411 lines
9.8 KiB
C
411 lines
9.8 KiB
C
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/*
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zip_hash.c -- hash table string -> uint64
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Copyright (C) 2015-2017 Dieter Baron and Thomas Klausner
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This file is part of libzip, a library to manipulate ZIP archives.
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The authors can be contacted at <libzip@nih.at>
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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1. Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in
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the documentation and/or other materials provided with the
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distribution.
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3. The names of the authors may not be used to endorse or promote
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products derived from this software without specific prior
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written permission.
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THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS
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OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
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DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
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GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
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IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
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IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "zipint.h"
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#include <stdlib.h>
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#include <string.h>
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/* parameter for the string hash function */
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#define HASH_MULTIPLIER 33
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#define HASH_START 5381
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/* hash table's fill ratio is kept between these by doubling/halfing its size as necessary */
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#define HASH_MAX_FILL .75
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#define HASH_MIN_FILL .01
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/* but hash table size is kept between these */
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#define HASH_MIN_SIZE 256
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#define HASH_MAX_SIZE 0x80000000ul
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struct zip_hash_entry {
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const zip_uint8_t *name;
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zip_int64_t orig_index;
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zip_int64_t current_index;
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struct zip_hash_entry *next;
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zip_uint32_t hash_value;
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};
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typedef struct zip_hash_entry zip_hash_entry_t;
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struct zip_hash {
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zip_uint32_t table_size;
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zip_uint64_t nentries;
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zip_hash_entry_t **table;
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};
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/* free list of entries */
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static void
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free_list(zip_hash_entry_t *entry) {
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while (entry != NULL) {
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zip_hash_entry_t *next = entry->next;
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free(entry);
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entry = next;
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}
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}
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/* compute hash of string, full 32 bit value */
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static zip_uint32_t
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hash_string(const zip_uint8_t *name) {
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zip_uint64_t value = HASH_START;
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if (name == NULL) {
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return 0;
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}
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while (*name != 0) {
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value = (zip_uint64_t)(((value * HASH_MULTIPLIER) + (zip_uint8_t)*name) % 0x100000000ul);
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name++;
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}
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return (zip_uint32_t)value;
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}
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/* resize hash table; new_size must be a power of 2, can be larger or smaller than current size */
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static bool
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hash_resize(zip_hash_t *hash, zip_uint32_t new_size, zip_error_t *error) {
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zip_hash_entry_t **new_table;
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if (new_size == hash->table_size) {
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return true;
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}
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if ((new_table = (zip_hash_entry_t **)calloc(new_size, sizeof(zip_hash_entry_t *))) == NULL) {
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zip_error_set(error, ZIP_ER_MEMORY, 0);
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return false;
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}
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if (hash->nentries > 0) {
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zip_uint32_t i;
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for (i = 0; i < hash->table_size; i++) {
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zip_hash_entry_t *entry = hash->table[i];
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while (entry) {
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zip_hash_entry_t *next = entry->next;
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zip_uint32_t new_index = entry->hash_value % new_size;
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entry->next = new_table[new_index];
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new_table[new_index] = entry;
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entry = next;
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}
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}
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}
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free(hash->table);
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hash->table = new_table;
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hash->table_size = new_size;
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return true;
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}
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static zip_uint32_t
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size_for_capacity(zip_uint64_t capacity) {
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double needed_size = capacity / HASH_MAX_FILL;
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zip_uint32_t v;
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if (needed_size > ZIP_UINT32_MAX) {
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v = ZIP_UINT32_MAX;
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}
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else {
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v = (zip_uint32_t)needed_size;
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}
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if (v > HASH_MAX_SIZE) {
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return HASH_MAX_SIZE;
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}
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/* From Bit Twiddling Hacks by Sean Eron Anderson <seander@cs.stanford.edu>
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(http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2). */
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v--;
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v |= v >> 1;
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v |= v >> 2;
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v |= v >> 4;
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v |= v >> 8;
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v |= v >> 16;
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v++;
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return v;
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}
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zip_hash_t *
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_zip_hash_new(zip_error_t *error) {
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zip_hash_t *hash;
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if ((hash = (zip_hash_t *)malloc(sizeof(zip_hash_t))) == NULL) {
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zip_error_set(error, ZIP_ER_MEMORY, 0);
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return NULL;
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}
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hash->table_size = 0;
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hash->nentries = 0;
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hash->table = NULL;
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return hash;
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}
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void
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_zip_hash_free(zip_hash_t *hash) {
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zip_uint32_t i;
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if (hash == NULL) {
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return;
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}
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if (hash->table != NULL) {
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for (i = 0; i < hash->table_size; i++) {
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if (hash->table[i] != NULL) {
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free_list(hash->table[i]);
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}
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}
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free(hash->table);
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}
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free(hash);
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}
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/* insert into hash, return error on existence or memory issues */
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bool
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_zip_hash_add(zip_hash_t *hash, const zip_uint8_t *name, zip_uint64_t index, zip_flags_t flags, zip_error_t *error) {
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zip_uint32_t hash_value, table_index;
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zip_hash_entry_t *entry;
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if (hash == NULL || name == NULL || index > ZIP_INT64_MAX) {
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zip_error_set(error, ZIP_ER_INVAL, 0);
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return false;
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}
