1 /* 2 * Copyright (c) 1988, 1989, 1990 The Regents of the University of California. 3 * Copyright (c) 1988, 1989 by Adam de Boor 4 * Copyright (c) 1989 by Berkeley Softworks 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Adam de Boor. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * $NetBSD: hash.c,v 1.1.1.1 1999/11/19 04:30:56 mrg Exp $ 39 * $DragonFly: src/sbin/rcorder/hash.c,v 1.5 2004/12/18 21:43:40 swildner Exp $ 40 */ 41 42 #ifdef MAKE_BOOTSTRAP 43 static char rcsid[] = "$NetBSD: hash.c,v 1.1.1.1 1999/11/19 04:30:56 mrg Exp $"; 44 #else 45 #include <sys/cdefs.h> 46 #ifndef lint 47 #if 0 48 static char sccsid[] = "@(#)hash.c 8.1 (Berkeley) 6/6/93"; 49 #else 50 __RCSID("$NetBSD: hash.c,v 1.1.1.1 1999/11/19 04:30:56 mrg Exp $"); 51 #endif 52 #endif /* not lint */ 53 #endif 54 55 #include <sys/types.h> 56 57 #include <stdlib.h> 58 #include <string.h> 59 #include <unistd.h> 60 61 /* hash.c -- 62 * 63 * This module contains routines to manipulate a hash table. 64 * See hash.h for a definition of the structure of the hash 65 * table. Hash tables grow automatically as the amount of 66 * information increases. 67 */ 68 #include "sprite.h" 69 #ifndef ORDER 70 #include "make.h" 71 #endif /* ORDER */ 72 #include "hash.h" 73 #include "ealloc.h" 74 75 /* 76 * Forward references to local procedures that are used before they're 77 * defined: 78 */ 79 80 static void RebuildTable(Hash_Table *); 81 82 /* 83 * The following defines the ratio of # entries to # buckets 84 * at which we rebuild the table to make it larger. 85 */ 86 87 #define rebuildLimit 8 88 89 /* 90 *--------------------------------------------------------- 91 * 92 * Hash_InitTable -- 93 * 94 * This routine just sets up the hash table. 95 * 96 * Results: 97 * None. 98 * 99 * Side Effects: 100 * Memory is allocated for the initial bucket area. 101 * 102 *--------------------------------------------------------- 103 */ 104 105 /* 106 * Hash_Table *t; Structure to use to hold table. 107 * int numBuckets; How many buckets to create for starters. 108 * This number is rounded up to a power of 109 * two. If <= 0, a reasonable default is 110 * chosen. The table will grow in size later 111 * as needed. 112 */ 113 void 114 Hash_InitTable(Hash_Table *t, int numBuckets) 115 { 116 int i; 117 struct Hash_Entry **hp; 118 119 /* 120 * Round up the size to a power of two. 121 */ 122 if (numBuckets <= 0) 123 i = 16; 124 else { 125 for (i = 2; i < numBuckets; i <<= 1) 126 continue; 127 } 128 t->numEntries = 0; 129 t->size = i; 130 t->mask = i - 1; 131 t->bucketPtr = hp = (struct Hash_Entry **)emalloc(sizeof(*hp) * i); 132 while (--i >= 0) 133 *hp++ = NULL; 134 } 135 136 /* 137 *--------------------------------------------------------- 138 * 139 * Hash_DeleteTable -- 140 * 141 * This routine removes everything from a hash table 142 * and frees up the memory space it occupied (except for 143 * the space in the Hash_Table structure). 144 * 145 * Results: 146 * None. 147 * 148 * Side Effects: 149 * Lots of memory is freed up. 150 * 151 *--------------------------------------------------------- 152 */ 153 154 void 155 Hash_DeleteTable(Hash_Table *t) 156 { 157 struct Hash_Entry **hp, *h, *nexth = NULL; 158 int i; 159 160 for (hp = t->bucketPtr, i = t->size; --i >= 0;) { 161 for (h = *hp++; h != NULL; h = nexth) { 162 nexth = h->next; 163 free((char *)h); 164 } 165 } 166 free((char *)t->bucketPtr); 167 168 /* 169 * Set up the hash table to cause memory faults on any future access 170 * attempts until re-initialization. 