Merge from gnulib

This incorporates:
2017-04-30 strftime-fixes: New module
2017-04-30 mktime: Work around TZ problem on native Windows
2017-04-30 ctime, localtime: New modules
2017-04-30 gettimeofday: Provide higher resolution on native Windows
2017-04-29 utime-h: Modernize handling of 'struct utimbuf'
2017-04-29 Make use of module 'utime-h'
2017-04-30 Fix a few typos
* admin/merge-gnulib (AVOIDED_MODULES): Avoid utime-h, too.
* lib/gettimeofday.c, lib/mktime.c, lib/time.in.h, lib/utimens.c:
* m4/gettimeofday.m4, m4/include_next.m4, m4/mktime.m4:
* m4/strftime.m4, m4/time_h.m4, m4/timegm.m4, m4/utimens.m4:
Copy from gnulib.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.

14 files changed, 204 insertions, 69 deletions

diff --git a/admin/merge-gnulib b/admin/merge-gnulib
index 1f0e55f5860..c2ab3571fee 100755
--- a/admin/merge-gnulib
+++ b/admin/merge-gnulib
@@ -49,7 +49,7 @@ AVOIDED_MODULES='
   malloc-posix msvc-inval msvc-nothrow
   open openat-die opendir raise
   save-cwd select setenv sigprocmask stat stdarg stdbool
-  threadlib unsetenv
+  threadlib unsetenv utime-h
 '
 
 GNULIB_TOOL_FLAGS='
diff --git a/lib/gettimeofday.c b/lib/gettimeofday.c
index 18dcbda4db5..86f1a8c1d28 100644
--- a/lib/gettimeofday.c
+++ b/lib/gettimeofday.c
@@ -24,8 +24,9 @@
 
 #include <time.h>
 
-#if HAVE_SYS_TIMEB_H
-# include <sys/timeb.h>
+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+# define WINDOWS_NATIVE
+# include <windows.h>
 #endif
 
 #if GETTIMEOFDAY_CLOBBERS_LOCALTIME || TZSET_CLOBBERS_LOCALTIME
@@ -92,6 +93,28 @@ rpl_tzset (void)
   tzset ();
   *localtime_buffer_addr = save;
 }
+
+#endif
+
+#ifdef WINDOWS_NATIVE
+
+/* GetSystemTimePreciseAsFileTime was introduced only in Windows 8.  */
+typedef void (WINAPI * GetSystemTimePreciseAsFileTimeFuncType) (FILETIME *lpTime);
+static GetSystemTimePreciseAsFileTimeFuncType GetSystemTimePreciseAsFileTimeFunc = NULL;
+static BOOL initialized = FALSE;
+
+static void
+initialize (void)
+{
+  HMODULE kernel32 = LoadLibrary ("kernel32.dll");
+  if (kernel32 != NULL)
+    {
+      GetSystemTimePreciseAsFileTimeFunc =
+	(GetSystemTimePreciseAsFileTimeFuncType) GetProcAddress (kernel32, "GetSystemTimePreciseAsFileTime");
+    }
+  initialized = TRUE;
+}
+
 #endif
 
 /* This is a wrapper for gettimeofday.  It is used only on systems
@@ -130,12 +153,35 @@ gettimeofday (struct timeval *restrict tv, void *restrict tz)
 
