--- loncom/xml/run.pm	2003/06/09 21:37:54	1.37
+++ loncom/xml/run.pm	2008/11/24 18:55:01	1.60
@@ -1,6 +1,6 @@
 package Apache::run;
 #
-# $Id: run.pm,v 1.37 2003/06/09 21:37:54 albertel Exp $
+# $Id: run.pm,v 1.60 2008/11/24 18:55:01 jms Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -27,51 +27,85 @@ package Apache::run;
 
 use HTML::Entities;
 
-$Apache::run::EVALUATE_STRING=<<'ENDEVALUATE';  
-  my %_LONCAPA_INTERNAL_oldexpressions=();
-  while (!$_LONCAPA_INTERNAL_oldexpressions{$_}) {
+$Apache::run::EVALUATE_STRING=<<'ENDEVALUATE';
+my %_LONCAPA_INTERNAL_oldexpressions=();
+while (!$_LONCAPA_INTERNAL_oldexpressions{$_}) {
     $_LONCAPA_INTERNAL_oldexpressions{$_}=1;
-    $_ =~s/((?:\$|\&)(?:[\#|\$]*[A-Za-z][\w]*|\{[A-Za-z][\w]*\}))([\[\{][^\$\&\]\}]+[\]\}])*?(\([^\$\&\)]+\))*?(?=[^\[\{\(]|$)/eval(defined(eval($1.$2))?eval('$1.$2.$3'):'$1.$2.$3')/seg;
+    $_ =~s/  # $1 will be the variable reference or subroutine name
+            ((?:\$|\&) #look for a starting $ or &
+             (?:[\#|\$]* #support $$ or $#$ etc.
+              [A-Za-z][\w]*| # get variable name
+              \{[A-Za-z][\w]*\})) # for ${a}
+             # $2 is 0 or more array dereferences []
+             #             or  hash dereferences {}
+             # the ^$ and ^& is because we do this iteratively
+             #    $a[$c] becomes $a[3] which then evaluates
+             ([\[\{][^\$\&\]\}]+[\]\}])*?
+             # $3 is the list of arguments
+             (\([^\$\&\)]+\))*?
+                # only match the above if there is not { [ ( coming up
+                # Why? (I.e. this fails &a(1)[2]
+                (?=[^\[\{\(]|$)/
+		 my ($__LC__a,$__LC__b,$__LC__c)=($1,$2,$3);
+		 my $__LC__prefix;
+		 my $__LC__result;
+		 while (1) {
+		     if ($__LC__a =~ m-^&(theta|pi|rho)$-) { last; }
+		     { 
+			 use strict;
+			 no strict "vars";
+			 if (eval(defined(eval($__LC__a.$__LC__b)))) {
+			     $__LC__result= $__LC__prefix.eval($__LC__a.$__LC__b.$__LC__c);
+			     last;
+			 }
+		     }
+		     $__LC__prefix.=substr($__LC__a,0,1,"");
+		     if ($__LC__a!~m-^(\$|&|\#)-) { last; }
+		 }
+		 if (!defined($__LC__result)) {
+		     $__LC__result=$__LC__prefix.$__LC__a.$__LC__b.$__LC__c;
+		 }
+		 $__LC__result;
+                  /sexg;
     if (scalar(values(%_LONCAPA_INTERNAL_oldexpressions))>10) {last;}
-  }
+}
 ENDEVALUATE
 