171 */ 172 t->bucketPtr = NULL; 173 } 174 175 /* 176 *--------------------------------------------------------- 177 * 178 * Hash_FindEntry -- 179 * 180 * Searches a hash table for an entry corresponding to key. 181 * 182 * Results: 183 * The return value is a pointer to the entry for key, 184 * if key was present in the table. If key was not 185 * present, NULL is returned. 186 * 187 * Side Effects: 188 * None. 189 * 190 *--------------------------------------------------------- 191 */ 192 193 Hash_Entry * 194 Hash_FindEntry(Hash_Table *t, char *key) 195 { 196 Hash_Entry *e; 197 unsigned h; 198 char *p; 199 200 for (h = 0, p = key; *p;) 201 h = (h << 5) - h + *p++; 202 p = key; 203 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) 204 if (e->namehash == h && strcmp(e->name, p) == 0) 205 return (e); 206 return (NULL); 207 } 208 209 /* 210 *--------------------------------------------------------- 211 * 212 * Hash_CreateEntry -- 213 * 214 * Searches a hash table for an entry corresponding to 215 * key. If no entry is found, then one is created. 216 * 217 * Results: 218 * The return value is a pointer to the entry. If *newPtr 219 * isn't NULL, then *newPtr is filled in with TRUE if a 220 * new entry was created, and FALSE if an entry already existed 221 * with the given key. 222 * 223 * Side Effects: 224 * Memory may be allocated, and the hash buckets may be modified. 225 *--------------------------------------------------------- 226 */ 227 228 Hash_Entry * 229 Hash_CreateEntry(Hash_Table *t, char *key, Boolean *newPtr) 230 { 231 Hash_Entry *e; 232 unsigned h; 233 char *p; 234 int keylen; 235 struct Hash_Entry **hp; 236 237 /* 238 * Hash the key. As a side effect, save the length (strlen) of the 239 * key in case we need to create the entry. 240 */ 241 for (h = 0, p = key; *p;) 242 h = (h << 5) - h + *p++; 243 keylen = p - key; 244 p = key; 245 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) { 246 if (e->namehash == h && strcmp(e->name, p) == 0) { 247 if (newPtr != NULL) 248 *newPtr = FALSE; 249 return (e); 250 } 251 } 252 253 /* 254 * The desired entry isn't there. Before allocating a new entry, 255 * expand the table if necessary (and this changes the resulting 256 * bucket chain). 257 */ 258 if (t->numEntries >= rebuildLimit * t->size) 259 RebuildTable(t); 260 e = (Hash_Entry *) emalloc(sizeof(*e) + keylen); 261 hp = &t->bucketPtr[h & t->mask]; 262 e->next = *hp; 263 *hp = e; 264 e->clientData = NULL; 265 e->namehash = h; 266 strcpy(e->name, p); 267 t->numEntries++; 268 269 if (newPtr != NULL) 270 *newPtr = TRUE; 271 return (e); 272 } 273 274 /* 275 *--------------------------------------------------------- 276 * 277 * Hash_DeleteEntry -- 278 * 279 * Delete the given hash table entry and free memory associated with 280 * it. 281 * 282 * Results: 283 * None. 284 * 285 * Side Effects: 286 * Hash chain that entry lives in is modified and memory is freed. 