emacs/lib/localtime-buffer.c

/* Provide access to the last buffer returned by localtime() or gmtime().

   Copyright (C) 2001-2003, 2005-2007, 2009-2020 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 <https://www.gnu.org/licenses/>.  */

/* written by Jim Meyering */

#include <config.h>

/* Specification.  */
#include "localtime-buffer.h"

#if GETTIMEOFDAY_CLOBBERS_LOCALTIME || TZSET_CLOBBERS_LOCALTIME

static struct tm tm_zero_buffer;
struct tm *localtime_buffer_addr = &tm_zero_buffer;

/* This is a wrapper for localtime.

   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)
#undef localtime
{
  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)
#undef gmtime
{
  struct tm *tm = gmtime (timep);

  if (localtime_buffer_addr == &tm_zero_buffer)
    localtime_buffer_addr = tm;

  return tm;
}

#endif