/*
 *  Copyright (C) 2013-2019 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
 *  Copyright (C) 2007-2013 Sourcefire, Inc.
 *
 *  Authors: Török Edvin
 *
 *  Summary: Hash-table and -set data structures.
 *
 *  Acknowledgements: hash32shift() is an implementation of Thomas Wang's
 * 	                  32-bit integer hash function:
 * 	                  http://www.cris.com/~Ttwang/tech/inthash.htm
 *
 *  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.
 */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "clamav.h"
#include "clamav-config.h"
#include "others.h"
#include "hashtab.h"

#define MODULE_NAME "hashtab: "

static const char DELETED_KEY[] = "";
#define DELETED_HTU32_KEY ((uint32_t)(-1))

static unsigned long nearest_power(unsigned long num)
{
    unsigned long n = 64;

    while (n < num) {
        n <<= 1;
        if (n == 0) {
            return num;
        }
    }
    return n;
}

#ifdef PROFILE_HASHTABLE
/* I know, this is ugly, most of these functions get a const s, that gets its const-ness discarded,
 * and then these functions modify something the compiler assumes is readonly.
 * Please, never use PROFILE_HASHTABLE in production code, and in releases. Use it for development only!*/

static inline void PROFILE_INIT(struct cli_hashtable *s)
{
    memset(&s->PROFILE_STRUCT, 0, sizeof(s->PROFILE_STRUCT));
}

static inline void PROFILE_CALC_HASH(struct cli_hashtable *s)
{
    s->PROFILE_STRUCT.calc_hash++;
}

static inline void PROFILE_FIND_ELEMENT(struct cli_hashtable *s)
{
    s->PROFILE_STRUCT.find_req++;
}

static inline void PROFILE_FIND_NOTFOUND(struct cli_hashtable *s, size_t tries)
{
    s->PROFILE_STRUCT.not_found++;
    s->PROFILE_STRUCT.not_found_tries += tries;
}

static inline void PROFILE_FIND_FOUND(struct cli_hashtable *s, size_t tries)
{
    s->PROFILE_STRUCT.found++;
    s->PROFILE_STRUCT.found_tries += tries;
}

static inline void PROFILE_HASH_EXHAUSTED(struct cli_hashtable *s)
{
    s->PROFILE_STRUCT.hash_exhausted++;
}

static inline void PROFILE_GROW_START(struct cli_hashtable *s)
{
    s->PROFILE_STRUCT.grow++;
}

static inline void PROFILE_GROW_FOUND(struct cli_hashtable *s, size_t tries)
{
    s->PROFILE_STRUCT.grow_found++;
    s->PROFILE_STRUCT.grow_found_tries += tries;
}

static inline void PROFILE_GROW_DONE(struct cli_hashtable *s)
{
}

static inline void PROFILE_DELETED_REUSE(struct cli_hashtable *s, size_t tries)
{
    s->PROFILE_STRUCT.deleted_reuse++;
    s->PROFILE_STRUCT.deleted_tries += tries;
}

static inline void PROFILE_INSERT(struct cli_hashtable *s, size_t tries)
{
    s->PROFILE_STRUCT.inserts++;
    s->PROFILE_STRUCT.insert_tries += tries;
}

static inline void PROFILE_DATA_UPDATE(struct cli_hashtable *s, size_t tries)
{
    s->PROFILE_STRUCT.update++;
    s->PROFILE_STRUCT.update_tries += tries;
}

static inline void PROFILE_HASH_DELETE(struct cli_hashtable *s)
{
    s->PROFILE_STRUCT.deletes++;
}

static inline void PROFILE_HASH_CLEAR(struct cli_hashtable *s)
{
    s->PROFILE_STRUCT.clear++;
}

static inline void PROFILE_REPORT(const struct cli_hashtable *s)
{
    size_t lookups, queries, insert_tries, inserts;
    cli_dbgmsg("--------Hashtable usage report for %p--------------\n", (const void *)s);
    cli_dbgmsg("hash function calculations:%ld\n", s->PROFILE_STRUCT.calc_hash);
    cli_dbgmsg("successful finds/total searches: %ld/%ld; lookups: %ld\n", s->PROFILE_STRUCT.found, s->PROFILE_STRUCT.find_req, s->PROFILE_STRUCT.found_tries);
    cli_dbgmsg("unsuccessful finds/total searches: %ld/%ld; lookups: %ld\n", s->PROFILE_STRUCT.not_found, s->PROFILE_STRUCT.find_req, s->PROFILE_STRUCT.not_found_tries);
    cli_dbgmsg("successful finds during grow:%ld; lookups: %ld\n", s->PROFILE_STRUCT.grow_found, s->PROFILE_STRUCT.grow_found_tries);
    lookups = s->PROFILE_STRUCT.found_tries + s->PROFILE_STRUCT.not_found_tries + s->PROFILE_STRUCT.grow_found_tries;
    queries = s->PROFILE_STRUCT.find_req + s->PROFILE_STRUCT.grow_found;
    cli_dbgmsg("Find Lookups/total queries: %ld/%ld = %3f\n", lookups, queries, lookups * 1.0 / queries);
    insert_tries = s->PROFILE_STRUCT.insert_tries + s->PROFILE_STRUCT.update_tries + s->PROFILE_STRUCT.deleted_tries;

