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/*	$NetBSD: snprintf.c,v 1.5 2007/07/20 00:11:25 tnn Exp $	*/

/*-
 * Copyright (c) 2007 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Tobias Nygren.
 *
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *        This product includes software developed by the NetBSD
 *        Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * 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 <nbcompat.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#if HAVE_STDARG_H
#include <stdarg.h>
#endif

#define MIN(a, b) ((a)<(b)?(a):(b))

int
snprintf(char *str, size_t size, const char *format, ...)
{
	va_list ap;
	int len;

	va_start(ap, format);
	len = vsnprintf(str, size, format, ap);
	va_end(ap);
	return len;
}

static FILE *devnull = 0;

int
vsnprintf(char *str, size_t size, const char *format, va_list ap)
{
	int len;
	char buf[129];
	char *p = buf;

	if (!devnull) {
		devnull = fopen("/dev/null", "w");
		if (!devnull)
			return -1;
	}

	len = vfprintf(devnull, format, ap);
	if (len < 0)
		return len;

	if (len > 128) {
			p = malloc(len + 1);
			if (!p)
			return -1;
	}

	vsprintf(p, format, ap);
	
	if (size > 0) {
		memcpy(str, p, MIN(len, size));
		str[MIN(len, size - 1)] = 0;
	}

	if (p != buf)
		free(p);

	return len;
}