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      1 /*
      2  * CDDL HEADER START
      3  *
      4  * The contents of this file are subject to the terms of the
      5  * Common Development and Distribution License (the "License").
      6  * You may not use this file except in compliance with the License.
      7  *
      8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      9  * or http://www.opensolaris.org/os/licensing.
     10  * See the License for the specific language governing permissions
     11  * and limitations under the License.
     12  *
     13  * When distributing Covered Code, include this CDDL HEADER in each
     14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     15  * If applicable, add the following below this CDDL HEADER, with the
     16  * fields enclosed by brackets "[]" replaced with your own identifying
     17  * information: Portions Copyright [yyyy] [name of copyright owner]
     18  *
     19  * CDDL HEADER END
     20  */
     21 
     22 /*
     23  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
     24  * Use is subject to license terms.
     25  */
     26 
     27 #ifndef _SHAREFS_SHARETAB_H
     28 #define	_SHAREFS_SHARETAB_H
     29 
     30 #pragma ident	"@(#)sharetab.h	1.1	07/04/02 SMI"
     31 
     32 /*
     33  * This header defines the glue to keeping a sharetab in memory.
     34  * It is broken out from sharefs.h in the case that it will be
     35  * reused in userland.
     36  */
     37 
     38 /*
     39  * Note:
     40  * Must include share/share.h before this header.
     41  */
     42 
     43 #ifdef __cplusplus
     44 extern "C" {
     45 #endif
     46 
     47 typedef struct sh_list {		/* cached share list */
     48 	struct sh_list	*shl_next;
     49 	share_t		*shl_sh;
     50 } sh_list_t;
     51 
     52 typedef struct sharefs_hash_head {
     53 	share_t		*ssh_sh;
     54 	uint_t		ssh_count;
     55 } sharefs_hash_head_t;
     56 
     57 #define	SHARETAB_HASHES		256
     58 
     59 typedef struct sharetab {
     60 	sharefs_hash_head_t	s_buckets[SHARETAB_HASHES];
     61 	char			*s_fstype;
     62 	struct sharetab		*s_next;
     63 	uint_t			s_count;
     64 } sharetab_t;
     65 
     66 #define	MOD2(a, pow_of_2)	(a) & ((pow_of_2) - 1)
     67 
     68 /*
     69  * Pearson's string hash
     70  *
     71  * See: Communications of the ACM, June 1990 Vol 33 pp 677-680
     72  * http://www.acm.org/pubs/citations/journals/cacm/1990-33-6/p677-pearson
     73  */
     74 #define	SHARETAB_HASH_IT(hash, path)					\
     75 {									\
     76 	uint_t		key = 0x12345678;	/* arbitrary value */	\
     77 	int		i, len;						\
     78 									\
     79 	len = strlen((path));						\
     80 									\
     81 	(hash) = MOD2((key + len), SHARETAB_HASHES);			\
     82 									\
     83 	for (i = 0; i < len; i++) {					\
     84 		(hash) = MOD2(((hash) + (path)[i]), SHARETAB_HASHES);	\
     85 		(hash) = pkp_tab[(hash)];				\
     86 	}								\
     87 }
     88 
     89 #ifdef __cplusplus
     90 }
     91 #endif
     92 
     93 #endif /* !_SHAREFS_SHARETAB_H */
     94