event_attr_engine.c

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/*
** Copyright (C) 2005 by Kevin L. Mitchell <klmitch@mit.edu>
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
** GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software
** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
**
** @(#)$Id: event_attr_engine.c,v 1.4 2005/07/18 22:01:40 klmitch Exp $
*/
#include "engines_int.h"

#include <stdlib.h>
#include <string.h>

RCSTAG("@(#)$Id: event_attr_engine.c,v 1.4 2005/07/18 22:01:40 klmitch Exp $");

ev_err_t
event_attr_engine(ev_attr_t *attr, ev_engine_t *engine)
{
  int cmp;
  ev_engine_t *englist, *last;

  ev_init(); /* initialize library... */

  if (!ea_verify(attr) || !eng_verify(engine) || /* attr valid?  engine? */

      /* make sure engine is valid... */
      !engine->eng_name || !engine->eng_init || !engine->eng_poll ||

      /* If it has a socket component, does it have the socket methods? */
      ((engine->eng_flags & EV_ENGINE_SOCKET) &&
       (!engine->eng_socket.eso_add || !engine->eng_socket.eso_rem ||
        !engine->eng_socket.eso_ev)) ||

      /* If it has a signal component, does it have the signal methods? */
      ((engine->eng_flags & EV_ENGINE_SIGNAL) &&
       (!engine->eng_signal.esi_add || !engine->eng_signal.esi_rem)))
    /* timer components don't necessarily need add/remove callbacks */
    ev_return(EINVAL);

  if ((engine->eng_runfl & EV_ENGINE_REGISTERED) ||
      engine->eng_list.el_next || engine->eng_list.el_prev)
    ev_return(EBUSY); /* already registered... */

  /* walk through the list of engines... */
  for (englist = ea_engines(attr), last = 0; englist;
       last = englist, englist = englist->eng_list.el_next)
    if (!(cmp = strcmp(englist->eng_name, engine->eng_name)))
      ev_return(EEXIST); /* hmmm, already registered? */
    else if (cmp > 0) /* larger than what we're inserting... */
      break; /* so here's where we'll insert the new engine */

  engine->eng_list.el_next = englist; /* link it into the list... */
  engine->eng_list.el_prev = last;

  if (englist) /* update everyone else's link pointers */
    englist->eng_list.el_prev = engine;
  if (last)
    last->eng_list.el_next = engine;
  else
    ea_engines(attr) = engine;

  ev_return(0);
}

---