--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,17 @@
+2007-03-27  Bruno Haible  <bruno@clisp.org>
+
+	* lib/stat-time.h: Include <sys/stat.h>.
+
+2007-03-27  James Youngman  <jay@gnu.org>
+
+	* lib/stat-time.h (get_stat_birthtime): New function for
+	  retrieving st_birthtime as provided by UFS2 (hence *BSD).
+	* m4/stat-time.m4 (gl_STAT_BIRTHTIME): Probe for st_birthtime
+	  and its variants.
+	* modules/stat-time (configure.ac): call gl_STAT_BIRTHTIME.
+	* modules/stat-time-test: New file.
+	* tests/test-stat-time.c: New test, devised by Bruno Haible.
+
 2007-03-26  Bruno Haible  <bruno@clisp.org>
 
 	Better support of signalling NaNs.

--- a/lib/stat-time.h
+++ b/lib/stat-time.h
@@ -21,6 +21,7 @@
 #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
@@ -44,6 +45,13 @@
 # define STAT_TIMESPEC_NS(st, st_xtim) ((st)->st_xtim.st__tim.tv_nsec)
 #endif
 
+#if defined HAVE_STRUCT_STAT_ST_BIRTHTIME || defined HAVE_STRUCT_STAT_ST_BIRTHTIMENSEC || defined HAVE_STRUCT_STAT_ST_BIRTHTIMESPEC_TV_NSEC || defined HAVE_STRUCT_STAT_ST_SPARE4
+# define USE_BIRTHTIME 1
+#else
+# undef USE_BIRTHTIME
+#endif
+
+
 /* Return the nanosecond component of *ST's access time.  */
 static inline long int
 get_stat_atime_ns (struct stat const *st)
@@ -89,6 +97,28 @@
 # endif
 }
 
+/* Return the nanosecond component of *ST's birth time.  */
+static inline long int
+get_stat_birthtime_ns (struct stat const *st)
+{
+# if defined USE_BIRTHTIME
+#  if defined STAT_TIMESPEC && defined HAVE_STRUCT_STAT_ST_BIRTHTIMESPEC_TV_NSEC
+  return STAT_TIMESPEC (st, st_birthtim).tv_nsec;
+#  elif defined STAT_TIMESPEC_NS && defined HAVE_STRUCT_STAT_ST_BIRTHTIMESPEC_TV_SEC
+  return STAT_TIMESPEC_NS (st, st_birthtim);
+#  elif defined HAVE_STRUCT_STAT_ST_SPARE4
+  /* Cygwin, without __CYGWIN_USE_BIG_TYPES__ */
+  return st->st_spare4[1] * 1000L;
+#  else
+  /* Birthtime is available, but not at nanosecond resolution.  */
+  return 0;
+#  endif
+# else
+  /* Birthtime is not available, so indicate this in the returned value.  */
+  return 0;
+# endif 
+}
+
 /* Return *ST's access time.  */
 static inline struct timespec
 get_stat_atime (struct stat const *st)
@@ -131,4 +161,69 @@
 #endif
 }
 
+/* Return *ST's birth time, if available, in *PTS.  A nonzero value is
+ * returned if the stat structure appears to indicate that the
+ * timestamp is available.
+ *
+ * The return value of this function does not reliably indicate that the 
+ * returned data is valid; see the comments within the body of the 
+ * function for an explanation.
+ */
+static inline int
+get_stat_birthtime (struct stat const *st,
+		    struct timespec *pts)
+{
+#if defined USE_BIRTHTIME
+# ifdef STAT_TIMESPEC
+  *pts = STAT_TIMESPEC (st, st_birthtim);
+# else
+  struct timespec t;
+  pts->tv_sec = st->st_birthtime;
+  pts->tv_nsec = get_stat_birthtime_ns (st);
+# endif
+
+  /* NetBSD sometimes signals the absence of knowledge of the file's
+   * birth time by using zero.  We indicate we don't know, by
+   * returning 0 from this function when that happens.  This is
+   * slightly problematic since (time_t)0 is otherwise a valid, albeit
+   * unlikely, timestamp.  
+   *
+   * NetBSD sometimes returns 0 for unknown values (for example on
+   * ffs) and sometimes begative values for tv_nsec (for example on
+   * NFS).  For some filesystems (e.g. msdos) NetBSD also appears to
+   * fail to update the st_birthtime member at all, and just leaves in
+   * there whatever junk existed int he uninitialised stat structure
+   * the caller provided.  Therefore, callers are advised to initialise
+   * the tv_nsec number to a negative value before they call stat in
+   * order to detect this problem.
+   */
+  if (pts->tv_sec == (time_t)0)
+    {
+      return 0;			/* result probably invalid, see above. */
+    }
+  else
+    {
+      /* Sometimes NetBSD returns junk in the birth time fields, so 
+       * do a simple range check on the data, and return 0 to indicate
+       * that the data is invalid if it just looks wrong. 
+       */
+      return (pts->tv_nsec >= 0) && (pts->tv_nsec <= 1000000000);
+    }
+#elif (defined _WIN32 || defined __WIN32__) && !defined __CYGWIN__
+  /* Woe32 native platforms (mingw, msvc, but not Cygwin) put the
+   * "file creation time" in st_ctime (!).  See for example the
+   * article
+   * <http://msdn2.microsoft.com/de-de/library/14h5k7ff(VS.80).aspx>
+   */
+  pts->tv_sec = st->st_ctime;
+  pts->tv_nsec = 0;
+  return 1;			/* result is valid */
+#else
+  /* Birth time not supported.  */
+  pts->tv_sec = 0;
+  pts->tv_nsec = 0;
+  return 0;			/* result is not valid */
 #endif
+}
+
+#endif

