root/ext/zip/lib/zip_hash.c

DEFINITIONS

1. _zip_hash_new
2. _free_list
3. _zip_hash_free
4. _hash_string
5. _zip_hash_add
6. _zip_hash_delete
7. _zip_hash_lookup
8. _zip_hash_revert

   1 /*
   2   zip_hash.c -- hash table string -> uint64
   3   Copyright (C) 2015-2016 Dieter Baron and Thomas Klausner
   4 
   5   This file is part of libzip, a library to manipulate ZIP archives.
   6   The authors can be contacted at <libzip@nih.at>
   7 
   8   Redistribution and use in source and binary forms, with or without
   9   modification, are permitted provided that the following conditions
  10   are met:
  11   1. Redistributions of source code must retain the above copyright
  12      notice, this list of conditions and the following disclaimer.
  13   2. Redistributions in binary form must reproduce the above copyright
  14      notice, this list of conditions and the following disclaimer in
  15      the documentation and/or other materials provided with the
  16      distribution.
  17   3. The names of the authors may not be used to endorse or promote
  18      products derived from this software without specific prior
  19      written permission.
  20  
  21   THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS
  22   OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  23   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24   ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
  25   DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26   DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
  27   GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  28   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
  29   IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  30   OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
  31   IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32 */
  33 
  34 #include <stdlib.h>
  35 #include <string.h>
  36 #include "zipint.h"
  37 
  38 struct zip_hash_entry {
  39     const zip_uint8_t *name;
  40     zip_int64_t orig_index;
  41     zip_int64_t current_index;
  42     struct zip_hash_entry *next;
  43 };
  44 typedef struct zip_hash_entry zip_hash_entry_t;
  45 
  46 struct zip_hash {
  47     zip_uint16_t table_size;
  48     zip_hash_entry_t **table;
  49 };
  50 
  51 zip_hash_t *
  52 _zip_hash_new(zip_uint16_t table_size, zip_error_t *error)
  53 {
  54     zip_hash_t *hash;
  55 
  56     if (table_size == 0) {
  57         zip_error_set(error, ZIP_ER_INTERNAL, 0);
  58         return NULL;
  59     }
  60 
  61     if ((hash=(zip_hash_t *)malloc(sizeof(zip_hash_t))) == NULL) {
  62         zip_error_set(error, ZIP_ER_MEMORY, 0);
  63         return NULL;
  64     }
  65     hash->table_size = table_size;
  66     if ((hash->table=(zip_hash_entry_t**)calloc(table_size, sizeof(zip_hash_entry_t *))) == NULL) {
  67         free(hash);
  68         zip_error_set(error, ZIP_ER_MEMORY, 0);
  69         return NULL;
  70     }
  71 
  72     return hash;
  73 }
  74 
  75 static void
  76 _free_list(zip_hash_entry_t *entry)
  77 {
  78     zip_hash_entry_t *next;
  79     do {
  80         next = entry->next;
  81         free(entry);
  82         entry = next;
  83     } while (entry != NULL);
  84 }
  85 
  86 void
  87 _zip_hash_free(zip_hash_t *hash)
  88 {
  89     zip_uint16_t i;
  90 
  91     if (hash == NULL) {
  92         return;
  93     }
  94 
  95     for (i=0; i<hash->table_size; i++) {
  96         if (hash->table[i] != NULL) {
  97             _free_list(hash->table[i]);
  98         }
  99     }
 100     free(hash->table);
 101     free(hash);
 102 }
 103 
 104 static zip_uint16_t
 105 _hash_string(const zip_uint8_t *name, zip_uint16_t size)
 106 {
 107 #define HASH_MULTIPLIER 33
 108     zip_uint16_t value = 5381;
 109 
 110     if (name == NULL)
 111         return 0;
 112 
 113     while (*name != 0) {
 114         value = (zip_uint16_t)(((value * HASH_MULTIPLIER) + (zip_uint8_t)*name) % size);
 115         name++;
 116     }
 117 
 118     return value;
 119 }
 120 
 121 /* insert into hash, return error on existence or memory issues */
 122 bool
 123 _zip_hash_add(zip_hash_t *hash, const zip_uint8_t *name, zip_uint64_t index, zip_flags_t flags, zip_error_t *error)
 124 {
 125     zip_uint16_t hash_value;
 126     zip_hash_entry_t *entry;
 127 
 128     if (hash == NULL || name == NULL || index > ZIP_INT64_MAX) {
 129         zip_error_set(error, ZIP_ER_INVAL, 0);
 130         return false;
 131     }
 132 
