/*
 * Copyright (c) 2011, 2012 Nicira Networks.
 * Distributed under the terms of the GNU GPL version 2.
 *
 * Significant portions of this file may be copied from parts of the Linux
 * kernel, by Linus Torvalds and others.
 */

#ifndef COMPAT_H
#define COMPAT_H 1

#include <linux/netlink.h>

#ifndef HAVE_NLA_NUL_STRING
static inline int CHECK_NUL_STRING(struct nlattr *attr, int maxlen)
{
	char *s;
	int len;
	if (!attr)
		return 0;

	len = nla_len(attr);
	if (len >= maxlen)
		return -EINVAL;

	s = nla_data(attr);
	if (s[len - 1] != '\0')
		return -EINVAL;

	return 0;
}
#else
static inline int CHECK_NUL_STRING(struct nlattr *attr, int maxlen)
{
	return 0;
}
#endif  /* !HAVE_NLA_NUL_STRING */

/*
 * Enforces mutual exclusion with the Linux bridge module, by declaring and
 * exporting br_should_route_hook.  Because the bridge module also exports the
 * same symbol, the module loader will refuse to load both modules at the same
 * time (e.g. "bridge: exports duplicate symbol br_should_route_hook (owned by
 * openvswitch_mod)").
 *
 * Before Linux 2.6.36, Open vSwitch cannot safely coexist with the Linux
 * bridge module, so openvswitch_mod uses this macro in those versions.  In
 * Linux 2.6.36 and later, Open vSwitch can coexist with the bridge module, but
 * it makes no sense to load both bridge and brcompat_mod, so brcompat_mod uses
 * this macro in those versions.
 *
 * The use of "typeof" here avoids the need to track changes in the type of
 * br_should_route_hook over various kernel versions.
 */
#define BRIDGE_MUTUAL_EXCLUSION					\
	typeof(br_should_route_hook) br_should_route_hook;	\
	EXPORT_SYMBOL(br_should_route_hook)

#endif /* compat.h */