287 * 288 *--------------------------------------------------------- 289 */ 290 291 void 292 Hash_DeleteEntry(Hash_Table *t, Hash_Entry *e) 293 { 294 Hash_Entry **hp, *p; 295 296 if (e == NULL) 297 return; 298 for (hp = &t->bucketPtr[e->namehash & t->mask]; 299 (p = *hp) != NULL; hp = &p->next) { 300 if (p == e) { 301 *hp = p->next; 302 free((char *)p); 303 t->numEntries--; 304 return; 305 } 306 } 307 write(2, "bad call to Hash_DeleteEntry\n", 29); 308 abort(); 309 } 310 311 /* 312 *--------------------------------------------------------- 313 * 314 * Hash_EnumFirst -- 315 * This procedure sets things up for a complete search 316 * of all entries recorded in the hash table. 317 * 318 * Results: 319 * The return value is the address of the first entry in 320 * the hash table, or NULL if the table is empty. 321 * 322 * Side Effects: 323 * The information in searchPtr is initialized so that successive 324 * calls to Hash_Next will return successive HashEntry's 325 * from the table. 326 * 327 *--------------------------------------------------------- 328 */ 329 330 Hash_Entry * 331 Hash_EnumFirst(Hash_Table *t, Hash_Search *searchPtr) 332 { 333 searchPtr->tablePtr = t; 334 searchPtr->nextIndex = 0; 335 searchPtr->hashEntryPtr = NULL; 336 return Hash_EnumNext(searchPtr); 337 } 338 339 /* 340 *--------------------------------------------------------- 341 * 342 * Hash_EnumNext -- 343 * This procedure returns successive entries in the hash table. 344 * 345 * Results: 346 * The return value is a pointer to the next HashEntry 347 * in the table, or NULL when the end of the table is 348 * reached. 349 * 350 * Side Effects: 351 * The information in searchPtr is modified to advance to the 352 * next entry. 353 * 354 *--------------------------------------------------------- 355 */ 356 357 Hash_Entry * 358 Hash_EnumNext(Hash_Search *searchPtr) 359 { 360 Hash_Entry *e; 361 Hash_Table *t = searchPtr->tablePtr; 362 363 /* 364 * The hashEntryPtr field points to the most recently returned 365 * entry, or is nil if we are starting up. If not nil, we have 366 * to start at the next one in the chain. 367 */ 368 e = searchPtr->hashEntryPtr; 369 if (e != NULL) 370 e = e->next; 371 /* 372 * If the chain ran out, or if we are starting up, we need to 373 * find the next nonempty chain. 374 */ 375 while (e == NULL) { 376 if (searchPtr->nextIndex >= t->size) 377 return (NULL); 378 e = t->bucketPtr[searchPtr->nextIndex++]; 379 } 380 searchPtr->hashEntryPtr = e; 381 return (e); 382 } 383 384 /* 385 *--------------------------------------------------------- 386 * 387 * RebuildTable -- 388 * This local routine makes a new hash table that 389 * is larger than the old one. 390 * 391 * Results: 392 * None. 393 * 394 * Side Effects: 395 * The entire hash table is moved, so any bucket numbers 396 * from the old table are invalid. 397 * 398 *--------------------------------------------------------- 399 */ 400 401 static void 402 RebuildTable(Hash_Table *t) 403 { 404 Hash_Entry *e, *next = NULL, **hp, **xp; 405 int i, mask; 406 Hash_Entry **oldhp; 407 int oldsize; 408 409 oldhp = t->bucketPtr; 410 oldsize = i = t->size; 411 i <<= 1; 412 t->size = i; 413 t->mask = mask = i - 1; 414 t->bucketPtr = hp = (struct Hash_Entry **) emalloc(sizeof(*hp) * i); 415 while (--i >= 0) 416 *hp++ = NULL; 417 for (hp = oldhp, i = oldsize; --i >= 0;) { 418 for (e = *hp++; e != NULL; e = next) { 419 next = e->next; 420 xp = &t->bucketPtr[e->namehash & mask]; 421 e->next = *xp; 422 *xp = e; 423 } 424 } 425 free((char *)oldhp); 426 } 427