--- loncom/localize/lonlocal.pm	2008/05/31 23:37:49	1.45
+++ loncom/localize/lonlocal.pm	2008/07/02 21:31:32	1.47
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # Localization routines
 #
-# $Id: lonlocal.pm,v 1.45 2008/05/31 23:37:49 raeburn Exp $
+# $Id: lonlocal.pm,v 1.47 2008/07/02 21:31:32 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -165,6 +165,7 @@ use Apache::localize;
 use locale;
 use POSIX qw(locale_h strftime);
 use DateTime();
+use DateTime::TimeZone;
 
 require Exporter;
 
@@ -267,17 +268,23 @@ sub get_language_handle {
 
 # ========================================================== Localize localtime
 sub gettimezone {
+    my $timezone; 
     if ($Apache::lonnet::env{'course.'.$Apache::lonnet::env{'request.course.id'}.'.timezone'}) {
-	return $Apache::lonnet::env{'course.'.$Apache::lonnet::env{'request.course.id'}.'.timezone'};
+        $timezone = $Apache::lonnet::env{'course.'.$Apache::lonnet::env{'request.course.id'}.'.timezone'};    
     } elsif ($Apache::lonnet::env{'request.course.id'} ne '') {
         my $cdom = $Apache::lonnet::env{'course.'.$Apache::lonnet::env{'request.course.id'}.'.domain'};
         if ($cdom ne '') {
             my %domdefaults = &Apache::lonnet::get_domain_defaults($cdom);
             if ($domdefaults{'timezone_def'} ne '') {
-                return $domdefaults{'timezone_def'};
+                $timezone = $domdefaults{'timezone_def'};
             }
         }
     }
+    if ($timezone ne '') {
+        if (DateTime::TimeZone->is_valid_name($timezone)) {
+            return $timezone;
+        }
+    }
     return 'local';
 }
 
@@ -286,6 +293,14 @@ sub locallocaltime {
     if (!defined($thistime) || $thistime eq '') {
 	return &mt('Never');
     }
+    if (($thistime < 0) || ($thistime eq 'NaN')) {
+        &Apache::lonnet::logthis("Unexpected time (negative or NaN) '$thistime' passed to lonlocal::locallocaltime");  
+        return &mt('Never');
+    }
+    if ($thistime !~ /^\d+$/) {
+        &Apache::lonnet::logthis("Unexpected non-numeric time '$thistime' passed to lonlocal::locallocaltime");
+        return &mt('Never');
+    }
 
     my $dt = DateTime->from_epoch(epoch => $thistime)
                      ->set_time_zone(&gettimezone());