Add the timegm Gnulib module

11 files changed, 1321 insertions, 2 deletions

diff --git a/gl/Makefile.am b/gl/Makefile.am
index 1a407c58..cae814fd 100644
--- a/gl/Makefile.am
+++ b/gl/Makefile.am
@@ -9,7 +9,7 @@
 # the same distribution terms as the rest of that program.
 #
 # Generated by gnulib-tool.
-# Reproduce by: gnulib-tool --import --dir=. --lib=libgnu --source-base=gl --m4-base=gl/m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --no-libtool --macro-prefix=gl base64 dirname floorf fsusage getaddrinfo gethostname getloadavg getopt gettext mountlist regex vasprintf vsnprintf
+# Reproduce by: gnulib-tool --import --dir=. --lib=libgnu --source-base=gl --m4-base=gl/m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --no-libtool --macro-prefix=gl base64 dirname floorf fsusage getaddrinfo gethostname getloadavg getopt gettext mountlist regex timegm vasprintf vsnprintf
 
 AUTOMAKE_OPTIONS = 1.5 gnits
 
@@ -589,6 +589,15 @@ EXTRA_libgnu_a_SOURCES += mbsinit.c
 
 ## end   gnulib module mbsinit
 
+## begin gnulib module mktime
+
+
+EXTRA_DIST += mktime.c
+
+EXTRA_libgnu_a_SOURCES += mktime.c
+
+## end   gnulib module mktime
+
 ## begin gnulib module mountlist
 
 
@@ -1056,6 +1065,51 @@ EXTRA_DIST += sys_socket.in.h
 
 ## end   gnulib module sys_socket
 
+## begin gnulib module time
+
+BUILT_SOURCES += time.h
+
+# We need the following in order to create <time.h> when the system
+# doesn't have one that works with the given compiler.
+time.h: time.in.h
+	rm -f $@-t $@
+	{ echo '/* DO NOT EDIT! GENERATED AUTOMATICALLY! */' && \
+	  sed -e 's|@''INCLUDE_NEXT''@|$(INCLUDE_NEXT)|g' \
+	      -e 's|@''PRAGMA_SYSTEM_HEADER''@|@PRAGMA_SYSTEM_HEADER@|g' \
+	      -e 's|@NEXT_TIME_H''@|$(NEXT_TIME_H)|g' \
+	      -e 's|@REPLACE_LOCALTIME_R''@|$(REPLACE_LOCALTIME_R)|g' \
+	      -e 's|@REPLACE_NANOSLEEP''@|$(REPLACE_NANOSLEEP)|g' \
+	      -e 's|@REPLACE_STRPTIME''@|$(REPLACE_STRPTIME)|g' \
+	      -e 's|@REPLACE_TIMEGM''@|$(REPLACE_TIMEGM)|g' \
+	      -e 's|@SYS_TIME_H_DEFINES_STRUCT_TIMESPEC''@|$(SYS_TIME_H_DEFINES_STRUCT_TIMESPEC)|g' \
+	      -e 's|@TIME_H_DEFINES_STRUCT_TIMESPEC''@|$(TIME_H_DEFINES_STRUCT_TIMESPEC)|g' \
+	      < $(srcdir)/time.in.h; \
+	} > $@-t
+	mv $@-t $@
+MOSTLYCLEANFILES += time.h time.h-t
+
+EXTRA_DIST += time.in.h
+
+## end   gnulib module time
+
+## begin gnulib module time_r
+
+
+EXTRA_DIST += time_r.c
+
+EXTRA_libgnu_a_SOURCES += time_r.c
+
+## end   gnulib module time_r
+
+## begin gnulib module timegm
+
+
+EXTRA_DIST += timegm.c
+
+EXTRA_libgnu_a_SOURCES += timegm.c
+
+## end   gnulib module timegm
+
 ## begin gnulib module unistd
 
 BUILT_SOURCES += unistd.h
diff --git a/gl/m4/gnulib-cache.m4 b/gl/m4/gnulib-cache.m4
index eb471340..385f5432 100644
--- a/gl/m4/gnulib-cache.m4
+++ b/gl/m4/gnulib-cache.m4
@@ -15,7 +15,7 @@
 
 
 # Specification in the form of a command-line invocation:
-#   gnulib-tool --import --dir=. --lib=libgnu --source-base=gl --m4-base=gl/m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --no-libtool --macro-prefix=gl base64 dirname floorf fsusage getaddrinfo gethostname getloadavg getopt gettext mountlist regex vasprintf vsnprintf
+#   gnulib-tool --import --dir=. --lib=libgnu --source-base=gl --m4-base=gl/m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --no-libtool --macro-prefix=gl base64 dirname floorf fsusage getaddrinfo gethostname getloadavg getopt gettext mountlist regex timegm vasprintf vsnprintf
 
 # Specification in the form of a few gnulib-tool.m4 macro invocations:
 gl_LOCAL_DIR([])
@@ -31,6 +31,7 @@ gl_MODULES([
   gettext
   mountlist
   regex
+  timegm
   vasprintf
   vsnprintf
 ])
diff --git a/gl/m4/gnulib-comp.m4 b/gl/m4/gnulib-comp.m4
index 99fa45dc..c6171dea 100644
--- a/gl/m4/gnulib-comp.m4
+++ b/gl/m4/gnulib-comp.m4
@@ -94,6 +94,7 @@ AC_DEFUN([gl_INIT],
   gl_WCHAR_MODULE_INDICATOR([mbrtowc])
   gl_FUNC_MBSINIT
   gl_WCHAR_MODULE_INDICATOR([mbsinit])
+  gl_FUNC_MKTIME
   gl_MOUNTLIST
   gl_MULTIARCH
   gl_HEADER_NETDB
@@ -125,6 +126,9 @@ AC_DEFUN([gl_INIT],
   gl_HEADER_SYS_SOCKET
   gl_MODULE_INDICATOR([sys_socket])
   AC_PROG_MKDIR_P
+  gl_HEADER_TIME_H
+  gl_TIME_R
+  gl_FUNC_TIMEGM
   gl_UNISTD_H
   gl_UNISTD_SAFER
   gl_FUNC_VASNPRINTF
@@ -332,6 +336,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/math.in.h
   lib/mbrtowc.c
   lib/mbsinit.c
+  lib/mktime.c
   lib/mountlist.c
   lib/mountlist.h
   lib/netdb.in.h
@@ -369,6 +374,9 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/strndup.c
   lib/strnlen.c
   lib/sys_socket.in.h
+  lib/time.in.h
+  lib/time_r.c
+  lib/timegm.c
   lib/unistd--.h
   lib/unistd-safer.h
   lib/unistd.in.h
@@ -444,6 +452,7 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/mbrtowc.m4
   m4/mbsinit.m4
   m4/mbstate_t.m4
+  m4/mktime.m4
   m4/mountlist.m4
   m4/multiarch.m4
   m4/netdb_h.m4
@@ -475,6 +484,9 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/strnlen.m4
   m4/sys_socket_h.m4
   m4/threadlib.m4
+  m4/time_h.m4
+  m4/time_r.m4
+  m4/timegm.m4
   m4/uintmax_t.m4
   m4/unistd-safer.m4
   m4/unistd_h.m4
diff --git a/gl/m4/mktime.m4 b/gl/m4/mktime.m4
new file mode 100644
index 00000000..223b9f1f
--- /dev/null
+++ b/gl/m4/mktime.m4
@@ -0,0 +1,224 @@
+# serial 14
+dnl Copyright (C) 2002-2003, 2005-2007, 2009 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl From Jim Meyering.
