lib/isccc/symtab.c

/*
 * Portions Copyright (C) 2001, 2004, 2005, 2007, 2016  Internet Systems Consortium, Inc. ("ISC")
 *
 * 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 http://mozilla.org/MPL/2.0/.
 *
 * Portions Copyright (C) 2001  Nominum, Inc.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC AND NOMINUM DISCLAIMS ALL
 * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY
 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/* $Id: symtab.c,v 1.11 2007/09/13 04:45:18 each Exp $ */

/*! \file */

#include <config.h>

#include <ctype.h>
#include <stdlib.h>

#include <isc/assertions.h>
#include <isc/magic.h>
#include <isc/string.h>

#include <isccc/result.h>
#include <isccc/symtab.h>
#include <isccc/util.h>

typedef struct elt {
    char *              key;
    unsigned int            type;
    isccc_symvalue_t            value;
    ISC_LINK(struct elt)        link;
} elt_t;

typedef ISC_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 isccc_symtab {
    unsigned int            magic;
    unsigned int            size;
    eltlist_t *         table;
    isccc_symtabundefaction_t       undefine_action;
    void *              undefine_arg;
    isc_boolean_t           case_sensitive;
};

isc_result_t
isccc_symtab_create(unsigned int size,
          isccc_symtabundefaction_t undefine_action,
          void *undefine_arg,
          isc_boolean_t case_sensitive,
          isccc_symtab_t **symtabp)
{
    isccc_symtab_t *symtab;
    unsigned int i;

    REQUIRE(symtabp != NULL && *symtabp == NULL);
    REQUIRE(size > 0);  /* Should be prime. */

    symtab = malloc(sizeof(*symtab));
    if (symtab == NULL)
        return (ISC_R_NOMEMORY);
    symtab->table = malloc(size * sizeof(eltlist_t));
    if (symtab->table == NULL) {
        free(symtab);
        return (ISC_R_NOMEMORY);
    }
    for (i = 0; i < size; i++)
        ISC_LIST_INIT(symtab->table[i]);
    symtab->size = size;
    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);
}

static inline void
free_elt(isccc_symtab_t *symtab, unsigned int bucket, elt_t *elt) {
    ISC_LIST_UNLINK(symtab->table[bucket], elt, link);
    if (symtab->undefine_action != NULL)
        (symtab->undefine_action)(elt->key, elt->type, elt->value,
                      symtab->undefine_arg);
    free(elt);
}

void
isccc_symtab_destroy(isccc_symtab_t **symtabp) {
    isccc_symtab_t *symtab;
    unsigned int i;
    elt_t *elt, *nelt;

    REQUIRE(symtabp != NULL);
    symtab = *symtabp;
    REQUIRE(VALID_SYMTAB(symtab));

    for (i = 0; i < symtab->size; i++) {
        for (elt = ISC_LIST_HEAD(symtab->table[i]);
             elt != NULL;
             elt = nelt) {
            nelt = ISC_LIST_NEXT(elt, link);
            free_elt(symtab, i, elt);
        }
    }
    free(symtab->table);
    symtab->magic = 0;
    free(symtab);

    *symtabp = NULL;
}

static inline unsigned int
hash(const char *key, isc_boolean_t case_sensitive) {
    const char *s;
    unsigned int h = 0;
    unsigned int g;
    int c;

    /*
     * P. J. Weinberger's hash function, adapted from p. 436 of
     * _Compilers: Principles, Techniques, and Tools_, Aho, Sethi
     * and Ullman, Addison-Wesley, 1986, ISBN 0-201-10088-6.
     */

    if (case_sensitive) {
        for (s = key; *s != '\0'; s++) {
            h = ( h << 4 ) + *s;
            if ((g = ( h & 0xf0000000 )) != 0) {
                h = h ^ (g >> 24);
                h = h ^ g;
            }
        }
    } else {
        for (s = key; *s != '\0'; s++) {
            c = *s;
            c = tolower((unsigned char)c);
            h = ( h << 4 ) + c;
            if ((g = ( h & 0xf0000000 )) != 0) {
                h = h ^ (g >> 24);
                h = h ^ g;
            }
        }
    }

    return (h);
}

#define FIND(s, k, t, b, e) \
    b = hash((k), (s)->case_sensitive) % (s)->size; \
    if ((s)->case_sensitive) { \
        for (e = ISC_LIST_HEAD((s)->table[b]); \
             e != NULL; \
             e = ISC_LIST_NEXT(e, link)) { \
            if (((t) == 0 || e->type == (t)) && \
                strcmp(e->key, (k)) == 0) \
                break; \
        } \
    } else { \
        for (e = ISC_LIST_HEAD((s)->table[b]); \
             e != NULL; \
             e = ISC_LIST_NEXT(e, link)) { \
            if (((t) == 0 || e->type == (t)) && \
                strcasecmp(e->key, (k)) == 0) \
                break; \
        } \
    }

isc_result_t
isccc_symtab_lookup(isccc_symtab_t *symtab, const char *key, unsigned int type,
          isccc_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);
}

isc_result_t
isccc_symtab_define(isccc_symtab_t *symtab, char *key, unsigned int type,
          isccc_symvalue_t value, isccc_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 != isccc_symexists_add && elt != NULL) {
        if (exists_policy == isccc_symexists_reject)
            return (ISC_R_EXISTS);
        INSIST(exists_policy == isccc_symexists_replace);
        ISC_LIST_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 = malloc(sizeof(*elt));
        if (elt == NULL)
            return (ISC_R_NOMEMORY);
        ISC_LINK_INIT(elt, link);
    }

    elt->key = key;
    elt->type = type;
    elt->value = value;

    /*
     * We prepend so that the most recent definition will be found.
     */
    ISC_LIST_PREPEND(symtab->table[bucket], elt, link);

    return (ISC_R_SUCCESS);
}

isc_result_t
isccc_symtab_undefine(isccc_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);

    free_elt(symtab, bucket, elt);

    return (ISC_R_SUCCESS);
}

void
isccc_symtab_foreach(isccc_symtab_t *symtab, isccc_symtabforeachaction_t action,
           void *arg)
{
    unsigned int i;
    elt_t *elt, *nelt;

    REQUIRE(VALID_SYMTAB(symtab));
    REQUIRE(action != NULL);

    for (i = 0; i < symtab->size; i++) {
        for (elt = ISC_LIST_HEAD(symtab->table[i]);
             elt != NULL;
             elt = nelt) {
            nelt = ISC_LIST_NEXT(elt, link);
            if ((action)(elt->key, elt->type, elt->value, arg))
                free_elt(symtab, i, elt);
        }
    }
}