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1 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
2  * All rights reserved.
3  *
4  * This package is an SSL implementation written
5  * by Eric Young (eay@cryptsoft.com).
6  * The implementation was written so as to conform with Netscapes SSL.
7  *
8  * This library is free for commercial and non-commercial use as long as
9  * the following conditions are aheared to.  The following conditions
10  * apply to all code found in this distribution, be it the RC4, RSA,
11  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
12  * included with this distribution is covered by the same copyright terms
13  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
14  *
15  * Copyright remains Eric Young's, and as such any Copyright notices in
16  * the code are not to be removed.
17  * If this package is used in a product, Eric Young should be given attribution
18  * as the author of the parts of the library used.
19  * This can be in the form of a textual message at program startup or
20  * in documentation (online or textual) provided with the package.
21  *
22  * Redistribution and use in source and binary forms, with or without
23  * modification, are permitted provided that the following conditions
24  * are met:
25  * 1. Redistributions of source code must retain the copyright
26  *    notice, this list of conditions and the following disclaimer.
27  * 2. Redistributions in binary form must reproduce the above copyright
28  *    notice, this list of conditions and the following disclaimer in the
29  *    documentation and/or other materials provided with the distribution.
30  * 3. All advertising materials mentioning features or use of this software
31  *    must display the following acknowledgement:
32  *    "This product includes cryptographic software written by
33  *     Eric Young (eay@cryptsoft.com)"
34  *    The word 'cryptographic' can be left out if the rouines from the library
35  *    being used are not cryptographic related :-).
36  * 4. If you include any Windows specific code (or a derivative thereof) from
37  *    the apps directory (application code) you must include an acknowledgement:
38  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
39  *
40  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
41  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
43  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
44  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
45  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
46  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
48  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
49  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
50  * SUCH DAMAGE.
51  *
52  * The licence and distribution terms for any publically available version or
53  * derivative of this code cannot be changed.  i.e. this code cannot simply be
54  * copied and put under another distribution licence
55  * [including the GNU Public Licence.] */
56 
57 #ifndef OPENSSL_HEADER_LHASH_H
58 #define OPENSSL_HEADER_LHASH_H
59 
60 #include <openssl/base.h>
61 #include <openssl/type_check.h>
62 
63 #if defined(__cplusplus)
64 extern "C" {
65 #endif
66 
67 
68 /* lhash is a traditional, chaining hash table that automatically expands and
69  * contracts as needed. One should not use the lh_* functions directly, rather
70  * use the type-safe macro wrappers:
71  *
72  * A hash table of a specific type of object has type |LHASH_OF(type)|. This
73  * can be defined (once) with |DEFINE_LHASH_OF(type)| and declared where needed
74  * with |DECLARE_LHASH_OF(type)|. For example:
75  *
76  *   struct foo {
77  *     int bar;
78  *   };
79  *
80  *   DEFINE_LHASH_OF(struct foo);
81  *
82  * Although note that the hash table will contain /pointers/ to |foo|.
