First Commit

3rdparty/libzip/lib/zip_hash.c

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+/*
+  zip_hash.c -- hash table string -> uint64
+  Copyright (C) 2015-2022 Dieter Baron and Thomas Klausner
+
+  This file is part of libzip, a library to manipulate ZIP archives.
+  The authors can be contacted at <info@libzip.org>
+
+  Redistribution and use in source and binary forms, with or without
+  modification, are permitted provided that the following conditions
+  are met:
+  1. Redistributions of source code must retain the above copyright
+     notice, this list of conditions and the following disclaimer.
+  2. Redistributions in binary form must reproduce the above copyright
+     notice, this list of conditions and the following disclaimer in
+     the documentation and/or other materials provided with the
+     distribution.
+  3. The names of the authors may not be used to endorse or promote
+     products derived from this software without specific prior
+     written permission.
+
+  THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS
+  OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+  ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
+  DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
+  GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
+  IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+  OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
+  IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include "zipint.h"
+#include <stdlib.h>
+#include <string.h>
+
+/* parameter for the string hash function */
+#define HASH_MULTIPLIER 33
+#define HASH_START 5381
+
+/* hash table's fill ratio is kept between these by doubling/halfing its size as necessary */
+#define HASH_MAX_FILL .75
+#define HASH_MIN_FILL .01
+
+/* but hash table size is kept between these */
+#define HASH_MIN_SIZE 256
+#define HASH_MAX_SIZE 0x80000000ul
+
+struct zip_hash_entry {
+    const zip_uint8_t *name;
+    zip_int64_t orig_index;
+    zip_int64_t current_index;
+    struct zip_hash_entry *next;
+    zip_uint32_t hash_value;
+};
+typedef struct zip_hash_entry zip_hash_entry_t;
+
+struct zip_hash {
+    zip_uint32_t table_size;
+    zip_uint64_t nentries;
+    zip_hash_entry_t **table;
+};
+
+
+/* free list of entries */
+static void
+free_list(zip_hash_entry_t *entry) {
+    while (entry != NULL) {
+        zip_hash_entry_t *next = entry->next;
+        free(entry);
+        entry = next;
+    }
+}
+
+
+/* compute hash of string, full 32 bit value */
+static zip_uint32_t
+hash_string(const zip_uint8_t *name) {
+    zip_uint64_t value = HASH_START;
+
+    if (name == NULL) {
+        return 0;
+    }
+
+    while (*name != 0) {
+        value = (zip_uint64_t)(((value * HASH_MULTIPLIER) + (zip_uint8_t)*name) % 0x100000000ul);
+        name++;
+    }
+
+    return (zip_uint32_t)value;
+}
+
+
+/* resize hash table; new_size must be a power of 2, can be larger or smaller than current size */
+static bool
+hash_resize(zip_hash_t *hash, zip_uint32_t new_size, zip_error_t *error) {
+    zip_hash_entry_t **new_table;
+
+    if (new_size == hash->table_size) {
+        return true;
+    }
+
+    if ((new_table = (zip_hash_entry_t **)calloc(new_size, sizeof(zip_hash_entry_t *))) == NULL) {
+        zip_error_set(error, ZIP_ER_MEMORY, 0);
+        return false;
+    }
+
+    if (hash->nentries > 0) {
+        zip_uint32_t i;
+
+        for (i = 0; i < hash->table_size; i++) {
+            zip_hash_entry_t *entry = hash->table[i];
+            while (entry) {
+                zip_hash_entry_t *next = entry->next;
+
+                zip_uint32_t new_index = entry->hash_value % new_size;
+
+                entry->next = new_table[new_index];
