contrib/bind/lib/isc/symtab.c

   1 /*
   2  * Copyright (C) 2004, 2005, 2007  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 1996-2001  Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and/or distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  10  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  11  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  12  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  13  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  14  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  15  * PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 /* $Id: symtab.c,v 1.30 2007/06/19 23:47:17 tbox Exp $ */
  19
  20 /*! \file */
  21
  22 #include <config.h>
  23
  24 #include <ctype.h>
  25
  26 #include <isc/magic.h>
  27 #include <isc/mem.h>
  28 #include <isc/string.h>
  29 #include <isc/symtab.h>
  30 #include <isc/util.h>
  31
  32 typedef struct elt {
  33         char *                          key;
  34         unsigned int                    type;
  35         isc_symvalue_t                  value;
  36         LINK(struct elt)                link;
  37 } elt_t;
  38
  39 typedef LIST(elt_t)                     eltlist_t;
  40
  41 #define SYMTAB_MAGIC                    ISC_MAGIC('S', 'y', 'm', 'T')
  42 #define VALID_SYMTAB(st)                ISC_MAGIC_VALID(st, SYMTAB_MAGIC)
  43
  44 struct isc_symtab {
  45         /* Unlocked. */
  46         unsigned int                    magic;
  47         isc_mem_t *                     mctx;
  48         unsigned int                    size;
  49         eltlist_t *                     table;
  50         isc_symtabaction_t              undefine_action;
  51         void *                          undefine_arg;
  52         isc_boolean_t                   case_sensitive;
  53 };
  54
  55 isc_result_t
  56 isc_symtab_create(isc_mem_t *mctx, unsigned int size,
  57                   isc_symtabaction_t undefine_action,
  58                   void *undefine_arg,
  59                   isc_boolean_t case_sensitive,
  60                   isc_symtab_t **symtabp)
  61 {
  62         isc_symtab_t *symtab;
  63         unsigned int i;
  64
  65         REQUIRE(mctx != NULL);
  66         REQUIRE(symtabp != NULL && *symtabp == NULL);
  67         REQUIRE(size > 0);      /* Should be prime. */
  68
  69         symtab = (isc_symtab_t *)isc_mem_get(mctx, sizeof(*symtab));
  70         if (symtab == NULL)
  71                 return (ISC_R_NOMEMORY);
  72         symtab->table = (eltlist_t *)isc_mem_get(mctx,
  73                                                  size * sizeof(eltlist_t));
  74         if (symtab->table == NULL) {
  75                 isc_mem_put(mctx, symtab, sizeof(*symtab));
  76                 return (ISC_R_NOMEMORY);
  77         }
  78         for (i = 0; i < size; i++)
  79                 INIT_LIST(symtab->table[i]);
  80         symtab->mctx = mctx;
  81         symtab->size = size;
  82         symtab->undefine_action = undefine_action;
  83         symtab->undefine_arg = undefine_arg;
  84         symtab->case_sensitive = case_sensitive;
  85         symtab->magic = SYMTAB_MAGIC;
  86
  87         *symtabp = symtab;
  88
  89         return (ISC_R_SUCCESS);
  90 }
  91
  92 void
  93 isc_symtab_destroy(isc_symtab_t **symtabp) {
  94         isc_symtab_t *symtab;
  95         unsigned int i;
  96         elt_t *elt, *nelt;
  97
  98         REQUIRE(symtabp != NULL);
  99         symtab = *symtabp;
 100         REQUIRE(VALID_SYMTAB(symtab));
 101
 102         for (i = 0; i < symtab->size; i++) {
 103                 for (elt = HEAD(symtab->table[i]); elt != NULL; elt = nelt) {
 104                         nelt = NEXT(elt, link);
 105                         if (symtab->undefine_action != NULL)
 106                                (symtab->undefine_action)(elt->key,
 107                                                          elt->type,
 108                                                          elt->value,
 109                                                          symtab->undefine_arg);
 110                         isc_mem_put(symtab->mctx, elt, sizeof(*elt));
 111                 }
 112         }
 113         isc_mem_put(symtab->mctx, symtab->table,
 114                     symtab->size * sizeof(eltlist_t));
 115         symtab->magic = 0;
 116         isc_mem_put(symtab->mctx, symtab, sizeof(*symtab));
 117
 118         *symtabp = NULL;
 119 }
 120
 121 static inline unsigned int
 122 hash(const char *key, isc_boolean_t case_sensitive) {
 123         const char *s;
 124         unsigned int h = 0;
 125         int c;
 126
 127         /*
 128          * This hash function is similar to the one Ousterhout
 129          * uses in Tcl.
