Fix phpGH-16131: prevent subclass ctor/driver connection string mismatch

We now use the create driver-specific codepath without an object to
change, so we go through the exceptions thrown there when there's any
mismatches between the class being used and the connection string.

The class entry fetch in the entry points was also wrong and did not
get a valid class entry, this was also fixed.

A test was added for this, although I'm not pleased by the fact it needs
two real PDO drivers. A better way to test this would be nice, although
it does match the original sample case.

ext/pdo/pdo_dbh.c

@@ -244,7 +244,8 @@ static bool create_driver_specific_pdo_object(pdo_driver_t *driver, zend_class_e
 			}
 
 			/* A driver-specific implementation was instantiated via the connect() method of the appropriate driver class */
-			object_init_ex(new_object, ce_based_on_called_object);
+			if (new_object)
+				object_init_ex(new_object, ce_based_on_called_object);
 			return true;
 		} else {
 			zend_throw_exception_ex(pdo_exception_ce, 0,
@@ -266,10 +267,12 @@ static bool create_driver_specific_pdo_object(pdo_driver_t *driver, zend_class_e
 		}
 
 		/* A driver-specific implementation was instantiated via PDO::__construct() */
-		object_init_ex(new_object, ce_based_on_driver_name);
+		if (new_object)
+			object_init_ex(new_object, ce_based_on_driver_name);
 	} else {
 		/* No driver-specific implementation found */
-		object_init_ex(new_object, called_scope);
+		if (new_object)
+			object_init_ex(new_object, called_scope);
 	}
 
 	return true;
@@ -351,6 +354,10 @@ static void internal_construct(INTERNAL_FUNCTION_PARAMETERS, zend_object *object
 
 		dbh = Z_PDO_DBH_P(new_zval_object);
 	} else {
+		if (!create_driver_specific_pdo_object(driver, current_scope, NULL)) {
+			RETURN_THROWS();
+		}
+
 		dbh = php_pdo_dbh_fetch_inner(object);
 	}
 
@@ -497,14 +504,14 @@ static void internal_construct(INTERNAL_FUNCTION_PARAMETERS, zend_object *object
 /* {{{ */
 PHP_METHOD(PDO, __construct)
 {
-	internal_construct(INTERNAL_FUNCTION_PARAM_PASSTHRU, Z_OBJ(EX(This)), EX(This).value.ce, NULL);
+	internal_construct(INTERNAL_FUNCTION_PARAM_PASSTHRU, Z_OBJ(EX(This)), Z_OBJ(EX(This))->ce, NULL);
 }
 /* }}} */
 
 /* {{{ */
 PHP_METHOD(PDO, connect)
 {
-	internal_construct(INTERNAL_FUNCTION_PARAM_PASSTHRU, Z_OBJ(EX(This)), EX(This).value.ce, return_value);
+	internal_construct(INTERNAL_FUNCTION_PARAM_PASSTHRU, Z_OBJ(EX(This)), Z_OBJ(EX(This))->ce, return_value);
 }
 /* }}} */
 

ext/pdo/tests/gh-16131.phpt

@@ -0,0 +1,20 @@
+--TEST--
+GH-16131: Can use wrong driver in connection string with driver subclass
+--EXTENSIONS--
+pdo
+pdo_mysql
+pdo_sqlite
+--FILE--
+<?php
+
+// XXX: The fact we need two specific drivers makes this test annoying,
+// since we need two real drivers (or it gives a diff error for missing)
+// can it be done better?
+$db = new Pdo\Mysql('sqlite::memory:');
+var_dump($db->getAttribute(PDO::ATTR_DRIVER_NAME));
+--EXPECTF--
+Fatal error: Uncaught PDOException: Pdo\%s::connect() cannot be called when connecting to the "%s" driver, either Pdo\%s::connect() or PDO::connect() must be called instead in %s:%d
+Stack trace:
+#0 %s(%d): PDO->__construct('%s')
+#1 {main}
+  thrown in %s on line %d