/*	$NetBSD: prop_bool.c,v 1.17 2009/01/03 18:31:33 pooka Exp $	*/

/*-
 * Copyright (c) 2006 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe.
 *
 * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

#include <libprop/prop_bool.h>
#include "prop_object_impl.h"
#include <stdlib.h>	/* DF5693 rig: getenv */
#include <unistd.h>	/* DF5693 rig: usleep */

/*
 * DF5693 rig: window-widening knobs.  Read ONCE by a constructor,
 * single-threaded before main(), so that the un-widened path inside
 * _prop_bool_init costs two predictable branches (~1ns) and does NOT
 * itself widen the race window.  (An earlier rig version called
 * getenv() inside _prop_bool_init: libc getenv scans environ and costs
 * microseconds, which self-widened the "realistic window" battery and
 * produced a bogus 30% anomaly rate — see run.first-attempt.log.)
 */
static int rig_w1_ms = -1, rig_w2_ms = -1;

static void __attribute__((constructor)) rig_read_knobs(void)
{
	const char *w;

	if ((w = getenv("PROP_WIDEN_MS")) != NULL)
		rig_w1_ms = atoi(w);
	if ((w = getenv("PROP_WIDEN2_MS")) != NULL)
		rig_w2_ms = atoi(w);
}

struct _prop_bool {
	struct _prop_object	pb_obj;
	bool		pb_value;
};

static struct _prop_bool _prop_bool_true;
static struct _prop_bool _prop_bool_false;

static _prop_object_free_rv_t
		_prop_bool_free(prop_stack_t, prop_object_t *);
static bool	_prop_bool_externalize(
				struct _prop_object_externalize_context *,
				void *);
static _prop_object_equals_rv_t
		_prop_bool_equals(prop_object_t, prop_object_t,
				  void **, void **,
				  prop_object_t *, prop_object_t *);

static const struct _prop_object_type _prop_object_type_bool = {
	.pot_type	=	PROP_TYPE_BOOL,
	.pot_free	=	_prop_bool_free,
	.pot_extern	=	_prop_bool_externalize,
	.pot_equals	=	_prop_bool_equals,
};

#define	prop_object_is_bool(x)		\
	((x) != NULL && (x)->pb_obj.po_type == &_prop_object_type_bool)

/* ARGSUSED */
static _prop_object_free_rv_t
_prop_bool_free(prop_stack_t stack, prop_object_t *obj)
{
	/*
	 * This should never happen as we "leak" our initial reference
	 * count.
	 */

	/* XXX forced assertion failure? */
	return (_PROP_OBJECT_FREE_DONE);
}

static bool
_prop_bool_externalize(struct _prop_object_externalize_context *ctx,
		       void *v)
{
	prop_bool_t pb = v;

	return (_prop_object_externalize_empty_tag(ctx,
	    pb->pb_value ? "true" : "false"));
}

/* ARGSUSED */
static _prop_object_equals_rv_t
_prop_bool_equals(prop_object_t v1, prop_object_t v2,
    void **stored_pointer1, void **stored_pointer2,
    prop_object_t *next_obj1, prop_object_t *next_obj2)
{
	prop_bool_t b1 = v1;
	prop_bool_t b2 = v2;

	if (! (prop_object_is_bool(b1) &&
	       prop_object_is_bool(b2)))
		return (_PROP_OBJECT_EQUALS_FALSE);

	/*
	 * Since we only ever allocate one true and one false,
	 * save ourselves a couple of memory operations.
	 */
	if (b1 == b2)
		return (_PROP_OBJECT_EQUALS_TRUE);
	else
		return (_PROP_OBJECT_EQUALS_FALSE);
}

_PROP_ONCE_DECL(_prop_bool_init_once)

static int
_prop_bool_init(void)
{
	/* rig: widen the "winner inside f(), nothing stored yet" window */
	if (rig_w1_ms > 0)
		usleep(rig_w1_ms);

	_prop_object_init(&_prop_bool_true.pb_obj,
	    &_prop_object_type_bool);

	/* rig: widen the "po_type stored, pb_value still stale" window */
	if (rig_w2_ms > 0)
		usleep(rig_w2_ms);

	_prop_bool_true.pb_value = true;

	_prop_object_init(&_prop_bool_false.pb_obj,
	    &_prop_object_type_bool);
	_prop_bool_false.pb_value = false;

	return 0;
}

static prop_bool_t
_prop_bool_alloc(bool val)
{
	prop_bool_t pb;

	_PROP_ONCE_RUN(_prop_bool_init_once, _prop_bool_init);
	pb = val ? &_prop_bool_true : &_prop_bool_false;
	prop_object_retain(pb);

	return (pb);
}

/*
 * prop_bool_create --
 *	Create a prop_bool_t and initialize it with the
 *	provided boolean value.
 */
prop_bool_t
prop_bool_create(bool val)
{

	return (_prop_bool_alloc(val));
}

/*
 * prop_bool_copy --
 *	Copy a prop_bool_t.
 */
prop_bool_t
prop_bool_copy(prop_bool_t opb)
{

	if (! prop_object_is_bool(opb))
		return (NULL);

	/*
	 * Because we only ever allocate one true and one false, this
	 * can be reduced to a simple retain operation.
	 */
	prop_object_retain(opb);
	return (opb);
}

/*
 * prop_bool_true --
 *	Get the value of a prop_bool_t.
 */
bool
prop_bool_true(prop_bool_t pb)
{

	if (! prop_object_is_bool(pb))
		return (false);

	return (pb->pb_value);
}

/*
 * prop_bool_equals --
 *	Return true if the boolean values are equivalent.
 */
bool
prop_bool_equals(prop_bool_t b1, prop_bool_t b2)
{
	if (!prop_object_is_bool(b1) || !prop_object_is_bool(b2))
		return (false);

	return (prop_object_equals(b1, b2));
}

/*
 * _prop_bool_internalize --
 *	Parse a <true/> or <false/> and return the object created from
 *	the external representation.
 */

/* ARGSUSED */
bool
_prop_bool_internalize(prop_stack_t stack, prop_object_t *obj,
    struct _prop_object_internalize_context *ctx)
{
	bool val;

	/* No attributes, and it must be an empty element. */
	if (ctx->poic_tagattr != NULL ||
	    ctx->poic_is_empty_element == false)
		return (true);

	if (_PROP_TAG_MATCH(ctx, "true"))
		val = true;
	else {
		_PROP_ASSERT(_PROP_TAG_MATCH(ctx, "false"));
		val = false;
	}
	*obj = prop_bool_create(val);
	return (true);
}