 #else
 
-# if HAVE__FTIME
-
-  struct _timeb timebuf;
-  _ftime (&timebuf);
-  tv->tv_sec = timebuf.time;
-  tv->tv_usec = timebuf.millitm * 1000;
+# ifdef WINDOWS_NATIVE
+
+  /* On native Windows, there are two ways to get the current time:
+     GetSystemTimeAsFileTime
+     <https://msdn.microsoft.com/en-us/library/ms724397.aspx>
+     or
+     GetSystemTimePreciseAsFileTime
+     <https://msdn.microsoft.com/en-us/library/hh706895.aspx>.  */
+  FILETIME current_time;
+
+  if (!initialized)
+    initialize ();
+  if (GetSystemTimePreciseAsFileTimeFunc != NULL)
+    GetSystemTimePreciseAsFileTimeFunc (&current_time);
+  else
+    GetSystemTimeAsFileTime (&current_time);
+
+  /* Convert from FILETIME to 'struct timeval'.  */
+  /* FILETIME: <https://msdn.microsoft.com/en-us/library/ms724284.aspx> */
+  ULONGLONG since_1601 =
+    ((ULONGLONG) current_time.dwHighDateTime << 32)
+    | (ULONGLONG) current_time.dwLowDateTime;
+  /* Between 1601-01-01 and 1970-01-01 there were 280 normal years and 89 leap
+     years, in total 134774 days.  */
+  ULONGLONG since_1970 =
+    since_1601 - (ULONGLONG) 134774 * (ULONGLONG) 86400 * (ULONGLONG) 10000000;
+  ULONGLONG microseconds_since_1970 = since_1970 / (ULONGLONG) 10;
+  tv->tv_sec = microseconds_since_1970 / (ULONGLONG) 1000000;
+  tv->tv_usec = microseconds_since_1970 % (ULONGLONG) 1000000;
 
 # else
 
diff --git a/lib/gnulib.mk.in b/lib/gnulib.mk.in
index af26648c0e0..59cdbdb847a 100644
--- a/lib/gnulib.mk.in
+++ b/lib/gnulib.mk.in
@@ -21,7 +21,7 @@
 # the same distribution terms as the rest of that program.
 #
 # Generated by gnulib-tool.
-# Reproduce by: gnulib-tool --import --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --avoid=close --avoid=dup --avoid=fchdir --avoid=fstat --avoid=malloc-posix --avoid=msvc-inval --avoid=msvc-nothrow --avoid=open --avoid=openat-die --avoid=opendir --avoid=raise --avoid=save-cwd --avoid=select --avoid=setenv --avoid=sigprocmask --avoid=stat --avoid=stdarg --avoid=stdbool --avoid=threadlib --avoid=unsetenv --gnu-make --makefile-name=gnulib.mk.in --conditional-dependencies --no-libtool --macro-prefix=gl --no-vc-files alloca-opt binary-io byteswap c-ctype c-strcase careadlinkat close-stream count-leading-zeros count-one-bits count-trailing-zeros crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512 dtoastr dtotimespec dup2 environ execinfo faccessat fcntl fcntl-h fdatasync fdopendir filemode filevercmp flexmember fstatat fsync getloadavg getopt-gnu gettime gettimeofday gitlog-to-changelog ignore-value intprops largefile lstat manywarnings memrchr mkostemp mktime pipe2 pselect pthread_sigmask putenv qcopy-acl readlink readlinkat sig2str socklen stat-time std-gnu11 stdalign stddef stdio stpcpy strftime strtoimax strtoumax symlink sys_stat sys_time time time_r time_rz timegm timer-time timespec-add timespec-sub update-copyright utimens vla warnings
+# Reproduce by: gnulib-tool --import --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --avoid=close --avoid=dup --avoid=fchdir --avoid=fstat --avoid=malloc-posix --avoid=msvc-inval --avoid=msvc-nothrow --avoid=open --avoid=openat-die --avoid=opendir --avoid=raise --avoid=save-cwd --avoid=select --avoid=setenv --avoid=sigprocmask --avoid=stat --avoid=stdarg --avoid=stdbool --avoid=threadlib --avoid=unsetenv --avoid=utime-h --gnu-make --makefile-name=gnulib.mk.in --conditional-dependencies --no-libtool --macro-prefix=gl --no-vc-files alloca-opt binary-io byteswap c-ctype c-strcase careadlinkat close-stream count-leading-zeros count-one-bits count-trailing-zeros crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512 dtoastr dtotimespec dup2 environ execinfo faccessat fcntl fcntl-h fdatasync fdopendir filemode filevercmp flexmember fstatat fsync getloadavg getopt-gnu gettime gettimeofday gitlog-to-changelog ignore-value intprops largefile lstat manywarnings memrchr mkostemp mktime pipe2 pselect pthread_sigmask putenv qcopy-acl readlink readlinkat sig2str socklen stat-time std-gnu11 stdalign stddef stdio stpcpy strftime strtoimax strtoumax symlink sys_stat sys_time time time_r time_rz timegm timer-time timespec-add timespec-sub update-copyright utimens vla warnings
 
