Function recvmsg_impl 

pub fn recvmsg_impl(
    locked: &mut Locked<Unlocked>,
    current_task: &CurrentTask,
    fd: FdNumber,
    user_message_header: &mut MsgHdrRef,
    flags: u32,
) -> Result<usize, Errno>

Implementation of recvmsg.

This function is used by sys_recvmsg, but can also be called from other parts of the kernel that need to override the iovec from the msghdr. For example, when using io_uring with ring buffers.