Add \PDO::SQLITE_ATTR_READONLY_STATEMENT

This attribute is a boolean value. It is taken from the return value of
sqlite3_stmt_readonly(), indicating if and only if the prepared statement makes
no direct changes to the content of the database.

Author: bohwaz

ext/pdo_sqlite/pdo_sqlite.c

@@ -75,6 +75,7 @@ PHP_MINIT_FUNCTION(pdo_sqlite)
 	REGISTER_PDO_CLASS_CONST_LONG("SQLITE_OPEN_READONLY", (zend_long)SQLITE_OPEN_READONLY);
 	REGISTER_PDO_CLASS_CONST_LONG("SQLITE_OPEN_READWRITE", (zend_long)SQLITE_OPEN_READWRITE);
 	REGISTER_PDO_CLASS_CONST_LONG("SQLITE_OPEN_CREATE", (zend_long)SQLITE_OPEN_CREATE);
+	REGISTER_PDO_CLASS_CONST_LONG("SQLITE_ATTR_READONLY_STATEMENT", (zend_long)PDO_SQLITE_ATTR_READONLY_STATEMENT);
 
 	return php_pdo_register_driver(&pdo_sqlite_driver);
 }

ext/pdo_sqlite/php_pdo_sqlite_int.h

@@ -76,6 +76,7 @@ extern const struct pdo_stmt_methods sqlite_stmt_methods;
 
 enum {
 	PDO_SQLITE_ATTR_OPEN_FLAGS = PDO_ATTR_DRIVER_SPECIFIC,
+	PDO_SQLITE_ATTR_READONLY_STATEMENT
 };
 
 #endif

ext/pdo_sqlite/sqlite_statement.c

@@ -350,6 +350,28 @@ static int pdo_sqlite_stmt_cursor_closer(pdo_stmt_t *stmt)
 	return 1;
 }
 
+static int pdo_sqlite_stmt_get_attribute(pdo_stmt_t *stmt, zend_long attr, zval *val)
+{
+	pdo_sqlite_stmt *S = (pdo_sqlite_stmt*)stmt->driver_data;
+
+	switch (attr) {
+		case PDO_SQLITE_ATTR_READONLY_STATEMENT:
+			ZVAL_FALSE(val);
+
+#if SQLITE_VERSION_NUMBER >= 3007004
+				if (sqlite3_stmt_readonly(S->stmt)) {
+					ZVAL_TRUE(val);
+				}
+#endif
+			break;
+
+		default:
+			return 0;
+	}
+
+	return 1;
+}
+
 const struct pdo_stmt_methods sqlite_stmt_methods = {
 	pdo_sqlite_stmt_dtor,
 	pdo_sqlite_stmt_execute,
@@ -358,7 +380,7 @@ const struct pdo_stmt_methods sqlite_stmt_methods = {
 	pdo_sqlite_stmt_get_col,
 	pdo_sqlite_stmt_param_hook,
 	NULL, /* set_attr */
-	NULL, /* get_attr */
+	pdo_sqlite_stmt_get_attribute, /* get_attr */
 	pdo_sqlite_stmt_col_meta,
 	NULL, /* next_rowset */
 	pdo_sqlite_stmt_cursor_closer

ext/pdo_sqlite/tests/pdo_sqlite_statement_getattribute.phpt

@@ -0,0 +1,20 @@
+--TEST--
+PDO_sqlite: Testing PDOStatement::getAttribute()
+--SKIPIF--
+<?php if (!extension_loaded('pdo_sqlite')) print 'skip not loaded'; ?>
+--FILE--
+<?php
+
+$db = new PDO('sqlite::memory:');
+
+$st = $db->prepare('SELECT 1;');
+
+var_dump($st->getAttribute(PDO::SQLITE_ATTR_READONLY_STATEMENT));
+
+$st = $db->prepare('CREATE TABLE test (a TEXT);');
+
+var_dump($st->getAttribute(PDO::SQLITE_ATTR_READONLY_STATEMENT));
+?>
+--EXPECTF--
+bool(true)
+bool(false)