+
+# Redefine AC_FUNC_MKTIME, to fix a bug in Autoconf 2.61a and earlier.
+# This redefinition can be removed once a new version of Autoconf is assumed.
+# The redefinition is taken from
+# <http://cvs.sv.gnu.org/viewcvs/*checkout*/autoconf/autoconf/lib/autoconf/functions.m4?rev=1.119>.
+# AC_FUNC_MKTIME
+# --------------
+AC_DEFUN([AC_FUNC_MKTIME],
+[AC_CHECK_HEADERS_ONCE([unistd.h])
+AC_CHECK_FUNCS_ONCE([alarm])
+AC_CACHE_CHECK([for working mktime], [ac_cv_func_working_mktime],
+[AC_RUN_IFELSE([AC_LANG_SOURCE(
+[[/* Test program from Paul Eggert and Tony Leneis.  */
+#include <limits.h>
+#include <stdlib.h>
+#include <time.h>
+
+#ifdef HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+
+#ifndef HAVE_ALARM
+# define alarm(X) /* empty */
+#endif
+
+/* Work around redefinition to rpl_putenv by other config tests.  */
+#undef putenv
+
+static time_t time_t_max;
+static time_t time_t_min;
+
+/* Values we'll use to set the TZ environment variable.  */
+static char *tz_strings[] = {
+  (char *) 0, "TZ=GMT0", "TZ=JST-9",
+  "TZ=EST+3EDT+2,M10.1.0/00:00:00,M2.3.0/00:00:00"
+};
+#define N_STRINGS (sizeof (tz_strings) / sizeof (tz_strings[0]))
+
+/* Return 0 if mktime fails to convert a date in the spring-forward gap.
+   Based on a problem report from Andreas Jaeger.  */
+static int
+spring_forward_gap ()
+{
+  /* glibc (up to about 1998-10-07) failed this test. */
+  struct tm tm;
+
+  /* Use the portable POSIX.1 specification "TZ=PST8PDT,M4.1.0,M10.5.0"
+     instead of "TZ=America/Vancouver" in order to detect the bug even
+     on systems that don't support the Olson extension, or don't have the
+     full zoneinfo tables installed.  */
+  putenv ("TZ=PST8PDT,M4.1.0,M10.5.0");
+
+  tm.tm_year = 98;
+  tm.tm_mon = 3;
+  tm.tm_mday = 5;
+  tm.tm_hour = 2;
+  tm.tm_min = 0;
+  tm.tm_sec = 0;
+  tm.tm_isdst = -1;
+  return mktime (&tm) != (time_t) -1;
+}
+
+static int
+mktime_test1 (time_t now)
+{
+  struct tm *lt;
+  return ! (lt = localtime (&now)) || mktime (lt) == now;
+}
+
+static int
+mktime_test (time_t now)
+{
+  return (mktime_test1 (now)
+	  && mktime_test1 ((time_t) (time_t_max - now))
+	  && mktime_test1 ((time_t) (time_t_min + now)));
+}
+
+static int
+irix_6_4_bug ()
+{
+  /* Based on code from Ariel Faigon.  */
+  struct tm tm;
+  tm.tm_year = 96;
+  tm.tm_mon = 3;
+  tm.tm_mday = 0;
+  tm.tm_hour = 0;
+  tm.tm_min = 0;
+  tm.tm_sec = 0;
+  tm.tm_isdst = -1;
+  mktime (&tm);
+  return tm.tm_mon == 2 && tm.tm_mday == 31;
+}
+
+static int
+bigtime_test (int j)
+{
+  struct tm tm;
+  time_t now;
+  tm.tm_year = tm.tm_mon = tm.tm_mday = tm.tm_hour = tm.tm_min = tm.tm_sec = j;
+  now = mktime (&tm);
+  if (now != (time_t) -1)
+    {
+      struct tm *lt = localtime (&now);
+      if (! (lt
+	     && lt->tm_year == tm.tm_year
+	     && lt->tm_mon == tm.tm_mon
+	     && lt->tm_mday == tm.tm_mday
+	     && lt->tm_hour == tm.tm_hour
+	     && lt->tm_min == tm.tm_min
+	     && lt->tm_sec == tm.tm_sec
+	     && lt->tm_yday == tm.tm_yday
+	     && lt->tm_wday == tm.tm_wday
+	     && ((lt->tm_isdst < 0 ? -1 : 0 < lt->tm_isdst)
+		  == (tm.tm_isdst < 0 ? -1 : 0 < tm.tm_isdst))))
+	return 0;
+    }
+  return 1;
+}
+
+static int
+year_2050_test ()
+{
+  /* The correct answer for 2050-02-01 00:00:00 in Pacific time,
+     ignoring leap seconds.  */
+  unsigned long int answer = 2527315200UL;
+
+  struct tm tm;
+  time_t t;
+  tm.tm_year = 2050 - 1900;
+  tm.tm_mon = 2 - 1;
+  tm.tm_mday = 1;
+  tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
+  tm.tm_isdst = -1;
+
+  /* Use the portable POSIX.1 specification "TZ=PST8PDT,M4.1.0,M10.5.0"
+     instead of "TZ=America/Vancouver" in order to detect the bug even
+     on systems that don't support the Olson extension, or don't have the
+     full zoneinfo tables installed.  */
+  putenv ("TZ=PST8PDT,M4.1.0,M10.5.0");
+
+  t = mktime (&tm);
+
+  /* Check that the result is either a failure, or close enough
+     to the correct answer that we can assume the discrepancy is
+     due to leap seconds.  */
+  return (t == (time_t) -1
+	  || (0 < t && answer - 120 <= t && t <= answer + 120));
+}
+
+int
+main ()
+{
+  time_t t, delta;
+  int i, j;
+
+  /* This test makes some buggy mktime implementations loop.
