pub fn read_tail_len(data: &[u8], body_end: usize) -> Result<u32, ProgramError>Expand description
Read the tail’s u32-LE length prefix.
body_end is the byte offset immediately after the layout’s fixed
body (i.e. TYPE_OFFSET + WIRE_SIZE for a layout with no header
beyond the 16-byte Hopper prefix, otherwise HEADER_LEN + WIRE_SIZE). Returns AccountDataTooSmall if the account has
fewer than 4 tail bytes available.