1 /* $NetBSD: symtab.c,v 1.7 2025/01/26 16:25:38 christos Exp $ */ 2 3 /* 4 * Copyright (C) Internet Systems Consortium, Inc. ("ISC") 5 * 6 * SPDX-License-Identifier: MPL-2.0 7 * 8 * This Source Code Form is subject to the terms of the Mozilla Public 9 * License, v. 2.0. If a copy of the MPL was not distributed with this 10 * file, you can obtain one at https://mozilla.org/MPL/2.0/. 11 * 12 * See the COPYRIGHT file distributed with this work for additional 13 * information regarding copyright ownership. 14 */ 15 16 /*! \file */ 17 18 #include <stdbool.h> 19 20 #include <isc/ascii.h> 21 #include <isc/magic.h> 22 #include <isc/mem.h> 23 #include <isc/string.h> 24 #include <isc/symtab.h> 25 #include <isc/util.h> 26 27 typedef struct elt { 28 char *key; 29 unsigned int type; 30 isc_symvalue_t value; 31 LINK(struct elt) link; 32 } elt_t; 33 34 typedef LIST(elt_t) eltlist_t; 35 36 #define SYMTAB_MAGIC ISC_MAGIC('S', 'y', 'm', 'T') 37 #define VALID_SYMTAB(st) ISC_MAGIC_VALID(st, SYMTAB_MAGIC) 38 39 struct isc_symtab { 40 /* Unlocked. */ 41 unsigned int magic; 42 isc_mem_t *mctx; 43 unsigned int size; 44 unsigned int count; 45 unsigned int maxload; 46 eltlist_t *table; 47 isc_symtabaction_t undefine_action; 48 void *undefine_arg; 49 bool case_sensitive; 50 }; 51 52 isc_result_t 53 isc_symtab_create(isc_mem_t *mctx, unsigned int size, 54 isc_symtabaction_t undefine_action, void *undefine_arg, 55 bool case_sensitive, isc_symtab_t **symtabp) { 56 isc_symtab_t *symtab; 57 unsigned int i; 58 59 REQUIRE(mctx != NULL); 60 REQUIRE(symtabp != NULL && *symtabp == NULL); 61 REQUIRE(size > 0); /* Should be prime. */ 62 63 symtab = isc_mem_get(mctx, sizeof(*symtab)); 64 65 symtab->mctx = NULL; 66 isc_mem_attach(mctx, &symtab->mctx); 67 symtab->table = isc_mem_cget(mctx, size, sizeof(eltlist_t)); 68 for (i = 0; i < size; i++) { 69 INIT_LIST(symtab->table[i]); 70 } 71 symtab->size = size; 72 symtab->count = 0; 73 symtab->maxload = size * 3 / 4; 74 symtab->undefine_action = undefine_action; 75 symtab->undefine_arg = undefine_arg; 76 symtab->case_sensitive = case_sensitive; 77 symtab->magic = SYMTAB_MAGIC; 78 79 *symtabp = symtab; 80 81 return ISC_R_SUCCESS; 82 } 83 84 void 85 isc_symtab_destroy(isc_symtab_t **symtabp) { 86 isc_symtab_t *symtab; 87 unsigned int i; 88 elt_t *elt, *nelt; 89 90 REQUIRE(symtabp != NULL); 91 symtab = *symtabp; 92 *symtabp = NULL; 93 REQUIRE(VALID_SYMTAB(symtab)); 94 95 for (i = 0; i < symtab->size; i++) { 96 for (elt = HEAD(symtab->table[i]); elt != NULL; elt = nelt) { 97 nelt = NEXT(elt, link); 98 if (symtab->undefine_action != NULL) { 99 (symtab->undefine_action)(elt->key, elt->type, 100 elt->value, 101 symtab->undefine_arg); 102 } 103 isc_mem_put(symtab->mctx, elt, sizeof(*elt)); 104 } 105 } 106 isc_mem_cput(symtab->mctx, symtab->table, symtab->size, 107 sizeof(eltlist_t)); 108 symtab->magic = 0; 109 isc_mem_putanddetach(&symtab->mctx, symtab, sizeof(*symtab)); 110 } 111 112 static unsigned int 113 hash(const char *key, bool case_sensitive) { 114 const char *s; 115 unsigned int h = 0; 116 117 /* 118 * This hash function is similar to the one Ousterhout 119 * uses in Tcl. 120 */ 121 122 if (case_sensitive) { 123 for (s = key; *s != '\0'; s++) { 124 h += (h << 3) + *s; 125 } 126 } else { 127 for (s = key; *s != '\0'; s++) { 128 h += (h << 3) + isc_ascii_tolower(*s); 129 } 130 } 131 132 return h; 133 } 134 135 #define FIND(s, k, t, b, e) \ 136 b = hash((k), (s)->case_sensitive) % (s)->size; \ 137 if ((s)->case_sensitive) { \ 138 for (e = HEAD((s)->table[b]); e != NULL; e = NEXT(e, link)) { \ 139 if (((t) == 0 || e->type == (t)) && \ 140 strcmp(e->key, (k)) == 0) \ 141 break; \ 142 } \ 143 } else { \ 144 for (e = HEAD((s)->table[b]); e != NULL; e = NEXT(e, link)) { \ 145 if (((t) == 0 || e->type == (t)) && \ 146 strcasecmp(e->key, (k)) == 0) \ 147 break; \ 148 } \ 149 } 150 151 isc_result_t 152 isc_symtab_lookup(isc_symtab_t *symtab, const char *key, unsigned int type, 153 isc_symvalue_t *value) { 154 unsigned int bucket; 155 elt_t *elt; 156 157 REQUIRE(VALID_SYMTAB(symtab)); 158 REQUIRE(key != NULL); 159 160 FIND(symtab, key, type, bucket, elt); 161 162 if (elt == NULL) { 163 return ISC_R_NOTFOUND; 164 } 165 166 SET_IF_NOT_NULL(value, elt->value); 167 168 return ISC_R_SUCCESS; 169 } 170 171 static void 172 grow_table(isc_symtab_t *symtab) { 173 eltlist_t *newtable; 174 unsigned int i, newsize, newmax; 175 176 REQUIRE(symtab != NULL); 177 178 newsize = symtab->size * 2; 179 newmax = newsize * 3 / 4; 180 INSIST(newsize > 0U && newmax > 0U); 181 182 newtable = isc_mem_cget(symtab->mctx, newsize, sizeof(eltlist_t)); 183 184 for (i = 0; i < newsize; i++) { 185 INIT_LIST(newtable[i]); 186 } 187 188 for (i = 0; i < symtab->size; i++) { 189 elt_t *elt, *nelt; 190 191 for (elt = HEAD(symtab->table[i]); elt != NULL; elt = nelt) { 192 unsigned int hv; 193 194 nelt = NEXT(elt, link); 195 196 UNLINK(symtab->table[i], elt, link); 197 hv = hash(elt->key, symtab->case_sensitive); 198 APPEND(newtable[hv % newsize], elt, link); 199 } 200 } 201 202 isc_mem_cput(symtab->mctx, symtab->table, symtab->size, 203 sizeof(eltlist_t)); 204 205 symtab->table = newtable; 206 symtab->size = newsize; 207 symtab->maxload = newmax; 208 } 209 210 isc_result_t 211 isc_symtab_define(isc_symtab_t *symtab, const char *key, unsigned int type, 212 isc_symvalue_t value, isc_symexists_t exists_policy) { 213 unsigned int bucket; 214 elt_t *elt; 215 216 REQUIRE(VALID_SYMTAB(symtab)); 217 REQUIRE(key != NULL); 218 REQUIRE(type != 0); 219 220 FIND(symtab, key, type, bucket, elt); 221 222 if (exists_policy != isc_symexists_add && elt != NULL) { 223 if (exists_policy == isc_symexists_reject) { 224 return ISC_R_EXISTS; 225 } 226 INSIST(exists_policy == isc_symexists_replace); 227 UNLINK(symtab->table[bucket], elt, link); 228 if (symtab->undefine_action != NULL) { 229 (symtab->undefine_action)(elt->key, elt->type, 230 elt->value, 231 symtab->undefine_arg); 232 } 233 } else { 234 elt = isc_mem_get(symtab->mctx, sizeof(*elt)); 235 ISC_LINK_INIT(elt, link); 236 symtab->count++; 237 } 238 239 /* 240 * Though the "key" can be const coming in, it is not stored as const 241 * so that the calling program can easily have writable access to 242 * it in its undefine_action function. In the event that it *was* 243 * truly const coming in and then the caller modified it anyway ... 244 * well, don't do that! 245 */ 246 elt->key = UNCONST(key); 247 elt->type = type; 248 elt->value = value; 249 250 /* 251 * We prepend so that the most recent definition will be found. 252 */ 253 PREPEND(symtab->table[bucket], elt, link); 254 255 if (symtab->count > symtab->maxload) { 256 grow_table(symtab); 257 } 258 259 return ISC_R_SUCCESS; 260 } 261 262 isc_result_t 263 isc_symtab_undefine(isc_symtab_t *symtab, const char *key, unsigned int type) { 264 unsigned int bucket; 265 elt_t *elt; 266 267 REQUIRE(VALID_SYMTAB(symtab)); 268 REQUIRE(key != NULL); 269 270 FIND(symtab, key, type, bucket, elt); 271 272 if (elt == NULL) { 273 return ISC_R_NOTFOUND; 274 } 275 276 if (symtab->undefine_action != NULL) { 277 (symtab->undefine_action)(elt->key, elt->type, elt->value, 278 symtab->undefine_arg); 279 } 280 UNLINK(symtab->table[bucket], elt, link); 281 isc_mem_put(symtab->mctx, elt, sizeof(*elt)); 282 symtab->count--; 283 284 return ISC_R_SUCCESS; 285 } 286 287 unsigned int 288 isc_symtab_count(isc_symtab_t *symtab) { 289 REQUIRE(VALID_SYMTAB(symtab)); 290 return symtab->count; 291 } 292