path: root/net/9p/conv.c

/*
 * net/9p/conv.c
 *
 * 9P protocol conversion functions
 *
 *  Copyright (C) 2004, 2005 by Latchesar Ionkov <lucho@ionkov.net>
 *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
 *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *
 *  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:
 *  Free Software Foundation
 *  51 Franklin Street, Fifth Floor
 *  Boston, MA  02111-1301  USA
 *
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/idr.h>
#include <linux/uaccess.h>
#include <net/9p/9p.h>

/*
 * Buffer to help with string parsing
 */
struct cbuf {
	unsigned char *sp;
	unsigned char *p;
	unsigned char *ep;
};

static inline void buf_init(struct cbuf *buf, void *data, int datalen)
{
	buf->sp = buf->p = data;
	buf->ep = data + datalen;
}

static inline int buf_check_overflow(struct cbuf *buf)
{
	return buf->p > buf->ep;
}

static int buf_check_size(struct cbuf *buf, int len)
{
	if (buf->p + len > buf->ep) {
		if (buf->p < buf->ep) {
			P9_EPRINTK(KERN_ERR,
				"buffer overflow: want %d has %d\n", len,
				(int)(buf->ep - buf->p));
			dump_stack();
			buf->p = buf->ep + 1;
		}

		return 0;
	}

	return 1;
}

static void *buf_alloc(struct cbuf *buf, int len)
{
	void *ret = NULL;

	if (buf_check_size(buf, len)) {
		ret = buf->p;
		buf->p += len;
	}

	return ret;
}

static void buf_put_int8(struct cbuf *buf, u8 val)
{
	if (buf_check_size(buf, 1)) {
		buf->p[0] = val;
		buf->p++;
	}
}

static void buf_put_int16(struct cbuf *buf, u16 val)
{
	if (buf_check_size(buf, 2)) {
		*(__le16 *) buf->p = cpu_to_le16(val);
		buf->p += 2;
	}
}

static void buf_put_int32(struct cbuf *buf, u32 val)
{
	if (buf_check_size(buf, 4)) {
		*(__le32 *)buf->p = cpu_to_le32(val);
		buf->p += 4;
	}
}

static void buf_put_int64(struct cbuf *buf, u64 val)
{
	if (buf_check_size(buf, 8)) {
		*(__le64 *)buf->p = cpu_to_le64(val);
		buf->p += 8;
	}
}

static char *buf_put_stringn(struct cbuf *buf, const char *s, u16 slen)
{
	char *ret;

	ret = NULL;
	if (buf_check_size(buf, slen + 2)) {
		buf_put_int16(buf, slen);
		ret = buf->p;
		memcpy(buf->p, s, slen);
		buf->p += slen;
	}

	return ret;
}

static u8 buf_get_int8(struct cbuf *buf)
{
	u8 ret = 0;

	if (buf_check_size(buf, 1)) {
		ret = buf->p[0];
		buf->p++;
	}

	return ret;
}

static u16 buf_get_int16(struct cbuf *buf)
{
	u16 ret = 0;

	if (buf_check_size(buf, 2)) {
		ret = l