    cli_dbgmsg("new item insert tries/new items: %ld/%ld\n", s->PROFILE_STRUCT.insert_tries, s->PROFILE_STRUCT.inserts);
    cli_dbgmsg("update tries/updates: %ld/%ld\n", s->PROFILE_STRUCT.update_tries, s->PROFILE_STRUCT.update);
    cli_dbgmsg("deleted item reuse tries/deleted&reused items: %ld/%ld\n", s->PROFILE_STRUCT.deleted_tries, s->PROFILE_STRUCT.deleted_reuse);
    inserts = s->PROFILE_STRUCT.inserts + s->PROFILE_STRUCT.update + s->PROFILE_STRUCT.deleted_reuse;
    cli_dbgmsg("Insert tries/total inserts: %ld/%ld = %3f\n", insert_tries, inserts, insert_tries * 1.0 / inserts);

    cli_dbgmsg("Grows: %ld, Deletes : %ld, hashtable clears: %ld\n", s->PROFILE_STRUCT.grow, s->PROFILE_STRUCT.deletes, s->PROFILE_STRUCT.clear);
    cli_dbgmsg("--------Report end-------------\n");
}

#else
#define PROFILE_INIT(s)
#define PROFILE_CALC_HASH(s)
#define PROFILE_FIND_ELEMENT(s)
#define PROFILE_FIND_NOTFOUND(s, tries)
#define PROFILE_FIND_FOUND(s, tries)
#define PROFILE_HASH_EXHAUSTED(s)
#define PROFILE_GROW_START(s)
#define PROFILE_GROW_FOUND(s, tries)
#define PROFILE_GROW_DONE(s)
#define PROFILE_DELETED_REUSE(s, tries)
#define PROFILE_INSERT(s, tries)
#define PROFILE_DATA_UPDATE(s, tries)
#define PROFILE_HASH_DELETE(s)
#define PROFILE_HASH_CLEAR(s)
#define PROFILE_REPORT(s)
#endif

int cli_hashtab_init(struct cli_hashtable *s, size_t capacity)
{
    if (!s)
        return CL_ENULLARG;

    PROFILE_INIT(s);

    capacity  = nearest_power(capacity);
    s->htable = cli_calloc(capacity, sizeof(*s->htable));
    if (!s->htable)
        return CL_EMEM;
    s->capacity = capacity;
    s->used     = 0;
    s->maxfill  = 8 * capacity / 10;
    return 0;
}

int cli_htu32_init(struct cli_htu32 *s, size_t capacity, mpool_t *mempool)
{
    if (!s)
        return CL_ENULLARG;

    PROFILE_INIT(s);

    capacity  = nearest_power(capacity);
    s->htable = MPOOL_CALLOC(mempool, capacity, sizeof(*s->htable));
    if (!s->htable)
        return CL_EMEM;
    s->capacity = capacity;
    s->used     = 0;
    s->maxfill  = 8 * capacity / 10;
    return 0;
}

static inline uint32_t hash32shift(uint32_t key)
{
    key = ~key + (key << 15);
    key = key ^ (key >> 12);
    key = key + (key << 2);
    key = key ^ (key >> 4);
    key = (key + (key << 3)) + (key << 11);
    key = key ^ (key >> 16);
    return key;
}

static inline size_t hash(const unsigned char *k, const size_t len, const size_t SIZE)
{
    size_t Hash = 1;
    size_t i;
    for (i = 0; i < len; i++) {
        /* a simple add is good, because we use the mixing function below */
        Hash += k[i];
        /* mixing function */
        Hash = hash32shift(Hash);
    }
    /* SIZE is power of 2 */
    return Hash & (SIZE - 1);
}

static inline size_t hash_htu32(uint32_t k, const size_t SIZE)
{
    /* mixing function */
    size_t Hash = hash32shift(k);
    /* SIZE is power of 2 */
    return Hash & (SIZE - 1);
}