 
 MOSTLYCLEANFILES += core *.stackdump
@@ -117,6 +117,7 @@ GNULIB_CHDIR = @GNULIB_CHDIR@
 GNULIB_CHOWN = @GNULIB_CHOWN@
 GNULIB_CLOSE = @GNULIB_CLOSE@
 GNULIB_CLOSEDIR = @GNULIB_CLOSEDIR@
+GNULIB_CTIME = @GNULIB_CTIME@
 GNULIB_DIRFD = @GNULIB_DIRFD@
 GNULIB_DPRINTF = @GNULIB_DPRINTF@
 GNULIB_DUP = @GNULIB_DUP@
@@ -183,6 +184,7 @@ GNULIB_LCHMOD = @GNULIB_LCHMOD@
 GNULIB_LCHOWN = @GNULIB_LCHOWN@
 GNULIB_LINK = @GNULIB_LINK@
 GNULIB_LINKAT = @GNULIB_LINKAT@
+GNULIB_LOCALTIME = @GNULIB_LOCALTIME@
 GNULIB_LSEEK = @GNULIB_LSEEK@
 GNULIB_LSTAT = @GNULIB_LSTAT@
 GNULIB_MALLOC_POSIX = @GNULIB_MALLOC_POSIX@
@@ -281,6 +283,7 @@ GNULIB_STRCHRNUL = @GNULIB_STRCHRNUL@
 GNULIB_STRDUP = @GNULIB_STRDUP@
 GNULIB_STRERROR = @GNULIB_STRERROR@
 GNULIB_STRERROR_R = @GNULIB_STRERROR_R@
+GNULIB_STRFTIME = @GNULIB_STRFTIME@
 GNULIB_STRNCAT = @GNULIB_STRNCAT@
 GNULIB_STRNDUP = @GNULIB_STRNDUP@
 GNULIB_STRNLEN = @GNULIB_STRNLEN@
@@ -669,6 +672,7 @@ REPLACE_CANONICALIZE_FILE_NAME = @REPLACE_CANONICALIZE_FILE_NAME@
 REPLACE_CHOWN = @REPLACE_CHOWN@
 REPLACE_CLOSE = @REPLACE_CLOSE@
 REPLACE_CLOSEDIR = @REPLACE_CLOSEDIR@
+REPLACE_CTIME = @REPLACE_CTIME@
 REPLACE_DIRFD = @REPLACE_DIRFD@
 REPLACE_DPRINTF = @REPLACE_DPRINTF@
 REPLACE_DUP = @REPLACE_DUP@
@@ -760,6 +764,7 @@ REPLACE_STRCHRNUL = @REPLACE_STRCHRNUL@
 REPLACE_STRDUP = @REPLACE_STRDUP@
 REPLACE_STRERROR = @REPLACE_STRERROR@
 REPLACE_STRERROR_R = @REPLACE_STRERROR_R@
+REPLACE_STRFTIME = @REPLACE_STRFTIME@
 REPLACE_STRNCAT = @REPLACE_STRNCAT@
 REPLACE_STRNDUP = @REPLACE_STRNDUP@
 REPLACE_STRNLEN = @REPLACE_STRNLEN@
@@ -2701,9 +2706,12 @@ time.h: time.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H) $(
 	      -e 's|@''PRAGMA_SYSTEM_HEADER''@|@PRAGMA_SYSTEM_HEADER@|g' \
 	      -e 's|@''PRAGMA_COLUMNS''@|@PRAGMA_COLUMNS@|g' \
 	      -e 's|@''NEXT_TIME_H''@|$(NEXT_TIME_H)|g' \
+	      -e 's/@''GNULIB_CTIME''@/$(GNULIB_CTIME)/g' \
 	      -e 's/@''GNULIB_GETTIMEOFDAY''@/$(GNULIB_GETTIMEOFDAY)/g' \
+	      -e 's/@''GNULIB_LOCALTIME''@/$(GNULIB_LOCALTIME)/g' \
 	      -e 's/@''GNULIB_MKTIME''@/$(GNULIB_MKTIME)/g' \
 	      -e 's/@''GNULIB_NANOSLEEP''@/$(GNULIB_NANOSLEEP)/g' \
+	      -e 's/@''GNULIB_STRFTIME''@/$(GNULIB_STRFTIME)/g' \
 	      -e 's/@''GNULIB_STRPTIME''@/$(GNULIB_STRPTIME)/g' \
 	      -e 's/@''GNULIB_TIMEGM''@/$(GNULIB_TIMEGM)/g' \
 	      -e 's/@''GNULIB_TIME_R''@/$(GNULIB_TIME_R)/g' \
@@ -2713,11 +2721,13 @@ time.h: time.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H) $(
 	      -e 's|@''HAVE_STRPTIME''@|$(HAVE_STRPTIME)|g' \
 	      -e 's|@''HAVE_TIMEGM''@|$(HAVE_TIMEGM)|g' \
 	      -e 's|@''HAVE_TIMEZONE_T''@|$(HAVE_TIMEZONE_T)|g' \
+	      -e 's|@''REPLACE_CTIME''@|$(REPLACE_CTIME)|g' \
 	      -e 's|@''REPLACE_GMTIME''@|$(REPLACE_GMTIME)|g' \
 	      -e 's|@''REPLACE_LOCALTIME''@|$(REPLACE_LOCALTIME)|g' \
 	      -e 's|@''REPLACE_LOCALTIME_R''@|$(REPLACE_LOCALTIME_R)|g' \
 	      -e 's|@''REPLACE_MKTIME''@|$(REPLACE_MKTIME)|g' \
 	      -e 's|@''REPLACE_NANOSLEEP''@|$(REPLACE_NANOSLEEP)|g' \
+	      -e 's|@''REPLACE_STRFTIME''@|$(REPLACE_STRFTIME)|g' \
 	      -e 's|@''REPLACE_TIMEGM''@|$(REPLACE_TIMEGM)|g' \
 	      -e 's|@''PTHREAD_H_DEFINES_STRUCT_TIMESPEC''@|$(PTHREAD_H_DEFINES_STRUCT_TIMESPEC)|g' \
 	      -e 's|@''SYS_TIME_H_DEFINES_STRUCT_TIMESPEC''@|$(SYS_TIME_H_DEFINES_STRUCT_TIMESPEC)|g' \
diff --git a/lib/mktime.c b/lib/mktime.c
index 998882f5860..06d5916e910 100644
--- a/lib/mktime.c
+++ b/lib/mktime.c
@@ -23,6 +23,19 @@
 # define DEBUG_MKTIME 0
 #endif
 