+     Give up after 60 seconds; a mktime slower than that
+     isn't worth using anyway.  */
+  alarm (60);
+
+  for (;;)
+    {
+      t = (time_t_max << 1) + 1;
+      if (t <= time_t_max)
+	break;
+      time_t_max = t;
+    }
+  time_t_min = - ((time_t) ~ (time_t) 0 == (time_t) -1) - time_t_max;
+
+  delta = time_t_max / 997; /* a suitable prime number */
+  for (i = 0; i < N_STRINGS; i++)
+    {
+      if (tz_strings[i])
+	putenv (tz_strings[i]);
+
+      for (t = 0; t <= time_t_max - delta; t += delta)
+	if (! mktime_test (t))
+	  return 1;
+      if (! (mktime_test ((time_t) 1)
+	     && mktime_test ((time_t) (60 * 60))
+	     && mktime_test ((time_t) (60 * 60 * 24))))
+	return 1;
+
+      for (j = 1; ; j <<= 1)
+	if (! bigtime_test (j))
+	  return 1;
+	else if (INT_MAX / 2 < j)
+	  break;
+      if (! bigtime_test (INT_MAX))
+	return 1;
+    }
+  return ! (irix_6_4_bug () && spring_forward_gap () && year_2050_test ());
+}]])],
+	       [ac_cv_func_working_mktime=yes],
+	       [ac_cv_func_working_mktime=no],
+	       [ac_cv_func_working_mktime=no])])
+if test $ac_cv_func_working_mktime = no; then
+  AC_LIBOBJ([mktime])
+fi
+])# AC_FUNC_MKTIME
+
+AC_DEFUN([gl_FUNC_MKTIME],
+[
+  AC_FUNC_MKTIME
+  dnl Note: AC_FUNC_MKTIME does AC_LIBOBJ([mktime]).
+  if test $ac_cv_func_working_mktime = no; then
+    AC_DEFINE([mktime], [rpl_mktime],
+      [Define to rpl_mktime if the replacement function should be used.])
+    gl_PREREQ_MKTIME
+  fi
+])
+
+# Prerequisites of lib/mktime.c.
+AC_DEFUN([gl_PREREQ_MKTIME],
+[
+  AC_REQUIRE([AC_C_INLINE])
+])
diff --git a/gl/m4/time_h.m4 b/gl/m4/time_h.m4
new file mode 100644
index 00000000..d42a635e
--- /dev/null
+++ b/gl/m4/time_h.m4
@@ -0,0 +1,74 @@
+# Configure a more-standard replacement for <time.h>.
+
+# Copyright (C) 2000, 2001, 2003, 2004, 2005, 2006, 2007 Free Software
+# Foundation, Inc.
+
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+# Written by Paul Eggert and Jim Meyering.
+
+AC_DEFUN([gl_HEADER_TIME_H],
+[
+  dnl Use AC_REQUIRE here, so that the default behavior below is expanded
+  dnl once only, before all statements that occur in other macros.
+  AC_REQUIRE([gl_HEADER_TIME_H_BODY])
+])
+
+AC_DEFUN([gl_HEADER_TIME_H_BODY],
+[
+  AC_REQUIRE([AC_C_RESTRICT])
+  AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
+  gl_CHECK_NEXT_HEADERS([time.h])
+  AC_REQUIRE([gl_CHECK_TYPE_STRUCT_TIMESPEC])
+])
+
+AC_DEFUN([gl_HEADER_TIME_H_DEFAULTS],
+[
+  dnl If another module says to replace or to not replace, do that.
+  dnl Otherwise, replace only if someone compiles with -DGNULIB_PORTCHECK;
+  dnl this lets maintainers check for portability.
+  REPLACE_LOCALTIME_R=GNULIB_PORTCHECK;  AC_SUBST([REPLACE_LOCALTIME_R])
+  REPLACE_NANOSLEEP=GNULIB_PORTCHECK;    AC_SUBST([REPLACE_NANOSLEEP])
+  REPLACE_STRPTIME=GNULIB_PORTCHECK;     AC_SUBST([REPLACE_STRPTIME])
+  REPLACE_TIMEGM=GNULIB_PORTCHECK;       AC_SUBST([REPLACE_TIMEGM])
+])
+
+dnl Define HAVE_STRUCT_TIMESPEC if `struct timespec' is declared
+dnl in time.h or sys/time.h.
+
+AC_DEFUN([gl_CHECK_TYPE_STRUCT_TIMESPEC],
+[
+  AC_CHECK_HEADERS_ONCE([sys/time.h])
+  AC_CACHE_CHECK([for struct timespec in <time.h>],
+    [gl_cv_sys_struct_timespec_in_time_h],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+	  [[#include <time.h>
+	  ]],
+	  [[static struct timespec x; x.tv_sec = x.tv_nsec;]])],
+       [gl_cv_sys_struct_timespec_in_time_h=yes],
+       [gl_cv_sys_struct_timespec_in_time_h=no])])
+
+  TIME_H_DEFINES_STRUCT_TIMESPEC=0
+  SYS_TIME_H_DEFINES_STRUCT_TIMESPEC=0
+  if test $gl_cv_sys_struct_timespec_in_time_h = yes; then
+    TIME_H_DEFINES_STRUCT_TIMESPEC=1
+  else
+    AC_CACHE_CHECK([for struct timespec in <sys/time.h>],
+      [gl_cv_sys_struct_timespec_in_sys_time_h],
+      [AC_COMPILE_IFELSE(
+	 [AC_LANG_PROGRAM(
+	    [[#include <sys/time.h>
+	    ]],
+	    [[static struct timespec x; x.tv_sec = x.tv_nsec;]])],
+	 [gl_cv_sys_struct_timespec_in_sys_time_h=yes],
+	 [gl_cv_sys_struct_timespec_in_sys_time_h=no])])
+    if test $gl_cv_sys_struct_timespec_in_sys_time_h = yes; then
+      SYS_TIME_H_DEFINES_STRUCT_TIMESPEC=1
+    fi
+  fi
+  AC_SUBST([TIME_H_DEFINES_STRUCT_TIMESPEC])
+  AC_SUBST([SYS_TIME_H_DEFINES_STRUCT_TIMESPEC])
+])
diff --git a/gl/m4/time_r.m4 b/gl/m4/time_r.m4
new file mode 100644
index 00000000..c871b56d
--- /dev/null
+++ b/gl/m4/time_r.m4
@@ -0,0 +1,43 @@
+dnl Reentrant time functions like localtime_r.
+
+dnl Copyright (C) 2003, 2006, 2007, 2008 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl Written by Paul Eggert.
+
+AC_DEFUN([gl_TIME_R],
+[
+ dnl Persuade glibc and Solaris <time.h> to declare localtime_r.
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
+  AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
+  AC_REQUIRE([AC_C_RESTRICT])
+
+  AC_CACHE_CHECK([whether localtime_r is compatible with its POSIX signature],
+    [gl_cv_time_r_posix],
+    [AC_TRY_COMPILE(
+       [#include <time.h>],
+       [/* We don't need to append 'restrict's to the argument types,
+	   even though the POSIX signature has the 'restrict's,
+	   since C99 says they can't affect type compatibility.  */
+	struct tm * (*ptr) (time_t const *, struct tm *) = localtime_r;
+        if (ptr) return 0;
+        /* Check the return type is a pointer.  On HP-UX 10 it is 'int'.  */
+        *localtime_r (0, 0);],
+       [gl_cv_time_r_posix=yes],
+       [gl_cv_time_r_posix=no])])
+  if test $gl_cv_time_r_posix = yes; then
+    REPLACE_LOCALTIME_R=0
+  else
+    REPLACE_LOCALTIME_R=1
+    AC_LIBOBJ([time_r])
+    gl_PREREQ_TIME_R
+  fi
+])
+
+# Prerequisites of lib/time_r.c.