/* if returned element has key==NULL, then key was not found in table */
struct cli_element *cli_hashtab_find(const struct cli_hashtable *s, const char *key, const size_t len)
{
    struct cli_element *element;
    size_t tries = 1;
    size_t idx;

    if (!s)
        return NULL;
    PROFILE_CALC_HASH(s);
    PROFILE_FIND_ELEMENT(s);
    idx     = hash((const unsigned char *)key, len, s->capacity);
    element = &s->htable[idx];
    do {
        if (!element->key) {
            PROFILE_FIND_NOTFOUND(s, tries);
            return NULL; /* element not found, place is empty*/
        } else if (element->key != DELETED_KEY && len == element->len && (key == element->key || strncmp(key, element->key, len) == 0)) {
            PROFILE_FIND_FOUND(s, tries);
            return element; /* found */
        } else {
            idx     = (idx + tries++) & (s->capacity - 1);
            element = &s->htable[idx];
        }
    } while (tries <= s->capacity);
    PROFILE_HASH_EXHAUSTED(s);
    return NULL; /* not found */
}

const struct cli_htu32_element *cli_htu32_find(const struct cli_htu32 *s, uint32_t key)
{
    struct cli_htu32_element *element;
    size_t tries = 1;
    size_t idx;

    if (!s)
        return NULL;
    PROFILE_CALC_HASH(s);
    PROFILE_FIND_ELEMENT(s);
    idx     = hash_htu32(key, s->capacity);
    element = &s->htable[idx];
    do {
        if (!element->key) {
            PROFILE_FIND_NOTFOUND(s, tries);
            return NULL; /* element not found, place is empty */
        } else if (key == element->key) {
            PROFILE_FIND_FOUND(s, tries);
            return element; /* found */
        } else {
            idx     = (idx + tries++) & (s->capacity - 1);
            element = &s->htable[idx];
        }
    } while (tries <= s->capacity);
    PROFILE_HASH_EXHAUSTED(s);
    return NULL; /* not found */
}

/* linear enumeration - start with current = NULL, returns next item if present or NULL if not */
const struct cli_htu32_element *cli_htu32_next(const struct cli_htu32 *s, const struct cli_htu32_element *current)
{
    size_t ncur;
    if (!s || !s->capacity)
        return NULL;

    if (!current)
        ncur = 0;
    else {
        ncur = current - s->htable;
        if (ncur >= s->capacity)
            return NULL;

        ncur++;
    }
    for (; ncur < s->capacity; ncur++) {
        const struct cli_htu32_element *item = &s->htable[ncur & (s->capacity - 1)];
        if (item->key && item->key != DELETED_HTU32_KEY)
            return item;
    }
    return NULL;
}

static int cli_hashtab_grow(struct cli_hashtable *s)
{
    const size_t new_capacity = nearest_power(s->capacity + 1);
    struct cli_element *htable;
    size_t i, idx, used = 0;

    cli_dbgmsg("hashtab.c: new capacity: %llu\n", (long long unsigned)new_capacity);
    if (new_capacity == s->capacity) {
        cli_errmsg("hashtab.c: capacity problem growing from: %llu\n", (long long unsigned)s->capacity);
        return CL_EMEM;
    }
    htable = cli_calloc(new_capacity, sizeof(*s->htable));
    if (!htable) {
        return CL_EMEM;
    }

    PROFILE_GROW_START(s);
    cli_dbgmsg("hashtab.c: Warning: growing open-addressing hashtables is slow. Either allocate more storage when initializing, or use other hashtable types!\n");
    for (i = 0; i < s->capacity; i++) {
        if (s->htable[i].key && s->htable[i].key != DELETED_KEY) {
            struct cli_element *element;
            size_t tries = 1;

            PROFILE_CALC_HASH(s);
            idx     = hash((const unsigned char *)s->htable[i].key, s->htable[i].len, new_capacity);
            element = &htable[idx];

            while (element->key && tries <= new_capacity) {
                idx     = (idx + tries++) & (new_capacity - 1);
                element = &htable[idx];
            }
            if (!element->key) {
                /* copy element from old hashtable to new */
                PROFILE_GROW_FOUND(s, tries);
                *element = s->htable[i];
                used++;
            } else {
                cli_errmsg("hashtab.c: Impossible - unable to rehash table");
                free(htable);
                return CL_EMEM; /* this means we didn't find enough room for all elements in the new table, should never happen */
            }
        }
    }
    free(s->htable);
    s->htable   = htable;
    s->used     = used;
    s->capacity = new_capacity;
    s->maxfill  = new_capacity * 8 / 10;
    cli_dbgmsg("Table %p size after grow:%llu\n", (void *)s, (long long unsigned)s->capacity);
    PROFILE_GROW_DONE(s);
    return CL_SUCCESS;
}

