1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
|
/*
* Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
* Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <openssl/crypto.h>
#include <openssl/bn.h>
#include "crypto/sparse_array.h"
/*
* How many bits are used to index each level in the tree structure?
* This setting determines the number of pointers stored in each node of the
* tree used to represent the sparse array. Having more pointers reduces the
* depth of the tree but potentially wastes more memory. That is, this is a
* direct space versus time tradeoff.
*
* The large memory model uses twelve bits which means that the are 4096
* pointers in each tree node. This is more than sufficient to hold the
* largest defined NID (as of Feb 2019). This means that using a NID to
* index a sparse array becomes a constant time single array look up.
*
* The small memory model uses four bits which means the tree nodes contain
* sixteen pointers. This reduces the amount of unused space significantly
* at a cost in time.
*
* The library builder is also permitted to define other sizes in the closed
* interval [2, sizeof(ossl_uintmax_t) * 8].
*/
#ifndef OPENSSL_SA_BLOCK_BITS
# ifdef OPENSSL_SMALL_FOOTPRINT
# define OPENSSL_SA_BLOCK_BITS 4
# else
# define OPENSSL_SA_BLOCK_BITS 12
# endif
#elif OPENSSL_SA_BLOCK_BITS < 2 || OPENSSL_SA_BLOCK_BITS > (BN_BITS2 - 1)
# error OPENSSL_SA_BLOCK_BITS is out of range
#endif
/*
* From the number of bits, work out:
* the number of pointers in a tree node;
* a bit mask to quickly extract an index and
* the maximum depth of the tree structure.
*/
#define SA_BLOCK_MAX (1 << OPENSSL_SA_BLOCK_BITS)
#define SA_BLOCK_MASK (SA_BLOCK_MAX - 1)
#define SA_BLOCK_MAX_LEVELS (((int)sizeof(ossl_uintmax_t) * 8 \
+ OPENSSL_SA_BLOCK_BITS - 1) \
/ OPENSSL_SA_BLOCK_BITS)
struct sparse_array_st {
int levels;
ossl_uintmax_t top;
size_t nelem;
void **nodes;
};
OPENSSL_SA *OPENSSL_SA_new(void)
{
OPENSSL_SA *res = OPENSSL_zalloc(sizeof(*res));
return res;
}
static void sa_doall(const OPENSSL_SA *sa, void (*node)(void **),
void (*leaf)(ossl_uintmax_t, void *, void *), void *arg)
{
int i[SA_BLOCK_MAX_LEVELS];
void *nodes[SA_BLOCK_MAX_LEVELS];
ossl_uintmax_t idx = 0;
int l = 0;
i[0] = 0;
nodes[0] = sa->nodes;
while (l >= 0) {
const int n = i[l];
void ** const p = nodes[l];
if (n >= SA_BLOCK_MAX) {
if (p != NULL && node != NULL)
(*node)(p);
l--;
idx >>= OPENSSL_SA_BLOCK_BITS;
} else {
i[l] = n + 1;
if (p != NULL && p[n] != NULL) {
idx = (idx & ~SA_BLOCK_MASK) | n;
if (l < sa->levels - 1) {
i[++l] = 0;
nodes[l] = p[n];
idx <<= OPENSSL_SA_BLOCK_BITS;
} else if (leaf != NULL) {
(*leaf)(idx, p[n], arg);
}
}
}
}
}
static void sa_free_node(void **p)
{
OPENSSL_free(p);
}
static void sa_free_leaf(ossl_uintmax_t n, void *p, void *arg)
{
OPENSSL_free(p);
}
void OPENSSL_SA_free(OPENSSL_SA *sa)
{
sa_doall(sa, &sa_free_node, NULL, NULL);
OPENSSL_free(sa);
}
void OPENSSL_SA_free_leaves(OPENSSL_SA *sa)
{
sa_doall(sa, &sa_free_node, &sa_free_leaf, NULL);
OPENSSL_free(sa);
}
/* Wrap this in a structure to avoid compiler warnings */
struct trampoline_st {
void (*func)(ossl_uintmax_t, void *);
};
static void trampoline(ossl_uintmax_t n, void *l, void *arg)
{
((const struct trampoline_st *)arg)->func(n, l);
}
void OPENSSL_SA_doall(const OPENSSL_SA *sa, void (*leaf)(ossl_uintmax_t,
void *))
{
struct trampoline_st tramp;
tramp.func = leaf;
if (sa != NULL)
sa_doall(sa, NULL, &trampoline, &tramp);
}
void OPENSSL_SA_doall_arg(const OPENSSL_SA *sa,
void (*leaf)(ossl_uintmax_t, void *, void *),
void *arg)
{
if (sa != NULL)
sa_doall(sa, NULL, leaf, arg);
}
size_t OPENSSL_SA_num(const OPENSSL_SA *sa)
{
return sa == NULL ? 0 : sa->nelem;
}
void *OPENSSL_SA_get(const OPENSSL_SA *sa, ossl_uintmax_t n)
{
int level;
void **p, *r = NULL;
if (sa == NULL)
return NULL;
if (n <= sa->top) {
p = sa->nodes;
for (level = sa->levels - 1; p != NULL && level > 0; level--)
p = (void **)p[(n >> (OPENSSL_SA_BLOCK_BITS * level))
& SA_BLOCK_MASK];
r = p == NULL ? NULL : p[n & SA_BLOCK_MASK];
}
return r;
}
static ossl_inline void **alloc_node(void)
{
return OPENSSL_zalloc(SA_BLOCK_MAX * sizeof(void *));
}
int OPENSSL_SA_set(OPENSSL_SA *sa, ossl_uintmax_t posn, void *val)
{
int i, level = 1;
ossl_uintmax_t n = posn;
void **p;
if (sa == NULL)
return 0;
for (level = 1; level < SA_BLOCK_MAX_LEVELS; level++)
if ((n >>= OPENSSL_SA_BLOCK_BITS) == 0)
break;
for (;sa->levels < level; sa->levels++) {
p = alloc_node();
if (p == NULL)
return 0;
p[0] = sa->nodes;
sa->nodes = p;
}
if (sa->top < posn)
sa->top = posn;
p = sa->nodes;
for (level = sa->levels - 1; level > 0; level--) {
i = (posn >> (OPENSSL_SA_BLOCK_BITS * level)) & SA_BLOCK_MASK;
if (p[i] == NULL && (p[i] = alloc_node()) == NULL)
return 0;
p = p[i];
}
p += posn & SA_BLOCK_MASK;
if (val == NULL && *p != NULL)
sa->nelem--;
else if (val != NULL && *p == NULL)
sa->nelem++;
*p = val;
return 1;
}
|
