1 /* 2 * Copyright (c) 2001 Christopher G. Demetriou 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed for the 16 * NetBSD Project. See http://www.netbsd.org/ for 17 * information about NetBSD. 18 * 4. The name of the author may not be used to endorse or promote products 19 * derived from this software without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 * 32 * <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>> 33 * 34 * $NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $ 35 * $FreeBSD: src/lib/libc/stdlib/hcreate.c,v 1.4 2008/07/06 11:31:20 danger Exp $ 36 * $DragonFly: src/lib/libc/stdlib/hcreate.c,v 1.2 2003/06/17 04:26:46 dillon Exp $ 37 */ 38 39 /* 40 * hcreate() / hsearch() / hdestroy() 41 * 42 * SysV/XPG4 hash table functions. 43 * 44 * Implementation done based on NetBSD manual page and Solaris manual page, 45 * plus my own personal experience about how they're supposed to work. 46 * 47 * I tried to look at Knuth (as cited by the Solaris manual page), but 48 * nobody had a copy in the office, so... 49 */ 50 51 #include <sys/types.h> 52 #include <sys/queue.h> 53 #include <errno.h> 54 #include <search.h> 55 #include <stdlib.h> 56 #include <string.h> 57 58 /* 59 * DO NOT MAKE THIS STRUCTURE LARGER THAN 32 BYTES (4 ptrs on 64-bit 60 * ptr machine) without adjusting MAX_BUCKETS_LG2 below. 61 */ 62 struct internal_entry { 63 SLIST_ENTRY(internal_entry) link; 64 ENTRY ent; 65 }; 66 SLIST_HEAD(internal_head, internal_entry); 67 68 #define MIN_BUCKETS_LG2 4 69 #define MIN_BUCKETS (1 << MIN_BUCKETS_LG2) 70 71 /* 72 * max * sizeof internal_entry must fit into size_t. 73 * assumes internal_entry is <= 32 (2^5) bytes. 74 */ 75 #define MAX_BUCKETS_LG2 (sizeof (size_t) * 8 - 1 - 5) 76 #define MAX_BUCKETS ((size_t)1 << MAX_BUCKETS_LG2) 77 78 /* Default hash function, from db/hash/hash_func.c */ 79 extern u_int32_t (*__default_hash)(const void *, size_t); 80 81 static struct internal_head *htable; 82 static size_t htablesize; 83 84 int 85 hcreate(size_t nel) 86 { 87 size_t idx; 88 unsigned int p2; 89 90 /* Make sure this is not called when a table already exists. */ 91 if (htable != NULL) { 92 errno = EINVAL; 93 return 0; 94 } 95 96 /* If nel is too small, make it min sized. */ 97 if (nel < MIN_BUCKETS) 98 nel = MIN_BUCKETS; 99 100 /* If it is too large, cap it. */ 101 if (nel > MAX_BUCKETS) 102 nel = MAX_BUCKETS; 103 104 /* If it is not a power of two in size, round up. */ 105 if ((nel & (nel - 1)) != 0) { 106 for (p2 = 0; nel != 0; p2++) 107 nel >>= 1; 108 nel = 1 << p2; 109 } 110 111 /* Allocate the table. */ 112 htablesize = nel; 113 htable = malloc(htablesize * sizeof htable[0]); 114 if (htable == NULL) { 115 errno = ENOMEM; 116 return 0; 117 } 118 119 /* Initialize it. */ 120 for (idx = 0; idx < htablesize; idx++) 121 SLIST_INIT(&htable[idx]); 122 123 return 1; 124 } 125 126 void 127 hdestroy(void) 128 { 129 struct internal_entry *ie; 130 size_t idx; 131 132 if (htable == NULL) 133 return; 134 135 for (idx = 0; idx < htablesize; idx++) { 136 while (!SLIST_EMPTY(&htable[idx])) { 137 ie = SLIST_FIRST(&htable[idx]); 138 SLIST_REMOVE_HEAD(&htable[idx], link); 139 free(ie->ent.key); 140 free(ie); 141 } 142 } 143 free(htable); 144 htable = NULL; 145 } 146 147 ENTRY * 148 hsearch(ENTRY item, ACTION action) 149 { 150 struct internal_head *head; 151 struct internal_entry *ie; 152 uint32_t hashval; 153 size_t len; 154 155 len = strlen(item.key); 156 hashval = (*__default_hash)(item.key, len); 157 158 head = &htable[hashval & (htablesize - 1)]; 159 ie = SLIST_FIRST(head); 160 while (ie != NULL) { 161 if (strcmp(ie->ent.key, item.key) == 0) 162 break; 163 ie = SLIST_NEXT(ie, link); 164 } 165 166 if (ie != NULL) 167 return &ie->ent; 168 else if (action == FIND) 169 return NULL; 170 171 ie = malloc(sizeof *ie); 172 if (ie == NULL) 173 return NULL; 174 ie->ent.key = item.key; 175 ie->ent.data = item.data; 176 177 SLIST_INSERT_HEAD(head, ie, link); 178 return &ie->ent; 179 } 180