struct msqid_ds {
  struct ipc_perm msg_perm;
  time_t msg_stime;
  int __unused1;
  time_t msg_rtime;
  int __unused2;
  time_t msg_ctime;
  int __unused3;
  unsigned long msg_cbytes;
  msgqnum_t msg_qnum;
  msglen_t msg_qbytes;
  pid_t msg_lspid;
  pid_t msg_lrpid;
  unsigned long __unused[2];
};