--- loncom/LONCAPA.pm	2006/06/19 10:00:27	1.7
+++ loncom/LONCAPA.pm	2006/06/27 14:49:29	1.9
@@ -1,7 +1,7 @@
 # The LearningOnline Network
 # Base routines
 #
-# $Id: LONCAPA.pm,v 1.7 2006/06/19 10:00:27 albertel Exp $
+# $Id: LONCAPA.pm,v 1.9 2006/06/27 14:49:29 albertel Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -40,9 +40,19 @@ my $loncapa_max_wait_time = 13;
 
 require Exporter;
 our @ISA = qw (Exporter);
-our @EXPORT = qw(&add_get_param &escape &unescape &tie_domain_hash &untie_domain_hash &tie_user_hash &untie_user_hash &propath);
+our @EXPORT = qw(&escape_LaTeX &add_get_param &escape &unescape &tie_domain_hash &untie_domain_hash &tie_user_hash &untie_user_hash &propath);
 my %perlvar;
 
+# Escape a LaTeX string of special characters that according to LaTeX line by line
+# pg 9 are: # $ % & \ ^ _ { } ~  These are escaped by prepending a \
+#
+sub escape_LaTeX {
+    my ($string) = @_;
+    $string =~ s/[\#\$\%\&\\^_{}]/\\$&/g;
+    return $string;
+}
+
+
 # Inputs are a url, and a hash ref of
 # form name => value pairs
 # takes care of properly adding the form name elements and values to the 
@@ -221,6 +231,10 @@ sub _do_hash_untie {
 
     sub _locking_hash_tie {
 	my ($file_prefix,$namespace,$how,$loghead,$what) = @_;
+	if (defined($sym)) {
+	    die('Nested locking attempted, this is unsupportted');
+	}
+
         my $lock_type=LOCK_SH;
 # Are we reading or writing?
         if ($how eq &GDBM_READER()) {
@@ -238,16 +252,22 @@ sub _do_hash_untie {
                open($sym,">>$file_prefix.db.lock");
            }
 # Do a shared lock
-           if (!&flock_sym(LOCK_SH)) { return undef; } 
+           if (!&flock_sym(LOCK_SH)) { 
+	       return undef; 
+	   } 
 # If this is compressed, we will actually need an exclusive lock
 	   if (-e "$file_prefix.db.gz") {
-	       if (!&flock_sym(LOCK_EX)) { return undef; }
+	       if (!&flock_sym(LOCK_EX)) {
+		   return undef;
+	       }
 	   }
         } elsif ($how eq &GDBM_WRCREAT()) {
 # We are writing
            open($sym,">>$file_prefix.db.lock");
 # Writing needs exclusive lock
-           if (!&flock_sym(LOCK_EX)) { return undef; }
+           if (!&flock_sym(LOCK_EX)) {
+	       return undef;
+	   }
         } else {
            die("Unknown method $how for $file_prefix");
         }