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if (hash->table_size == 0) {
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if (!hash_resize(hash, HASH_MIN_SIZE, error)) {
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return false;
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}
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}
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hash_value = hash_string(name);
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table_index = hash_value % hash->table_size;
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for (entry = hash->table[table_index]; entry != NULL; entry = entry->next) {
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if (entry->hash_value == hash_value && strcmp((const char *)name, (const char *)entry->name) == 0) {
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if (((flags & ZIP_FL_UNCHANGED) && entry->orig_index != -1) || entry->current_index != -1) {
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zip_error_set(error, ZIP_ER_EXISTS, 0);
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return false;
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}
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else {
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break;
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}
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}
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}
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if (entry == NULL) {
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if ((entry = (zip_hash_entry_t *)malloc(sizeof(zip_hash_entry_t))) == NULL) {
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zip_error_set(error, ZIP_ER_MEMORY, 0);
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return false;
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}
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entry->name = name;
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entry->next = hash->table[table_index];
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hash->table[table_index] = entry;
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entry->hash_value = hash_value;
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entry->orig_index = -1;
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hash->nentries++;
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if (hash->nentries > hash->table_size * HASH_MAX_FILL && hash->table_size < HASH_MAX_SIZE) {
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if (!hash_resize(hash, hash->table_size * 2, error)) {
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return false;
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}
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}
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}
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if (flags & ZIP_FL_UNCHANGED) {
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entry->orig_index = (zip_int64_t)index;
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}
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entry->current_index = (zip_int64_t)index;
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return true;
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}
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/* remove entry from hash, error if not found */
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bool
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_zip_hash_delete(zip_hash_t *hash, const zip_uint8_t *name, zip_error_t *error) {
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zip_uint32_t hash_value, index;
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zip_hash_entry_t *entry, *previous;
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if (hash == NULL || name == NULL) {
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zip_error_set(error, ZIP_ER_INVAL, 0);
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return false;
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}
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if (hash->nentries > 0) {
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hash_value = hash_string(name);
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index = hash_value % hash->table_size;
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previous = NULL;
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entry = hash->table[index];
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while (entry) {
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if (entry->hash_value == hash_value && strcmp((const char *)name, (const char *)entry->name) == 0) {
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if (entry->orig_index == -1) {
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if (previous) {
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previous->next = entry->next;
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}
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else {
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hash->table[index] = entry->next;
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}
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free(entry);
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hash->nentries--;
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if (hash->nentries < hash->table_size * HASH_MIN_FILL && hash->table_size > HASH_MIN_SIZE) {
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if (!hash_resize(hash, hash->table_size / 2, error)) {
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return false;
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}
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}
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}
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else {
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entry->current_index = -1;
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}
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return true;
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}
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previous = entry;
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entry = entry->next;
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}
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}
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zip_error_set(error, ZIP_ER_NOENT, 0);
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return false;
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}
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/* find value for entry in hash, -1 if not found */
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zip_int64_t
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_zip_hash_lookup(zip_hash_t *hash, const zip_uint8_t *name, zip_flags_t flags, zip_error_t *error) {
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zip_uint32_t hash_value, index;
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zip_hash_entry_t *entry;
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if (hash == NULL || name == NULL) {
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zip_error_set(error, ZIP_ER_INVAL, 0);
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return -1;
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}
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if (hash->nentries > 0) {
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hash_value = hash_string(name);
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index = hash_value % hash->table_size;
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for (entry = hash->table[index]; entry != NULL; entry = entry->next) {
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if (strcmp((const char *)name, (const char *)entry->name) == 0) {
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if (flags & ZIP_FL_UNCHANGED) {
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if (entry->orig_index != -1) {
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return entry->orig_index;
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}
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}
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else {
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if (entry->current_index != -1) {
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return entry->current_index;
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}
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}
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break;
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}
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}
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}
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zip_error_set(error, ZIP_ER_NOENT, 0);
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return -1;
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}
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bool
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_zip_hash_reserve_capacity(zip_hash_t *hash, zip_uint64_t capacity, zip_error_t *error) {
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zip_uint32_t new_size;
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if (capacity == 0) {
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return true;
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}
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new_size = size_for_capacity(capacity);
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if (new_size <= hash->table_size) {
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return true;
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}
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if (!hash_resize(hash, new_size, error)) {
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return false;
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}
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return true;
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}
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bool
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_zip_hash_revert(zip_hash_t *hash, zip_error_t *error) {
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zip_uint32_t i;
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zip_hash_entry_t *entry, *previous;
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for (i = 0; i < hash->table_size; i++) {
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previous = NULL;
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entry = hash->table[i];
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while (entry) {
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if (entry->orig_index == -1) {
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zip_hash_entry_t *p;
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if (previous) {
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previous->next = entry->next;
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}
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else {
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hash->table[i] = entry->next;
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}
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p = entry;
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entry = entry->next;
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/* previous does not change */
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free(p);
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hash->nentries--;
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}
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else {
|
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|
|
entry->current_index = entry->orig_index;
|
||
|
|
previous = entry;
|
||
|
|
entry = entry->next;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
if (hash->nentries < hash->table_size * HASH_MIN_FILL && hash->table_size > HASH_MIN_SIZE) {
|
||
|
|
zip_uint32_t new_size = hash->table_size / 2;
|
||
|
|
while (hash->nentries < new_size * HASH_MIN_FILL && new_size > HASH_MIN_SIZE) {
|
||
|
|
new_size /= 2;
|
||
|
|
}
|
||
|
|
if (!hash_resize(hash, new_size, error)) {
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return true;
|
||
|
|
}
|