/* $NetBSD: symtab.c,v 1.1.2.2 2024/02/24 13:07:22 martin Exp $ */ /* * Copyright (C) Internet Systems Consortium, Inc. ("ISC") * * SPDX-License-Identifier: MPL-2.0 * * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, you can obtain one at https://mozilla.org/MPL/2.0/. * * See the COPYRIGHT file distributed with this work for additional * information regarding copyright ownership. */ /*! \file */ #include #include #include #include #include #include #include typedef struct elt { char *key; unsigned int type; isc_symvalue_t value; LINK(struct elt) link; } elt_t; typedef LIST(elt_t) eltlist_t; #define SYMTAB_MAGIC ISC_MAGIC('S', 'y', 'm', 'T') #define VALID_SYMTAB(st) ISC_MAGIC_VALID(st, SYMTAB_MAGIC) struct isc_symtab { /* Unlocked. */ unsigned int magic; isc_mem_t *mctx; unsigned int size; unsigned int count; unsigned int maxload; eltlist_t *table; isc_symtabaction_t undefine_action; void *undefine_arg; bool case_sensitive; }; isc_result_t isc_symtab_create(isc_mem_t *mctx, unsigned int size, isc_symtabaction_t undefine_action, void *undefine_arg, bool case_sensitive, isc_symtab_t **symtabp) { isc_symtab_t *symtab; unsigned int i; REQUIRE(mctx != NULL); REQUIRE(symtabp != NULL && *symtabp == NULL); REQUIRE(size > 0); /* Should be prime. */ symtab = isc_mem_get(mctx, sizeof(*symtab)); symtab->mctx = NULL; isc_mem_attach(mctx, &symtab->mctx); symtab->table = isc_mem_get(mctx, size * sizeof(eltlist_t)); for (i = 0; i < size; i++) { INIT_LIST(symtab->table[i]); } symtab->size = size; symtab->count = 0; symtab->maxload = size * 3 / 4; symtab->undefine_action = undefine_action; symtab->undefine_arg = undefine_arg; symtab->case_sensitive = case_sensitive; symtab->magic = SYMTAB_MAGIC; *symtabp = symtab; return (ISC_R_SUCCESS); } void isc_symtab_destroy(isc_symtab_t **symtabp) { isc_symtab_t *symtab; unsigned int i; elt_t *elt, *nelt; REQUIRE(symtabp != NULL); symtab = *symtabp; *symtabp = NULL; REQUIRE(VALID_SYMTAB(symtab)); for (i = 0; i < symtab->size; i++) { for (elt = HEAD(symtab->table[i]); elt != NULL; elt = nelt) { nelt = NEXT(elt, link); if (symtab->undefine_action != NULL) { (symtab->undefine_action)(elt->key, elt->type, elt->value, symtab->undefine_arg); } isc_mem_put(symtab->mctx, elt, sizeof(*elt)); } } isc_mem_put(symtab->mctx, symtab->table, symtab->size * sizeof(eltlist_t)); symtab->magic = 0; isc_mem_putanddetach(&symtab->mctx, symtab, sizeof(*symtab)); } static unsigned int hash(const char *key, bool case_sensitive) { const char *s; unsigned int h = 0; int c; /* * This hash function is similar to the one Ousterhout * uses in Tcl. */ if (case_sensitive) { for (s = key; *s != '\0'; s++) { h += (h << 3) + *s; } } else { for (s = key; *s != '\0'; s++) { c = *s; c = tolower((unsigned char)c); h += (h << 3) + c; } } return (h); } #define FIND(s, k, t, b, e) \ b = hash((k), (s)->case_sensitive) % (s)->size; \ if ((s)->case_sensitive) { \ for (e = HEAD((s)->table[b]); e != NULL; e = NEXT(e, link)) { \ if (((t) == 0 || e->type == (t)) && \ strcmp(e->key, (k)) == 0) \ break; \ } \ } else { \ for (e = HEAD((s)->table[b]); e != NULL; e = NEXT(e, link)) { \ if (((t) == 