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diff --git a/m4/mktime.m4 b/m4/mktime.m4
new file mode 100644 (file)
index 0000000..5314c63
--- /dev/null
+++ b/m4/mktime.m4
@@ -0,0 +1,161 @@
+#serial 1000
+
+dnl Just like mktime.m4 from automake-1.3b, but with an additional test.
+
+undefine([AM_FUNC_MKTIME])
+AC_DEFUN(AM_FUNC_MKTIME,
+[AC_REQUIRE([AC_HEADER_TIME])dnl
+ AC_CHECK_HEADERS(sys/time.h unistd.h)
+ AC_CHECK_FUNCS(alarm)
+ AC_CACHE_CHECK([for working mktime], am_cv_func_working_mktime,
+  [AC_TRY_RUN(
+changequote(<<, >>)dnl
+<</* Test program from Paul Eggert (eggert@twinsun.com)
+   and Tony Leneis (tony@plaza.ds.adp.com).  */
+#if TIME_WITH_SYS_TIME
+# include <sys/time.h>
+# include <time.h>
+#else
+# if HAVE_SYS_TIME_H
+#  include <sys/time.h>
+# else
+#  include <time.h>
+# endif
+#endif
+
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+
+#if !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;
+
+/* Values we'll use to set the TZ environment variable.  */
+static const char *const tz_strings[] = {
+  (const 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]))
+
+/* Fail if mktime fails to convert a date in the spring-forward gap.
+   Based on a problem report from Andreas Jaeger.  */
+static void
+spring_forward_gap ()
+{
+  /* glibc (up to about 1998-10-07) failed this test) */
+  struct tm tm;
+  putenv ("TZ=America/Vancouver");
+  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;
+  if (mktime (&tm) == (time_t)-1)
+    exit (1);
+}
+
+static void
+mktime_test (now)
+     time_t now;
+{
+  struct tm *lt;
+  if ((lt = localtime (&now)) && mktime (lt) != now)
+    exit (1);
+  now = time_t_max - now;
+  if ((lt = localtime (&now)) && mktime (lt) != now)
+    exit (1);
+}
+
+static void
+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);
+  if (tm.tm_mon != 2 || tm.tm_mday != 31)
+    exit (1);
+}
+
+static void
+bigtime_test (j)
+     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;
+  /* This test makes some buggy mktime implementations loop.
+     Give up after 10 seconds.  */
+  alarm (10);
+  now = mktime (&tm);
+  alarm (0);
+  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))))
+       exit (1);
+    }
+}
+
+int
+main ()
+{
+  time_t t, delta;
+  int i, j;
+
+  for (time_t_max = 1; 0 < time_t_max; time_t_max *= 2)
+    continue;
+  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)
+       mktime_test (t);
+      mktime_test ((time_t) 60 * 60);
+      mktime_test ((time_t) 60 * 60 * 24);
+
+      for (j = 1; 0 < j; j *= 2)
+        bigtime_test (j);
+      bigtime_test (j - 1);
+    }
+  irix_6_4_bug ();
+  spring_forward_gap ();
+  exit (0);
+}
+             >>,
+changequote([, ])dnl
+            am_cv_func_working_mktime=yes, am_cv_func_working_mktime=no,
+            dnl When crosscompiling, assume mktime is missing or broken.
+            am_cv_func_working_mktime=no)
+  ])
+  if test $am_cv_func_working_mktime = no; then
+    LIBOBJS="$LIBOBJS mktime.o"
+  fi
+])