#ifndef USE_MPOOL
#define cli_htu32_grow(A, B) cli_htu32_grow(A)
#endif

static int cli_htu32_grow(struct cli_htu32 *s, mpool_t *mempool)
{
    const size_t new_capacity        = nearest_power(s->capacity + 1);
    struct cli_htu32_element *htable = MPOOL_CALLOC(mempool, new_capacity, sizeof(*s->htable));
    size_t i, idx, used = 0;
    cli_dbgmsg("hashtab.c: new capacity: %llu\n", (long long unsigned)new_capacity);
    if (new_capacity == s->capacity || !htable)
        return CL_EMEM;

    PROFILE_GROW_START(s);

    for (i = 0; i < s->capacity; i++) {
        if (s->htable[i].key && s->htable[i].key != DELETED_HTU32_KEY) {
            struct cli_htu32_element *element;
            size_t tries = 1;

            PROFILE_CALC_HASH(s);
            idx     = hash_htu32(s->htable[i].key, new_capacity);
            element = &htable[idx];

            while (element->key && tries <= new_capacity) {
                idx     = (idx + tries++) & (new_capacity - 1);
                element = &htable[idx];
            }
            if (!element->key) {
                /* copy element from old hashtable to new */
                PROFILE_GROW_FOUND(s, tries);
                *element = s->htable[i];
                used++;
            } else {
                cli_errmsg("hashtab.c: Impossible - unable to rehash table");
                return CL_EMEM; /* this means we didn't find enough room for all elements in the new table, should never happen */
            }
        }
    }
    MPOOL_FREE(mempool, s->htable);
    s->htable   = htable;
    s->used     = used;
    s->capacity = new_capacity;
    s->maxfill  = new_capacity * 8 / 10;
    cli_dbgmsg("Table %p size after grow:%llu\n", (void *)s, (long long unsigned)s->capacity);
    PROFILE_GROW_DONE(s);
    return CL_SUCCESS;
}

const struct cli_element *cli_hashtab_insert(struct cli_hashtable *s, const char *key, const size_t len, const cli_element_data data)
{
    struct cli_element *element;
    struct cli_element *deleted_element = NULL;
    size_t tries                        = 1;
    size_t idx;
    if (!s)
        return NULL;
    if (s->used > s->maxfill) {
        cli_dbgmsg("hashtab.c:Growing hashtable %p, because it has exceeded maxfill, old size:%llu\n", (void *)s, (long long unsigned)s->capacity);
        cli_hashtab_grow(s);
    }
    do {
        PROFILE_CALC_HASH(s);
        idx     = hash((const unsigned char *)key, len, s->capacity);
        element = &s->htable[idx];

        do {
            if (!element->key) {
                char *thekey;
                /* element not found, place is empty, insert*/
                if (deleted_element) {
                    /* reuse deleted elements*/
                    element = deleted_element;
                    PROFILE_DELETED_REUSE(s, tries);
                } else {
                    PROFILE_INSERT(s, tries);
                }
                thekey = cli_malloc(len + 1);
                if (!thekey) {
                    cli_errmsg("hashtab.c: Unable to allocate memory for thekey\n");
                    return NULL;
                }
                strncpy(thekey, key, len + 1);
                thekey[len]   = '\0';
                element->key  = thekey;
                element->data = data;
                element->len  = len;
                s->used++;
                return element;
            } else if (element->key == DELETED_KEY) {
                deleted_element = element;
                element->key    = NULL;
            } else if (len == element->len && strncmp(key, element->key, len) == 0) {
                PROFILE_DATA_UPDATE(s, tries);
                element->data = data; /* key found, update */
                return element;
            } else {
                idx     = (idx + tries++) % s->capacity;
                element = &s->htable[idx];
            }
        } while (tries <= s->capacity);
        /* no free place found*/
        PROFILE_HASH_EXHAUSTED(s);
        cli_dbgmsg("hashtab.c: Growing hashtable %p, because its full, old size:%llu.\n", (void *)s, (long long unsigned)s->capacity);
    } while (cli_hashtab_grow(s) >= 0);
    cli_warnmsg("hashtab.c: Unable to grow hashtable\n");
    return NULL;
}

