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emacs/lib/gettimeofday.c
2013-01-01 09:11:05 +00:00

155 lines
4.0 KiB
C

/* Provide gettimeofday for systems that don't have it or for which it's broken.
Copyright (C) 2001-2003, 2005-2007, 2009-2013 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, see <http://www.gnu.org/licenses/>. */
/* written by Jim Meyering */
#include <config.h>
/* Specification. */
#include <sys/time.h>
#include <time.h>
#if HAVE_SYS_TIMEB_H
# include <sys/timeb.h>
#endif
#if GETTIMEOFDAY_CLOBBERS_LOCALTIME || TZSET_CLOBBERS_LOCALTIME
/* Work around the bug in some systems whereby gettimeofday clobbers
the static buffer that localtime uses for its return value. The
gettimeofday function from Mac OS X 10.0.4 (i.e., Darwin 1.3.7) has
this problem. The tzset replacement is necessary for at least
Solaris 2.5, 2.5.1, and 2.6. */
static struct tm tm_zero_buffer;
static struct tm *localtime_buffer_addr = &tm_zero_buffer;
# undef localtime
extern struct tm *localtime (time_t const *);
# undef gmtime
extern struct tm *gmtime (time_t const *);
/* This is a wrapper for localtime. It is used only on systems for which
gettimeofday clobbers the static buffer used for localtime's result.
On the first call, record the address of the static buffer that
localtime uses for its result. */
struct tm *
rpl_localtime (time_t const *timep)
{
struct tm *tm = localtime (timep);
if (localtime_buffer_addr == &tm_zero_buffer)
localtime_buffer_addr = tm;
return tm;
}
/* Same as above, since gmtime and localtime use the same buffer. */
struct tm *
rpl_gmtime (time_t const *timep)
{
struct tm *tm = gmtime (timep);
if (localtime_buffer_addr == &tm_zero_buffer)
localtime_buffer_addr = tm;
return tm;
}
#endif /* GETTIMEOFDAY_CLOBBERS_LOCALTIME || TZSET_CLOBBERS_LOCALTIME */
#if TZSET_CLOBBERS_LOCALTIME
# undef tzset
extern void tzset (void);
/* This is a wrapper for tzset, for systems on which tzset may clobber
the static buffer used for localtime's result. */
void
rpl_tzset (void)
{
/* Save and restore the contents of the buffer used for localtime's
result around the call to tzset. */
struct tm save = *localtime_buffer_addr;
tzset ();
*localtime_buffer_addr = save;
}
#endif
/* This is a wrapper for gettimeofday. It is used only on systems
that lack this function, or whose implementation of this function
causes problems. */
int
gettimeofday (struct timeval *restrict tv, void *restrict tz)
{
#undef gettimeofday
#if HAVE_GETTIMEOFDAY
# if GETTIMEOFDAY_CLOBBERS_LOCALTIME
/* Save and restore the contents of the buffer used for localtime's
result around the call to gettimeofday. */
struct tm save = *localtime_buffer_addr;
# endif
# if defined timeval /* 'struct timeval' overridden by gnulib? */
# undef timeval
struct timeval otv;
int result = gettimeofday (&otv, (struct timezone *) tz);
if (result == 0)
{
tv->tv_sec = otv.tv_sec;
tv->tv_usec = otv.tv_usec;
}
# else
int result = gettimeofday (tv, (struct timezone *) tz);
# endif
# if GETTIMEOFDAY_CLOBBERS_LOCALTIME
*localtime_buffer_addr = save;
# endif
return result;
#else
# if HAVE__FTIME
struct _timeb timebuf;
_ftime (&timebuf);
tv->tv_sec = timebuf.time;
tv->tv_usec = timebuf.millitm * 1000;
# else
# if !defined OK_TO_USE_1S_CLOCK
# error "Only 1-second nominal clock resolution found. Is that intended?" \
"If so, compile with the -DOK_TO_USE_1S_CLOCK option."
# endif
tv->tv_sec = time (NULL);
tv->tv_usec = 0;
# endif
return 0;
#endif
}