 133     hash_value = _hash_string(name, hash->table_size);
 134     for (entry = hash->table[hash_value]; entry != NULL; entry = entry->next) {
 135         if (strcmp((const char *)name, (const char *)entry->name) == 0) {
 136             if (((flags & ZIP_FL_UNCHANGED) && entry->orig_index != -1) || entry->current_index != -1) {
 137                 zip_error_set(error, ZIP_ER_EXISTS, 0);
 138                 return false;
 139             }
 140             else {
 141                 break;
 142             }
 143         }
 144     }
 145 
 146     if (entry == NULL) {
 147         if ((entry=(zip_hash_entry_t *)malloc(sizeof(zip_hash_entry_t))) == NULL) {
 148             zip_error_set(error, ZIP_ER_MEMORY, 0);
 149             return false;
 150         }
 151         entry->name = name;
 152         entry->next = hash->table[hash_value];
 153         hash->table[hash_value] = entry;
 154         entry->orig_index = -1;
 155     }
 156 
 157     if (flags & ZIP_FL_UNCHANGED) {
 158         entry->orig_index = (zip_int64_t)index;
 159     }
 160     entry->current_index = (zip_int64_t)index;
 161 
 162     return true;
 163 }
 164 
 165 /* remove entry from hash, error if not found */
 166 bool
 167 _zip_hash_delete(zip_hash_t *hash, const zip_uint8_t *name, zip_error_t *error)
 168 {
 169     zip_uint16_t hash_value;
 170     zip_hash_entry_t *entry, *previous;
 171 
 172     if (hash == NULL || name == NULL) {
 173         zip_error_set(error, ZIP_ER_INVAL, 0);
 174         return false;
 175     }
 176 
 177     hash_value = _hash_string(name, hash->table_size);
 178     previous = NULL;
 179     entry = hash->table[hash_value];
 180     while (entry) {
 181         if (strcmp((const char *)name, (const char *)entry->name) == 0) {
 182             if (entry->orig_index == -1) {
 183                 if (previous) {
 184                     previous->next = entry->next;
 185                 }
 186                 else {
 187                     hash->table[hash_value] = entry->next;
 188                 }
 189                 free(entry);
 190             }
 191             else {
 192                 entry->current_index = -1;
 193             }
 194             return true;
 195         }
 196         previous = entry;
 197         entry = entry->next;
 198     };
 199 
 200     zip_error_set(error, ZIP_ER_NOENT, 0);
 201     return false;
 202 }
 203 
 204 /* find value for entry in hash, -1 if not found */
 205 zip_int64_t
 206 _zip_hash_lookup(zip_hash_t *hash, const zip_uint8_t *name, zip_flags_t flags, zip_error_t *error)
 207 {
 208     zip_uint16_t hash_value;
 209     zip_hash_entry_t *entry;
 210 
 211     if (hash == NULL || name == NULL) {
 212         zip_error_set(error, ZIP_ER_INVAL, 0);
 213         return -1;
 214     }
 215 
 216     hash_value = _hash_string(name, hash->table_size);
 217     for (entry = hash->table[hash_value]; entry != NULL; entry = entry->next) {
 218         if (strcmp((const char *)name, (const char *)entry->name) == 0) {
 219             if (flags & ZIP_FL_UNCHANGED) {
 220                 if (entry->orig_index != -1) {
 221                     return entry->orig_index;
 222                 }
 223             }
 224             else {
 225                 if (entry->current_index != -1) {
 226                     return entry->current_index;
 227                 }
 228             }
 229             break;
 230         }
 231     }
 232 
 233     zip_error_set(error, ZIP_ER_NOENT, 0);
 234     return -1;    
 235 }
 236 
 237 void
 238 _zip_hash_revert(zip_hash_t *hash)
 239 {
 240     zip_uint16_t i;
 241     zip_hash_entry_t *entry, *previous;
 242     
 243     for (i = 0; i < hash->table_size; i++) {
 244         previous = NULL;
 245         entry = hash->table[i];
 246         while (entry) {
 247             if (entry->orig_index == -1) {
 248                 zip_hash_entry_t *p;
 249                 if (previous) {
 250                     previous->next = entry->next;
 251                 }
 252                 else {
 253                     hash->table[i] = entry->next;
 254                 }
 255                 p = entry;
 256                 entry = entry->next;
 257                 /* previous does not change */
 258                 free(p);
 259             }
 260             else {
 261                 entry->current_index = entry->orig_index;
 262                 previous = entry;
 263                 entry = entry->next;
 264             }
 265         }
 266     }
 267 }