--- loncom/cgi/plot.gif	2004/06/21 20:04:29	1.11
+++ loncom/cgi/plot.gif	2016/08/19 05:15:21	1.15
@@ -1,6 +1,6 @@
 #!/usr/bin/perl
 #
-# $Id: plot.gif,v 1.11 2004/06/21 20:04:29 matthew Exp $
+# $Id: plot.gif,v 1.15 2016/08/19 05:15:21 musolffc Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -25,6 +25,7 @@
 # http://www.lon-capa.org/
 #
 use strict;
+use bytes;
 
 $|=1;
 
@@ -37,21 +38,29 @@ foreach (split/&/,$ENV{'QUERY_STRING'})
 my $filename = $data{'file'};
 # unescape filename
 $filename =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
-
 die if ($filename =~ /\// || $filename !~ /_plot.data$/);
 $filename = $tmpdir . $filename;
 die "$data{'file'} does not exist\n" if (! -e $filename);
 
 my $output = $data{'output'};
+if ($output eq '') {
+    $output = (split('\.',$0))[-1];
+}
+
 if ($output eq 'gif' || $output eq 'png') {
-    open PLOT, "gnuplot $filename |";
+    open(my $plot, "gnuplot $filename |");
+    my $image_content= '';
+    while (my $line = <$plot>) {
+        $image_content .= $line;
+    }
+    my $length = bytes::length($image_content);
     print <<"END";
 Content-type: image/$output
+Content-length: $length
 
+$image_content
 END
-    while ($_=<PLOT>) {
-	print;
-    }
+
 } elsif ($output eq 'eps') {
     print <<"END";
 Content-type: text/html
@@ -62,7 +71,7 @@ Content-type: text/html
 
 END
     if (! system ("gnuplot $filename")) {
-        print "<h2>An error occured.</h2>\n".
+        print "<h2>An error occurred.</h2>\n".
             "I am not going to tell you about it as I have not bothered ".
             "to figure out how to get you the error text.\n";
     } else {