--- a/m4/stat-time.m4
+++ b/m4/stat-time.m4
@@ -10,11 +10,13 @@
 dnl From Paul Eggert.
 
 # st_atim.tv_nsec - Linux, Solaris
-# st_atimespec.tv_nsec - FreeBSD, if ! defined _POSIX_SOURCE
-# st_atimensec - FreeBSD, if defined _POSIX_SOURCE
+# st_atimespec.tv_nsec - FreeBSD, NetBSD, if ! defined _POSIX_SOURCE
+# st_atimensec - FreeBSD, NetBSD, if defined _POSIX_SOURCE
 # st_atim.st__tim.tv_nsec - UnixWare (at least 2.1.2 through 7.1)
 # st_spare1 - Cygwin?
 
+# st_birthtimespec present on NetBSD (probably also FreBSD, OpenBSD)
+
 AC_DEFUN([gl_STAT_TIME],
 [
   AC_REQUIRE([AC_C_INLINE])
@@ -61,3 +63,26 @@
     [#include <sys/types.h>
      #include <sys/stat.h>])
 ])
+
+# Checks for st_birthtime, which is a feature from UFS2 (FreeBSD, NetBSD, OpenBSD, etc.)
+# There was a time when this field was named st_createtime (21 June 2002 to 16 July 2002)
+# But that window is very small and applied only to development code, so systems still
+# using that configuration are not a realistic development target.
+# See revisions 1.10 and 1.11 of FreeBSD's src/sys/ufs/ufs/dinode.h.
+#
+AC_DEFUN([gl_STAT_BIRTHTIME],
+[
+  AC_REQUIRE([AC_C_INLINE])
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+  AC_CHECK_HEADERS_ONCE([sys/time.h])
+  AC_CHECK_MEMBERS([struct stat.st_birthtimespec.tv_sec, struct stat.st_birthtimespec.tv_nsec], [],
+    [AC_CHECK_MEMBERS([struct stat.st_birthtime, struct stat.st_birthtimensec], [], 
+       [AC_CHECK_MEMBERS([struct stat.st_spare4], [], 
+ 	   [],
+	   [#include <sys/types.h>
+ 	    #include <sys/stat.h>])],
+       [#include <sys/types.h>
+	#include <sys/stat.h>])],
+    [#include <sys/types.h>
+     #include <sys/stat.h>])
+])

--- a/modules/stat-time
+++ b/modules/stat-time
@@ -10,6 +10,7 @@
 
 configure.ac:
 gl_STAT_TIME
+gl_STAT_BIRTHTIME
 
 Makefile.am:
 

new file mode 100644
--- /dev/null
+++ b/modules/stat-time-tests
@@ -0,0 +1,11 @@
+Files:
+tests/test-stat-time.c
+
+Depends-on:
+time
+
+configure.ac:
+
+Makefile.am:
+TESTS += test-stat-time
+check_PROGRAMS += test-stat-time