83  *
84  * A macro will be defined for each of the lh_* functions below. For
85  * LHASH_OF(foo), the macros would be lh_foo_new, lh_foo_num_items etc. */
86 
87 
88 #define LHASH_OF(type) struct lhash_st_##type
89 
90 #define DEFINE_LHASH_OF(type) LHASH_OF(type) { int dummy; }
91 
92 #define DECLARE_LHASH_OF(type) LHASH_OF(type);
93 
94 /* The make_macros.sh script in this directory parses the following lines and
95  * generates the lhash_macros.h file that contains macros for the following
96  * types of stacks:
97  *
98  * LHASH_OF:ASN1_OBJECT
99  * LHASH_OF:CONF_VALUE
100  * LHASH_OF:CRYPTO_BUFFER
101  * LHASH_OF:SSL_SESSION */
102 
103 #define IN_LHASH_H
104 #include <openssl/lhash_macros.h>
105 #undef IN_LHASH_H
106 
107 
108 /* lhash_item_st is an element of a hash chain. It points to the opaque data
109  * for this element and to the next item in the chain. The linked-list is NULL
110  * terminated. */
111 typedef struct lhash_item_st {
112   void *data;
113   struct lhash_item_st *next;
114   /* hash contains the cached, hash value of |data|. */
115   uint32_t hash;
116 } LHASH_ITEM;
117 
118 /* lhash_cmp_func is a comparison function that returns a value equal, or not
119  * equal, to zero depending on whether |*a| is equal, or not equal to |*b|,
120  * respectively. Note the difference between this and |stack_cmp_func| in that
121  * this takes pointers to the objects directly. */
122 typedef int (*lhash_cmp_func)(const void *a, const void *b);
123 
124 /* lhash_hash_func is a function that maps an object to a uniformly distributed
125  * uint32_t. */
126 typedef uint32_t (*lhash_hash_func)(const void *a);
127 
128 typedef struct lhash_st {
129   /* num_items contains the total number of items in the hash table. */
130   size_t num_items;
131   /* buckets is an array of |num_buckets| pointers. Each points to the head of
132    * a chain of LHASH_ITEM objects that have the same hash value, mod
133    * |num_buckets|. */
134   LHASH_ITEM **buckets;
135   /* num_buckets contains the length of |buckets|. This value is always >=
136    * kMinNumBuckets. */
137   size_t num_buckets;
138   /* callback_depth contains the current depth of |lh_doall| or |lh_doall_arg|
139    * calls. If non-zero then this suppresses resizing of the |buckets| array,
140    * which would otherwise disrupt the iteration. */
141   unsigned callback_depth;
142 
143   lhash_cmp_func comp;
144   lhash_hash_func hash;
145 } _LHASH;
146 
147 /* lh_new returns a new, empty hash table or NULL on error. */
148 OPENSSL_EXPORT _LHASH *lh_new(lhash_hash_func hash, lhash_cmp_func comp);
149 
150 /* lh_free frees the hash table itself but none of the elements. See
151  * |lh_doall|. */
152 OPENSSL_EXPORT void lh_free(_LHASH *lh);
153 
154 /* lh_num_items returns the number of items in |lh|. */
155 OPENSSL_EXPORT size_t lh_num_items(const _LHASH *lh);
156 
157 /* lh_retrieve finds an element equal to |data| in the hash table and returns
158  * it. If no such element exists, it returns NULL. */
159 OPENSSL_EXPORT void *lh_retrieve(const _LHASH *lh, const void *data);
160 
161 /* lh_insert inserts |data| into the hash table. If an existing element is
162  * equal to |data| (with respect to the comparison function) then |*old_data|
163  * will be set to that value and it will be replaced. Otherwise, or in the
164  * event of an error, |*old_data| will be set to NULL. It returns one on
165  * success or zero in the case of an allocation error. */
166 OPENSSL_EXPORT int lh_insert(_LHASH *lh, void **old_data, void *data);
167 
168 /* lh_delete removes an element equal to |data| from the hash table and returns
169  * it. If no such element is found, it returns NULL. */
170 OPENSSL_EXPORT void *lh_delete(_LHASH *lh, const void *data);
171 
172 /* lh_doall calls |func| on each element of the hash table.
173  * TODO(fork): rename this */
174 OPENSSL_EXPORT void lh_doall(_LHASH *lh, void (*func)(void *));
175 
176 /* lh_doall_arg calls |func| on each element of the hash table and also passes
177  * |arg| as the second argument.
178  * TODO(fork): rename this */
179 OPENSSL_EXPORT void lh_doall_arg(_LHASH *lh, void (*func)(void *, void *),
180                                  void *arg);
181 
182 /* lh_strhash is the default hash function which processes NUL-terminated
183  * strings. */
184 OPENSSL_EXPORT uint32_t lh_strhash(const char *c);
185 
186 
187 #if defined(__cplusplus)
188 } /* extern C */
189 #endif
190 
191 #endif /* OPENSSL_HEADER_LHASH_H */
192