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 1.1.2.2 2001/10/02 11:22:56 ru 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/cdefs.h> 52 53 #include <sys/types.h> 54 #include <sys/queue.h> 55 #include <errno.h> 56 #include <search.h> 57 #include <stdlib.h> 58 #include <string.h> 59 60 /* 61 * DO NOT MAKE THIS STRUCTURE LARGER THAN 32 BYTES (4 ptrs on 64-bit 62 * ptr machine) without adjusting MAX_BUCKETS_LG2 below. 63 */ 64 struct internal_entry { 65 SLIST_ENTRY(internal_entry) link; 66 ENTRY ent; 67 }; 68 SLIST_HEAD(internal_head, internal_entry); 69 70 #define MIN_BUCKETS_LG2 4 71 #define MIN_BUCKETS (1 << MIN_BUCKETS_LG2) 72 73 /* 74 * max * sizeof internal_entry must fit into size_t. 75 * assumes internal_entry is <= 32 (2^5) bytes. 76 */ 77 #define MAX_BUCKETS_LG2 (sizeof (size_t) * 8 - 1 - 5) 78 #define MAX_BUCKETS ((size_t)1 << MAX_BUCKETS_LG2) 79 80 /* Default hash function, from db/hash/hash_func.c */ 81 extern u_int32_t (*__default_hash)(const void *, size_t); 82 83 static struct internal_head *htable; 84 static size_t htablesize; 85 86 int 87 hcreate(size_t nel) 88 { 89 size_t idx; 90 unsigned int p2; 91 92 /* Make sure this this isn't called when a table already exists. */ 93 if (htable != NULL) { 94 errno = EINVAL; 95 return 0; 96 } 97 98 /* If nel is too small, make it min sized. */ 99 if (nel < MIN_BUCKETS) 100 nel = MIN_BUCKETS; 101 102 /* If it's too large, cap it. */ 103 if (nel > MAX_BUCKETS) 104 nel = MAX_BUCKETS; 105 106 /* If it's is not a power of two in size, round up. */ 107 if ((nel & (nel - 1)) != 0) { 108 for (p2 = 0; nel != 0; p2++) 109 nel >>= 1; 110 nel = 1 << p2; 111 } 112 113 /* Allocate the table. */ 114 htablesize = nel; 115 htable = malloc(htablesize * sizeof htable[0]); 116 if (htable == NULL) { 117 errno = ENOMEM; 118 return 0; 119 } 120 121 /* Initialize it. */ 122 for (idx = 0; idx < htablesize; idx++) 123 SLIST_INIT(&htable[idx]); 124 125 return 1; 126 } 127 128 void 129 hdestroy(void) 130 { 131 struct internal_entry *ie; 132 size_t idx; 133 134 if (htable == NULL) 135 return; 136 137 for (idx = 0; idx < htablesize; idx++) { 138 while (!SLIST_EMPTY(&htable[idx])) { 139 ie = SLIST_FIRST(&htable[idx]); 140 SLIST_REMOVE_HEAD(&htable[idx], link); 141 free(ie->ent.key); 142 free(ie); 143 } 144 } 145 free(htable); 146 htable = NULL; 147 } 148 149 ENTRY * 150 hsearch(ENTRY item, ACTION action) 151 { 152 struct internal_head *head; 153 struct internal_entry *ie; 154 uint32_t hashval; 155 size_t len; 156 157 len = strlen(item.key); 158 hashval = (*__default_hash)(item.key, len); 159 160 head = &htable[hashval & (htablesize - 1)]; 161 ie = SLIST_FIRST(head); 162 while (ie != NULL) { 163 if (strcmp(ie->ent.key, item.key) == 0) 164 break; 165 ie = SLIST_NEXT(ie, link); 166 } 167 168 if (ie != NULL) 169 return &ie->ent; 170 else if (action == FIND) 171 return NULL; 172 173 ie = malloc(sizeof *ie); 174 if (ie == NULL) 175 return NULL; 176 ie->ent.key = item.key; 177 ie->ent.data = item.data; 178 179 SLIST_INSERT_HEAD(head, ie, link); 180 return &ie->ent; 181 } 182