int cli_htu32_insert(struct cli_htu32 *s, const struct cli_htu32_element *item, mpool_t *mempool)
{
    struct cli_htu32_element *element;
    struct cli_htu32_element *deleted_element = NULL;
    size_t tries                              = 1;
    size_t idx;
    int ret;

    if (!s)
        return CL_ENULLARG;
    if (s->used > s->maxfill) {
        cli_dbgmsg("hashtab.c:Growing hashtable %p, because it has exceeded maxfill, old size:%llu\n", (void *)s, (long long unsigned)s->capacity);
        cli_htu32_grow(s, mempool);
    }
    do {
        PROFILE_CALC_HASH(s);
        idx     = hash_htu32(item->key, s->capacity);
        element = &s->htable[idx];

        do {
            if (!element->key) {
                /* element not found, place is empty, insert*/
                if (deleted_element) {
                    /* reuse deleted elements*/
                    element = deleted_element;
                    PROFILE_DELETED_REUSE(s, tries);
                } else {
                    PROFILE_INSERT(s, tries);
                }
                *element = *item;
                s->used++;
                return 0;
            } else if (element->key == DELETED_HTU32_KEY) {
                deleted_element = element;
                element->key    = 0;
            } else if (item->key == element->key) {
                PROFILE_DATA_UPDATE(s, tries);
                element->data = item->data; /* key found, update */
                return 0;
            } else {
                idx     = (idx + tries++) % s->capacity;
                element = &s->htable[idx];
            }
        } while (tries <= s->capacity);
        /* no free place found*/
        PROFILE_HASH_EXHAUSTED(s);
        cli_dbgmsg("hashtab.c: Growing hashtable %p, because its full, old size:%llu.\n", (void *)s, (long long unsigned)s->capacity);
    } while ((ret = cli_htu32_grow(s, mempool)) >= 0);
    cli_warnmsg("hashtab.c: Unable to grow hashtable\n");
    return ret;
}

void cli_hashtab_delete(struct cli_hashtable *s, const char *key, const size_t len)
{
    struct cli_element *el = cli_hashtab_find(s, key, len);
    if (!el || el->key == DELETED_KEY)
        return;
    free((void *)el->key);
    el->key = DELETED_KEY;
}

void cli_htu32_delete(struct cli_htu32 *s, uint32_t key)
{
    struct cli_htu32_element *el = (struct cli_htu32_element *)cli_htu32_find(s, key);
    if (el)
        el->key = DELETED_HTU32_KEY;
}

void cli_hashtab_clear(struct cli_hashtable *s)
{
    size_t i;
    PROFILE_HASH_CLEAR(s);
    for (i = 0; i < s->capacity; i++) {
        if (s->htable[i].key && s->htable[i].key != DELETED_KEY)
            free((void *)s->htable[i].key);
    }
    if (s->htable)
        memset(s->htable, 0, s->capacity * sizeof(*s->htable));
    s->used = 0;
}

void cli_htu32_clear(struct cli_htu32 *s)
{
    PROFILE_HASH_CLEAR(s);
    if (s->htable)
        memset(s->htable, 0, s->capacity * sizeof(struct cli_htu32_element));
    s->used = 0;
}

void cli_hashtab_free(struct cli_hashtable *s)
{
    cli_hashtab_clear(s);
    free(s->htable);
    s->htable   = NULL;
    s->capacity = 0;
}

void cli_htu32_free(struct cli_htu32 *s, mpool_t *mempool)
{
    MPOOL_FREE(mempool, s->htable);
    s->htable   = NULL;
    s->capacity = 0;
}

size_t cli_htu32_numitems(struct cli_htu32 *s)
{
    if (!s) return 0;
    return s->capacity;
}

int cli_hashtab_store(const struct cli_hashtable *s, FILE *out)
{
    size_t i;
    for (i = 0; i < s->capacity; i++) {
        const struct cli_element *e = &s->htable[i];
        if (e->key && e->key != DELETED_KEY) {
            fprintf(out, "%ld %s\n", e->data, e->key);
        }
    }
    return CL_SUCCESS;
}

int cli_hashtab_generate_c(const struct cli_hashtable *s, const char *name)
{
    size_t i;
    printf("/* TODO: include GPL headers */\n");
    printf("#include <hashtab.h>\n");
    printf("static struct cli_element %s_elements[] = {\n", name);
    for (i = 0; i < s->capacity; i++) {
        const struct cli_element *e = &s->htable[i];
        if (!e->key)
            printf("\t{NULL,0,0},\n");
        else if (e->key == DELETED_KEY)
            printf("\t{DELETED_KEY,0,0},\n");
        else
            printf("\t{\"%s\", %ld, %llu},\n", e->key, e->data, (long long unsigned)e->len);
    }
    printf("};\n");
    printf("const struct cli_hashtable %s = {\n", name);
    printf("\t%s_elements, %llu, %llu, %llu", name, (long long unsigned)s->capacity,
           (long long unsigned)s->used, (long long unsigned)s->maxfill);
    printf("\n};\n");

