Modified test for tzset to not rely on tm->tm_zone's existence. Also added

sanity checks on tzname if HAVE_TZNAME defined.

Closes bug #1096244.  Thanks Gregory Bond.

Misc/ACKS

@@ -66,6 +66,7 @@ Finn Bock
 Paul Boddie
 Matthew Boedicker
 David Bolen
+Gregory Bond
 Jurjen Bos
 Peter Bosch
 Eric Bouck

Misc/NEWS

@@ -161,6 +161,11 @@ Build
   ``-L/opt/local/lib`` for DarwinPorts) and CPPFLAGS (``-I/sw/include`` for
   Fink, ``-I/opt/local/include`` for DarwinPorts).
 
+- Test in configure.in that checks for tzset no longer dependent on tm->tm_zone
+  to exist in the struct (not required by either ISO C nor the UNIX 2 spec).
+  Tests for sanity in tzname when HAVE_TZNAME defined were also defined.
+  Closes bug #1096244.  Thanks Gregory Bond.
+
 
 C API
 -----

configure.in

@@ -2917,45 +2917,74 @@ then
       [Define if poll() sets errno on invalid file descriptors.])
 fi
 
+# Before we can test tzset, we need to check if struct tm has a tm_zone 
+# (which is not required by ISO C or UNIX spec) and/or if we support
+# tzname[]
+AC_STRUCT_TIMEZONE
 
-# tzset(3) exists and works like we expect it to
+# check tzset(3) exists and works like we expect it to
 AC_MSG_CHECKING(for working tzset())
 AC_CACHE_VAL(ac_cv_working_tzset, [
 AC_TRY_RUN([
 #include <stdlib.h>
 #include <time.h>
 #include <string.h>
+
+#if HAVE_TZNAME
+extern char *tzname[];
+#endif
+
 int main()
 {
 	/* Note that we need to ensure that not only does tzset(3)
 	   do 'something' with localtime, but it works as documented
 	   in the library reference and as expected by the test suite.
+	   This includes making sure that tzname is set properly if
+	   tm->tm_zone does not exist since it is the alternative way
+	   of getting timezone info.
 
 	   Red Hat 6.2 doesn't understand the southern hemisphere 
-	   after New Year's Day; it thinks swaps on that day.
+	   after New Year's Day.
 	*/
 
-	time_t groundhogday = 1044144000; /* GMT-based; well, it's a colony */
+	time_t groundhogday = 1044144000; /* GMT-based */
 	time_t midyear = groundhogday + (365 * 24 * 3600 / 2);
 
 	putenv("TZ=UTC+0");
 	tzset();
 	if (localtime(&groundhogday)->tm_hour != 0)
 	    exit(1);
+#if HAVE_TZNAME
+	/* For UTC, tzname[1] is sometimes "", sometimes "   " */
+	if (strcmp(tzname[0], "UTC") || 
+		(tzname[1][0] != 0 && tzname[1][0] != ' '))
+	    exit(1);
+#endif
 
 	putenv("TZ=EST+5EDT,M4.1.0,M10.5.0");
 	tzset();
 	if (localtime(&groundhogday)->tm_hour != 19)
 	    exit(1);
+#if HAVE_TZNAME
+	if (strcmp(tzname[0], "EST") || strcmp(tzname[1], "EDT"))
+	    exit(1);
+#endif
 
 	putenv("TZ=AEST-10AEDT-11,M10.5.0,M3.5.0");
 	tzset();
 	if (localtime(&groundhogday)->tm_hour != 11)
 	    exit(1);
+#if HAVE_TZNAME
+	if (strcmp(tzname[0], "AEST") || strcmp(tzname[1], "AEDT"))
+	    exit(1);
+#endif
+
+#if HAVE_STRUCT_TM_TM_ZONE
 	if (strcmp(localtime(&groundhogday)->tm_zone, "AEDT"))
 	    exit(1);
 	if (strcmp(localtime(&midyear)->tm_zone, "AEST"))
 	    exit(1);
+#endif
 
 	exit(0);
 }