0 || e->type == (t)) && \ strcasecmp(e->key, (k)) == 0) \ break; \ } \ } isc_result_t isc_symtab_lookup(isc_symtab_t *symtab, const char *key, unsigned int type, isc_symvalue_t *value) { unsigned int bucket; elt_t *elt; REQUIRE(VALID_SYMTAB(symtab)); REQUIRE(key != NULL); FIND(symtab, key, type, bucket, elt); if (elt == NULL) { return (ISC_R_NOTFOUND); } if (value != NULL) { *value = elt->value; } return (ISC_R_SUCCESS); } static void grow_table(isc_symtab_t *symtab) { eltlist_t *newtable; unsigned int i, newsize, newmax; REQUIRE(symtab != NULL); newsize = symtab->size * 2; newmax = newsize * 3 / 4; INSIST(newsize > 0U && newmax > 0U); newtable = isc_mem_get(symtab->mctx, newsize * sizeof(eltlist_t)); for (i = 0; i < newsize; i++) { INIT_LIST(newtable[i]); } for (i = 0; i < symtab->size; i++) { elt_t *elt, *nelt; for (elt = HEAD(symtab->table[i]); elt != NULL; elt = nelt) { unsigned int hv; nelt = NEXT(elt, link); UNLINK(symtab->table[i], elt, link); hv = hash(elt->key, symtab->case_sensitive); APPEND(newtable[hv % newsize], elt, link); } } isc_mem_put(symtab->mctx, symtab->table, symtab->size * sizeof(eltlist_t)); symtab->table = newtable; symtab->size = newsize; symtab->maxload = newmax; } isc_result_t isc_symtab_define(isc_symtab_t *symtab, const char *key, unsigned int type, isc_symvalue_t value, isc_symexists_t exists_policy) { unsigned int bucket; elt_t *elt; REQUIRE(VALID_SYMTAB(symtab)); REQUIRE(key != NULL); REQUIRE(type != 0); FIND(symtab, key, type, bucket, elt); if (exists_policy != isc_symexists_add && elt != NULL) { if (exists_policy == isc_symexists_reject) { return (ISC_R_EXISTS); } INSIST(exists_policy == isc_symexists_replace); UNLINK(symtab->table[bucket], elt, link); if (symtab->undefine_action != NULL) { (symtab->undefine_action)(elt->key, elt->type, elt->value, symtab->undefine_arg); } } else { elt = isc_mem_get(symtab->mctx, sizeof(*elt)); ISC_LINK_INIT(elt, link); symtab->count++; } /* * Though the "key" can be const coming in, it is not stored as const * so that the calling program can easily have writable access to * it in its undefine_action function. In the event that it *was* * truly const coming in and then the caller modified it anyway ... * well, don't do that! */ DE_CONST(key, elt->key); elt->type = type; elt->value = value; /* * We prepend so that the most recent definition will be found. */ PREPEND(symtab->table[bucket], elt, link); if (symtab->count > symtab->maxload) { grow_table(symtab); } return (ISC_R_SUCCESS); } isc_result_t isc_symtab_undefine(isc_symtab_t *symtab, const char *key, unsigned int type) { unsigned int bucket; elt_t *elt; REQUIRE(VALID_SYMTAB(symtab)); REQUIRE(key != NULL); FIND(symtab, key, type, bucket, elt); if (elt == NULL) { return (ISC_R_NOTFOUND); } if (symtab->undefine_action != NULL) { (symtab->undefine_action)(elt->key, elt->type, elt->value, symtab->undefine_arg); } UNLINK(symtab->table[bucket], elt, link); isc_mem_put(symtab->mctx, elt, sizeof(*elt)); symtab->count--; return (ISC_R_SUCCESS); } unsigned int isc_symtab_count(isc_symtab_t *symtab) { REQUIRE(VALID_SYMTAB(symtab)); return (symtab->count); }