    PROFILE_REPORT(s);
    return 0;
}

int cli_hashtab_load(FILE *in, struct cli_hashtable *s)
{
    char line[1024];
    while (fgets(line, sizeof(line), in)) {
        char l[1024];
        int val;
        sscanf(line, "%d %1023s", &val, l);
        cli_hashtab_insert(s, l, strlen(l), val);
    }
    return CL_SUCCESS;
}

/* Initialize hashset. @initial_capacity is rounded to nearest power of 2.
 * Load factor is between 50 and 99. When capacity*load_factor/100 is reached, the hashset is growed */
int cli_hashset_init(struct cli_hashset *hs, size_t initial_capacity, uint8_t load_factor)
{
    if (load_factor < 50 || load_factor > 99) {
        cli_dbgmsg(MODULE_NAME "Invalid load factor: %u, using default of 80%%\n", load_factor);
        load_factor = 80;
    }
    initial_capacity = nearest_power(initial_capacity);
    hs->limit        = initial_capacity * load_factor / 100;
    hs->capacity     = initial_capacity;
    hs->mask         = initial_capacity - 1;
    hs->count        = 0;
    hs->keys         = cli_malloc(initial_capacity * sizeof(*hs->keys));
    hs->mempool      = NULL;
    if (!hs->keys) {
        cli_errmsg("hashtab.c: Unable to allocate memory for hs->keys\n");
        return CL_EMEM;
    }
    hs->bitmap = cli_calloc(initial_capacity >> 5, sizeof(*hs->bitmap));
    if (!hs->bitmap) {
        free(hs->keys);
        cli_errmsg("hashtab.c: Unable to allocate memory for hs->bitmap\n");
        return CL_EMEM;
    }
    return 0;
}

int cli_hashset_init_pool(struct cli_hashset *hs, size_t initial_capacity, uint8_t load_factor, mpool_t *mempool)
{
    if (load_factor < 50 || load_factor > 99) {
        cli_dbgmsg(MODULE_NAME "Invalid load factor: %u, using default of 80%%\n", load_factor);
        load_factor = 80;
    }
    initial_capacity = nearest_power(initial_capacity);
    hs->limit        = initial_capacity * load_factor / 100;
    hs->capacity     = initial_capacity;
    hs->mask         = initial_capacity - 1;
    hs->count        = 0;
    hs->mempool      = mempool;
    hs->keys         = MPOOL_MALLOC(mempool, initial_capacity * sizeof(*hs->keys));
    if (!hs->keys) {
        cli_errmsg("hashtab.c: Unable to allocate memory pool for hs->keys\n");
        return CL_EMEM;
    }
    hs->bitmap = MPOOL_CALLOC(mempool, initial_capacity >> 5, sizeof(*hs->bitmap));
    if (!hs->bitmap) {
        MPOOL_FREE(mempool, hs->keys);
        cli_errmsg("hashtab.c: Unable to allocate/initialize memory for hs->keys\n");
        return CL_EMEM;
    }
    return 0;
}

void cli_hashset_destroy(struct cli_hashset *hs)
{
    cli_dbgmsg(MODULE_NAME "Freeing hashset, elements: %u, capacity: %u\n", hs->count, hs->capacity);
    if (hs->mempool) {
        MPOOL_FREE(hs->mempool, hs->keys);
        MPOOL_FREE(hs->mempool, hs->bitmap);
    } else {
        free(hs->keys);
        free(hs->bitmap);
    }
    hs->keys = hs->bitmap = NULL;
    hs->capacity          = 0;
}

#define BITMAP_CONTAINS(bmap, val) ((bmap)[(val) >> 5] & ((uint64_t) 1 << ((val)&0x1f)))
#define BITMAP_INSERT(bmap, val) ((bmap)[(val) >> 5] |= ((uint64_t) 1 << ((val)&0x1f)))
#define BITMAP_REMOVE(bmap, val) ((bmap)[(val) >> 5] &= ~((uint64_t) 1 << ((val)&0x1f)))

