common/sharefs/sharetab.h

	sharetab.h revision bfbb13c994c87d0453ca6bb826470ec99a909992
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#ifndef _SHAREFS_SHARETAB_H
#define _SHAREFS_SHARETAB_H

#pragma ident   "%Z%%M% %I% %E% SMI"

/*
 * This header defines the glue to keeping a sharetab in memory.
 * It is broken out from sharefs.h in the case that it will be
 * reused in userland.
 */

/*
 * Note:
 * Must include share/share.h before this header.
 */

#ifdef __cplusplus
extern "C" {
#endif

typedef struct sh_list {        /* cached share list */
    struct sh_list  *shl_next;
    share_t     *shl_sh;
} sh_list_t;

typedef struct sharefs_hash_head {
    share_t     *ssh_sh;
    uint_t      ssh_count;
} sharefs_hash_head_t;

#define SHARETAB_HASHES     256

typedef struct sharetab {
    sharefs_hash_head_t s_buckets[SHARETAB_HASHES];
    char            *s_fstype;
    struct sharetab     *s_next;
    uint_t          s_count;
} sharetab_t;

#define MOD2(a, pow_of_2)   (a) & ((pow_of_2) - 1)

/*
 * Pearson's string hash
 *
 * See: Communications of the ACM, June 1990 Vol 33 pp 677-680
 * http://www.acm.org/pubs/citations/journals/cacm/1990-33-6/p677-pearson
 */
#define SHARETAB_HASH_IT(hash, path)                    \
{                                   \
    uint_t      key = 0x12345678;   /* arbitrary value */   \
    int     i, len;                     \
                                    \
    len = strlen((path));                       \
                                    \
    (hash) = MOD2((key + len), SHARETAB_HASHES);            \
                                    \
    for (i = 0; i < len; i++) {                 \
        (hash) = MOD2(((hash) + (path)[i]), SHARETAB_HASHES);   \
        (hash) = pkp_tab[(hash)];               \
    }                               \
}

#ifdef __cplusplus
}
#endif

#endif /* !_SHAREFS_SHARETAB_H */