+/* The following macros influence what gets defined when this file is compiled:
+
+   Macro/expression            Which gnulib module    This compilation unit
+                                                      should define
+
+   NEED_MKTIME_WORKING         mktime                 rpl_mktime
+   || NEED_MKTIME_WINDOWS
+
+   NEED_MKTIME_INTERNAL        mktime-internal        mktime_internal
+
+   DEBUG_MKTIME                (defined manually)     my_mktime, main
+ */
+
 #if !defined _LIBC && !DEBUG_MKTIME
 # include <config.h>
 #endif
@@ -51,6 +64,13 @@
 # define mktime my_mktime
 #endif
 
+#if NEED_MKTIME_WINDOWS /* on native Windows */
+# include <stdlib.h>
+# include <string.h>
+#endif
+
+#if NEED_MKTIME_WORKING || NEED_MKTIME_INTERNAL || DEBUG_MKTIME
+
 /* A signed type that can represent an integer number of years
    multiplied by three times the number of seconds in a year.  It is
    needed when converting a tm_year value times the number of seconds
@@ -458,25 +478,46 @@ __mktime_internal (struct tm *tp,
   return t;
 }
 
+#endif /* NEED_MKTIME_WORKING || NEED_MKTIME_INTERNAL || DEBUG_MKTIME */
+
+#if NEED_MKTIME_WORKING || NEED_MKTIME_WINDOWS || DEBUG_MKTIME
 
