Struct zbq_msg_header 

#[repr(C, align(16))]
pub struct zbq_msg_header {
    pub payload_len: u32,
    pub fd_count: u8,
    pub flags: u8,
    pub reserved: u16,
    pub seq_id: u64,
}

16-byte packed message header, 16-byte aligned.

Every committed run starts with this header followed by payload_len bytes of payload. total_len (used by the consumer view) is sizeof(zbq_msg_header) + payload_len.

Fields

payload_len: u32

Length in bytes of the payload that follows this header.

fd_count: u8

Number of file descriptors attached to this message (0..253).

flags: u8

Message-specific flags (reserved, currently ignored on the wire).

reserved: u16

Reserved for future use.

seq_id: u64

Sequence ID used to correlate the ring entry with FD records sent over the per-consumer side socket.