database: don't iterate if there are no entries

Checking the valid bit could lead to a segmentation fault.

Signed-off-by: Anna Schumaker <anna@ocarinaproject.net>

include/database.hpp

@@ -119,6 +119,9 @@ unsigned int Database<T> :: actual_size()
 template <class T>
 typename Database<T>::iterator Database<T> :: begin()
 {
+	if (size() == 0)
+		return end();
+
 	iterator it = _db.begin();
 	if ( (*it).valid == true )
 		return it;

tests/database

@@ -7,7 +7,7 @@ function test_autosave
 {
 	new_test "Database Test (n = $1, autosave = true)"
 	src/database.run -a $1
-	if [ ! -f $DATA_DIR/database.db ]; then
+	if [ ! -f $DATA_DIR/database.db ] && [ $1 != 0 ]; then
 		echo "ERROR: $DATA_DIR/database.db doesn't exist!"
 		exit 1
 	fi
@@ -34,6 +34,8 @@ function run_test
 	fi
 }
 
+run_test 0
+echo
 run_test 10
 echo
 run_test 100