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Diffstat (limited to '')
-rw-r--r-- | lib/isc/symtab.c | 294 |
1 files changed, 294 insertions, 0 deletions
diff --git a/lib/isc/symtab.c b/lib/isc/symtab.c new file mode 100644 index 0000000..ff022a2 --- /dev/null +++ b/lib/isc/symtab.c @@ -0,0 +1,294 @@ +/* + * 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 <ctype.h> +#include <stdbool.h> + +#include <isc/magic.h> +#include <isc/mem.h> +#include <isc/string.h> +#include <isc/symtab.h> +#include <isc/util.h> + +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); +} |