ref: bfe9da47cfa2f51ebef78c59332b5ba2deba306d
dir: /third_party/boringssl/src/crypto/lhash/lhash.c/
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* 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 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* "This product includes cryptographic software written by
* Eric Young (eay@cryptsoft.com)"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``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 AUTHOR OR CONTRIBUTORS 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.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.] */
#include <openssl/lhash.h>
#include <assert.h>
#include <limits.h>
#include <string.h>
#include <openssl/mem.h>
#include "internal.h"
#include "../internal.h"
// kMinNumBuckets is the minimum size of the buckets array in an |_LHASH|.
static const size_t kMinNumBuckets = 16;
// kMaxAverageChainLength contains the maximum, average chain length. When the
// average chain length exceeds this value, the hash table will be resized.
static const size_t kMaxAverageChainLength = 2;
static const size_t kMinAverageChainLength = 1;
// lhash_item_st is an element of a hash chain. It points to the opaque data
// for this element and to the next item in the chain. The linked-list is NULL
// terminated.
typedef struct lhash_item_st {
void *data;
struct lhash_item_st *next;
// hash contains the cached, hash value of |data|.
uint32_t hash;
} LHASH_ITEM;
struct lhash_st {
// num_items contains the total number of items in the hash table.
size_t num_items;
// buckets is an array of |num_buckets| pointers. Each points to the head of
// a chain of LHASH_ITEM objects that have the same hash value, mod
// |num_buckets|.
LHASH_ITEM **buckets;
// num_buckets contains the length of |buckets|. This value is always >=
// kMinNumBuckets.
size_t num_buckets;
// callback_depth contains the current depth of |lh_doall| or |lh_doall_arg|
// calls. If non-zero then this suppresses resizing of the |buckets| array,
// which would otherwise disrupt the iteration.
unsigned callback_depth;
lhash_cmp_func comp;
lhash_hash_func hash;
};
_LHASH *OPENSSL_lh_new(lhash_hash_func hash, lhash_cmp_func comp) {
_LHASH *ret = OPENSSL_malloc(sizeof(_LHASH));
if (ret == NULL) {
return NULL;
}
OPENSSL_memset(ret, 0, sizeof(_LHASH));
ret->num_buckets = kMinNumBuckets;
ret->buckets = OPENSSL_malloc(sizeof(LHASH_ITEM *) * ret->num_buckets);
if (ret->buckets == NULL) {
OPENSSL_free(ret);
return NULL;
}
OPENSSL_memset(ret->buckets, 0, sizeof(LHASH_ITEM *) * ret->num_buckets);
ret->comp = comp;
ret->hash = hash;
return ret;
}
void OPENSSL_lh_free(_LHASH *lh) {
if (lh == NULL) {
return;
}
for (size_t i = 0; i < lh->num_buckets; i++) {
LHASH_ITEM *next;
for (LHASH_ITEM *n = lh->buckets[i]; n != NULL; n = next) {
next = n->next;
OPENSSL_free(n);
}
}
OPENSSL_free(lh->buckets);
OPENSSL_free(lh);
}
size_t OPENSSL_lh_num_items(const _LHASH *lh) { return lh->num_items; }
// get_next_ptr_and_hash returns a pointer to the pointer that points to the
// item equal to |data|. In other words, it searches for an item equal to |data|
// and, if it's at the start of a chain, then it returns a pointer to an
// element of |lh->buckets|, otherwise it returns a pointer to the |next|
// element of the previous item in the chain. If an element equal to |data| is
// not found, it returns a pointer that points to a NULL pointer. If |out_hash|
// is not NULL, then it also puts the hash value of |data| in |*out_hash|.
static LHASH_ITEM **get_next_ptr_and_hash(const _LHASH *lh, uint32_t *out_hash,
const void *data,
lhash_hash_func_helper call_hash_func,
lhash_cmp_func_helper call_cmp_func) {
const uint32_t hash = call_hash_func(lh->hash, data);
if (out_hash != NULL) {
*out_hash = hash;
}
LHASH_ITEM **ret = &lh->buckets[hash % lh->num_buckets];
for (LHASH_ITEM *cur = *ret; cur != NULL; cur = *ret) {
if (call_cmp_func(lh->comp, cur->data, data) == 0) {
break;
}
ret = &cur->next;
}
return ret;
}
// get_next_ptr_by_key behaves like |get_next_ptr_and_hash| but takes a key
// which may be a different type from the values stored in |lh|.