 130          */
 131
 132         if (case_sensitive) {
 133                 for (s = key; *s != '\0'; s++) {
 134                         h += (h << 3) + *s;
 135                 }
 136         } else {
 137                 for (s = key; *s != '\0'; s++) {
 138                         c = *s;
 139                         c = tolower((unsigned char)c);
 140                         h += (h << 3) + c;
 141                 }
 142         }
 143
 144         return (h);
 145 }
 146
 147 #define FIND(s, k, t, b, e) \
 148         b = hash((k), (s)->case_sensitive) % (s)->size; \
 149         if ((s)->case_sensitive) { \
 150                 for (e = HEAD((s)->table[b]); e != NULL; e = NEXT(e, link)) { \
 151                         if (((t) == 0 || e->type == (t)) && \
 152                             strcmp(e->key, (k)) == 0) \
 153                                 break; \
 154                 } \
 155         } else { \
 156                 for (e = HEAD((s)->table[b]); e != NULL; e = NEXT(e, link)) { \
 157                         if (((t) == 0 || e->type == (t)) && \
 158                             strcasecmp(e->key, (k)) == 0) \
 159                                 break; \
 160                 } \
 161         }
 162
 163 isc_result_t
 164 isc_symtab_lookup(isc_symtab_t *symtab, const char *key, unsigned int type,
 165                   isc_symvalue_t *value)
 166 {
 167         unsigned int bucket;
 168         elt_t *elt;
 169
 170         REQUIRE(VALID_SYMTAB(symtab));
 171         REQUIRE(key != NULL);
 172
 173         FIND(symtab, key, type, bucket, elt);
 174
 175         if (elt == NULL)
 176                 return (ISC_R_NOTFOUND);
 177
 178         if (value != NULL)
 179                 *value = elt->value;
 180
 181         return (ISC_R_SUCCESS);
 182 }
 183
 184 isc_result_t
 185 isc_symtab_define(isc_symtab_t *symtab, const char *key, unsigned int type,
 186                   isc_symvalue_t value, isc_symexists_t exists_policy)
 187 {
 188         unsigned int bucket;
 189         elt_t *elt;
 190
 191         REQUIRE(VALID_SYMTAB(symtab));
 192         REQUIRE(key != NULL);
 193         REQUIRE(type != 0);
 194
 195         FIND(symtab, key, type, bucket, elt);
 196
 197         if (exists_policy != isc_symexists_add && elt != NULL) {
 198                 if (exists_policy == isc_symexists_reject)
 199                         return (ISC_R_EXISTS);
 200                 INSIST(exists_policy == isc_symexists_replace);
 201                 UNLINK(symtab->table[bucket], elt, link);
 202                 if (symtab->undefine_action != NULL)
 203                         (symtab->undefine_action)(elt->key, elt->type,
 204                                                   elt->value,
 205                                                   symtab->undefine_arg);
 206         } else {
 207                 elt = (elt_t *)isc_mem_get(symtab->mctx, sizeof(*elt));
 208                 if (elt == NULL)
 209                         return (ISC_R_NOMEMORY);
 210                 ISC_LINK_INIT(elt, link);
 211         }
 212
 213         /*
 214          * Though the "key" can be const coming in, it is not stored as const
 215          * so that the calling program can easily have writable access to
 216          * it in its undefine_action function.  In the event that it *was*
 217          * truly const coming in and then the caller modified it anyway ...
 218          * well, don't do that!
 219          */
 220         DE_CONST(key, elt->key);
 221         elt->type = type;
 222         elt->value = value;
 223
 224         /*
 225          * We prepend so that the most recent definition will be found.
 226          */
 227         PREPEND(symtab->table[bucket], elt, link);
 228
 229         return (ISC_R_SUCCESS);
 230 }
 231
 232 isc_result_t
 233 isc_symtab_undefine(isc_symtab_t *symtab, const char *key, unsigned int type) {
 234         unsigned int bucket;
 235         elt_t *elt;
 236
 237         REQUIRE(VALID_SYMTAB(symtab));
 238         REQUIRE(key != NULL);
 239
 240         FIND(symtab, key, type, bucket, elt);
 241
 242         if (elt == NULL)
 243                 return (ISC_R_NOTFOUND);
 244
 245         if (symtab->undefine_action != NULL)
 246                 (symtab->undefine_action)(elt->key, elt->type,
 247                                           elt->value, symtab->undefine_arg);
 248         UNLINK(symtab->table[bucket], elt, link);
 249         isc_mem_put(symtab->mctx, elt, sizeof(*elt));
 250
 251         return (ISC_R_SUCCESS);
 252 }