emacs/lib/stat-time.h

/* stat-related time functions.

   Copyright (C) 2005, 2007, 2009-2012 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 of the License, 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 Paul Eggert.  */

#ifndef STAT_TIME_H
#define STAT_TIME_H 1

#include <sys/stat.h>
#include <time.h>

/* STAT_TIMESPEC (ST, ST_XTIM) is the ST_XTIM member for *ST of type
   struct timespec, if available.  If not, then STAT_TIMESPEC_NS (ST,
   ST_XTIM) is the nanosecond component of the ST_XTIM member for *ST,
   if available.  ST_XTIM can be st_atim, st_ctim, st_mtim, or st_birthtim
   for access, status change, data modification, or birth (creation)
   time respectively.

   These macros are private to stat-time.h.  */
#if defined HAVE_STRUCT_STAT_ST_ATIM_TV_NSEC
# ifdef TYPEOF_STRUCT_STAT_ST_ATIM_IS_STRUCT_TIMESPEC
#  define STAT_TIMESPEC(st, st_xtim) ((st)->st_xtim)
# else
#  define STAT_TIMESPEC_NS(st, st_xtim) ((st)->st_xtim.tv_nsec)
# endif
#elif defined HAVE_STRUCT_STAT_ST_ATIMESPEC_TV_NSEC
# define STAT_TIMESPEC(st, st_xtim) ((st)->st_xtim##espec)
#elif defined HAVE_STRUCT_STAT_ST_ATIMENSEC
# define STAT_TIMESPEC_NS(st, st_xtim) ((st)->st_xtim##ensec)
#elif defined HAVE_STRUCT_STAT_ST_ATIM_ST__TIM_TV_NSEC
# define STAT_TIMESPEC_NS(st, st_xtim) ((st)->st_xtim.st__tim.tv_nsec)
#endif

/* Return the nanosecond component of *ST's access time.  */
static inline long int
get_stat_atime_ns (struct stat const *st)
{
# if defined STAT_TIMESPEC
  return STAT_TIMESPEC (st, st_atim).tv_nsec;
# elif defined STAT_TIMESPEC_NS
  return STAT_TIMESPEC_NS (st, st_atim);
# else
  return 0;
# endif
}

/* Return the nanosecond component of *ST's status change time.  */
static inline long int
get_stat_ctime_ns (struct stat const *st)
{
# if defined STAT_TIMESPEC
  return STAT_TIMESPEC (st, st_ctim).tv_nsec;
# elif defined STAT_TIMESPEC_NS
  return STAT_TIMESPEC_NS (st, st_ctim);
# else
  return 0;
# endif
}

/* Return the nanosecond component of *ST's data modification time.  */
static inline long int
get_stat_mtime_ns (struct stat const *st)
{
# if defined STAT_TIMESPEC
  return STAT_TIMESPEC (st, st_mtim).tv_nsec;
# elif defined STAT_TIMESPEC_NS
  return STAT_TIMESPEC_NS (st, st_mtim);
# else
  return 0;
# endif
}

/* Return the nanosecond component of *ST's birth time.  */
static inline long int
get_stat_birthtime_ns (struct stat const *st)
{
# if defined HAVE_STRUCT_STAT_ST_BIRTHTIMESPEC_TV_NSEC
  return STAT_TIMESPEC (st, st_birthtim).tv_nsec;
# elif defined HAVE_STRUCT_STAT_ST_BIRTHTIMENSEC
  return STAT_TIMESPEC_NS (st, st_birthtim);
# else
  /* Avoid a "parameter unused" warning.  */
  (void) st;
  return 0;
# endif
}

/* Return *ST's access time.  */
static inline struct timespec
get_stat_atime (struct stat const *st)
{
#ifdef STAT_TIMESPEC
  return STAT_TIMESPEC (st, st_atim);
#else
  struct timespec t;
  t.tv_sec = st->st_atime;
  t.tv_nsec = get_stat_atime_ns (st);
  return t;
#endif
}

/* Return *ST's status change time.  */
static inline struct timespec
get_stat_ctime (struct stat const *st)
{
#ifdef STAT_TIMESPEC
  return STAT_TIMESPEC (st, st_ctim);
#else
  struct timespec t;
  t.tv_sec = st->st_ctime;
  t.tv_nsec = get_stat_ctime_ns (st);
  return t;
#endif
}

/* Return *ST's data modification time.  */
static inline struct timespec
get_stat_mtime (struct stat const *st)
{
#ifdef STAT_TIMESPEC
  return STAT_TIMESPEC (st, st_mtim);
#else
  struct timespec t;
  t.tv_sec = st->st_mtime;
  t.tv_nsec = get_stat_mtime_ns (st);
  return t;
#endif
}

/* Return *ST's birth time, if available; otherwise return a value
   with tv_sec and tv_nsec both equal to -1.  */
static inline struct timespec
get_stat_birthtime (struct stat const *st)
{
  struct timespec t;

#if (defined HAVE_STRUCT_STAT_ST_BIRTHTIMESPEC_TV_NSEC \
     || defined HAVE_STRUCT_STAT_ST_BIRTHTIM_TV_NSEC)
  t = STAT_TIMESPEC (st, st_birthtim);
#elif defined HAVE_STRUCT_STAT_ST_BIRTHTIMENSEC
  t.tv_sec = st->st_birthtime;
  t.tv_nsec = st->st_birthtimensec;
#elif (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  /* Native Windows platforms (but not Cygwin) put the "file creation
     time" in st_ctime (!).  See
     <http://msdn2.microsoft.com/de-de/library/14h5k7ff(VS.80).aspx>.  */
  t.tv_sec = st->st_ctime;
  t.tv_nsec = 0;
#else
  /* Birth time is not supported.  */
  t.tv_sec = -1;
  t.tv_nsec = -1;
  /* Avoid a "parameter unused" warning.  */
  (void) st;
#endif

#if (defined HAVE_STRUCT_STAT_ST_BIRTHTIMESPEC_TV_NSEC \
     || defined HAVE_STRUCT_STAT_ST_BIRTHTIM_TV_NSEC \
     || defined HAVE_STRUCT_STAT_ST_BIRTHTIMENSEC)
  /* FreeBSD and NetBSD sometimes signal the absence of knowledge by
     using zero.  Attempt to work around this problem.  Alas, this can
     report failure even for valid time stamps.  Also, NetBSD
     sometimes returns junk in the birth time fields; work around this
     bug if it is detected.  */
  if (! (t.tv_sec && 0 <= t.tv_nsec && t.tv_nsec < 1000000000))
    {
      t.tv_sec = -1;
      t.tv_nsec = -1;
    }
#endif

  return t;
}

#endif