Index: database_manager.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lib/ddl/database_manager.php,v
retrieving revision 1.12
diff -u -r1.12 database_manager.php
--- database_manager.php	13 Jul 2008 20:27:14 -0000	1.12
+++ database_manager.php	24 Jul 2008 07:45:46 -0000
@@ -906,6 +906,69 @@
 
         $this->execute_sql_arr($sqlarr);
     }
+
+    /**
+     * Reads the install.xml files for Moodle core and modules and returns an array of
+     * xmldb_structure object with xmldb_table from these files.
+     * @return xmldb_structure schema from install.xml files
+     */
+    public static function get_install_xml_schema() {
+        global $CFG;
+        $schema = new xmldb_structure('export');
+        $schema->setVersion($CFG->version);
+        $dbdirs = get_db_directories();
+        foreach ($dbdirs as $dbdir) {
+            $xmldb_file = new xmldb_file($dbdir.'/install.xml');
+            if (!($xmldb_file->fileExists() && $xmldb_file->loadXMLStructure())) {
+                continue;
+            }
+            $structure = $xmldb_file->getStructure();
+            $tables = $structure->getTables();
+            foreach($tables as $table) {
+                $table->setPrevious(null);
+                $table->setNext(null);
+                $schema->addTable($table);
+            }
+        }
+        return $schema;
+    }
+    
+    /**
+     * Checks the database schema against a schema specified by an xmldb_structure object
+     * @return array keyed by table name with array of difference messages as values 
+     */
+    public function check_database_schema(xmldb_structure $schema) {
+        $errors = array();
+        $dbtables = $this->mdb->get_tables();
+        $tables = $schema->getTables();
+        //TODO: localize strings
+        // check for required tables and we ignore other tables from the 
+        // database since this can be a shared with other applications 
+        foreach($tables as $table) {
+            $tablename = $table->getName();
+            if(empty($dbtables[$tablename])) {
+                $errors[$tablename][] = 'Table is missing.';
+                continue;
+            }
+            // if table is found, then
+            $dbfields = $this->mdb->get_columns($tablename, false);
+            // a) check for required fields
+            $fields = $table->getFields();
+            foreach($fields as $field) {
+                $fieldname = $field->getName();
+                if(empty($dbfields[$fieldname])) {
+                    $errors[$tablename][] = 'Field ' . $fieldname . ' is missing.';
+                }
+                unset($dbfields[$fieldname]);
+            }
+            // b) check for extra fields (which indicates a hack and we don't 
+            // support them for now)
+            foreach($dbfields as $fieldname=>$info) {
+                $errors[$tablename][] = 'Field ' . $fieldname . ' is unexpected.';
+            }
+        }
+        return $errors;
+    }
 }