1 /* $NetBSD: hcreate.c,v 1.9 2014/07/20 13:34:17 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 1.9 2014/07/20 13:34:17 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 */ 67 struct internal_entry { 68 SLIST_ENTRY(internal_entry) link; 69 ENTRY ent; 70 }; 71 SLIST_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 */ 84 extern u_int32_t (*__default_hash)(const void *, size_t); 85 86 static struct hsearch_data htable; 87 88 int 89 hcreate(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 } 100 101 int 102 hcreate_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 } 142 143 void 144 hdestroy1(int flags) 145 { 146 _DIAGASSERT(htable.table != NULL); 147 hdestroy1_r(&htable, flags); 148 } 149 150 void 151 hdestroy(void) 152 { 153 hdestroy1(0); 154 } 155 156 void 157 hdestroy1_r(struct hsearch_data *head, int flags) 158 { 159 struct internal_entry *ie; 160 size_t idx; 161 void *p; 162 struct internal_head *table; 163 164 if (head == NULL) 165 return; 166 167 p = head->table; 168 head->table = NULL; 169 table = p; 170 171 for (idx = 0; idx < head->size; idx++) { 172 while (!SLIST_EMPTY(&table[idx])) { 173 ie = SLIST_FIRST(&table[idx]); 174 SLIST_REMOVE_HEAD(&table[idx], link); 175 if (flags & FREE_KEY) 176 free(ie->ent.key); 177 if (flags & FREE_DATA) 178 free(ie->ent.data); 179 free(ie); 180 } 181 } 182 free(table); 183 } 184 185 void 186 hdestroy_r(struct hsearch_data *head) 187 { 188 hdestroy1_r(head, 0); 189 } 190 191 ENTRY * 192 hsearch(ENTRY item, ACTION action) 193 { 194 ENTRY *ep; 195 _DIAGASSERT(htable.table != NULL); 196 (void)hsearch_r(item, action, &ep, &htable); 197 return ep; 198 } 199 200 int 201 hsearch_r(ENTRY item, ACTION action, ENTRY **itemp, struct hsearch_data *head) 202 { 203 struct internal_head *table, *chain; 204 struct internal_entry *ie; 205 uint32_t hashval; 206 size_t len; 207 void *p; 208 209 _DIAGASSERT(item.key != NULL); 210 _DIAGASSERT(action == ENTER || action == FIND); 211 212 p = head->table; 213 table = p; 214 215 len = strlen(item.key); 216 hashval = (*__default_hash)(item.key, len); 217 218 chain = &table[hashval & (head->size - 1)]; 219 ie = SLIST_FIRST(chain); 220 while (ie != NULL) { 221 if (strcmp(ie->ent.key, item.key) == 0) 222 break; 223 ie = SLIST_NEXT(ie, link); 224 } 225 226 if (ie != NULL) { 227 *itemp = &ie->ent; 228 return 1; 229 } else if (action == FIND) { 230 *itemp = NULL; 231 errno = ESRCH; 232 return 1; 233 } 234 235 ie = malloc(sizeof *ie); 236 if (ie == NULL) 237 return 0; 238 ie->ent.key = item.key; 239 ie->ent.data = item.data; 240 241 SLIST_INSERT_HEAD(chain, ie, link); 242 *itemp = &ie->ent; 243 head->filled++; 244 return 1; 245 } 246