Function alloc_socket

components/net/lwip/lwip-2.1.2/src/api/sockets.c:519–560

* Allocate a new socket for a given netconn. * * @param newconn the netconn for which to allocate a socket * @param accepted 1 if socket has been created by accept(), * 0 if socket has been created by socket() * @return the index of the new socket; -1 on error */

 * @return the index of the new socket; -1 on error
 */
static int
alloc_socket(struct netconn *newconn, int accepted)
{
  int i;
  SYS_ARCH_DECL_PROTECT(lev);
  LWIP_UNUSED_ARG(accepted);

  /* allocate a new socket identifier */
  for (i = 0; i < NUM_SOCKETS; ++i) {
    /* Protect socket array */
    SYS_ARCH_PROTECT(lev);
    if (!sockets[i].conn) {
#if LWIP_NETCONN_FULLDUPLEX
      if (sockets[i].fd_used) {
        SYS_ARCH_UNPROTECT(lev);
        continue;
      }
      sockets[i].fd_used    = 1;
      sockets[i].fd_free_pending = 0;
#endif
      sockets[i].conn       = newconn;
      /* The socket is not yet known to anyone, so no need to protect
         after having marked it as used. */
      SYS_ARCH_UNPROTECT(lev);
      sockets[i].lastdata.pbuf = NULL;
#if LWIP_SOCKET_SELECT || LWIP_SOCKET_POLL
      LWIP_ASSERT("sockets[i].select_waiting == 0", sockets[i].select_waiting == 0);
      sockets[i].rcvevent   = 0;
      /* TCP sendbuf is empty, but the socket is not yet writable until connected
       * (unless it has been created by accept()). */
      sockets[i].sendevent  = (NETCONNTYPE_GROUP(newconn->type) == NETCONN_TCP ? (accepted != 0) : 1);
      sockets[i].errevent   = 0;
#endif /* LWIP_SOCKET_SELECT || LWIP_SOCKET_POLL */
#ifdef SAL_USING_POSIX
      rt_wqueue_init(&sockets[i].wait_head);
#endif
      return i + LWIP_SOCKET_OFFSET;
    }
    SYS_ARCH_UNPROTECT(lev);
  }
  return -1;
}

/** Free a socket (under lock)
 *