问PHP上传图片的文件权限

EN

$uploaddir = $root_path."images/uploaded_images/category/"; 
            $small_file_name = trim($_FILES['cat_image1']['name']);
            $small_file_len = strlen($small_file_name);
            $small_file_ext = strtolower(substr($small_file_name,-4)); // select last 4 characters
            $small_uploadfile = $uploaddir. $_FILES['cat_image1']['name'];  
            if($small_file_len>4 and ($small_file_ext==".gif" or $small_file_ext==".jpg" or $small_file_ext=="jpeg")){
                if ($small_file_ext=="jpeg")
                    $uniqname = uniqid(rand()).".".$small_file_ext;
                else
                    $uniqname = uniqid(rand()).$small_file_ext;
                $thumb_filename1 = "thumb_".$uniqname;  //  store uniqname into database
                $uploadfile = $uploaddir.$uniqname; //uncomment for local testing 
                if (move_uploaded_file($_FILES['cat_image1']['tmp_name'], $uploadfile)) {
                    chmod($uploadfile,0777);
                    list($width, $height, $type, $attr) = getimagesize($uploadfile);
                    $max_width = 276;
                    $max_height = 162;
                    $a = new Thumbnail($uploadfile,$max_width,$max_height,$uploaddir.$thumb_filename1,100,'');
                    $a->create();

                }else{  
                        $flag=1;
                        $frm_server_side_error= $frm_server_side_error."Error in uploading image,";
                }
            }
            else{
                $flag=2;
                $frm_server_side_error= $frm_server_side_error."Image not in gif or jpg format,";

            }