+                new_table[new_index] = entry;
+
+                entry = next;
+            }
+        }
+    }
+
+    free(hash->table);
+    hash->table = new_table;
+    hash->table_size = new_size;
+
+    return true;
+}
+
+
+static zip_uint32_t
+size_for_capacity(zip_uint64_t capacity) {
+    double needed_size = capacity / HASH_MAX_FILL;
+    zip_uint32_t v;
+
+    if (needed_size > ZIP_UINT32_MAX) {
+        v = ZIP_UINT32_MAX;
+    }
+    else {
+        v = (zip_uint32_t)needed_size;
+    }
+
+    if (v > HASH_MAX_SIZE) {
+        return HASH_MAX_SIZE;
+    }
+
+    /* From Bit Twiddling Hacks by Sean Eron Anderson <seander@cs.stanford.edu>
+     (http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2). */
+
+    v--;
+    v |= v >> 1;
+    v |= v >> 2;
+    v |= v >> 4;
+    v |= v >> 8;
+    v |= v >> 16;
+    v++;
+
+    return v;
+}
+
+
+zip_hash_t *
+_zip_hash_new(zip_error_t *error) {
+    zip_hash_t *hash;
+
+    if ((hash = (zip_hash_t *)malloc(sizeof(zip_hash_t))) == NULL) {
+        zip_error_set(error, ZIP_ER_MEMORY, 0);
+        return NULL;
+    }
+
+    hash->table_size = 0;
+    hash->nentries = 0;
+    hash->table = NULL;
+
+    return hash;
+}
+
+
+void
+_zip_hash_free(zip_hash_t *hash) {
+    zip_uint32_t i;
+
+    if (hash == NULL) {
+        return;
+    }
+
+    if (hash->table != NULL) {
+        for (i = 0; i < hash->table_size; i++) {
+            if (hash->table[i] != NULL) {
+                free_list(hash->table[i]);
+            }
+        }
+        free(hash->table);
+    }
+    free(hash);
+}
+
+
+/* insert into hash, return error on existence or memory issues */
+bool
+_zip_hash_add(zip_hash_t *hash, const zip_uint8_t *name, zip_uint64_t index, zip_flags_t flags, zip_error_t *error) {
+    zip_uint32_t hash_value, table_index;
+    zip_hash_entry_t *entry;
+
+    if (hash == NULL || name == NULL || index > ZIP_INT64_MAX) {
+        zip_error_set(error, ZIP_ER_INVAL, 0);
+        return false;
+    }
+
+    if (hash->table_size == 0) {
+        if (!hash_resize(hash, HASH_MIN_SIZE, error)) {
+            return false;
+        }
+    }
+
+    hash_value = hash_string(name);
+    table_index = hash_value % hash->table_size;
+
+    for (entry = hash->table[table_index]; entry != NULL; entry = entry->next) {
+        if (entry->hash_value == hash_value && strcmp((const char *)name, (const char *)entry->name) == 0) {
+            if (((flags & ZIP_FL_UNCHANGED) && entry->orig_index != -1) || entry->current_index != -1) {
+                zip_error_set(error, ZIP_ER_EXISTS, 0);
+                return false;
+            }
+            else {
+                break;
+            }
+        }
+    }
+
+    if (entry == NULL) {
+        if ((entry = (zip_hash_entry_t *)malloc(sizeof(zip_hash_entry_t))) == NULL) {
+            zip_error_set(error, ZIP_ER_MEMORY, 0);
+            return false;
+        }
+        entry->name = name;
+        entry->next = hash->table[table_index];
+        hash->table[table_index] = entry;
+        entry->hash_value = hash_value;
+        entry->orig_index = -1;
+        hash->nentries++;
+        if (hash->nentries > hash->table_size * HASH_MAX_FILL && hash->table_size < HASH_MAX_SIZE) {
+            if (!hash_resize(hash, hash->table_size * 2, error)) {
+                return false;
+            }
+        }
+    }
+
+    if (flags & ZIP_FL_UNCHANGED) {
+        entry->orig_index = (zip_int64_t)index;
+    }
+    entry->current_index = (zip_int64_t)index;
+
+    return true;
+}
+
+
+/* remove entry from hash, error if not found */
+bool
+_zip_hash_delete(zip_hash_t *hash, const zip_uint8_t *name, zip_error_t *error) {
+    zip_uint32_t hash_value, index;
+    zip_hash_entry_t *entry, *previous;
+
