Backport changes from #3959 to 1.3

Backport race condition fixes from 2.x to 1.3. This is a severe enough
issue that it warrants a fix.

Refs #3857

cake/libs/model/datasources/dbo_source.php

@@ -1879,7 +1879,7 @@ function defaultConditions(&$model, $conditions, $useAlias = true) {
 			return $conditions;
 		}
 		$exists = $model->exists();
-		if (!$exists && $conditions !== null) {
+		if (!$exists && ($conditions !== null || !empty($model->__safeUpdateMode))) {
 			return false;
 		} elseif (!$exists) {
 			return null;

cake/libs/model/model.php

@@ -357,6 +357,15 @@ class Model extends Overloadable {
  */
 	var $__affectedRows = null;
 
+/**
+ * Safe update mode
+ *
+ * If true, this prevents Model::save() from generating a query with WHERE 1 = 1 on race condition.
+ *
+ * @var bool
+ */
+	var $__safeUpdateMode = false;
+
 /**
  * List of valid finder method options, supplied as the first parameter to find().
  *
@@ -1324,7 +1333,9 @@ function save($data = null, $validate = true, $fieldList = array()) {
 			$cache = $this->_prepareUpdateFields(array_combine($fields, $values));
 
 			if (!empty($this->id)) {
+				$this->__safeUpdateMode = true;
 				$success = (bool)$db->update($this, $fields, $values);
+				$this->__safeUpdateMode = false;
 			} else {
 				$fInfo = $this->_schema[$this->primaryKey];
 				$isUUID = ($fInfo['length'] == 36 &&

cake/tests/cases/libs/model/datasources/dbo_source.test.php

@@ -4675,4 +4675,46 @@ function testFieldsUsingMethodCache() {
 		$this->testDb->fields($Article, null, array('title', 'body', 'published'));
 		$this->assertTrue(empty($this->testDb->methodCache['fields']), 'Cache not empty');
 	}
+
+/**
+ * Test defaultConditions()
+ *
+ * @return void
+ */
+	public function testDefaultConditions() {
+		$this->loadFixtures('Article');
+		$Article = ClassRegistry::init('Article');
+		$db = $Article->getDataSource();
+
+		// Creates a default set of conditions from the model if $conditions is null/empty.
+		$Article->id = 1;
+		$result = $db->defaultConditions($Article, null);
+		$this->assertEqual(array('Article.id' => 1), $result);
+
+		// $useAlias == false
+		$Article->id = 1;
+		$result = $db->defaultConditions($Article, null, false);
+		$this->assertEqual(array($db->fullTableName($Article, false) . '.id' => 1), $result);
+
+		// If conditions are supplied then they will be returned.
+		$Article->id = 1;
+		$result = $db->defaultConditions($Article, array('Article.title' => 'First article'));
+		$this->assertEqual(array('Article.title' => 'First article'), $result);
+
+		// If a model doesn't exist and no conditions were provided either null or false will be returned based on what was input.
+		$Article->id = 1000000;
+		$result = $db->defaultConditions($Article, null);
+		$this->assertNull($result);
+
+		$Article->id = 1000000;
+		$result = $db->defaultConditions($Article, false);
+		$this->assertFalse($result);
+
+		// Safe update mode
+		$Article->id = 1000000;
+		$Article->__safeUpdateMode = true;
+		$result = $db->defaultConditions($Article, null);
+		$this->assertFalse($result);
+	}
+
 }