gl/gettimeofday.c

   1 /* Provide gettimeofday for systems that don't have it or for which it's broken.
   2
   3    Copyright (C) 2001, 2002, 2003, 2005, 2006, 2007 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 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  19
  20 /* written by Jim Meyering */
  21
  22 #include <config.h>
  23
  24 /* Specification.  */
  25 #include <sys/time.h>
  26
  27 #include <time.h>
  28
  29 #if HAVE_SYS_TIMEB_H
  30 # include <sys/timeb.h>
  31 #endif
  32
  33 #if GETTIMEOFDAY_CLOBBERS_LOCALTIME || TZSET_CLOBBERS_LOCALTIME
  34
  35 /* Work around the bug in some systems whereby gettimeofday clobbers
  36    the static buffer that localtime uses for its return value.  The
  37    gettimeofday function from Mac OS X 10.0.4 (i.e., Darwin 1.3.7) has
  38    this problem.  The tzset replacement is necessary for at least
  39    Solaris 2.5, 2.5.1, and 2.6.  */
  40
  41 static struct tm tm_zero_buffer;
  42 static struct tm *localtime_buffer_addr = &tm_zero_buffer;
  43
  44 /* This is a wrapper for localtime.  It is used only on systems for which
  45    gettimeofday clobbers the static buffer used for localtime's result.
  46
  47    On the first call, record the address of the static buffer that
  48    localtime uses for its result.  */
  49
  50 struct tm *
  51 localtime (time_t const *timep)
  52 {
  53 #undef localtime
  54   extern struct tm *localtime (time_t const *);
  55   struct tm *tm = localtime (timep);
  56
  57   if (localtime_buffer_addr == &tm_zero_buffer)
  58     localtime_buffer_addr = tm;
  59
  60   return tm;
  61 }
  62
  63 /* Same as above, since gmtime and localtime use the same buffer.  */
  64 struct tm *
  65 gmtime (time_t const *timep)
  66 {
  67 #undef gmtime
  68   extern struct tm *gmtime (time_t const *);
  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 /* This is a wrapper for tzset, for systems on which tzset may clobber
  81    the static buffer used for localtime's result.  */
  82 void
  83 tzset (void)
  84 {
  85 #undef tzset
  86   extern void tzset (void);
  87
  88   /* Save and restore the contents of the buffer used for localtime's
  89      result around the call to tzset.  */
  90   struct tm save = *localtime_buffer_addr;
  91   tzset ();
  92   *localtime_buffer_addr = save;
  93 }
  94 #endif
  95
  96 /* This is a wrapper for gettimeofday.  It is used only on systems
  97    that lack this function, or whose implementation of this function
  98    causes problems.  */
  99
 100 int
 101 rpl_gettimeofday (struct timeval *restrict tv, void *restrict tz)
 102 {
 103 #undef gettimeofday
 104 #if HAVE_GETTIMEOFDAY
 105   extern int gettimeofday (/* unspecified arguments */);
 106
 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   int result = gettimeofday (tv, tz);
 114
 115 # if GETTIMEOFDAY_CLOBBERS_LOCALTIME
 116   *localtime_buffer_addr = save;
 117 # endif
 118
 119   return result;
 120
 121 #else
 122
 123 # if HAVE__FTIME
 124
 125   struct _timeb timebuf;
 126   _ftime (&timebuf);
 127   tv->tv_sec = timebuf.time;
 128   tv->tv_usec = timebuf.millitm * 1000;
 129
 130 # else
 131
 132 #  if !defined OK_TO_USE_1S_CLOCK
 133 #   error "Only 1-second nominal clock resolution found.  Is that intended?" \
 134           "If so, compile with the -DOK_TO_USE_1S_CLOCK option."
 135 #  endif
 136   tv->tv_sec = time (NULL);
 137   tv->tv_usec = 0;
 138
 139 # endif
 140
 141   return 0;
 142
 143 #endif
 144 }