1/* $NetBSD: hcreate.c,v 1.7 2011/09/14 23:33:51 christos Exp $ */ 2 3/* 4 * Copyright (c) 2001 Christopher G. Demetriou 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. The name of the author may not be used to endorse or promote products 16 * derived from this software without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 * 29 * <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>> 30 */ 31 32/* 33 * hcreate() / hsearch() / hdestroy() 34 * 35 * SysV/XPG4 hash table functions. 36 * 37 * Implementation done based on NetBSD manual page and Solaris manual page, 38 * plus my own personal experience about how they're supposed to work. 39 * 40 * I tried to look at Knuth (as cited by the Solaris manual page), but 41 * nobody had a copy in the office, so... 42 */ 43 44#include <sys/cdefs.h> 45#if defined(LIBC_SCCS) && !defined(lint) 46__RCSID("$NetBSD: hcreate.c,v 1.7 2011/09/14 23:33:51 christos Exp $"); 47#endif /* LIBC_SCCS and not lint */ 48 49#if !defined(lint) 50__COPYRIGHT("@(#) Copyright (c) 2001\ 51 Christopher G. Demetriou. All rights reserved."); 52#endif /* not lint */ 53 54#include "namespace.h" 55#include <assert.h> 56#include <errno.h> 57#include <inttypes.h> 58#include <search.h> 59#include <stdlib.h> 60#include <string.h> 61#include <sys/queue.h> 62 63/* 64 * DO NOT MAKE THIS STRUCTURE LARGER THAN 32 BYTES (4 ptrs on 64-bit 65 * ptr machine) without adjusting MAX_BUCKETS_LG2 below. 66 */ 67struct internal_entry { 68 SLIST_ENTRY(internal_entry) link; 69 ENTRY ent; 70}; 71SLIST_HEAD(internal_head, internal_entry); 72 73#define MIN_BUCKETS_LG2 4 74#define MIN_BUCKETS (1 << MIN_BUCKETS_LG2) 75 76/* 77 * max * sizeof internal_entry must fit into size_t. 78 * assumes internal_entry is <= 32 (2^5) bytes. 79 */ 80#define MAX_BUCKETS_LG2 (sizeof (size_t) * 8 - 1 - 5) 81#define MAX_BUCKETS ((size_t)1 << MAX_BUCKETS_LG2) 82 83/* Default hash function, from db/hash/hash_func.c */ 84extern u_int32_t (*__default_hash)(const void *, size_t); 85 86static struct hsearch_data htable; 87 88int 89hcreate(size_t nel) 90{ 91 _DIAGASSERT(htable.table == NULL); 92 93 /* Make sure this isn't called when a table already exists. */ 94 if (htable.table != NULL) { 95 errno = EINVAL; 96 return 0; 97 } 98 return hcreate_r(nel, &htable); 99} 100 101int 102hcreate_r(size_t nel, struct hsearch_data *head) 103{ 104 struct internal_head *table; 105 size_t idx; 106 unsigned int p2; 107 void *p; 108 109 /* If nel is too small, make it min sized. */ 110 if (nel < MIN_BUCKETS) 111 nel = MIN_BUCKETS; 112 113 /* If it's too large, cap it. */ 114 if (nel > MAX_BUCKETS) 115 nel = MAX_BUCKETS; 116 117 /* If it's is not a power of two in size, round up. */ 118 if ((nel & (nel - 1)) != 0) { 119 for (p2 = 0; nel != 0; p2++) 120 nel >>= 1; 121 _DIAGASSERT(p2 <= MAX_BUCKETS_LG2); 122 nel = 1 << p2; 123 } 124 125 /* Allocate the table. */ 126 head->size = nel; 127 head->filled = 0; 128 p = malloc(nel * sizeof table[0]); 129 if (p == NULL) { 130 errno = ENOMEM; 131 return 0; 132 } 133 head->table = p; 134 table = p; 135 136 /* Initialize it. */ 137 for (idx = 0; idx < nel; idx++) 138 SLIST_INIT(&table[idx]); 139 140 return 1; 141} 142 143void 144hdestroy(void) 145{ 146 _DIAGASSERT(htable.table != NULL); 147 hdestroy_r(&htable); 148} 149 150void 151hdestroy_r(struct hsearch_data *head) 152{ 153 struct internal_entry *ie; 154 size_t idx; 155 void *p; 156 struct internal_head *table; 157 158 if (head == NULL) 159 return; 160 161 p = head->table; 162 head->table = NULL; 163 table = p; 164 165 for (idx = 0; idx < head->size; idx++) { 166 while (!SLIST_EMPTY(&table[idx])) { 167 ie = SLIST_FIRST(&table[idx]); 168 SLIST_REMOVE_HEAD(&table[idx], link); 169 free(ie->ent.key); 170 free(ie); 171 } 172 } 173 free(table); 174} 175 176ENTRY * 177hsearch(ENTRY item, ACTION action) 178{ 179 ENTRY *ep; 180 _DIAGASSERT(htable.table != NULL); 181 (void)hsearch_r(item, action, &ep, &htable); 182 return ep; 183} 184 185int 186hsearch_r(ENTRY item, ACTION action, ENTRY **itemp, struct hsearch_data *head) 187{ 188 struct internal_head *table, *chain; 189 struct internal_entry *ie; 190 uint32_t hashval; 191 size_t len; 192 void *p; 193 194 _DIAGASSERT(item.key != NULL); 195 _DIAGASSERT(action == ENTER || action == FIND); 196 197 p = head->table; 198 table = p; 199 200 len = strlen(item.key); 201 hashval = (*__default_hash)(item.key, len); 202 203 chain = &table[hashval & (head->size - 1)]; 204 ie = SLIST_FIRST(chain); 205 while (ie != NULL) { 206 if (strcmp(ie->ent.key, item.key) == 0) 207 break; 208 ie = SLIST_NEXT(ie, link); 209 } 210 211 if (ie != NULL) { 212 *itemp = &ie->ent; 213 return 1; 214 } else if (action == FIND) { 215 *itemp = NULL; 216 errno = ESRCH; 217 return 1; 218 } 219 220 ie = malloc(sizeof *ie); 221 if (ie == NULL) 222 return 0; 223 ie->ent.key = item.key; 224 ie->ent.data = item.data; 225 226 SLIST_INSERT_HEAD(chain, ie, link); 227 *itemp = &ie->ent; 228 head->filled++; 229 return 1; 230} 231