static LHASH_ITEM **get_next_ptr_by_key(const _LHASH *lh, const void *key,
uint32_t key_hash,
int (*cmp_key)(const void *key,
const void *value)) {
LHASH_ITEM **ret = &lh->buckets[key_hash % lh->num_buckets];
for (LHASH_ITEM *cur = *ret; cur != NULL; cur = *ret) {
if (cmp_key(key, cur->data) == 0) {
break;
}
ret = &cur->next;
}
return ret;
}
void *OPENSSL_lh_retrieve(const _LHASH *lh, const void *data,
lhash_hash_func_helper call_hash_func,
lhash_cmp_func_helper call_cmp_func) {
LHASH_ITEM **next_ptr =
get_next_ptr_and_hash(lh, NULL, data, call_hash_func, call_cmp_func);
return *next_ptr == NULL ? NULL : (*next_ptr)->data;
}
void *OPENSSL_lh_retrieve_key(const _LHASH *lh, const void *key,
uint32_t key_hash,
int (*cmp_key)(const void *key,
const void *value)) {
LHASH_ITEM **next_ptr = get_next_ptr_by_key(lh, key, key_hash, cmp_key);
return *next_ptr == NULL ? NULL : (*next_ptr)->data;
}
// lh_rebucket allocates a new array of |new_num_buckets| pointers and
// redistributes the existing items into it before making it |lh->buckets| and
// freeing the old array.
static void lh_rebucket(_LHASH *lh, const size_t new_num_buckets) {
LHASH_ITEM **new_buckets, *cur, *next;
size_t i, alloc_size;
alloc_size = sizeof(LHASH_ITEM *) * new_num_buckets;
if (alloc_size / sizeof(LHASH_ITEM*) != new_num_buckets) {
return;
}
new_buckets = OPENSSL_malloc(alloc_size);
if (new_buckets == NULL) {
return;
}
OPENSSL_memset(new_buckets, 0, alloc_size);
for (i = 0; i < lh->num_buckets; i++) {
for (cur = lh->buckets[i]; cur != NULL; cur = next) {
const size_t new_bucket = cur->hash % new_num_buckets;
next = cur->next;
cur->next = new_buckets[new_bucket];
new_buckets[new_bucket] = cur;
}
}
OPENSSL_free(lh->buckets);
lh->num_buckets = new_num_buckets;
lh->buckets = new_buckets;
}
// lh_maybe_resize resizes the |buckets| array if needed.
static void lh_maybe_resize(_LHASH *lh) {
size_t avg_chain_length;
if (lh->callback_depth > 0) {
// Don't resize the hash if we are currently iterating over it.
return;
}
assert(lh->num_buckets >= kMinNumBuckets);
avg_chain_length = lh->num_items / lh->num_buckets;
if (avg_chain_length > kMaxAverageChainLength) {
const size_t new_num_buckets = lh->num_buckets * 2;
if (new_num_buckets > lh->num_buckets) {
lh_rebucket(lh, new_num_buckets);
}
} else if (avg_chain_length < kMinAverageChainLength &&
lh->num_buckets > kMinNumBuckets) {
size_t new_num_buckets = lh->num_buckets / 2;
if (new_num_buckets < kMinNumBuckets) {
new_num_buckets = kMinNumBuckets;
}
lh_rebucket(lh, new_num_buckets);
}
}
int OPENSSL_lh_insert(_LHASH *lh, void **old_data, void *data,
lhash_hash_func_helper call_hash_func,
lhash_cmp_func_helper call_cmp_func) {
uint32_t hash;
LHASH_ITEM **next_ptr, *item;
*old_data = NULL;
next_ptr =
get_next_ptr_and_hash(lh, &hash, data, call_hash_func, call_cmp_func);
if (*next_ptr != NULL) {
// An element equal to |data| already exists in the hash table. It will be
// replaced.
*old_data = (*next_ptr)->data;
(*next_ptr)->data = data;
return 1;
}
// An element equal to |data| doesn't exist in the hash table yet.
item = OPENSSL_malloc(sizeof(LHASH_ITEM));
if (item == NULL) {
return 0;
}
item->data = data;
item->hash = hash;
item->next = NULL;
*next_ptr = item;
lh->num_items++;
lh_maybe_resize(lh);
return 1;
}
void *OPENSSL_lh_delete(_LHASH *lh, const void *data,
lhash_hash_func_helper call_hash_func,
lhash_cmp_func_helper call_cmp_func) {
LHASH_ITEM **next_ptr, *item, *ret;
next_ptr =
get_next_ptr_and_hash(lh, NULL, data, call_hash_func, call_cmp_func);
if (*next_ptr == NULL) {
// No such element.
return NULL;
}
item = *next_ptr;
*next_ptr = item->next;
ret = item->data;
OPENSSL_free(item);
lh->num_items--;
lh_maybe_resize(lh);
return ret;
}
void OPENSSL_lh_doall_arg(_LHASH *lh, void (*func)(void *, void *), void *arg) {
if (lh == NULL) {
return;
}
if (lh->callback_depth < UINT_MAX) {
// |callback_depth| is a saturating counter.
lh->callback_depth++;
}
for (size_t i = 0; i < lh->num_buckets; i++) {
LHASH_ITEM *next;
for (LHASH_ITEM *cur = lh->buckets[i]; cur != NULL; cur = next) {
next = cur->next;
func(cur->data, arg);
}
}
if (lh->callback_depth < UINT_MAX) {
lh->callback_depth--;
}
// The callback may have added or removed elements and the non-zero value of
// |callback_depth| will have suppressed any resizing. Thus any needed
// resizing is done here.
lh_maybe_resize(lh);
}