wp-admin/includes/class-ftp.php:759$dir$modeoptional0777 function mmkdir($dir, $mode = 0777) { if(empty($dir)) return FALSE; if($this->is_exists($dir) or $dir == "/" ) return TRUE; if(!$this->mmkdir(dirname($dir), $mode)) return false; $r=$this->mkdir($dir, $mode); $this->chmod($dir,$mode); return $r; }Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/class-ftp.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.