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, 2009-2017 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3, or (at your option)
   8    any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, see <http://www.gnu.org/licenses/>.  */
  17
  18 /* written by Jim Meyering */
  19
  20 #include <config.h>
  21
  22 /* Specification.  */
  23 #include <sys/time.h>
  24
  25 #include <time.h>
  26
  27 #if HAVE_SYS_TIMEB_H
  28 # include <sys/timeb.h>
  29 #endif
  30
  31 #if GETTIMEOFDAY_CLOBBERS_LOCALTIME || TZSET_CLOBBERS_LOCALTIME
  32
  33 /* Work around the bug in some systems whereby gettimeofday clobbers
  34    the static buffer that localtime uses for its return value.  The
  35    gettimeofday function from Mac OS X 10.0.4 (i.e., Darwin 1.3.7) has
  36    this problem.  The tzset replacement is necessary for at least
  37    Solaris 2.5, 2.5.1, and 2.6.  */
  38
  39 static struct tm tm_zero_buffer;
  40 static struct tm *localtime_buffer_addr = &tm_zero_buffer;
  41
  42 # undef localtime
  43 extern struct tm *localtime (time_t const *);
  44
  45 # undef gmtime
  46 extern struct tm *gmtime (time_t const *);
  47
  48 /* This is a wrapper for localtime.  It is used only on systems for which
  49    gettimeofday clobbers the static buffer used for localtime's result.
  50
  51    On the first call, record the address of the static buffer that
  52    localtime uses for its result.  */
  53
  54 struct tm *
  55 rpl_localtime (time_t const *timep)
  56 {
  57   struct tm *tm = localtime (timep);
  58
  59   if (localtime_buffer_addr == &tm_zero_buffer)
  60     localtime_buffer_addr = tm;
  61
  62   return tm;
  63 }
  64
  65 /* Same as above, since gmtime and localtime use the same buffer.  */
  66 struct tm *
  67 rpl_gmtime (time_t const *timep)
  68 {
  69   struct tm *tm = gmtime (timep);
  70
  71   if (localtime_buffer_addr == &tm_zero_buffer)
  72     localtime_buffer_addr = tm;
  73
  74   return tm;
  75 }
  76
  77 #endif /* GETTIMEOFDAY_CLOBBERS_LOCALTIME || TZSET_CLOBBERS_LOCALTIME */
  78
  79 #if TZSET_CLOBBERS_LOCALTIME
  80
  81 # undef tzset
  82 extern void tzset (void);
  83
  84 /* This is a wrapper for tzset, for systems on which tzset may clobber
  85    the static buffer used for localtime's result.  */
  86 void
  87 rpl_tzset (void)
  88 {
  89   /* Save and restore the contents of the buffer used for localtime's
  90      result around the call to tzset.  */
  91   struct tm save = *localtime_buffer_addr;
  92   tzset ();
  93   *localtime_buffer_addr = save;
  94 }
  95 #endif
  96
  97 /* This is a wrapper for gettimeofday.  It is used only on systems
  98    that lack this function, or whose implementation of this function
  99    causes problems.  */
 100
 101 int
 102 gettimeofday (struct timeval *restrict tv, void *restrict tz)
 103 {
 104 #undef gettimeofday
 105 #if HAVE_GETTIMEOFDAY
 106 # if GETTIMEOFDAY_CLOBBERS_LOCALTIME
 107   /* Save and restore the contents of the buffer used for localtime's
 108      result around the call to gettimeofday.  */
 109   struct tm save = *localtime_buffer_addr;
 110 # endif
 111
 112 # if defined timeval /* 'struct timeval' overridden by gnulib?  */
 113 #  undef timeval
 114   struct timeval otv;
 115   int result = gettimeofday (&otv, (struct timezone *) tz);
 116   if (result == 0)
 117     {
 118       tv->tv_sec = otv.tv_sec;
 119       tv->tv_usec = otv.tv_usec;
 120     }
 121 # else
 122   int result = gettimeofday (tv, (struct timezone *) tz);
 123 # endif
 124
 125 # if GETTIMEOFDAY_CLOBBERS_LOCALTIME
 126   *localtime_buffer_addr = save;
 127 # endif
 128
 129   return result;
 130
 131 #else
 132
 133 # if HAVE__FTIME
 134
 135   struct _timeb timebuf;
 136   _ftime (&timebuf);
 137   tv->tv_sec = timebuf.time;
 138   tv->tv_usec = timebuf.millitm * 1000;
 139
 140 # else
 141
 142 #  if !defined OK_TO_USE_1S_CLOCK
 143 #   error "Only 1-second nominal clock resolution found.  Is that intended?" \
 144           "If so, compile with the -DOK_TO_USE_1S_CLOCK option."
 145 #  endif
 146   tv->tv_sec = time (NULL);
 147   tv->tv_usec = 0;
 148
 149 # endif
 150
 151   return 0;
 152
 153 #endif
 154 }