// SPDX-License-Identifier: GPL-2.0
// epoll zerocopy test:
//
// EPOLLERR is known to be not edge-triggered unlike EPOLLIN and EPOLLOUT but
// it is not level-triggered either.
//
// fire two sends with MSG_ZEROCOPY and receive the acks. confirm that EPOLLERR
// is correctly fired only once, when EPOLLET is set. send another packet with
// MSG_ZEROCOPY. confirm that EPOLLERR is correctly fired again only once.
`./defaults.sh`

    0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
   +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
   +0 setsockopt(3, SOL_SOCKET, SO_ZEROCOPY, [1], 4) = 0
   +0 bind(3, ..., ...) = 0
   +0 listen(3, 1) = 0

   +0 < S 0:0(0) win 32792 <mss 1000,sackOK,nop,nop,nop,wscale 7>
   +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
   +0 < . 1:1(0) ack 1 win 257

   +0 accept(3, ..., ...) = 4

   +0 fcntl(4, F_SETFL, O_RDWR|O_NONBLOCK) = 0
   +0 epoll_create(1) = 5
   +0 epoll_ctl(5, EPOLL_CTL_ADD, 4, {events=EPOLLOUT|EPOLLET, fd=4}) = 0
   +0 epoll_wait(5, {events=EPOLLOUT, fd=4}, 1, 0) = 1

   +0 send(4, ..., 4000, MSG_ZEROCOPY) = 4000
   +0 > P. 1:4001(4000) ack 1
   +0 < . 1:1(0) ack 4001 win 257

   +0 send(4, ..., 4000, MSG_ZEROCOPY) = 4000
   +0 > P. 4001:8001(4000) ack 1
   +0 < . 1:1(0) ack 8001 win 257

// receive only one EPOLLERR for the two sends above.
   +0 epoll_wait(5, {events=EPOLLERR|EPOLLOUT, fd=4}, 1, 0) = 1
   +0 epoll_wait(5, {events=0, ptr=0}, 1, 0) = 0

   +0 send(4, ..., 4000, MSG_ZEROCOPY) = 4000
   +0 > P. 8001:12001(4000) ack 1
   +0 < . 1:1(0) ack 12001 win 257

// receive only one EPOLLERR for the third send above.
   +0 epoll_wait(5, {events=EPOLLERR|EPOLLOUT, fd=4}, 1, 0) = 1
   +0 epoll_wait(5, {events=0, ptr=0}, 1, 0) = 0

   +0 recvmsg(4, {msg_name(...)=...,
                  msg_iov(1)=[{...,0}],
                  msg_flags=MSG_ERRQUEUE,
                  msg_control=[
                        {cmsg_level=CMSG_LEVEL_IP,
                         cmsg_type=CMSG_TYPE_RECVERR,
                         cmsg_data={ee_errno=0,
                                    ee_origin=SO_EE_ORIGIN_ZEROCOPY,
                                    ee_type=0,
                                    ee_code=SO_EE_CODE_ZEROCOPY_COPIED,
                                    ee_info=0,
                                    ee_data=2}}
                   ]}, MSG_ERRQUEUE) = 0