From 19dc3b0b0d360dc31de11a88f13170329ac632cf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20S=CC=8Ckoda?= <commits@skodak.org>
Date: Mon, 16 Dec 2013 09:44:04 +0800
Subject: [PATCH] MDL-43367 stop returning of bogus context children when path
 unknown

This also prevents deletion of system context.
---
 lib/accesslib.php | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/lib/accesslib.php b/lib/accesslib.php
index f035ae7b1e7..8e92faf325d 100644
--- a/lib/accesslib.php
+++ b/lib/accesslib.php
@@ -5462,6 +5462,10 @@ abstract class context extends stdClass implements IteratorAggregate {
     public function delete() {
         global $DB;
 
+        if ($this->_contextlevel <= CONTEXT_SYSTEM) {
+            throw new coding_exception('Cannot delete system context');
+        }
+
         // double check the context still exists
         if (!$DB->record_exists('context', array('id'=>$this->_id))) {
             context::cache_remove($this);
@@ -5557,6 +5561,11 @@ abstract class context extends stdClass implements IteratorAggregate {
     public function get_child_contexts() {
         global $DB;
 
+        if (empty($this->_path) or empty($this->_depth)) {
+            debugging('Can not find child contexts of context '.$this->_id.' try rebuilding of context paths');
+            return array();
+        }
+
         $sql = "SELECT ctx.*
                   FROM {context} ctx
                  WHERE ctx.path LIKE ?";
@@ -6557,6 +6566,11 @@ class context_coursecat extends context {
     public function get_child_contexts() {
         global $DB;
 
+        if (empty($this->_path) or empty($this->_depth)) {
+            debugging('Can not find child contexts of context '.$this->_id.' try rebuilding of context paths');
+            return array();
+        }
+
         $sql = "SELECT ctx.*
                   FROM {context} ctx
                  WHERE ctx.path LIKE ? AND (ctx.depth = ? OR ctx.contextlevel = ?)";