/*	$NetBSD: funopen.c,v 1.14 2012/03/28 15:21:11 christos Exp $	*/

/*-
 * Copyright (c) 2014 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Christos Zoulas.
 *
 * 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. 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 <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: funopen.c,v 1.14 2012/03/28 15:21:11 christos Exp $");
#endif /* LIBC_SCCS and not lint */

#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <stddef.h>
#ifndef HAVE_NBTOOL_CONFIG_H    
#include "reentrant.h"
#include "local.h"
#endif

struct str {
	const char *buf;
	size_t len;
	off_t off;
};

static ssize_t
readfn(void *c, void *buf, size_t len)
{
	struct str *s = c;
	size_t avail = s->len - (size_t)s->off;
	if (len > avail)
		len = avail;
	memcpy(buf, s->buf + s->off, len);
	return (ssize_t)len;
}

static off_t
seekfn(void *c, off_t off, int whence)
{
	struct str *s = c;

	switch (whence) {
	case SEEK_SET:
		s->off = off;
		break;
	case SEEK_END:
		s->off = s->len;
		break;
	case SEEK_CUR:
		s->off += off;
		break;
	default:
		errno = EINVAL;
		return -1;
	}
	if (s->off < 0)
		s->off = 0;
	else if ((size_t)s->off > s->len)
		s->off = s->len;
	return s->off;
}

static int
closefn(void *c)
{
	free(c);
	return 0;
}

FILE *
stropen(const char *str)
{
	struct str *c = malloc(sizeof(*c));

	if (c == NULL)
		return NULL;

	c->buf = str;
	c->off = 0;
	c->len = strlen(str);

	return funopen2(c, readfn, NULL, seekfn, NULL, closefn);
}