cookie.c

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/* -*- C -*- */
/*
 * Copyright (c) 2012-2020 Seagate Technology LLC and/or its Affiliates
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * For any questions about this software or licensing,
 * please email opensource@seagate.com or cortx-questions@seagate.com.
 *
 */


#ifdef __KERNEL__
#include <linux/string.h>
#else
#include <string.h>
#endif

#include "lib/types.h"
#include "lib/errno.h" /* -EPROTO */
#include "lib/cookie.h"
#include "lib/arith.h" /* M0_IS_8ALIGNED */
#include "lib/time.h"  /* m0_time_now() */

#define M0_TRACE_SUBSYSTEM M0_TRACE_SUBSYS_LIB
#include "lib/trace.h"

static uint64_t cookie_generation;

M0_INTERNAL const struct m0_cookie M0_COOKIE_NULL = {
        .co_generation = 0xffff,
        .co_addr       = 7,
};

M0_INTERNAL bool m0_arch_addr_is_sane(const void *addr);
M0_INTERNAL int m0_arch_cookie_global_init(void);
M0_INTERNAL void m0_arch_cookie_global_fini(void);

M0_INTERNAL int m0_cookie_global_init(void)
{
        cookie_generation = m0_time_now();
        return m0_arch_cookie_global_init();
}

M0_INTERNAL void m0_cookie_new(uint64_t * gen)
{
        M0_PRE(gen != NULL);

        *gen = ++cookie_generation;
}

M0_INTERNAL void m0_cookie_init(struct m0_cookie *cookie, const uint64_t *obj)
{
        M0_PRE(cookie != NULL);
        M0_PRE(obj != NULL);

        cookie->co_addr = (uint64_t)obj;
        cookie->co_generation = *obj;
}

M0_INTERNAL bool m0_addr_is_sane(const uint64_t *addr)
{
        return addr > (uint64_t *)4096 && m0_arch_addr_is_sane(addr);
}

M0_INTERNAL bool m0_addr_is_sane_and_aligned(const uint64_t *addr)
{
        return M0_IS_8ALIGNED(addr) && m0_addr_is_sane(addr);
}

M0_INTERNAL int m0_cookie_dereference(const struct m0_cookie *cookie,
                                      uint64_t ** addr)
{
        uint64_t *obj;

        M0_PRE(cookie != NULL);
        M0_PRE(addr != NULL);

        obj = (uint64_t *)cookie->co_addr;
        if (m0_addr_is_sane_and_aligned(obj) && cookie->co_generation == *obj) {
                *addr = obj;
                return 0;
        } else
                return -EPROTO;
}

M0_INTERNAL bool m0_cookie_is_null(const struct m0_cookie *cookie)
{
        return cookie->co_generation == M0_COOKIE_NULL.co_generation &&
                cookie->co_addr == M0_COOKIE_NULL.co_addr;
}

M0_INTERNAL bool m0_cookie_is_eq(const struct m0_cookie *cookie1,
                                 const struct m0_cookie *cookie2)
{
        return memcmp(cookie1, cookie2, sizeof *cookie1) == 0;
}

M0_INTERNAL void m0_cookie_global_fini(void)
{
        m0_arch_cookie_global_fini();
}

#undef M0_TRACE_SUBSYSTEM

/*
 *  Local variables:
 *  c-indentation-style: "K&R"
 *  c-basic-offset: 8
 *  tab-width: 8
 *  fill-column: 80
 *  scroll-step: 1
 *  End:
 */