+AC_DEFUN([gl_PREREQ_TIME_R], [
+  :
+])
diff --git a/gl/m4/timegm.m4 b/gl/m4/timegm.m4
new file mode 100644
index 00000000..be323c9b
--- /dev/null
+++ b/gl/m4/timegm.m4
@@ -0,0 +1,40 @@
+# timegm.m4 serial 6
+dnl Copyright (C) 2003, 2007, 2009 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_TIMEGM],
+[
+  AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
+  AC_REQUIRE([gl_FUNC_MKTIME])
+  if test $ac_cv_func_working_mktime = no; then
+    # Assume that timegm is buggy if mktime is.
+    AC_LIBOBJ([timegm])
+    ac_cv_func_timegm=no
+  else
+    AC_REPLACE_FUNCS([timegm])
+  fi
+  REPLACE_TIMEGM=1
+  if test $ac_cv_func_timegm = yes; then
+    AC_CHECK_DECLS([timegm], [REPLACE_TIMEGM=0], [], [#include <time.h>])
+  fi
+  if test $REPLACE_TIMEGM = 1; then
+    gl_PREREQ_TIMEGM
+  fi
+])
+
+# Prerequisites of lib/timegm.c.
+AC_DEFUN([gl_PREREQ_TIMEGM], [
+  AC_REQUIRE([gl_TIME_R])
+  AC_REQUIRE([gl_FUNC_MKTIME])
+  if test $ac_cv_func_working_mktime = yes; then
+    AC_CHECK_FUNC([__mktime_internal], ,
+      [# mktime works but it doesn't export __mktime_internal,
+       # so we need to substitute our own mktime implementation.
+       AC_LIBOBJ([mktime])
+       AC_DEFINE([mktime], [rpl_mktime],
+	 [Define to rpl_mktime if the replacement function should be used.])
+       gl_PREREQ_MKTIME])
+  fi
+])
diff --git a/gl/mktime.c b/gl/mktime.c
new file mode 100644
index 00000000..0f30d43f
--- /dev/null
+++ b/gl/mktime.c
@@ -0,0 +1,665 @@
+/* Convert a `struct tm' to a time_t value.
+   Copyright (C) 1993-1999, 2002-2005, 2006, 2007 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Paul Eggert <eggert@twinsun.com>.
+
+   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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+
+/* Define this to have a standalone program to test this implementation of
+   mktime.  */
+/* #define DEBUG 1 */
+
+#ifndef _LIBC
+# include <config.h>
+#endif
+
+/* Assume that leap seconds are possible, unless told otherwise.
+   If the host has a `zic' command with a `-L leapsecondfilename' option,
+   then it supports leap seconds; otherwise it probably doesn't.  */
+#ifndef LEAP_SECONDS_POSSIBLE
+# define LEAP_SECONDS_POSSIBLE 1
+#endif
+
+#include <time.h>
+
+#include <limits.h>
+
+#include <string.h>		/* For the real memcpy prototype.  */
+
+#if DEBUG
+# include <stdio.h>
+# include <stdlib.h>
+/* Make it work even if the system's libc has its own mktime routine.  */
+# define mktime my_mktime
+#endif /* DEBUG */
+
+/* Shift A right by B bits portably, by dividing A by 2**B and
+   truncating towards minus infinity.  A and B should be free of side
+   effects, and B should be in the range 0 <= B <= INT_BITS - 2, where
+   INT_BITS is the number of useful bits in an int.  GNU code can
+   assume that INT_BITS is at least 32.
+
+   ISO C99 says that A >> B is implementation-defined if A < 0.  Some
+   implementations (e.g., UNICOS 9.0 on a Cray Y-MP EL) don't shift
+   right in the usual way when A < 0, so SHR falls back on division if
+   ordinary A >> B doesn't seem to be the usual signed shift.  */
+#define SHR(a, b)	\
+  (-1 >> 1 == -1	\
+   ? (a) >> (b)		\
+   : (a) / (1 << (b)) - ((a) % (1 << (b)) < 0))
+
+/* The extra casts in the following macros work around compiler bugs,
+   e.g., in Cray C 5.0.3.0.  */
+
+/* True if the arithmetic type T is an integer type.  bool counts as
+   an integer.  */
+#define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
+
+/* True if negative values of the signed integer type T use two's
+   complement, ones' complement, or signed magnitude representation,
+   respectively.  Much GNU code assumes two's complement, but some
+   people like to be portable to all possible C hosts.  */
+#define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1)
+#define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0)
+#define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1)
+
+/* True if the arithmetic type T is signed.  */
+#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
+
+/* The maximum and minimum values for the integer type T.  These
+   macros have undefined behavior if T is signed and has padding bits.
+   If this is a problem for you, please let us know how to fix it for
+   your host.  */
+#define TYPE_MINIMUM(t) \
+  ((t) (! TYPE_SIGNED (t) \
+	? (t) 0 \
+	: TYPE_SIGNED_MAGNITUDE (t) \
+	? ~ (t) 0 \
+	: ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1)))
+#define TYPE_MAXIMUM(t) \
+  ((t) (! TYPE_SIGNED (t) \
+	? (t) -1 \
+	: ~ (~ (t) 0 << (sizeof (t) * CHAR_BIT - 1))))
+
+#ifndef TIME_T_MIN
+# define TIME_T_MIN TYPE_MINIMUM (time_t)
+#endif
+#ifndef TIME_T_MAX
+# define TIME_T_MAX TYPE_MAXIMUM (time_t)
+#endif
+#define TIME_T_MIDPOINT (SHR (TIME_T_MIN + TIME_T_MAX, 1) + 1)
+
+/* Verify a requirement at compile-time (unlike assert, which is runtime).  */
+#define verify(name, assertion) struct name { char a[(assertion) ? 1 : -1]; }
+
+verify (time_t_is_integer, TYPE_IS_INTEGER (time_t));
+verify (twos_complement_arithmetic, TYPE_TWOS_COMPLEMENT (int));
+/* The code also assumes that signed integer overflow silently wraps
+   around, but this assumption can't be stated without causing a
+   diagnostic on some hosts.  */
+
+#define EPOCH_YEAR 1970
+#define TM_YEAR_BASE 1900
+verify (base_year_is_a_multiple_of_100, TM_YEAR_BASE % 100 == 0);
+
+/* Return 1 if YEAR + TM_YEAR_BASE is a leap year.  */
+static inline int
+leapyear (long int year)
+{
+  /* Don't add YEAR to TM_YEAR_BASE, as that might overflow.
