gonzui

    1: /*      $OpenBSD: hcreate.c,v 1.4 2007/09/02 15:19:17 deraadt Exp $  */
    2: /*      $NetBSD: hcreate.c,v 1.5 2004/04/23 02:48:12 simonb Exp $    */
    3: 
    4: /*
    5:  * Copyright (c) 2001 Christopher G. Demetriou
    6:  * All rights reserved.
    7:  * 
    8:  * Redistribution and use in source and binary forms, with or without
    9:  * modification, are permitted provided that the following conditions
   10:  * are met:
   11:  * 1. Redistributions of source code must retain the above copyright
   12:  *    notice, this list of conditions and the following disclaimer.
   13:  * 2. Redistributions in binary form must reproduce the above copyright
   14:  *    notice, this list of conditions and the following disclaimer in the
   15:  *    documentation and/or other materials provided with the distribution.
   16:  * 3. The name of the author may not be used to endorse or promote products
   17:  *    derived from this software without specific prior written permission.
   18:  * 
   19:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   20:  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   21:  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   22:  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   23:  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   24:  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   25:  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   26:  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   27:  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   28:  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   29:  * 
   30:  * <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>>
   31:  */
   32: 
   33: /*
   34:  * hcreate_r() / hsearch() / hdestroy(, struct hsearch_data *htab)
   35:  *
   36:  * SysV/XPG4 hash table functions.
   37:  *
   38:  * Implementation done based on NetBSD manual page and Solaris manual page,
   39:  * plus my own personal experience about how they're supposed to work.
   40:  *
   41:  * I tried to look at Knuth (as cited by the Solaris manual page), but
   42:  * nobody had a copy in the office, so...
   43:  */
   44: 
   45: #include "namespace.h"
   46: #include <assert.h>
   47: #include <errno.h>
   48: #include <inttypes.h>
   49: #include <search.h>
   50: #include <stdlib.h>
   51: #include <string.h>
   52: #include <sys/queue.h>
   53: 
   54: #ifndef _DIAGASSERT
   55: #define _DIAGASSERT(x)
   56: #endif
   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: struct hsearch_data
   82: {struct internal_head *table; size_t size;};
   83: 
   84: int
   85: hcreate_r(size_t nel, struct hsearch_data *htab)
   86: {
   87:         size_t idx;
   88:         unsigned int p2;
   89: 
   90:         /* Make sure this isn't called when a table already exists. */
   91:         _DIAGASSERT(htab->table == NULL);
   92:         if (htab->table != NULL) {
   93:                 /*errno = EINVAL*/;
   94:                 return 0;
   95:         }
   96: 
   97:         /* If nel is too small, make it min sized. */
   98:         if (nel < MIN_BUCKETS)
   99:                 nel = MIN_BUCKETS;
  100: 
  101:         /* If it's too large, cap it. */
  102:         if (nel > MAX_BUCKETS)
  103:                 nel = MAX_BUCKETS;
  104: 
  105:         /* If it's is not a power of two in size, round up. */
  106:         if ((nel & (nel - 1)) != 0) {
  107:                 for (p2 = 0; nel != 0; p2++)
  108:                         nel >>= 1;
  109:                 _DIAGASSERT(p2 <= MAX_BUCKETS_LG2);
  110:                 nel = 1 << p2;
  111:         }
  112:         
  113:         /* Allocate the table. */
  114:         htab->size = nel;
  115:         htab->table = calloc(htab->size, sizeof htab->table[0]);
  116:         if (htab->table == NULL) {
  117:                 /*errno = ENOMEM*/;
  118:                 return 0;
  119:         }
  120: 
  121:         /* Initialize it. */
  122:         for (idx = 0; idx < htab->size; idx++)
  123:                 SLIST_INIT(&htab->table[idx]);
  124: 
  125:         return 1;
  126: }
  127: 
  128: void
  129: hdestroy_r(struct hsearch_data *htab)
  130: {
  131:         struct internal_entry *ie;
  132:         size_t idx;
  133: 
  134:         _DIAGASSERT(htab->table != NULL);
  135:         if (htab->table == NULL)
  136:                 return;
  137: 
  138:         for (idx = 0; idx < htab->size; idx++) {
  139:                 while (!SLIST_EMPTY(&htab->table[idx])) {
  140:                         ie = SLIST_FIRST(&htab->table[idx]);
  141:                         SLIST_REMOVE_HEAD(&htab->table[idx], link);
  142:                         //free(ie->ent.key);
  143:                         free(ie);
  144:                 }
  145:         }
  146:         free(htab->table);
  147:         htab->table = NULL;
  148: }
  149: 
  150: int
  151: hsearch_r(ENTRY item, ACTION action, ENTRY **result, struct hsearch_data *htab)
  152: {
  153:         struct internal_head *head;
  154:         struct internal_entry *ie;
  155:         uint32_t hashval;
  156:         size_t len;
  157: 
  158:         _DIAGASSERT(htab->table != NULL);
  159:         _DIAGASSERT(item.key != NULL);
  160:         _DIAGASSERT(action == ENTER || action == FIND);
  161: 
  162:         len = strlen(item.key);
  163:         hashval = (*__default_hash)(item.key, len);
  164: 
  165:         head = &htab->table[hashval & (htab->size - 1)];
  166:         ie = SLIST_FIRST(head);
  167:         while (ie != NULL) {
  168:                 if (strcmp(ie->ent.key, item.key) == 0)
  169:                         break;
  170:                 ie = SLIST_NEXT(ie, link);
  171:         }
  172: 
  173:         if (ie != NULL)
  174:                 return (*result = &ie->ent), 1;
  175:         else if (action == FIND)
  176:                 return 0;
  177: 
  178:         ie = malloc(sizeof *ie);
  179:         if (ie == NULL)
  180:                 return 0;
  181:         ie->ent.key = item.key;
  182:         ie->ent.data = item.data;
  183: 
  184:         SLIST_INSERT_HEAD(head, ie, link);
  185:         return (*result = &ie->ent), 1;
  186: }