+# if NEED_MKTIME_WORKING || DEBUG_MKTIME
 static mktime_offset_t localtime_offset;
+# endif
 
 /* Convert *TP to a time_t value.  */
 time_t
 mktime (struct tm *tp)
 {
-#ifdef _LIBC
+# if NEED_MKTIME_WINDOWS
+  /* If the environment variable TZ has been set by Cygwin, neutralize it.
+     The Microsoft CRT interprets TZ differently than Cygwin and produces
+     incorrect results if TZ has the syntax used by Cygwin.  */
+  const char *tz = getenv ("TZ");
+  if (tz != NULL && strchr (tz, '/') != NULL)
+    _putenv ("TZ=");
+# endif
+
+# if NEED_MKTIME_WORKING || DEBUG_MKTIME
+#  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 ();
-#elif HAVE_TZSET
+#  elif HAVE_TZSET
   tzset ();
-#endif
+#  endif
 
   return __mktime_internal (tp, __localtime_r, &localtime_offset);
+# else
+#  undef mktime
+  return mktime (tp);
+# endif
 }
 
+#endif /* NEED_MKTIME_WORKING || NEED_MKTIME_WINDOWS || DEBUG_MKTIME */
+
 #ifdef weak_alias
 weak_alias (mktime, timelocal)
 #endif
diff --git a/lib/time.in.h b/lib/time.in.h
index fef89807f8a..d2a0302f464 100644
--- a/lib/time.in.h
+++ b/lib/time.in.h
@@ -187,7 +187,7 @@ _GL_CXXALIASWARN (gmtime_r);
 /* Convert TIMER to RESULT, assuming local time and UTC respectively.  See
    <http://www.opengroup.org/susv3xsh/localtime.html> and
    <http://www.opengroup.org/susv3xsh/gmtime.html>.  */
-# if @GNULIB_GETTIMEOFDAY@
+# if @GNULIB_LOCALTIME@ || @GNULIB_GETTIMEOFDAY@
 #  if @REPLACE_LOCALTIME@
 #   if !(defined __cplusplus && defined GNULIB_NAMESPACE)
 #    undef localtime
@@ -233,6 +233,41 @@ _GL_CXXALIAS_SYS (strptime, char *, (char const *restrict __buf,
 _GL_CXXALIASWARN (strptime);
 # endif
 
+/* Convert *TP to a date and time string.  See
+   <http://pubs.opengroup.org/onlinepubs/9699919799/functions/ctime.html>.  */
+# if @GNULIB_CTIME@
+#  if @REPLACE_CTIME@
+#   if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#    define ctime rpl_ctime
+#   endif
+_GL_FUNCDECL_RPL (ctime, char *, (time_t const *__tp)
+                                 _GL_ARG_NONNULL ((1)));
+_GL_CXXALIAS_RPL (ctime, char *, (time_t const *__tp));
+#  else
+_GL_CXXALIAS_SYS (ctime, char *, (time_t const *__tp));
+#  endif
+_GL_CXXALIASWARN (ctime);
+# endif
+
+/* Convert *TP to a date and time string.  See
+   <http://pubs.opengroup.org/onlinepubs/9699919799/functions/strftime.html>.  */
+# if @GNULIB_STRFTIME@
+#  if @REPLACE_STRFTIME@
+#   if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#    define strftime rpl_strftime
+#   endif
+_GL_FUNCDECL_RPL (strftime, size_t, (char *__buf, size_t __bufsize,
+                                     const char *__fmt, const struct tm *__tp)
+                                    _GL_ARG_NONNULL ((1, 3, 4)));
+_GL_CXXALIAS_RPL (strftime, size_t, (char *__buf, size_t __bufsize,
+                                     const char *__fmt, const struct tm *__tp));
+#  else
+_GL_CXXALIAS_SYS (strftime, size_t, (char *__buf, size_t __bufsize,
+                                     const char *__fmt, const struct tm *__tp));
+#  endif
+_GL_CXXALIASWARN (strftime);
+# endif
+
 # if defined _GNU_SOURCE && @GNULIB_TIME_RZ@ && ! @HAVE_TIMEZONE_T@
 typedef struct tm_zone *timezone_t;
 _GL_FUNCDECL_SYS (tzalloc, timezone_t, (char const *__name));
diff --git a/lib/utimens.c b/lib/utimens.c
index 3643668c3a5..3b451193350 100644
--- a/lib/utimens.c
+++ b/lib/utimens.c
@@ -30,24 +30,11 @@
 #include <sys/stat.h>
 #include <sys/time.h>
 #include <unistd.h>
+#include <utime.h>
 