+     Also, work even if YEAR is negative.  */
+  return
+    ((year & 3) == 0
+     && (year % 100 != 0
+	 || ((year / 100) & 3) == (- (TM_YEAR_BASE / 100) & 3)));
+}
+
+/* How many days come before each month (0-12).  */
+#ifndef _LIBC
+static
+#endif
+const unsigned short int __mon_yday[2][13] =
+  {
+    /* Normal years.  */
+    { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
+    /* Leap years.  */
+    { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
+  };
+
+
+#ifndef _LIBC
+/* Portable standalone applications should supply a <time.h> that
+   declares a POSIX-compliant localtime_r, for the benefit of older
+   implementations that lack localtime_r or have a nonstandard one.
+   See the gnulib time_r module for one way to implement this.  */
+# undef __localtime_r
+# define __localtime_r localtime_r
+# define __mktime_internal mktime_internal
+#endif
+
+/* Return an integer value measuring (YEAR1-YDAY1 HOUR1:MIN1:SEC1) -
+   (YEAR0-YDAY0 HOUR0:MIN0:SEC0) in seconds, assuming that the clocks
+   were not adjusted between the time stamps.
+
+   The YEAR values uses the same numbering as TP->tm_year.  Values
+   need not be in the usual range.  However, YEAR1 must not be less
+   than 2 * INT_MIN or greater than 2 * INT_MAX.
+
+   The result may overflow.  It is the caller's responsibility to
+   detect overflow.  */
+
+static inline time_t
+ydhms_diff (long int year1, long int yday1, int hour1, int min1, int sec1,
+	    int year0, int yday0, int hour0, int min0, int sec0)
+{
+  verify (C99_integer_division, -1 / 2 == 0);
+  verify (long_int_year_and_yday_are_wide_enough,
+	  INT_MAX <= LONG_MAX / 2 || TIME_T_MAX <= UINT_MAX);
+
+  /* Compute intervening leap days correctly even if year is negative.
+     Take care to avoid integer overflow here.  */
+  int a4 = SHR (year1, 2) + SHR (TM_YEAR_BASE, 2) - ! (year1 & 3);
+  int b4 = SHR (year0, 2) + SHR (TM_YEAR_BASE, 2) - ! (year0 & 3);
+  int a100 = a4 / 25 - (a4 % 25 < 0);
+  int b100 = b4 / 25 - (b4 % 25 < 0);
+  int a400 = SHR (a100, 2);
+  int b400 = SHR (b100, 2);
+  int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400);
+
+  /* Compute the desired time in time_t precision.  Overflow might
+     occur here.  */
+  time_t tyear1 = year1;
+  time_t years = tyear1 - year0;
+  time_t days = 365 * years + yday1 - yday0 + intervening_leap_days;
+  time_t hours = 24 * days + hour1 - hour0;
+  time_t minutes = 60 * hours + min1 - min0;
+  time_t seconds = 60 * minutes + sec1 - sec0;
+  return seconds;
+}
+
+
+/* Return a time_t value corresponding to (YEAR-YDAY HOUR:MIN:SEC),
+   assuming that *T corresponds to *TP and that no clock adjustments
+   occurred between *TP and the desired time.
+   If TP is null, return a value not equal to *T; this avoids false matches.
+   If overflow occurs, yield the minimal or maximal value, except do not
+   yield a value equal to *T.  */
+static time_t
+guess_time_tm (long int year, long int yday, int hour, int min, int sec,
+	       const time_t *t, const struct tm *tp)
+{
+  if (tp)
+    {
+      time_t d = ydhms_diff (year, yday, hour, min, sec,
+			     tp->tm_year, tp->tm_yday,
+			     tp->tm_hour, tp->tm_min, tp->tm_sec);
+      time_t t1 = *t + d;
+      if ((t1 < *t) == (TYPE_SIGNED (time_t) ? d < 0 : TIME_T_MAX / 2 < d))
+	return t1;
+    }
+
+  /* Overflow occurred one way or another.  Return the nearest result
+     that is actually in range, except don't report a zero difference
+     if the actual difference is nonzero, as that would cause a false
+     match; and don't oscillate between two values, as that would
+     confuse the spring-forward gap detector.  */
+  return (*t < TIME_T_MIDPOINT
+	  ? (*t <= TIME_T_MIN + 1 ? *t + 1 : TIME_T_MIN)
+	  : (TIME_T_MAX - 1 <= *t ? *t - 1 : TIME_T_MAX));
+}
+
+/* Use CONVERT to convert *T to a broken down time in *TP.
+   If *T is out of range for conversion, adjust it so that
+   it is the nearest in-range value and then convert that.  */
+static struct tm *
+ranged_convert (struct tm *(*convert) (const time_t *, struct tm *),
+		time_t *t, struct tm *tp)
+{
+  struct tm *r = convert (t, tp);
+
+  if (!r && *t)
+    {
+      time_t bad = *t;
+      time_t ok = 0;
+
+      /* BAD is a known unconvertible time_t, and OK is a known good one.
+	 Use binary search to narrow the range between BAD and OK until
+	 they differ by 1.  */
+      while (bad != ok + (bad < 0 ? -1 : 1))
+	{
+	  time_t mid = *t = (bad < 0
+			     ? bad + ((ok - bad) >> 1)
+			     : ok + ((bad - ok) >> 1));
+	  r = convert (t, tp);
+	  if (r)
+	    ok = mid;
+	  else
+	    bad = mid;
+	}
+
+      if (!r && ok)
+	{
+	  /* The last conversion attempt failed;
+	     revert to the most recent successful attempt.  */
+	  *t = ok;
+	  r = convert (t, tp);
+	}
+    }
+
+  return r;
+}
+
+
+/* Convert *TP to a time_t value, inverting
+   the monotonic and mostly-unit-linear conversion function CONVERT.
+   Use *OFFSET to keep track of a guess at the offset of the result,
+   compared to what the result would be for UTC without leap seconds.
+   If *OFFSET's guess is correct, only one CONVERT call is needed.
+   This function is external because it is used also by timegm.c.  */
+time_t
+__mktime_internal (struct tm *tp,
+		   struct tm *(*convert) (const time_t *, struct tm *),
+		   time_t *offset)
+{
+  time_t t, gt, t0, t1, t2;
+  struct tm tm;
+
+  /* The maximum number of probes (calls to CONVERT) should be enough
+     to handle any combinations of time zone rule changes, solar time,
+     leap seconds, and oscillations around a spring-forward gap.
