From f1966027379222a7b29d1bf064a212d2570710ea Mon Sep 17 00:00:00 2001
From: Tim Hunt <T.J.Hunt@open.ac.uk>
Date: Tue, 27 Nov 2012 16:36:35 +0000
Subject: [PATCH] MDL-36845 excel export: don't output invalid sheet names.

We should clean any proposed worksheet name, to remove the characters
that Excel does not allow.
---
 lib/excellib.class.php | 7 +++++--
 lib/tablelib.php       | 2 +-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/lib/excellib.class.php b/lib/excellib.class.php
index 8b1262daa3518..289b7cad11053 100644
--- a/lib/excellib.class.php
+++ b/lib/excellib.class.php
@@ -74,8 +74,8 @@ function MoodleExcelWorkbook($filename) {
      * @param string $name Name of the sheet
      * @return object MoodleExcelWorksheet
      */
-    function &add_worksheet($name = '') {
-    /// Create the Moodle Worksheet. Returns one pointer to it
+    function add_worksheet($name = '') {
+        // Create the Moodle Worksheet. Returns one pointer to it
         $ws = new MoodleExcelWorksheet ($name, $this->pear_excel_workbook, $this->latin_output);
         return $ws;
     }
@@ -138,6 +138,9 @@ class MoodleExcelWorksheet {
      */
     function MoodleExcelWorksheet($name, &$workbook, $latin_output=false) {
 
+        // Replace any characters in the name that Excel cannot cope with.
+        $name = strtr($name, '[]*/\?:', '       ');
+
         if (strlen($name) > 31) {
             // Excel does not seem able to cope with sheet names > 31 chars.
             // With $latin_output = false, it does not cope at all.
diff --git a/lib/tablelib.php b/lib/tablelib.php
index 31fdee11ca6af..4514174c815cf 100644
--- a/lib/tablelib.php
+++ b/lib/tablelib.php
@@ -1505,7 +1505,7 @@ function start_document($filename) {
     }
 
     function start_table($sheettitle) {
-        $this->worksheet =& $this->workbook->add_worksheet($sheettitle);
+        $this->worksheet = $this->workbook->add_worksheet($sheettitle);
         $this->rownum=0;
     }