 #include "stat-time.h"
 #include "timespec.h"
 
-#if HAVE_UTIME_H
-# include <utime.h>
-#endif
-
-/* Some systems (even some that do have <utime.h>) don't declare this
-   structure anywhere.  */
-#ifndef HAVE_STRUCT_UTIMBUF
-struct utimbuf
-{
-  long actime;
-  long modtime;
-};
-#endif
-
 /* Avoid recursion with rpl_futimens or rpl_utimensat.  */
 #undef futimens
 #undef utimensat
diff --git a/m4/gettimeofday.m4 b/m4/gettimeofday.m4
index 4f501e5bf91..742b6c9e10e 100644
--- a/m4/gettimeofday.m4
+++ b/m4/gettimeofday.m4
@@ -1,4 +1,4 @@
-# serial 21
+# serial 22
 
 # Copyright (C) 2001-2003, 2005, 2007, 2009-2017 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@@ -132,7 +132,4 @@ AC_DEFUN([gl_GETTIMEOFDAY_REPLACE_LOCALTIME], [
 ])
 
 # Prerequisites of lib/gettimeofday.c.
-AC_DEFUN([gl_PREREQ_GETTIMEOFDAY], [
-  AC_CHECK_HEADERS([sys/timeb.h])
-  AC_CHECK_FUNCS([_ftime])
-])
+AC_DEFUN([gl_PREREQ_GETTIMEOFDAY], [:])
diff --git a/m4/gnulib-comp.m4 b/m4/gnulib-comp.m4
index 7dbfb9ae70d..136762430e0 100644
--- a/m4/gnulib-comp.m4
+++ b/m4/gnulib-comp.m4
@@ -516,7 +516,7 @@ AC_DEFUN([gl_INIT],
   {
     if ! $gl_gnulib_enabled_5264294aa0a5557541b53c8c741f7f31; then
       gl_FUNC_MKTIME_INTERNAL
-      if test $REPLACE_MKTIME = 1; then
+      if test $WANT_MKTIME_INTERNAL = 1; then
         AC_LIBOBJ([mktime])
         gl_PREREQ_MKTIME
       fi
@@ -1051,7 +1051,6 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/timespec.m4
   m4/tm_gmtoff.m4
   m4/unistd_h.m4
-  m4/utimbuf.m4
   m4/utimens.m4
   m4/utimes.m4
   m4/vararrays.m4
diff --git a/m4/include_next.m4 b/m4/include_next.m4
index e687e232a27..068f6f60a41 100644
--- a/m4/include_next.m4
+++ b/m4/include_next.m4
@@ -1,4 +1,4 @@
-# include_next.m4 serial 23
+# include_next.m4 serial 24
 dnl Copyright (C) 2006-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -6,7 +6,8 @@ dnl with or without modifications, as long as this notice is preserved.
 
 dnl From Paul Eggert and Derek Price.
 
-dnl Sets INCLUDE_NEXT and PRAGMA_SYSTEM_HEADER.
+dnl Sets INCLUDE_NEXT, INCLUDE_NEXT_AS_FIRST_DIRECTIVE, PRAGMA_SYSTEM_HEADER,
+dnl and PRAGMA_COLUMNS.
 dnl
 dnl INCLUDE_NEXT expands to 'include_next' if the compiler supports it, or to
 dnl 'include' otherwise.
diff --git a/m4/mktime.m4 b/m4/mktime.m4
index d594ddc58be..31da65e8b2d 100644
--- a/m4/mktime.m4
+++ b/m4/mktime.m4
@@ -1,4 +1,4 @@
-# serial 27
+# serial 28
 dnl Copyright (C) 2002-2003, 2005-2007, 2009-2017 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
@@ -21,9 +21,9 @@ AC_DEFUN([gl_TIME_T_IS_SIGNED],
   fi
 ])
 