+     POSIX.1 prohibits leap seconds, but some hosts have them anyway.  */
+  int remaining_probes = 6;
+
+  /* Time requested.  Copy it in case CONVERT modifies *TP; this can
+     occur if TP is localtime's returned value and CONVERT is localtime.  */
+  int sec = tp->tm_sec;
+  int min = tp->tm_min;
+  int hour = tp->tm_hour;
+  int mday = tp->tm_mday;
+  int mon = tp->tm_mon;
+  int year_requested = tp->tm_year;
+  /* Normalize the value.  */
+  int isdst = ((tp->tm_isdst >> (8 * sizeof (tp->tm_isdst) - 1))
+	       | (tp->tm_isdst != 0));
+
+  /* 1 if the previous probe was DST.  */
+  int dst2;
+
+  /* Ensure that mon is in range, and set year accordingly.  */
+  int mon_remainder = mon % 12;
+  int negative_mon_remainder = mon_remainder < 0;
+  int mon_years = mon / 12 - negative_mon_remainder;
+  long int lyear_requested = year_requested;
+  long int year = lyear_requested + mon_years;
+
+  /* The other values need not be in range:
+     the remaining code handles minor overflows correctly,
+     assuming int and time_t arithmetic wraps around.
+     Major overflows are caught at the end.  */
+
+  /* Calculate day of year from year, month, and day of month.
+     The result need not be in range.  */
+  int mon_yday = ((__mon_yday[leapyear (year)]
+		   [mon_remainder + 12 * negative_mon_remainder])
+		  - 1);
+  long int lmday = mday;
+  long int yday = mon_yday + lmday;
+
+  time_t guessed_offset = *offset;
+
+  int sec_requested = sec;
+
+  if (LEAP_SECONDS_POSSIBLE)
+    {
+      /* Handle out-of-range seconds specially,
+	 since ydhms_tm_diff assumes every minute has 60 seconds.  */
+      if (sec < 0)
+	sec = 0;
+      if (59 < sec)
+	sec = 59;
+    }
+
+  /* Invert CONVERT by probing.  First assume the same offset as last
+     time.  */
+
+  t0 = ydhms_diff (year, yday, hour, min, sec,
+		   EPOCH_YEAR - TM_YEAR_BASE, 0, 0, 0, - guessed_offset);
+
+  if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3)
+    {
+      /* time_t isn't large enough to rule out overflows, so check
+	 for major overflows.  A gross check suffices, since if t0
+	 has overflowed, it is off by a multiple of TIME_T_MAX -
+	 TIME_T_MIN + 1.  So ignore any component of the difference
+	 that is bounded by a small value.  */
+
+      /* Approximate log base 2 of the number of time units per
+	 biennium.  A biennium is 2 years; use this unit instead of
+	 years to avoid integer overflow.  For example, 2 average
+	 Gregorian years are 2 * 365.2425 * 24 * 60 * 60 seconds,
+	 which is 63113904 seconds, and rint (log2 (63113904)) is
+	 26.  */
+      int ALOG2_SECONDS_PER_BIENNIUM = 26;
+      int ALOG2_MINUTES_PER_BIENNIUM = 20;
+      int ALOG2_HOURS_PER_BIENNIUM = 14;
+      int ALOG2_DAYS_PER_BIENNIUM = 10;
+      int LOG2_YEARS_PER_BIENNIUM = 1;
+
+      int approx_requested_biennia =
+	(SHR (year_requested, LOG2_YEARS_PER_BIENNIUM)
+	 - SHR (EPOCH_YEAR - TM_YEAR_BASE, LOG2_YEARS_PER_BIENNIUM)
+	 + SHR (mday, ALOG2_DAYS_PER_BIENNIUM)
+	 + SHR (hour, ALOG2_HOURS_PER_BIENNIUM)
+	 + SHR (min, ALOG2_MINUTES_PER_BIENNIUM)
+	 + (LEAP_SECONDS_POSSIBLE
+	    ? 0
+	    : SHR (sec, ALOG2_SECONDS_PER_BIENNIUM)));
+
+      int approx_biennia = SHR (t0, ALOG2_SECONDS_PER_BIENNIUM);
+      int diff = approx_biennia - approx_requested_biennia;
+      int abs_diff = diff < 0 ? - diff : diff;
+
+      /* IRIX 4.0.5 cc miscaculates TIME_T_MIN / 3: it erroneously
+	 gives a positive value of 715827882.  Setting a variable
+	 first then doing math on it seems to work.
+	 (ghazi@caip.rutgers.edu) */
+      time_t time_t_max = TIME_T_MAX;
+      time_t time_t_min = TIME_T_MIN;
+      time_t overflow_threshold =
+	(time_t_max / 3 - time_t_min / 3) >> ALOG2_SECONDS_PER_BIENNIUM;
+
+      if (overflow_threshold < abs_diff)
+	{
+	  /* Overflow occurred.  Try repairing it; this might work if
+	     the time zone offset is enough to undo the overflow.  */
+	  time_t repaired_t0 = -1 - t0;
+	  approx_biennia = SHR (repaired_t0, ALOG2_SECONDS_PER_BIENNIUM);
+	  diff = approx_biennia - approx_requested_biennia;
+	  abs_diff = diff < 0 ? - diff : diff;
+	  if (overflow_threshold < abs_diff)
+	    return -1;
+	  guessed_offset += repaired_t0 - t0;
+	  t0 = repaired_t0;
+	}
+    }
+
+  /* Repeatedly use the error to improve the guess.  */
+
+  for (t = t1 = t2 = t0, dst2 = 0;
+       (gt = guess_time_tm (year, yday, hour, min, sec, &t,
+			    ranged_convert (convert, &t, &tm)),
+	t != gt);
+       t1 = t2, t2 = t, t = gt, dst2 = tm.tm_isdst != 0)
+    if (t == t1 && t != t2
+	&& (tm.tm_isdst < 0
+	    || (isdst < 0
+		? dst2 <= (tm.tm_isdst != 0)
+		: (isdst != 0) != (tm.tm_isdst != 0))))
+      /* We can't possibly find a match, as we are oscillating
+	 between two values.  The requested time probably falls
+	 within a spring-forward gap of size GT - T.  Follow the common
+	 practice in this case, which is to return a time that is GT - T
+	 away from the requested time, preferring a time whose
+	 tm_isdst differs from the requested value.  (If no tm_isdst
+	 was requested and only one of the two values has a nonzero
+	 tm_isdst, prefer that value.)  In practice, this is more
+	 useful than returning -1.  */
+      goto offset_found;
+    else if (--remaining_probes == 0)
+      return -1;
+
+  /* We have a match.  Check whether tm.tm_isdst has the requested
+     value, if any.  */
+  if (isdst != tm.tm_isdst && 0 <= isdst && 0 <= tm.tm_isdst)
+    {
+      /* tm.tm_isdst has the wrong value.  Look for a neighboring
+	 time with the right value, and use its UTC offset.
