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git.ipfire.org Git - thirdparty/openssl.git/blob - crypto/sparse_array.c
2 * Copyright 2019-2022 The OpenSSL Project Authors. All Rights Reserved.
3 * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
5 * Licensed under the Apache License 2.0 (the "License"). You may not use
6 * this file except in compliance with the License. You can obtain a copy
7 * in the file LICENSE in the source distribution or at
8 * https://www.openssl.org/source/license.html
11 #include <openssl/crypto.h>
12 #include <openssl/bn.h>
13 #include "crypto/sparse_array.h"
16 * How many bits are used to index each level in the tree structure?
17 * This setting determines the number of pointers stored in each node of the
18 * tree used to represent the sparse array. Having more pointers reduces the
19 * depth of the tree but potentially wastes more memory. That is, this is a
20 * direct space versus time tradeoff.
22 * The default is to use four bits which means that the are 16
23 * pointers in each tree node.
25 * The library builder is also permitted to define other sizes in the closed
26 * interval [2, sizeof(ossl_uintmax_t) * 8]. Space use generally scales
27 * exponentially with the block size, although the implementation only
28 * creates enough blocks to support the largest used index. The depth is:
29 * ceil(log_2(largest index) / 2^{block size})
30 * E.g. with a block size of 4, and a largest index of 1000, the depth
33 #ifndef OPENSSL_SA_BLOCK_BITS
34 # define OPENSSL_SA_BLOCK_BITS 4
35 #elif OPENSSL_SA_BLOCK_BITS < 2 || OPENSSL_SA_BLOCK_BITS > (BN_BITS2 - 1)
36 # error OPENSSL_SA_BLOCK_BITS is out of range
40 * From the number of bits, work out:
41 * the number of pointers in a tree node;
42 * a bit mask to quickly extract an index and
43 * the maximum depth of the tree structure.
45 #define SA_BLOCK_MAX (1 << OPENSSL_SA_BLOCK_BITS)
46 #define SA_BLOCK_MASK (SA_BLOCK_MAX - 1)
47 #define SA_BLOCK_MAX_LEVELS (((int)sizeof(ossl_uintmax_t) * 8 \
48 + OPENSSL_SA_BLOCK_BITS - 1) \
49 / OPENSSL_SA_BLOCK_BITS)
51 struct sparse_array_st
{
58 OPENSSL_SA
*ossl_sa_new(void)
60 OPENSSL_SA
*res
= OPENSSL_zalloc(sizeof(*res
));
65 static void sa_doall(const OPENSSL_SA
*sa
, void (*node
)(void **),
66 void (*leaf
)(ossl_uintmax_t
, void *, void *), void *arg
)
68 int i
[SA_BLOCK_MAX_LEVELS
];
69 void *nodes
[SA_BLOCK_MAX_LEVELS
];
70 ossl_uintmax_t idx
= 0;
77 void ** const p
= nodes
[l
];
79 if (n
>= SA_BLOCK_MAX
) {
80 if (p
!= NULL
&& node
!= NULL
)
83 idx
>>= OPENSSL_SA_BLOCK_BITS
;
86 if (p
!= NULL
&& p
[n
] != NULL
) {
87 idx
= (idx
& ~SA_BLOCK_MASK
) | n
;
88 if (l
< sa
->levels
- 1) {
91 idx
<<= OPENSSL_SA_BLOCK_BITS
;
92 } else if (leaf
!= NULL
) {
93 (*leaf
)(idx
, p
[n
], arg
);
100 static void sa_free_node(void **p
)
105 static void sa_free_leaf(ossl_uintmax_t n
, void *p
, void *arg
)
110 void ossl_sa_free(OPENSSL_SA
*sa
)
113 sa_doall(sa
, &sa_free_node
, NULL
, NULL
);
118 void ossl_sa_free_leaves(OPENSSL_SA
*sa
)
120 sa_doall(sa
, &sa_free_node
, &sa_free_leaf
, NULL
);
124 /* Wrap this in a structure to avoid compiler warnings */
125 struct trampoline_st
{
126 void (*func
)(ossl_uintmax_t
, void *);
129 static void trampoline(ossl_uintmax_t n
, void *l
, void *arg
)
131 ((const struct trampoline_st
*)arg
)->func(n
, l
);
134 void ossl_sa_doall(const OPENSSL_SA
*sa
, void (*leaf
)(ossl_uintmax_t
, void *))
136 struct trampoline_st tramp
;
140 sa_doall(sa
, NULL
, &trampoline
, &tramp
);
143 void ossl_sa_doall_arg(const OPENSSL_SA
*sa
,
144 void (*leaf
)(ossl_uintmax_t
, void *, void *),
148 sa_doall(sa
, NULL
, leaf
, arg
);
151 size_t ossl_sa_num(const OPENSSL_SA
*sa
)
153 return sa
== NULL
? 0 : sa
->nelem
;
156 void *ossl_sa_get(const OPENSSL_SA
*sa
, ossl_uintmax_t n
)
161 if (sa
== NULL
|| sa
->nelem
== 0)
166 for (level
= sa
->levels
- 1; p
!= NULL
&& level
> 0; level
--)
167 p
= (void **)p
[(n
>> (OPENSSL_SA_BLOCK_BITS
* level
))
169 r
= p
== NULL
? NULL
: p
[n
& SA_BLOCK_MASK
];
174 static ossl_inline
void **alloc_node(void)
176 return OPENSSL_zalloc(SA_BLOCK_MAX
* sizeof(void *));
179 int ossl_sa_set(OPENSSL_SA
*sa
, ossl_uintmax_t posn
, void *val
)
182 ossl_uintmax_t n
= posn
;
188 for (level
= 1; level
< SA_BLOCK_MAX_LEVELS
; level
++)
189 if ((n
>>= OPENSSL_SA_BLOCK_BITS
) == 0)
192 for (;sa
->levels
< level
; sa
->levels
++) {
203 for (level
= sa
->levels
- 1; level
> 0; level
--) {
204 i
= (posn
>> (OPENSSL_SA_BLOCK_BITS
* level
)) & SA_BLOCK_MASK
;
205 if (p
[i
] == NULL
&& (p
[i
] = alloc_node()) == NULL
)
209 p
+= posn
& SA_BLOCK_MASK
;
210 if (val
== NULL
&& *p
!= NULL
)
212 else if (val
!= NULL
&& *p
== NULL
)