-AC_DEFUN([gl_FUNC_MKTIME],
+dnl Test whether mktime works. Set gl_cv_func_working_mktime.
+AC_DEFUN([gl_FUNC_MKTIME_WORKS],
 [
-  AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
   AC_REQUIRE([gl_TIME_T_IS_SIGNED])
 
   dnl We don't use AC_FUNC_MKTIME any more, because it is no longer maintained
@@ -239,29 +239,50 @@ main ()
 }]])],
        [gl_cv_func_working_mktime=yes],
        [gl_cv_func_working_mktime=no],
-       [gl_cv_func_working_mktime=no])
+       [gl_cv_func_working_mktime="guessing no"])
     ])
+])
+
+dnl Main macro of module 'mktime'.
+AC_DEFUN([gl_FUNC_MKTIME],
+[
+  AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_REQUIRE([gl_FUNC_MKTIME_WORKS])
 
-  if test $gl_cv_func_working_mktime = no; then
+  REPLACE_MKTIME=0
+  if test "$gl_cv_func_working_mktime" != yes; then
     REPLACE_MKTIME=1
-  else
-    REPLACE_MKTIME=0
+    AC_DEFINE([NEED_MKTIME_WORKING], [1],
+      [Define if the compilation of mktime.c should define 'mktime'
+       with the algorithmic workarounds.])
   fi
+  case "$host_os" in
+    mingw*)
+      REPLACE_MKTIME=1
+      AC_DEFINE([NEED_MKTIME_WINDOWS], [1],
+        [Define if the compilation of mktime.c should define 'mktime'
+         with the native Windows TZ workaround.])
+      ;;
+  esac
 ])
 
+dnl Main macro of module 'mktime-internal'.
 AC_DEFUN([gl_FUNC_MKTIME_INTERNAL], [
-  AC_REQUIRE([gl_FUNC_MKTIME])
-  if test $REPLACE_MKTIME = 0; then
-    dnl BeOS has __mktime_internal in libc, but other platforms don't.
-    AC_CHECK_FUNC([__mktime_internal],
-      [AC_DEFINE([mktime_internal], [__mktime_internal],
-         [Define to the real name of the mktime_internal function.])
-      ],
-      [dnl mktime works but it doesn't export __mktime_internal,
-       dnl so we need to substitute our own mktime implementation.
-       REPLACE_MKTIME=1
-      ])
-  fi
+  AC_REQUIRE([gl_FUNC_MKTIME_WORKS])
+
+  WANT_MKTIME_INTERNAL=0
+  dnl BeOS has __mktime_internal in libc, but other platforms don't.
+  AC_CHECK_FUNC([__mktime_internal],
+    [AC_DEFINE([mktime_internal], [__mktime_internal],
+       [Define to the real name of the mktime_internal function.])
+    ],
+    [dnl mktime works but it doesn't export __mktime_internal,
+     dnl so we need to substitute our own mktime implementation.
+     WANT_MKTIME_INTERNAL=1
+     AC_DEFINE([NEED_MKTIME_INTERNAL], [1],
+       [Define if the compilation of mktime.c should define 'mktime_internal'.])
+    ])
 ])
 
 # Prerequisites of lib/mktime.c.
diff --git a/m4/strftime.m4 b/m4/strftime.m4
index 3a5db9b4e3c..d2dac9e2328 100644
--- a/m4/strftime.m4
+++ b/m4/strftime.m4
@@ -1,4 +1,4 @@
-# serial 33
+# serial 34
 
 # Copyright (C) 1996-1997, 1999-2007, 2009-2017 Free Software Foundation, Inc.
 #
@@ -10,12 +10,6 @@
 
 AC_DEFUN([gl_FUNC_GNU_STRFTIME],
 [
-  gl_FUNC_STRFTIME
-])
-
-# These are the prerequisite macros for GNU's strftime.c replacement.
-AC_DEFUN([gl_FUNC_STRFTIME],
-[
  # This defines (or not) HAVE_TZNAME and HAVE_TM_ZONE.
  AC_REQUIRE([AC_STRUCT_TIMEZONE])
 
diff --git a/m4/time_h.m4 b/m4/time_h.m4
index b92567875cb..e0f663ec711 100644
--- a/m4/time_h.m4
+++ b/m4/time_h.m4
@@ -2,7 +2,7 @@
 