+
+	 Heuristic: probe the adjacent timestamps in both directions,
+	 looking for the desired isdst.  This should work for all real
+	 time zone histories in the tz database.  */
+
+      /* Distance between probes when looking for a DST boundary.  In
+	 tzdata2003a, the shortest period of DST is 601200 seconds
+	 (e.g., America/Recife starting 2000-10-08 01:00), and the
+	 shortest period of non-DST surrounded by DST is 694800
+	 seconds (Africa/Tunis starting 1943-04-17 01:00).  Use the
+	 minimum of these two values, so we don't miss these short
+	 periods when probing.  */
+      int stride = 601200;
+
+      /* The longest period of DST in tzdata2003a is 536454000 seconds
+	 (e.g., America/Jujuy starting 1946-10-01 01:00).  The longest
+	 period of non-DST is much longer, but it makes no real sense
+	 to search for more than a year of non-DST, so use the DST
+	 max.  */
+      int duration_max = 536454000;
+
+      /* Search in both directions, so the maximum distance is half
+	 the duration; add the stride to avoid off-by-1 problems.  */
+      int delta_bound = duration_max / 2 + stride;
+
+      int delta, direction;
+
+      for (delta = stride; delta < delta_bound; delta += stride)
+	for (direction = -1; direction <= 1; direction += 2)
+	  {
+	    time_t ot = t + delta * direction;
+	    if ((ot < t) == (direction < 0))
+	      {
+		struct tm otm;
+		ranged_convert (convert, &ot, &otm);
+		if (otm.tm_isdst == isdst)
+		  {
+		    /* We found the desired tm_isdst.
+		       Extrapolate back to the desired time.  */
+		    t = guess_time_tm (year, yday, hour, min, sec, &ot, &otm);
+		    ranged_convert (convert, &t, &tm);
+		    goto offset_found;
+		  }
+	      }
+	  }
+    }
+
+ offset_found:
+  *offset = guessed_offset + t - t0;
+
+  if (LEAP_SECONDS_POSSIBLE && sec_requested != tm.tm_sec)
+    {
+      /* Adjust time to reflect the tm_sec requested, not the normalized value.
+	 Also, repair any damage from a false match due to a leap second.  */
+      int sec_adjustment = (sec == 0 && tm.tm_sec == 60) - sec;
+      t1 = t + sec_requested;
+      t2 = t1 + sec_adjustment;
+      if (((t1 < t) != (sec_requested < 0))
+	  | ((t2 < t1) != (sec_adjustment < 0))
+	  | ! convert (&t2, &tm))
+	return -1;
+      t = t2;
+    }
+
+  *tp = tm;
+  return t;
+}
+
+
+/* FIXME: This should use a signed type wide enough to hold any UTC
+   offset in seconds.  'int' should be good enough for GNU code.  We
+   can't fix this unilaterally though, as other modules invoke
+   __mktime_internal.  */
+static time_t localtime_offset;
+
+/* Convert *TP to a time_t value.  */
+time_t
+mktime (struct tm *tp)
+{
+#ifdef _LIBC
+  /* POSIX.1 8.1.1 requires that whenever mktime() is called, the
+     time zone names contained in the external variable `tzname' shall
+     be set as if the tzset() function had been called.  */
+  __tzset ();
+#endif
+
+  return __mktime_internal (tp, __localtime_r, &localtime_offset);
+}
+
+#ifdef weak_alias
+weak_alias (mktime, timelocal)
+#endif
+
+#ifdef _LIBC
+libc_hidden_def (mktime)
+libc_hidden_weak (timelocal)
+#endif
+
+#if DEBUG
+
+static int
+not_equal_tm (const struct tm *a, const struct tm *b)
+{
+  return ((a->tm_sec ^ b->tm_sec)
+	  | (a->tm_min ^ b->tm_min)
+	  | (a->tm_hour ^ b->tm_hour)
+	  | (a->tm_mday ^ b->tm_mday)
+	  | (a->tm_mon ^ b->tm_mon)
+	  | (a->tm_year ^ b->tm_year)
+	  | (a->tm_yday ^ b->tm_yday)
+	  | (a->tm_isdst ^ b->tm_isdst));
+}
+
+static void
+print_tm (const struct tm *tp)
+{
+  if (tp)
+    printf ("%04d-%02d-%02d %02d:%02d:%02d yday %03d wday %d isdst %d",
+	    tp->tm_year + TM_YEAR_BASE, tp->tm_mon + 1, tp->tm_mday,
+	    tp->tm_hour, tp->tm_min, tp->tm_sec,
+	    tp->tm_yday, tp->tm_wday, tp->tm_isdst);
+  else
+    printf ("0");
+}
+
+static int
+check_result (time_t tk, struct tm tmk, time_t tl, const struct tm *lt)
+{
+  if (tk != tl || !lt || not_equal_tm (&tmk, lt))
+    {
+      printf ("mktime (");
+      print_tm (lt);
+      printf (")\nyields (");
+      print_tm (&tmk);
+      printf (") == %ld, should be %ld\n", (long int) tk, (long int) tl);
+      return 1;
+    }
+
+  return 0;
+}
+
+int
+main (int argc, char **argv)
+{
+  int status = 0;
+  struct tm tm, tmk, tml;
+  struct tm *lt;
+  time_t tk, tl, tl1;
+  char trailer;
+
+  if ((argc == 3 || argc == 4)
+      && (sscanf (argv[1], "%d-%d-%d%c",
+		  &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &trailer)
+	  == 3)
+      && (sscanf (argv[2], "%d:%d:%d%c",
+		  &tm.tm_hour, &tm.tm_min, &tm.tm_sec, &trailer)
+	  == 3))
+    {
+      tm.tm_year -= TM_YEAR_BASE;
+      tm.tm_mon--;
+      tm.tm_isdst = argc == 3 ? -1 : atoi (argv[3]);
+      tmk = tm;
+      tl = mktime (&tmk);
+      lt = localtime (&tl);
+      if (lt)
+	{
+	  tml = *lt;
+	  lt = &tml;
+	}
+      printf ("mktime returns %ld == ", (long int) tl);
+      print_tm (&tmk);
+      printf ("\n");
+      status = check_result (tl, tmk, tl, lt);
+    }
+  else if (argc == 4 || (argc == 5 && strcmp (argv[4], "-") == 0))
+    {
+      time_t from = atol (argv[1]);
+      time_t by = atol (argv[2]);
+      time_t to = atol (argv[3]);
+
+      if (argc == 4)
+	for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1)
+	  {
+	    lt = localtime (&tl);
+	    if (lt)
+	      {
+		tmk = tml = *lt;
+		tk = mktime (&tmk);
+		status |= check_result (tk, tmk, tl, &tml);
+	      }
+	    else
+	      {
+		printf ("localtime (%ld) yields 0\n", (long int) tl);
+		status = 1;
+	      }
+	    tl1 = tl + by;
+	    if ((tl1 < tl) != (by < 0))
+	      break;
+	  }
+      else
+	for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1)
+	  {
+	    /* Null benchmark.  */
+	    lt = localtime (&tl);
+	    if (lt)
+	      {
+		tmk = tml = *lt;
+		tk = tl;
+		status |= check_result (tk, tmk, tl, &tml);
+	      }
+	    else
+	      {
+		printf ("localtime (%ld) yields 0\n", (long int) tl);
+		status = 1;
+	      }
+	    tl1 = tl + by;
+	    if ((tl1 < tl) != (by < 0))
+	      break;
+	  }
+    }
+  else
+    printf ("Usage:\
+\t%s YYYY-MM-DD HH:MM:SS [ISDST] # Test given time.\n\
+\t%s FROM BY TO # Test values FROM, FROM+BY, ..., TO.\n\
+\t%s FROM BY TO - # Do not test those values (for benchmark).\n",
+	    argv[0], argv[0], argv[0]);
+
+  return status;
+}
+
+#endif /* DEBUG */
+
+/*
+Local Variables:
+compile-command: "gcc -DDEBUG -Wall -W -O -g mktime.c -o mktime"
+End:
+*/
diff --git a/gl/time.in.h b/gl/time.in.h
new file mode 100644
index 00000000..dec37e85
--- /dev/null
+++ b/gl/time.in.h
@@ -0,0 +1,118 @@
+/* A more-standard <time.h>.