new file mode 100644
--- /dev/null
+++ b/tests/test-stat-time.c
@@ -0,0 +1,171 @@
+/* Test of <stat-time.h>.
+   Copyright (C) 2007 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 2, 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Written by James Youngman <jay@gnu.org>, 2007.  */
+
+#include <config.h>
+
+#include "stat-time.h"
+
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/fcntl.h>
+#include <unistd.h>
+
+#define ASSERT(condition) if (!(condition)) abort ()
+
+enum { NFILES = 4 };
+
+static void
+cleanup (int sig)
+{
+  /* Remove temporary files.  */
+  unlink ("t-stt-stamp1");
+  unlink ("t-stt-testfile");
+  unlink ("t-stt-stamp2");
+  unlink ("t-stt-renamed");
+  unlink ("t-stt-stamp3");
+}
+
+static int
+open_file (const char *filename, int flags)
+{
+  int fd = open (filename, flags | O_WRONLY, 0500);
+  if (fd >= 0)
+    {
+      close (fd);
+      return 1;
+    }
+  else
+    {
+      return 0;
+    }
+}
+
+static void
+create_file (const char *filename)
+{
+  ASSERT (open_file (filename, O_CREAT | O_EXCL));
+}
+
+static void
+do_stat (const char *filename, struct stat *p)
+{
+  ASSERT (stat (filename, p) == 0);
+}
+
+static void
+prepare_test (struct stat *statinfo, struct timespec *modtimes)
+{
+  int i;
+
+  create_file ("t-stt-stamp1");
+  sleep (2);
+  create_file ("t-stt-testfile");
+  sleep (2);
+  create_file ("t-stt-stamp2");
+  sleep (2);
+  ASSERT (rename ("t-stt-testfile", "t-stt-renamed") == 0);
+  sleep (2);
+  create_file ("t-stt-stamp3");
+
+  do_stat ("t-stt-stamp1",  &statinfo[0]);
+  do_stat ("t-stt-renamed", &statinfo[1]);
+  do_stat ("t-stt-stamp2",  &statinfo[2]);
+  do_stat ("t-stt-stamp3",  &statinfo[3]);
+
+  /* Now use our access functions. */
+  for (i = 0; i < NFILES; ++i)
+    {
+      modtimes[i] = get_stat_mtime (&statinfo[i]);
+    }
+}
+
+static void
+test_mtime (const struct stat *statinfo, struct timespec *modtimes)
+{
+  int i;
+
+  /* Use the struct stat fields directly. */
+  ASSERT (statinfo[0].st_mtime < statinfo[2].st_mtime); /* mtime(stamp1) < mtime(stamp2) */
+  ASSERT (statinfo[2].st_mtime < statinfo[3].st_mtime); /* mtime(stamp2) < mtime(stamp3) */
+  ASSERT (statinfo[2].st_mtime < statinfo[1].st_ctime); /* mtime(stamp2) < ctime(renamed) */
+
+  /* Now check the result of the access functions. */
+  ASSERT (modtimes[0].tv_sec < modtimes[2].tv_sec); /* mtime(stamp1) < mtime(stamp2) */
+  ASSERT (modtimes[2].tv_sec < modtimes[3].tv_sec); /* mtime(stamp2) < mtime(stamp3) */
+
+  /* verify equivalence */
+  for (i = 0; i < NFILES; ++i)
+    {
+      struct timespec ts;
+      ts = get_stat_mtime (&statinfo[i]);
+      ASSERT (ts.tv_sec == statinfo[i].st_mtime);
+    }
+
+  ASSERT (statinfo[2].st_mtime < statinfo[1].st_ctime); /* mtime(stamp2) < ctime(renamed) */
+}
+
+static void
+test_birthtime (const struct stat *statinfo,
+		const struct timespec *modtimes,
+		struct timespec *birthtimes)
+{
+  int i;
+
+  /* Collect the birth times.. */
+  for (i = 0; i < NFILES; ++i)
+    {
+      if (!get_stat_birthtime (&statinfo[i], &birthtimes[i]))
+	{
+	  return;
+	}
+    }
+
+  ASSERT (modtimes[0].tv_sec < birthtimes[1].tv_sec); /* mtime(stamp1) < birthtime(renamed) */
+  ASSERT (birthtimes[1].tv_sec < modtimes[2].tv_sec); /* birthtime(renamed) < mtime(stamp2) */
+}
+
+int
+main ()
+{
+  struct stat statinfo[NFILES];
+  struct timespec modtimes[NFILES];
+  struct timespec birthtimes[NFILES];
+
+#ifdef SIGHUP
+  signal (SIGHUP, cleanup);
+#endif
+#ifdef SIGINT
+  signal (SIGINT, cleanup);
+#endif
+#ifdef SIGQUIT
+  signal (SIGQUIT, cleanup);
+#endif
+#ifdef SIGTERM
+  signal (SIGTERM, cleanup);
+#endif
+
+  prepare_test (statinfo, modtimes);
+  test_mtime (statinfo, modtimes);
+  test_birthtime (statinfo, modtimes, birthtimes);
+
+  cleanup (0);
+  return 0;
+}