result around the call to tzset.  */
  92   struct tm save = *localtime_buffer_addr;
  93   tzset ();
  94   *localtime_buffer_addr = save;
  95 }
  96 #endif
  97
  98 /* This is a wrapper for gettimeofday.  It is used only on systems
  99    that lack this function, or whose implementation of this function
 100    causes problems.  */
 101
 102 int
 103 gettimeofday (struct timeval *restrict tv, void *restrict tz)
 104 {
 105 #undef gettimeofday
 106 #if HAVE_GETTIMEOFDAY
 107 # if GETTIMEOFDAY_CLOBBERS_LOCALTIME
 108   /* Save and restore the contents of the buffer used for localtime's
 109      result around the call to gettimeofday.  */
 110   struct tm save = *localtime_buffer_addr;
 111 # endif
 112
 113 # if defined timeval /* 'struct timeval' overridden by gnulib?  */
 114 #  undef timeval
 115   struct timeval otv;
 116   int result = gettimeofday (&otv, (struct timezone *) tz);
 117   if (result == 0)
 118     {
 119       tv->tv_sec = otv.tv_sec;
 120       tv->tv_usec = otv.tv_usec;
 121     }
 122 # else
 123   int result = gettimeofday (tv, (struct timezone *) tz);
 124 # endif
 125
 126 # if GETTIMEOFDAY_CLOBBERS_LOCALTIME
 127   *localtime_buffer_addr = save;
 128 # endif
 129
 130   return result;
 131
 132 #else
 133
 134 # if HAVE__FTIME
 135
 136   struct _timeb timebuf;
 137   _ftime (&timebuf);
 138   tv->tv_sec = timebuf.time;
 139   tv->tv_usec = timebuf.millitm * 1000;
 140
 141 # else
 142
 143 #  if !defined OK_TO_USE_1S_CLOCK
 144 #   error "Only 1-second nominal clock resolution found.  Is that intended?" \
 145           "If so, compile with the -DOK_TO_USE_1S_CLOCK option."
 146 #  endif
 147   tv->tv_sec = time (NULL);
 148   tv->tv_usec = 0;
 149
 150 # endif
 151
 152   return 0;
 153
 154 #endif
 155 }