+
+   Copyright (C) 2007-2008 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#if __GNUC__ >= 3
+@PRAGMA_SYSTEM_HEADER@
+#endif
+
+/* Don't get in the way of glibc when it includes time.h merely to
+   declare a few standard symbols, rather than to declare all the
+   symbols.  Also, Solaris 8 <time.h> eventually includes itself
+   recursively; if that is happening, just include the system <time.h>
+   without adding our own declarations.  */
+#if (defined __need_time_t || defined __need_clock_t \
+     || defined __need_timespec \
+     || defined _GL_TIME_H)
+
+# @INCLUDE_NEXT@ @NEXT_TIME_H@
+
+#else
+
+# define _GL_TIME_H
+
+# @INCLUDE_NEXT@ @NEXT_TIME_H@
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+/* Some systems don't define struct timespec (e.g., AIX 4.1, Ultrix 4.3).
+   Or they define it with the wrong member names or define it in <sys/time.h>
+   (e.g., FreeBSD circa 1997).  */
+# if ! @TIME_H_DEFINES_STRUCT_TIMESPEC@
+#  if @SYS_TIME_H_DEFINES_STRUCT_TIMESPEC@
+#   include <sys/time.h>
+#  else
+#   undef timespec
+#   define timespec rpl_timespec
+struct timespec
+{
+  time_t tv_sec;
+  long int tv_nsec;
+};
+#  endif
+# endif
+
+/* Sleep for at least RQTP seconds unless interrupted,  If interrupted,
+   return -1 and store the remaining time into RMTP.  See
+   <http://www.opengroup.org/susv3xsh/nanosleep.html>.  */
+# if @REPLACE_NANOSLEEP@
+#  define nanosleep rpl_nanosleep
+int nanosleep (struct timespec const *__rqtp, struct timespec *__rmtp);
+# endif
+
+/* Convert TIMER to RESULT, assuming local time and UTC respectively.  See
+   <http://www.opengroup.org/susv3xsh/localtime_r.html> and
+   <http://www.opengroup.org/susv3xsh/gmtime_r.html>.  */
+# if @REPLACE_LOCALTIME_R@
+#  undef localtime_r
+#  define localtime_r rpl_localtime_r
+#  undef gmtime_r
+#  define gmtime_r rpl_gmtime_r
+struct tm *localtime_r (time_t const *restrict __timer,
+			struct tm *restrict __result);
+struct tm *gmtime_r (time_t const *restrict __timer,
+		     struct tm *restrict __result);
+# endif
+
+/* Parse BUF as a time stamp, assuming FORMAT specifies its layout, and store
+   the resulting broken-down time into TM.  See
+   <http://www.opengroup.org/susv3xsh/strptime.html>.  */
+# if @REPLACE_STRPTIME@
+#  undef strptime
+#  define strptime rpl_strptime
+char *strptime (char const *restrict __buf, char const *restrict __format,
+		struct tm *restrict __tm);
+# endif
+
+/* Convert TM to a time_t value, assuming UTC.  */
+# if @REPLACE_TIMEGM@
+#  undef timegm
+#  define timegm rpl_timegm
+time_t timegm (struct tm *__tm);
+# endif
+
+/* Encourage applications to avoid unsafe functions that can overrun
+   buffers when given outlandish struct tm values.  Portable
+   applications should use strftime (or even sprintf) instead.  */
+# if GNULIB_PORTCHECK
+#  undef asctime
+#  define asctime eschew_asctime
+#  undef asctime_r
+#  define asctime_r eschew_asctime_r
+#  undef ctime
+#  define ctime eschew_ctime
+#  undef ctime_r
+#  define ctime_r eschew_ctime_r
+# endif
+
+# ifdef __cplusplus
+}
+# endif
+
+#endif
diff --git a/gl/time_r.c b/gl/time_r.c
new file mode 100644
index 00000000..d610e7fe
--- /dev/null
+++ b/gl/time_r.c
@@ -0,0 +1,47 @@
+/* Reentrant time functions like localtime_r.
+
+   Copyright (C) 2003, 2006, 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 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Written by Paul Eggert.  */
+
+#include <config.h>
+
+#include <time.h>
+
+#include <string.h>
+
+static struct tm *
+copy_tm_result (struct tm *dest, struct tm const *src)
+{
+  if (! src)
+    return 0;
+  *dest = *src;
+  return dest;
+}
+
+
+struct tm *
+gmtime_r (time_t const * restrict t, struct tm * restrict tp)
+{
+  return copy_tm_result (tp, gmtime (t));
+}
+
+struct tm *
+localtime_r (time_t const * restrict t, struct tm * restrict tp)
+{
+  return copy_tm_result (tp, localtime (t));
+}
diff --git a/gl/timegm.c b/gl/timegm.c
new file mode 100644
index 00000000..057f6459
--- /dev/null
+++ b/gl/timegm.c
@@ -0,0 +1,41 @@
+/* Convert UTC calendar time to simple time.  Like mktime but assumes UTC.
+
+   Copyright (C) 1994, 1997, 2003, 2004, 2006, 2007 Free Software
+   Foundation, Inc.  This file is part of the GNU C Library.
+
+   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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#ifndef _LIBC
+# include <config.h>
+#endif
+
+#include <time.h>
+
+#ifndef _LIBC
+# undef __gmtime_r
+# define __gmtime_r gmtime_r
+# define __mktime_internal mktime_internal
+time_t __mktime_internal (struct tm *,
+			  struct tm * (*) (time_t const *, struct tm *),
+			  time_t *);
+#endif
+
+time_t
+timegm (struct tm *tmp)
+{
+  static time_t gmtime_offset;
+  tmp->tm_isdst = 0;
+  return __mktime_internal (tmp, __gmtime_r, &gmtime_offset);
+}