/*
 * searches the hashset for the @key.
 * Returns the position the key is at, or a candidate position where it could be inserted.
 */
static inline size_t cli_hashset_search(const struct cli_hashset *hs, const uint32_t key)
{
    /* calculate hash value for this key, and map it to our table */
    size_t idx   = hash32shift(key) & (hs->mask);
    size_t tries = 1;

    /* check whether the entry is used, and if the key matches */
    while (BITMAP_CONTAINS(hs->bitmap, idx) && (hs->keys[idx] != key)) {
        /* entry used, key different -> collision */
        idx = (idx + tries++) & (hs->mask);
        /* quadratic probing, with c1 = c2 = 1/2, guaranteed to walk the entire table
		 * for table sizes power of 2.*/
    }
    /* we have either found the key, or a candidate insertion position */
    return idx;
}

static void cli_hashset_addkey_internal(struct cli_hashset *hs, const uint32_t key)
{
    const size_t idx = cli_hashset_search(hs, key);
    /* we know hashtable is not full, when this method is called */

    if (!BITMAP_CONTAINS(hs->bitmap, idx)) {
        /* add new key */
        BITMAP_INSERT(hs->bitmap, idx);
        hs->keys[idx] = key;
        hs->count++;
    }
}

static int cli_hashset_grow(struct cli_hashset *hs)
{
    struct cli_hashset new_hs;
    size_t i;
    int rc;

    /* in-place growing is not possible, since the new keys
	 * will hash to different locations. */
    cli_dbgmsg(MODULE_NAME "Growing hashset, used: %u, capacity: %u\n", hs->count, hs->capacity);
    /* create a bigger hashset */

    if (hs->mempool)
        rc = cli_hashset_init_pool(&new_hs, hs->capacity << 1, hs->limit * 100 / hs->capacity, hs->mempool);
    else
        rc = cli_hashset_init(&new_hs, hs->capacity << 1, hs->limit * 100 / hs->capacity);
    if (rc != 0)
        return rc;
    /* and copy keys */
    for (i = 0; i < hs->capacity; i++) {
        if (BITMAP_CONTAINS(hs->bitmap, i)) {
            const size_t key = hs->keys[i];
            cli_hashset_addkey_internal(&new_hs, key);
        }
    }
    cli_hashset_destroy(hs);
    /* replace old hashset with new one */
    *hs = new_hs;
    return 0;
}

int cli_hashset_addkey(struct cli_hashset *hs, const uint32_t key)
{
    /* check that we didn't reach the load factor.
	 * Even if we don't know yet whether we'd add this key */
    if (hs->count + 1 > hs->limit) {
        int rc = cli_hashset_grow(hs);
        if (rc) {
            return rc;
        }
    }
    cli_hashset_addkey_internal(hs, key);
    return 0;
}

int cli_hashset_removekey(struct cli_hashset *hs, const uint32_t key)
{
    const size_t idx = cli_hashset_search(hs, key);
    if (BITMAP_CONTAINS(hs->bitmap, idx)) {
        BITMAP_REMOVE(hs->bitmap, idx);
        hs->keys[idx] = 0;
        hs->count--;
        return 0;
    }
    return -1;
}

int cli_hashset_contains(const struct cli_hashset *hs, const uint32_t key)
{
    const size_t idx = cli_hashset_search(hs, key);
    return BITMAP_CONTAINS(hs->bitmap, idx);
}

ssize_t cli_hashset_toarray(const struct cli_hashset *hs, uint32_t **array)
{
    size_t i, j;
    uint32_t *arr;

    if (!array) {
        return CL_ENULLARG;
    }
    *array = arr = cli_malloc(hs->count * sizeof(*arr));
    if (!arr) {
        cli_errmsg("hashtab.c: Unable to allocate memory for array\n");
        return CL_EMEM;
    }

    for (i = 0, j = 0; i < hs->capacity && j < hs->count; i++) {
        if (BITMAP_CONTAINS(hs->bitmap, i)) {
            arr[j++] = hs->keys[i];
        }
    }
    return j;
}

void cli_hashset_init_noalloc(struct cli_hashset *hs)
{
    memset(hs, 0, sizeof(*hs));
}

int cli_hashset_contains_maybe_noalloc(const struct cli_hashset *hs, const uint32_t key)
{
    if (!hs->keys)
        return 0;
    return cli_hashset_contains(hs, key);
}