 sub evaluate {
     my ($expression,$safeeval,$decls) = @_;
-    &Apache::lonxml::debug("got $expression and decls $decls");
     unless (defined($expression)) { return ''; }
     if ($Apache::lonxml::evaluate < 1) { return $expression; }
     my $result = '';
     $@='';
     $Apache::run::timeout=0;
-    $main::SIG{'ALRM'} = sub {
+    local $main::SIG{'ALRM'} = sub {
 	$Apache::run::timeout=1;
 	die("timeout");
     };
     my $innererror;
     eval {
-	alarm($Apache::lonnet::perlvar{'lonScriptTimeout'});
+	&Apache::lonxml::start_alarm();
 	$safeeval->reval('{'.$decls.';$_=<<\'EXPRESSION\';'."\n".$expression.
 			 "\n".'EXPRESSION'."\n".$EVALUATE_STRING.'}');
 	$innererror=$@;
-	alarm(0);
+	&Apache::lonxml::end_alarm();
     };
-    my $error=$@;
+    my $error=$@; 
     if ($error eq '' && $innererror eq '' && !$Apache::run::timeout) {
 	$result = $safeeval->reval('return $_;');
 	chomp $result;
     } else {
 	if ($Apache::run::timeout) {
 	    $error = 'Code ran too long. It ran for more than '.
-		Apache->request->server->timeout.' seconds';
+		$Apache::lonnet::perlvar{'lonScriptTimeout'}.' seconds';
 	}
 	&Apache::lonxml::error('substitution on <pre>'.
-			       &HTML::Entities::encode($expression).
+			       &HTML::Entities::encode($expression,'<>&"').
 			       '</pre> with <pre>'.
-			       &HTML::Entities::encode($decls).
+			       &HTML::Entities::encode($decls,'<>&"').
 			       '</pre> caused <pre>'.
-			       &HTML::Entities::encode($error).' '.
-			       &HTML::Entities::encode($innererror).
+			       &HTML::Entities::encode($error,'<>&"').' '.
+			       &HTML::Entities::encode($innererror,'<>&"').
 			       '</pre>');
     }
     return $result
@@ -82,27 +116,37 @@ sub run {
     my @result;
     $@='';
     $Apache::run::timeout=0;
-    $main::SIG{'ALRM'} = sub {
+    local $main::SIG{'ALRM'} = sub {
 	$Apache::run::timeout=1;
 	die("timeout");
     };
     my $innererror;
     eval {
-	alarm($Apache::lonnet::perlvar{'lonScriptTimeout'});
+	&Apache::lonxml::start_alarm();
 	@result=$safeeval->reval($code);
 	$innererror=$@;
-	alarm(0);
+	&Apache::lonxml::end_alarm();
     };
     my $error=$@;
     if (($Apache::run::timeout || $error ne '' || $innererror ne '') && !$hideerrors) {
 	if ($Apache::run::timeout) {
 	    $error = 'Code ran too long. It ran for more than '.
-		Apache->request->server->timeout.' seconds';
+		$Apache::lonnet::perlvar{'lonScriptTimeout'}.' seconds';
+	}
+	my $errormsg='<pre>'.&HTML::Entities::encode($error,'<>&"').' '.
+	    &HTML::Entities::encode($innererror,'<>&"').
+	    '</pre> occurred while running <pre>';
+	$code=&HTML::Entities::encode($code,'<>&"');
+	if ($innererror=~/line (\d+)/) {
+	    my $linenumber=$1;
+	    my @code=split("\n",$code);
+	    if ($linenumber < scalar(@code)) {
+		$code[$linenumber-1]='<b><font color="red">'.
+		    $code[$linenumber-1].'</font></b>';
+	    }
+	    $code=join("\n",@code);
 	}
-	&Apache::lonxml::error('<pre>'.&HTML::Entities::encode($error).' '.
-			       &HTML::Entities::encode($innererror).
-			       '</pre> occured while running <pre>'.
-			       &HTML::Entities::encode($code).'</pre>');
+	&Apache::lonxml::error($errormsg.$code.'</pre>');
     }
     if ( $#result < '1') {
 	return $result[0];
@@ -113,30 +157,63 @@ sub run {
 }
 
 sub dump {
-  my ($target,$safeeval)=@_;
-  my $dump='';
-  foreach my $symname (sort keys %{$safeeval->varglob('main::')}) {
-    if (($symname!~/^\_/) && ($symname!~/\:$/)) {
-      my $line;
-      if ($safeeval->reval('defined($'.$symname.')')) {
-	$line='$'.$symname.'='.$safeeval->reval('$'.$symname);
-      }	
-      if ($safeeval->reval('defined(@'.$symname.')')) {
-	$line='@'.$symname.'=('.
-	  $safeeval->reval('join(",",@'.$symname.')').")";
-      }
-      if ($safeeval->reval('defined(%'.$symname.')')) {
-	$line='%'.$symname.'=(';
-	$line.=$safeeval->reval('join(",",map { $_."=>".$'.
-				$symname.'{$_} } sort keys %'.
-				$symname.')').")"
-      }
-      if ($line ne '') { $dump.=&HTML::Entities::encode($line)."<br />\n"; }
+    my ($target,$safeeval)=@_;
+    my $dump='';
+    foreach my $symname (sort keys %{$safeeval->varglob('main::')}) {
+	if (($symname!~ /^(INC|SIG)/) && ($symname!~/\027/) &&
+	    ($symname!~/^\_/) && ($symname!~/\:$/)) {
+	    my $line;
+	    if ($safeeval->reval('defined($'.$symname.')')) {
+		if ($symname =~ /^\w/) {
+		    $line.='$'.$symname.'='.$safeeval->reval('$'.$symname)."\n";
+		}
+	    }	
+	    if ($safeeval->reval('defined(@'.$symname.')')) {
+		$line.='@'.$symname.'=('.
+		    $safeeval->reval('join(",",@'.$symname.')').")"."\n";
+	    }
+	    if ($safeeval->reval('defined(%'.$symname.')')) {
+		$line.='%'.$symname.'=(';
+		$line.=$safeeval->reval('join(",",map { $_."=>".$'.
+					$symname.'{$_} } sort keys %'.
+					$symname.')').")"."\n";
+	    }
+	    if ($line ne '') {
+		$line=&HTML::Entities::encode($line,'<>&"');
+		$line=~s|\n|<br />|g;
+		$dump.=$line;
+	    }
+	}
     }
-  }
-  $dump.='';
-  return $dump;
+    $dump.='';
+    return $dump;
 }
 
 1;
 __END__;
+
+=pod
+
+=head1 NAME
+
+Apache::run.pm
+
+=head1 SYNOPSIS
+
+Used to prevent poorly written problems from
+causing lingering after effects
+
+This is part of the LearningOnline Network with CAPA project
+described at http://www.lon-capa.org.
+
+
+=head1 NOTABLE SUBROUTINES
+
+=over
+
+=item run(), dump(), evaluate()
+
+=back
+
+=cut
+