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-rw-r--r--lib/isc/symtab.c294
1 files changed, 294 insertions, 0 deletions
diff --git a/lib/isc/symtab.c b/lib/isc/symtab.c
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+/*
+ * 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);
+}
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