/*-
 * Copyright (c) 2009, 2013 The FreeBSD Foundation
 * All rights reserved.
 *
 * This software was developed by Ed Schouten under sponsorship from the
 * FreeBSD Foundation.
 *
 * Portions of this software were developed by Oleksandr Rybalko
 * under sponsorship from the FreeBSD Foundation.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD$
 */

#ifndef _VTSUBSYS_SELECT_H_
#define	_VTSUBSYS_SELECT_H_
#include <sys/cdefs.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/linker_set.h>

struct vtsubsys_data {
	char	*name;
	char	*envvar;
	char	*envprivar;
	int	priority;
};

SET_DECLARE(vtsubsys_set, struct vtsubsys_data);

static int
is_vtsubsys_selected(char *name)
{
	struct vtsubsys_data **data, *best, *me;
	int value, priority;

	/* If subsys $name is only one, return 0. */
	if (SET_COUNT(vtsubsys_set) <= 1)
		return (1);

	best = me = NULL;
	SET_FOREACH(data, vtsubsys_set) {
		/* Skip items marked as root.enabled=0. */
		if (getenv_int((*data)->envvar, &value) || value == 0)
			continue;

		/* Identify item with same name as passed. */
		if (strcmp((*data)->name, name) == 0)
			me = *data;

		/* Check if this module is better. Allow override priority. */
		if (best == NULL ||
		    ((getenv_int((*data)->envprivar, &priority)) ? priority :
		    (*data)->priority) > best->priority)
			best = *data;
	}

	if (me != NULL && me == best)
		return (1);

	return (0);
}

#define	VTSUBSYS_DECLARE(_name, _envvarroot, _priority)			\
	static struct vtsubsys_data _name ## _vtsubsys_data = {		\
		.name = #_name,						\
		.envvar = _envvarroot ".enabled",			\
		.envprivar = _envvarroot ".priority",			\
		.priority = (_priority),				\
	};								\
	DATA_SET(vtsubsys_set, _name ## _vtsubsys_data)

#endif /* _VTSUBSYS_SELECT_H_ */