--- loncom/xml/run.pm	2000/06/29 20:27:44	1.5
+++ loncom/xml/run.pm	2020/03/12 20:20:13	1.66
@@ -1,21 +1,223 @@
 package Apache::run;
+#
+# $Id: run.pm,v 1.66 2020/03/12 20:20:13 raeburn Exp $
+#
+# Copyright Michigan State University Board of Trustees
+#
+# This file is part of the LearningOnline Network with CAPA (LON-CAPA).
+#
+# LON-CAPA is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# LON-CAPA is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with LON-CAPA; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+# /home/httpd/html/adm/gpl.txt
+#
+# http://www.lon-capa.org/
+#
+
+use HTML::Entities;
+use Apache::lonlocal;
+
+$Apache::run::EVALUATE_STRING=<<'ENDEVALUATE';
+my %_LONCAPA_INTERNAL_oldexpressions=();
+while (!$_LONCAPA_INTERNAL_oldexpressions{$_}) {
+    $_LONCAPA_INTERNAL_oldexpressions{$_}=1;
+    $_ =~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) = @_;
-# print "inside2 evaluate with $expression\n";
-# gerd's old method interpolates unset vars
-# $safeeval->reval('return qq('.$expression.');');
-  unless (defined $expression) { return ''; }
-  $safeeval->reval('$_=\''.$expression.'\';');
-  $safeeval->reval('{'.$decls.'$_=~s/(\$\{?[A-Za-z]\w*\}?)/(defined(eval($1))?eval($1):$1)/ge;}');
-  $safeeval->reval('return $_;');
+    my ($expression,$safeeval,$decls) = @_;
+    unless (defined($expression)) { return ''; }
+    if ($Apache::lonxml::evaluate < 1) { return $expression; }
+    my $result = '';
+    $@='';
+    $Apache::run::timeout=0;
+    local $main::SIG{'ALRM'} = sub {
+	$Apache::run::timeout=1;
+	die("timeout");
+    };
+    my $innererror;
+    eval {
+	&Apache::lonxml::start_alarm();
+	$safeeval->reval('{'.$decls.';$_=<<\'EXPRESSION\';'."\n".$expression.
+			 "\n".'EXPRESSION'."\n".$EVALUATE_STRING.'}');
+	$innererror=$@;
+	&Apache::lonxml::end_alarm();
+    };
+    my $error=$@; 
+    if ($error eq '' && $innererror eq '' && !$Apache::run::timeout) {
+	$result = $safeeval->reval('return $_;');
+	chomp $result;
+    } else {
+        if ($Apache::run::timeout) {
+            $error =
+                &mt('Code ran too long. It ran for more than [_1] seconds.',
+                        $Apache::lonnet::perlvar{'lonScriptTimeout'});
+        }
+        &Apache::lonxml::error(
+            &mt('Substitution on [_1] with [_2] caused:',
+                    '<pre>'. &HTML::Entities::encode($expression,'<>&"').'</pre>',
+                    '<pre>'.&HTML::Entities::encode($decls,'<>&"').'</pre>')
+           .'<br />'
+           .'<pre>'.&HTML::Entities::encode($error,'<>&"').' '
+           .&HTML::Entities::encode($innererror,'<>&"').'</pre>');
+    }
+    return $result;
 }
 
 sub run {
-  my ($code,$safeeval) = @_;
-#  print "inside run\n";
-  $safeeval->reval($code);
+    my ($code,$safeeval,$hideerrors) = @_;
+    my @result;
+    $@='';
+    $Apache::run::timeout=0;
+    local $main::SIG{'ALRM'} = sub {
+	$Apache::run::timeout=1;
+	die("timeout");
+    };
+    my $innererror;
+    eval {
+	&Apache::lonxml::start_alarm();
+	@result=$safeeval->reval($code);
+	$innererror=$@;
+	&Apache::lonxml::end_alarm();
+    };
+    my $error=$@;
+    if (($Apache::run::timeout || $error ne '' || $innererror ne '') && !$hideerrors) {
+        if ($Apache::run::timeout) {
+            $error = &mt('Code ran too long. It ran for more than [_1] seconds.',
+                             $Apache::lonnet::perlvar{'lonScriptTimeout'});
+        }
+        $code=&HTML::Entities::encode($code,'<>&"');
+        if ($innererror=~/line (\d+)/) {
+            my $linenumber=$1;
+            my @code=split("\n",$code);
+            if ($linenumber < scalar(@code)) {
+                $code[$linenumber-1]=
+                    '<span style="color:red;font-weight:bold;">'.
+                    $code[$linenumber-1].'</span>';
+            }
+            $code=join("\n",@code);
+        }
+        &Apache::lonxml::error(
+            '<pre>'.&HTML::Entities::encode($error,'<>&"').' '.
+            &HTML::Entities::encode($innererror,'<>&"').
+            '</pre>'
+           .&mt('This occurred while running: [_1]',
+                   '<pre>'.$code.'</pre>'));
+    }
+    if ( $#result < '1') {
+	return $result[0];
+    } else {
+	&Apache::lonxml::debug("<b>Got lots results</b>:$#result:");
+	return (@result);
+    }
+}
+
+sub dump {
+    my ($target,$safeeval)=@_;
+    my $dump='';
+    foreach my $symname (sort(keys(%{$safeeval->varglob('main::')}))) {
+	if (($symname!~ /^(INC|SIG)/) && ($symname!~/\027/) && ($symname!~/\022/) && 
+	    ($symname!~/^\_/) && ($symname!~/\:$/) && ($symname ne '!')) {
+	    my $line;
+	    if ($safeeval->reval('defined($'.$symname.')')) {
+		if ($symname =~ /^\w/) {
+		    $line.='$'.$symname.'='.$safeeval->reval('$'.$symname)."\n";
+		}
+	    }	
+	    if ($safeeval->reval('@'.$symname)) {
+		$line.='@'.$symname.'=('.
+		    $safeeval->reval('join(",",@'.$symname.')').")"."\n";
+	    }
+	    if ($safeeval->reval('%'.$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;
 }
 
 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
+