Revert "Revert "Merge RFC https://wiki.php.net/rfc/session-create-id""

This reverts commit 663f1c8.

Author: Yasuo Ohgaki

ext/session/session.c

@@ -2014,7 +2014,6 @@ static PHP_FUNCTION(session_regenerate_id)
 
 /* {{{ proto void session_create_id([string prefix])
    Generate new session ID. Intended for user save handlers. */
-#if 0
 /* This is not used yet */
 static PHP_FUNCTION(session_create_id)
 {
@@ -2036,7 +2035,20 @@ static PHP_FUNCTION(session_create_id)
 	}
 
 	if (PS(session_status) == php_session_active) {
-		new_id = PS(mod)->s_create_sid(&PS(mod_data));
+		int limit = 3;
+		while (limit--) {
+			new_id = PS(mod)->s_create_sid(&PS(mod_data));
+			if (!PS(mod)->s_validate_sid) {
+				break;
+			} else {
+				/* Detect collision and retry */
+				if (PS(mod)->s_validate_sid(&PS(mod_data), new_id) == FAILURE) {
+					zend_string_release(new_id);
+					continue;
+				}
+				break;
+			}
+		}
 	} else {
 		new_id = php_session_create_id(NULL);
 	}
@@ -2051,9 +2063,7 @@ static PHP_FUNCTION(session_create_id)
 	}
 	smart_str_0(&id);
 	RETVAL_NEW_STR(id.s);
-	smart_str_free(&id);
 }
-#endif
 /* }}} */
 
 /* {{{ proto string session_cache_limiter([string new_cache_limiter])
@@ -2324,6 +2334,10 @@ ZEND_BEGIN_ARG_INFO_EX(arginfo_session_id, 0, 0, 0)
 	ZEND_ARG_INFO(0, id)
 ZEND_END_ARG_INFO()
 
+ZEND_BEGIN_ARG_INFO_EX(arginfo_session_create_id, 0, 0, 0)
+	ZEND_ARG_INFO(0, prefix)
+ZEND_END_ARG_INFO()
+
 ZEND_BEGIN_ARG_INFO_EX(arginfo_session_regenerate_id, 0, 0, 0)
 	ZEND_ARG_INFO(0, delete_old_session)
 ZEND_END_ARG_INFO()
@@ -2408,6 +2422,7 @@ static const zend_function_entry session_functions[] = {
 	PHP_FE(session_module_name,       arginfo_session_module_name)
 	PHP_FE(session_save_path,         arginfo_session_save_path)
 	PHP_FE(session_id,                arginfo_session_id)
+	PHP_FE(session_create_id,         arginfo_session_create_id)
 	PHP_FE(session_regenerate_id,     arginfo_session_regenerate_id)
 	PHP_FE(session_decode,            arginfo_session_decode)
 	PHP_FE(session_encode,            arginfo_session_void)