Having C functions isn't all that much better. You have replaced a crufty text format with crufty data structures full of paddings, unions, bitfields, VLAs, unaligned nested structs and other crazy stuff. Look at ioctls or cmsg. With C structs + 3rd-party kernel drivers you can even get UB because the driver returns data that is invalid under the struct definition (e.g. incorrect alignment, invalid bools).