clamav/libclamav/table.c

/*
 *  Copyright (C) 2015 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
 *  Copyright (C) 2007-2008 Sourcefire, Inc.
 *
 *  Authors: Nigel Horne
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 *  MA 02110-1301, USA.
 *
 * TODO: Allow individual items to be updated or removed
 *
 * It is up to the caller to create a mutex for the table if needed
 */

#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif

#include <stdlib.h>
#include <string.h>
#ifdef HAVE_STRINGS_H
#include <strings.h>
#endif
#include <assert.h>

#include "clamav.h"
#include "table.h"
#include "others.h"

struct table *
tableCreate(void)
{
    return (struct table *)cli_calloc(1, sizeof(struct table));
}

void tableDestroy(table_t *table)
{
    tableEntry *tableItem;

    assert(table != NULL);

    tableItem = table->tableHead;

    while (tableItem) {
        tableEntry *tableNext = tableItem->next;

        if (tableItem->key)
            free(tableItem->key);
        free(tableItem);

        tableItem = tableNext;
    }

    free(table);
}

/*
 * Returns the value, or -1 for failure
 */
int tableInsert(table_t *table, const char *key, int value)
{
    const int v = tableFind(table, key);

    if (v > 0)                            /* duplicate key */
        return (v == value) ? value : -1; /* allow real dups */

    assert(value != -1); /* that would confuse us */

    if (table->tableHead == NULL)
        table->tableLast = table->tableHead = (tableEntry *)cli_malloc(sizeof(tableEntry));
    else {
        /*
		 * Re-use deleted items
		 */
        if (table->flags & TABLE_HAS_DELETED_ENTRIES) {
            tableEntry *tableItem;

            assert(table->tableHead != NULL);

            for (tableItem = table->tableHead; tableItem; tableItem = tableItem->next)
                if (tableItem->key == NULL) {
                    /* This item has been deleted */
                    tableItem->key   = cli_strdup(key);
                    tableItem->value = value;
                    return value;
                }

            table->flags &= ~TABLE_HAS_DELETED_ENTRIES;
        }

        table->tableLast = table->tableLast->next =
            (tableEntry *)cli_malloc(sizeof(tableEntry));
    }

    if (table->tableLast == NULL) {
        cli_dbgmsg("tableInsert: Unable to allocate memory for table\n");
        return -1;
    }

    table->tableLast->next  = NULL;
    table->tableLast->key   = cli_strdup(key);
    table->tableLast->value = value;

    return value;
}

/*
 * Returns the value - -1 for not found. This means the value of a valid key
 *	can't be -1 :-(
 *
 * Linear search. Since tables are rarely more than 3 or 4 in size, and never
 *	reach double figures, there's no need for optimization
 */
int tableFind(const table_t *table, const char *key)
{
    const tableEntry *tableItem;
#ifdef CL_DEBUG
    int cost;
#endif

    assert(table != NULL);

    if (key == NULL)
        return -1; /* not treated as a fatal error */

#ifdef CL_DEBUG
    cost = 0;
#endif

    for (tableItem = table->tableHead; tableItem; tableItem = tableItem->next) {
#ifdef CL_DEBUG
        cost++;
#endif
        if (tableItem->key && (strcasecmp(tableItem->key, key) == 0)) {
#ifdef CL_DEBUG
            cli_dbgmsg("tableFind: Cost of '%s' = %d\n", key, cost);
#endif
            return tableItem->value;
        }
    }

    return -1; /* not found */
}

/*
 * Change a value in the table. If the key isn't in the table insert it
 * Returns -1 for error, otherwise the new value
 */
int tableUpdate(table_t *table, const char *key, int new_value)
{
    tableEntry *tableItem;

    assert(table != NULL);

    if (key == NULL)
        return -1; /* not treated as a fatal error */

    for (tableItem = table->tableHead; tableItem; tableItem = tableItem->next)
        if (tableItem->key && (strcasecmp(tableItem->key, key) == 0)) {
            tableItem->value = new_value;
            return new_value;
        }

    /* not found */
    return tableInsert(table, key, new_value);
}

/*
 * Remove an item from the table
 */
void tableRemove(table_t *table, const char *key)
{
    tableEntry *tableItem;

    assert(table != NULL);

    if (key == NULL)
        return; /* not treated as a fatal error */

    for (tableItem = table->tableHead; tableItem; tableItem = tableItem->next)
        if (tableItem->key && (strcasecmp(tableItem->key, key) == 0)) {
            free(tableItem->key);
            tableItem->key = NULL;
            table->flags |= TABLE_HAS_DELETED_ENTRIES;
            /* don't break, duplicate keys are allowed */
        }
}

void tableIterate(table_t *table, void (*callback)(char *key, int value, void *arg), void *arg)
{
    tableEntry *tableItem;

    if (table == NULL)
        return;

    for (tableItem = table->tableHead; tableItem; tableItem = tableItem->next)
        if (tableItem->key) /* check node has not been deleted */
            (*callback)(tableItem->key, tableItem->value, arg);
}