text: /* 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 <CJWTKitBoringSSL_lhash.h>
  
  #include <assert.h>
  #include <limits.h>
  #include <string.h>
  
  #include <CJWTKitBoringSSL_mem.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;
  
  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 *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 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 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 *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 *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 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 *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 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);
  }
  
  uint32_t lh_strhash(const char *c) {
    if (c == NULL) {
      return 0;
    }
  
    return OPENSSL_hash32(c, strlen(c));
  }
  