1 /* $NetBSD: hcreate.c,v 1.13 2022/03/13 01:44:37 kre 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 1.13 2022/03/13 01:44:37 kre 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; 107 108 /* If nel is too small, make it min sized. */ 109 if (nel < MIN_BUCKETS) 110 nel = MIN_BUCKETS; 111 112 /* If it's too large, cap it. */ 113 if (nel > MAX_BUCKETS) 114 nel = MAX_BUCKETS; 115 116 /* If it's is not a power of two in size, round up. */ 117 if ((nel & (nel - 1)) != 0) { 118 for (p2 = 0; nel != 0; p2++) 119 nel >>= 1; 120 _DIAGASSERT(p2 <= MAX_BUCKETS_LG2); 121 nel = 1 << p2; 122 } 123 124 /* Allocate the table. */ 125 head->size = nel; 126 head->filled = 0; 127 table = NULL; 128 errno = reallocarr(&table, nel, sizeof(*table)); 129 if (errno) 130 return 0; 131 head->table = (void *)table; 132 133 /* Initialize it. */ 134 for (idx = 0; idx < nel; idx++) 135 SLIST_INIT(&table[idx]); 136 137 return 1; 138 } 139 140 void 141 hdestroy1(void (*freekey)(void *), void (*freedata)(void *)) 142 { 143 _DIAGASSERT(htable.table != NULL); 144 hdestroy1_r(&htable, freekey, freedata); 145 } 146 147 void 148 hdestroy(void) 149 { 150 hdestroy1(NULL, NULL); 151 } 152 153 void 154 hdestroy1_r(struct hsearch_data *head, void (*freekey)(void *), 155 void (*freedata)(void *)) 156 { 157 struct internal_entry *ie; 158 size_t idx; 159 void *p; 160 struct internal_head *table; 161 162 if (head == NULL) 163 return; 164 165 p = head->table; 166 head->table = NULL; 167 table = p; 168 169 for (idx = 0; idx < head->size; idx++) { 170 while (!SLIST_EMPTY(&table[idx])) { 171 ie = SLIST_FIRST(&table[idx]); 172 SLIST_REMOVE_HEAD(&table[idx], link); 173 if (freekey) 174 (*freekey)(ie->ent.key); 175 if (freedata) 176 (*freedata)(ie->ent.data); 177 free(ie); 178 } 179 } 180 free(table); 181 } 182 183 void 184 hdestroy_r(struct hsearch_data *head) 185 { 186 hdestroy1_r(head, NULL, NULL); 187 } 188 189 ENTRY * 190 hsearch(ENTRY item, ACTION action) 191 { 192 ENTRY *ep; 193 _DIAGASSERT(htable.table != NULL); 194 (void)hsearch_r(item, action, &ep, &htable); 195 return ep; 196 } 197 198 int 199 hsearch_r(ENTRY item, ACTION action, ENTRY **itemp, struct hsearch_data *head) 200 { 201 struct internal_head *table, *chain; 202 struct internal_entry *ie; 203 uint32_t hashval; 204 size_t len; 205 void *p; 206 207 _DIAGASSERT(item.key != NULL); 208 _DIAGASSERT(action == ENTER || action == FIND); 209 210 p = head->table; 211 table = p; 212 213 len = strlen(item.key); 214 hashval = (*__default_hash)(item.key, len); 215 216 chain = &table[hashval & (head->size - 1)]; 217 ie = SLIST_FIRST(chain); 218 while (ie != NULL) { 219 if (strcmp(ie->ent.key, item.key) == 0) 220 break; 221 ie = SLIST_NEXT(ie, link); 222 } 223 224 if (ie != NULL) { 225 *itemp = &ie->ent; 226 return 1; 227 } else if (action == FIND) { 228 *itemp = NULL; 229 errno = ESRCH; 230 return 1; 231 } 232 233 ie = malloc(sizeof *ie); 234 if (ie == NULL) 235 return 0; 236 ie->ent.key = item.key; 237 ie->ent.data = item.data; 238 239 SLIST_INSERT_HEAD(chain, ie, link); 240 *itemp = &ie->ent; 241 head->filled++; 242 return 1; 243 } 244