/*
 * The Qubes OS Project, http://www.qubes-os.org
 *
 * Copyright (C) 2010  Rafal Wojtczuk  <rafal@invisiblethingslab.com>
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "buffer.h"

#define BUFFER_LIMIT 50000000
static int total_mem;
static char *limited_malloc(int len)
{
	char *ret;
	total_mem += len;
	if (total_mem > BUFFER_LIMIT) {
		fprintf(stderr, "attempt to allocate >BUFFER_LIMIT\n");
		exit(1);
	}
	ret = malloc(len);
	if (!ret) {
		perror("malloc");
		exit(1);
	}
	return ret;
}

static void limited_free(char *ptr, int len)
{
	free(ptr);
	total_mem -= len;
}

void buffer_init(struct buffer *b)
{
	b->buflen = 0;
	b->data = NULL;
}

void buffer_free(struct buffer *b)
{
	if (b->buflen)
		limited_free(b->data, b->buflen);
	buffer_init(b);
}

void buffer_append(struct buffer *b, char *data, int len)
{
	int newsize = len + b->buflen;
	char *qdata = limited_malloc(len + b->buflen);
	memcpy(qdata, b->data, b->buflen);
	memcpy(qdata + b->buflen, data, len);
	buffer_free(b);
	b->buflen = newsize;
	b->data = qdata;
}

void buffer_remove(struct buffer *b, int len)
{
	int newsize = b->buflen - len;
	char *qdata = limited_malloc(newsize);
	memcpy(qdata, b->data + len, newsize);
	buffer_free(b);
	b->buflen = newsize;
	b->data = qdata;
}

int buffer_len(struct buffer *b)
{
	return b->buflen;
}

void *buffer_data(struct buffer *b)
{
	return b->data;
}