-
由 Tom Lane 提交于
Since the code underlying pg_get_expr() is not secure against malformed input, and can't practically be made so, we need to prevent miscreants from feeding arbitrary data to it. We can do this securely by declaring pg_get_expr() to take a new datatype "pg_node_tree" and declaring the system catalog columns that hold nodeToString output to be of that type. There is no way at SQL level to create a non-null value of type pg_node_tree. Since the backend-internal operations that fill those catalog columns operate below the SQL level, they are oblivious to the datatype relabeling and don't need any changes.
303696c3