int cli_map_init(struct cli_map *m, int32_t keysize, int32_t valuesize,
                 int32_t capacity)
{
    if (keysize <= 0 || valuesize < 0 || capacity <= 0)
        return -CL_EARG;
    memset(m, 0, sizeof(*m));
    cli_hashtab_init(&m->htab, 16);
    m->keysize     = keysize;
    m->valuesize   = valuesize;
    m->last_insert = -1;
    m->last_find   = -1;
    return 0;
}

int cli_map_addkey(struct cli_map *m, const void *key, int32_t keysize)
{
    unsigned n;
    struct cli_element *el;
    if (m->keysize != keysize)
        return -CL_EARG;
    el = cli_hashtab_find(&m->htab, key, keysize);
    if (el) {
        m->last_insert = el->data;
        return 0;
    }
    n = m->nvalues + 1;
    if (m->valuesize) {
        void *v;
        v = cli_realloc(m->u.sized_values, n * m->valuesize);
        if (!v)
            return -CL_EMEM;
        m->u.sized_values = v;
        memset((char *)m->u.sized_values + (n - 1) * m->valuesize, 0, m->valuesize);
    } else {
        struct cli_map_value *v;
        v = cli_realloc(m->u.unsized_values, n * sizeof(*m->u.unsized_values));
        if (!v)
            return -CL_EMEM;
        m->u.unsized_values = v;
        memset(&m->u.unsized_values[n - 1], 0, sizeof(*m->u.unsized_values));
    }
    m->nvalues = n;
    if (!cli_hashtab_insert(&m->htab, key, keysize, n - 1))
        return -CL_EMEM;
    m->last_insert = n - 1;
    return 1;
}

int cli_map_removekey(struct cli_map *m, const void *key, int32_t keysize)
{
    struct cli_element *el;
    if (m->keysize != keysize)
        return -CL_EARG;
    el = cli_hashtab_find(&m->htab, key, keysize);
    if (!el)
        return 0;
    if (el->data >= m->nvalues || el->data < 0)
        return -CL_EARG;
    if (!m->valuesize) {
        struct cli_map_value *v = &m->u.unsized_values[el->data];
        free(v->value);
        v->value     = NULL;
        v->valuesize = 0;
    } else {
        char *v = (char *)m->u.sized_values + el->data * m->valuesize;
        memset(v, 0, m->valuesize);
    }
    cli_hashtab_delete(&m->htab, key, keysize);
    return 1;
}

int cli_map_setvalue(struct cli_map *m, const void *value, int32_t valuesize)
{
    if ((m->valuesize && m->valuesize != valuesize) || (uint32_t)(m->last_insert) >= m->nvalues || m->last_insert < 0)
        return -CL_EARG;
    if (m->valuesize) {
        memcpy((char *)m->u.sized_values + m->last_insert * m->valuesize,
               value, valuesize);
    } else {
        struct cli_map_value *v = &m->u.unsized_values[m->last_insert];
        if (v->value)
            free(v->value);
        v->value = cli_malloc(valuesize);
        if (!v->value) {
            cli_errmsg("hashtab.c: Unable to allocate  memory for v->value\n");
            return -CL_EMEM;
        }
        memcpy(v->value, value, valuesize);
        v->valuesize = valuesize;
    }
    return 0;
}

int cli_map_find(struct cli_map *m, const void *key, int32_t keysize)
{
    struct cli_element *el;
    if (m->keysize != keysize)
        return -CL_EARG;
    el = cli_hashtab_find(&m->htab, key, keysize);
    if (!el)
        return 0;
    m->last_find = el->data;
    return 1;
}

int cli_map_getvalue_size(struct cli_map *m)
{
    if (m->valuesize)
        return m->valuesize;
    if (m->last_find < 0 || (uint32_t)(m->last_find) >= m->nvalues)
        return -CL_EARG;
    return m->u.unsized_values[m->last_find].valuesize;
}

void *cli_map_getvalue(struct cli_map *m)
{
    if (m->last_find < 0 || (uint32_t)(m->last_find) >= m->nvalues)
        return NULL;
    if (m->valuesize)
        return (char *)m->u.sized_values + m->last_find * m->valuesize;
    return m->u.unsized_values[m->last_find].value;
}

void cli_map_delete(struct cli_map *m)
{
    cli_hashtab_free(&m->htab);
    if (!m->valuesize) {
        unsigned i;
        for (i = 0; i < m->nvalues; i++)
            free(m->u.unsized_values[i].value);
        free(m->u.unsized_values);
    } else {
        free(m->u.sized_values);
    }
    memset(m, 0, sizeof(*m));
}