From a8ee2c885d37e33e49cab61332fc8f1f97fd1a08 Mon Sep 17 00:00:00 2001
From: Russell Smith <mr-russ@smith2001.net>
Date: Tue, 23 Feb 2016 11:48:05 +1100
Subject: [PATCH] MDL-53206 caching: Ensure get_many and set_many dereference
 objects.

---
 cache/classes/dummystore.php |  4 ++--
 cache/classes/loaders.php    | 13 +++++++++++++
 cache/tests/cache_test.php   | 28 +++++++++++++++++++++++++++-
 3 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/cache/classes/dummystore.php b/cache/classes/dummystore.php
index 14eecd8e8cf..40508387382 100644
--- a/cache/classes/dummystore.php
+++ b/cache/classes/dummystore.php
@@ -190,9 +190,9 @@ class cachestore_dummy extends cache_store {
             foreach ($keyvaluearray as $pair) {
                 $this->store[$pair['key']] = $pair['value'];
             }
-            return count($keyvaluearray);
+
         }
-        return 0;
+        return count($keyvaluearray);
     }
 
     /**
diff --git a/cache/classes/loaders.php b/cache/classes/loaders.php
index e0a7723e079..fcc22ba31d2 100644
--- a/cache/classes/loaders.php
+++ b/cache/classes/loaders.php
@@ -450,6 +450,13 @@ class cache implements cache_loader {
         // Create an array with the original keys and the found values. This will be what we return.
         $fullresult = array();
         foreach ($result as $key => $value) {
+            if (!is_scalar($value)) {
+                // If data is an object it will be a reference.
+                // If data is an array if may contain references.
+                // We want to break references so that the cache cannot be modified outside of itself.
+                // Call the function to unreference it (in the best way possible).
+                $value = $this->unref($value);
+            }
             $fullresult[$parsedkeys[$key]] = $value;
         }
         unset($result);
@@ -1922,6 +1929,12 @@ class cache_session extends cache {
             if ($value instanceof cache_cached_object) {
                 /* @var cache_cached_object $value */
                 $value = $value->restore_object();
+            } else if (!is_scalar($value)) {
+                // If data is an object it will be a reference.
+                // If data is an array if may contain references.
+                // We want to break references so that the cache cannot be modified outside of itself.
+                // Call the function to unreference it (in the best way possible).
+                $value = $this->unref($value);
             }
             $return[$key] = $value;
             if ($value === false) {
diff --git a/cache/tests/cache_test.php b/cache/tests/cache_test.php
index 6c9f14ccae1..26ab1454f63 100644
--- a/cache/tests/cache_test.php
+++ b/cache/tests/cache_test.php
@@ -407,7 +407,7 @@ class core_cache_testcase extends advanced_testcase {
         $this->assertEquals('pork', $var->subobj->subobj->key);
         $this->assertTrue($cache->delete('obj'));
 
-        // Death reference test... basicaly we don't want this to die.
+        // Death reference test... basically we don't want this to die.
         $obj = new stdClass;
         $obj->key = 'value';
         $obj->self =& $obj;
@@ -433,6 +433,32 @@ class core_cache_testcase extends advanced_testcase {
 
         $this->assertTrue($cache->delete('obj'));
 
+        // Death reference test on get_many... basically we don't want this to die.
+        $obj = new stdClass;
+        $obj->key = 'value';
+        $obj->self =& $obj;
+        $this->assertEquals(1, $cache->set_many(array('obj' => $obj)));
+        $var = $cache->get_many(array('obj'));
+        $this->assertInstanceOf('stdClass', $var['obj']);
+        $this->assertEquals('value', $var['obj']->key);
+
+        // Reference test after retrieve.
+        $obj = new stdClass;
+        $obj->key = 'value';
+        $this->assertEquals(1, $cache->set_many(array('obj' => $obj)));
+
+        $var1 = $cache->get_many(array('obj'));
+        $this->assertInstanceOf('stdClass', $var1['obj']);
+        $this->assertEquals('value', $var1['obj']->key);
+        $var1['obj']->key = 'eulav';
+        $this->assertEquals('eulav', $var1['obj']->key);
+
+        $var2 = $cache->get_many(array('obj'));
+        $this->assertInstanceOf('stdClass', $var2['obj']);
+        $this->assertEquals('value', $var2['obj']->key);
+
+        $this->assertTrue($cache->delete('obj'));
+
         // Test strictness exceptions.
         try {
             $cache->get('exception', MUST_EXIST);