 # Copyright (C) 2000-2001, 2003-2007, 2009-2017 Free Software Foundation, Inc.
 
-# serial 9
+# serial 10
 
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -104,8 +104,11 @@ AC_DEFUN([gl_TIME_MODULE_INDICATOR],
 
 AC_DEFUN([gl_HEADER_TIME_H_DEFAULTS],
 [
+  GNULIB_CTIME=0;                        AC_SUBST([GNULIB_CTIME])
   GNULIB_MKTIME=0;                       AC_SUBST([GNULIB_MKTIME])
+  GNULIB_LOCALTIME=0;                    AC_SUBST([GNULIB_LOCALTIME])
   GNULIB_NANOSLEEP=0;                    AC_SUBST([GNULIB_NANOSLEEP])
+  GNULIB_STRFTIME=0;                     AC_SUBST([GNULIB_STRFTIME])
   GNULIB_STRPTIME=0;                     AC_SUBST([GNULIB_STRPTIME])
   GNULIB_TIMEGM=0;                       AC_SUBST([GNULIB_TIMEGM])
   GNULIB_TIME_R=0;                       AC_SUBST([GNULIB_TIME_R])
@@ -118,9 +121,11 @@ 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_CTIME=GNULIB_PORTCHECK;        AC_SUBST([REPLACE_CTIME])
   REPLACE_LOCALTIME_R=GNULIB_PORTCHECK;  AC_SUBST([REPLACE_LOCALTIME_R])
   REPLACE_MKTIME=GNULIB_PORTCHECK;       AC_SUBST([REPLACE_MKTIME])
   REPLACE_NANOSLEEP=GNULIB_PORTCHECK;    AC_SUBST([REPLACE_NANOSLEEP])
+  REPLACE_STRFTIME=GNULIB_PORTCHECK;     AC_SUBST([REPLACE_STRFTIME])
   REPLACE_TIMEGM=GNULIB_PORTCHECK;       AC_SUBST([REPLACE_TIMEGM])
 
   dnl Hack so that the time module doesn't depend on the sys_time module.
diff --git a/m4/timegm.m4 b/m4/timegm.m4
index 510e25ab4b0..1f18552e9f5 100644
--- a/m4/timegm.m4
+++ b/m4/timegm.m4
@@ -1,4 +1,4 @@
-# timegm.m4 serial 11
+# timegm.m4 serial 12
 dnl Copyright (C) 2003, 2007, 2009-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -7,11 +7,11 @@ 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])
+  AC_REQUIRE([gl_FUNC_MKTIME_WORKS])
   REPLACE_TIMEGM=0
   AC_CHECK_FUNCS_ONCE([timegm])
   if test $ac_cv_func_timegm = yes; then
-    if test $gl_cv_func_working_mktime = no; then
+    if test "$gl_cv_func_working_mktime" != yes; then
       # Assume that timegm is buggy if mktime is.
       REPLACE_TIMEGM=1
     fi
diff --git a/m4/utimens.m4 b/m4/utimens.m4
index c58e93caaae..f3feab38da3 100644
--- a/m4/utimens.m4
+++ b/m4/utimens.m4
@@ -3,14 +3,13 @@ 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 serial 7
+dnl serial 8
 
 AC_DEFUN([gl_UTIMENS],
 [
   dnl Prerequisites of lib/utimens.c.
   AC_REQUIRE([gl_FUNC_UTIMES])
   AC_REQUIRE([gl_CHECK_TYPE_STRUCT_TIMESPEC])
-  AC_REQUIRE([gl_CHECK_TYPE_STRUCT_UTIMBUF])
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
   AC_CHECK_FUNCS_ONCE([futimes futimesat futimens utimensat lutimes])