+    if (hash == NULL || name == NULL) {
+        zip_error_set(error, ZIP_ER_INVAL, 0);
+        return false;
+    }
+
+    if (hash->nentries > 0) {
+        hash_value = hash_string(name);
+        index = hash_value % hash->table_size;
+        previous = NULL;
+        entry = hash->table[index];
+        while (entry) {
+            if (entry->hash_value == hash_value && strcmp((const char *)name, (const char *)entry->name) == 0) {
+                if (entry->orig_index == -1) {
+                    if (previous) {
+                        previous->next = entry->next;
+                    }
+                    else {
+                        hash->table[index] = entry->next;
+                    }
+                    free(entry);
+                    hash->nentries--;
+                    if (hash->nentries < hash->table_size * HASH_MIN_FILL && hash->table_size > HASH_MIN_SIZE) {
+                        if (!hash_resize(hash, hash->table_size / 2, error)) {
+                            return false;
+                        }
+                    }
+                }
+                else {
+                    entry->current_index = -1;
+                }
+                return true;
+            }
+            previous = entry;
+            entry = entry->next;
+        }
+    }
+
+    zip_error_set(error, ZIP_ER_NOENT, 0);
+    return false;
+}
+
+
+/* find value for entry in hash, -1 if not found */
+zip_int64_t
+_zip_hash_lookup(zip_hash_t *hash, const zip_uint8_t *name, zip_flags_t flags, zip_error_t *error) {
+    zip_uint32_t hash_value, index;
+    zip_hash_entry_t *entry;
+
+    if (hash == NULL || name == NULL) {
+        zip_error_set(error, ZIP_ER_INVAL, 0);
+        return -1;
+    }
+
+    if (hash->nentries > 0) {
+        hash_value = hash_string(name);
+        index = hash_value % hash->table_size;
+        for (entry = hash->table[index]; entry != NULL; entry = entry->next) {
+            if (strcmp((const char *)name, (const char *)entry->name) == 0) {
+                if (flags & ZIP_FL_UNCHANGED) {
+                    if (entry->orig_index != -1) {
+                        return entry->orig_index;
+                    }
+                }
+                else {
+                    if (entry->current_index != -1) {
+                        return entry->current_index;
+                    }
+                }
+                break;
+            }
+        }
+    }
+
+    zip_error_set(error, ZIP_ER_NOENT, 0);
+    return -1;
+}
+
+
+bool
+_zip_hash_reserve_capacity(zip_hash_t *hash, zip_uint64_t capacity, zip_error_t *error) {
+    zip_uint32_t new_size;
+
+    if (capacity == 0) {
+        return true;
+    }
+
+    new_size = size_for_capacity(capacity);
+
+    if (new_size <= hash->table_size) {
+        return true;
+    }
+
+    if (!hash_resize(hash, new_size, error)) {
+        return false;
+    }
+
+    return true;
+}
+
+
+bool
+_zip_hash_revert(zip_hash_t *hash, zip_error_t *error) {
+    zip_uint32_t i;
+    zip_hash_entry_t *entry, *previous;
+
+    for (i = 0; i < hash->table_size; i++) {
+        previous = NULL;
+        entry = hash->table[i];
+        while (entry) {
+            if (entry->orig_index == -1) {
+                zip_hash_entry_t *p;
+                if (previous) {
+                    previous->next = entry->next;
+                }
+                else {
+                    hash->table[i] = entry->next;
+                }
+                p = entry;
+                entry = entry->next;
+                /* previous does not change */
+                free(p);
+                hash->nentries--;
+            }
+            else {
+                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;
+}