2 * Copyright 2019 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 "internal/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 large memory model uses twelve bits which means that the are 4096
23 * pointers in each tree node. This is more than sufficient to hold the
24 * largest defined NID (as of Feb 2019). This means that using a NID to
25 * index a sparse array becomes a constant time single array look up.
27 * The small memory model uses four bits which means the tree nodes contain
28 * sixteen pointers. This reduces the amount of unused space significantly
31 * The library builder is also permitted to define other sizes in the closed
32 * interval [2, sizeof(ossl_uintmax_t) * 8].
34 #ifndef OPENSSL_SA_BLOCK_BITS
35 # ifdef OPENSSL_SMALL_FOOTPRINT
36 # define OPENSSL_SA_BLOCK_BITS 4
38 # define OPENSSL_SA_BLOCK_BITS 12
40 #elif OPENSSL_SA_BLOCK_BITS < 2 || OPENSSL_SA_BLOCK_BITS > (BN_BITS2 - 1)
41 # error OPENSSL_SA_BLOCK_BITS is out of range
45 * From the number of bits, work out:
46 * the number of pointers in a tree node;
47 * a bit mask to quickly extract an index and
48 * the maximum depth of the tree structure.
50 #define SA_BLOCK_MAX (1 << OPENSSL_SA_BLOCK_BITS)
51 #define SA_BLOCK_MASK (SA_BLOCK_MAX - 1)
52 #define SA_BLOCK_MAX_LEVELS (((int)sizeof(ossl_uintmax_t) * 8 \
53 + OPENSSL_SA_BLOCK_BITS - 1) \
54 / OPENSSL_SA_BLOCK_BITS)
56 struct sparse_array_st {
63 OPENSSL_SA *OPENSSL_SA_new(void)
65 OPENSSL_SA *res = OPENSSL_zalloc(sizeof(*res));
70 static void sa_doall(const OPENSSL_SA *sa, void (*node)(void **),
71 void (*leaf)(ossl_uintmax_t, void *, void *), void *arg)
73 int i[SA_BLOCK_MAX_LEVELS];
74 void *nodes[SA_BLOCK_MAX_LEVELS];
75 ossl_uintmax_t idx = 0;
82 void ** const p = nodes[l];
84 if (n >= SA_BLOCK_MAX) {
85 if (p != NULL && node != NULL)
88 idx >>= OPENSSL_SA_BLOCK_BITS;
91 if (p != NULL && p[n] != NULL) {
92 idx = (idx & ~SA_BLOCK_MASK) | n;
93 if (l < sa->levels - 1) {
96 idx <<= OPENSSL_SA_BLOCK_BITS;
97 } else if (leaf != NULL) {
98 (*leaf)(idx, p[n], arg);
105 static void sa_free_node(void **p)
110 static void sa_free_leaf(ossl_uintmax_t n, void *p, void *arg)
115 void OPENSSL_SA_free(OPENSSL_SA *sa)
117 sa_doall(sa, &sa_free_node, NULL, NULL);
121 void OPENSSL_SA_free_leaves(OPENSSL_SA *sa)
123 sa_doall(sa, &sa_free_node, &sa_free_leaf, NULL);
127 /* Wrap this in a structure to avoid compiler warnings */
128 struct trampoline_st {
129 void (*func)(ossl_uintmax_t, void *);
132 static void trampoline(ossl_uintmax_t n, void *l, void *arg)
134 ((const struct trampoline_st *)arg)->func(n, l);
137 void OPENSSL_SA_doall(const OPENSSL_SA *sa, void (*leaf)(ossl_uintmax_t,
140 struct trampoline_st tramp;
144 sa_doall(sa, NULL, &trampoline, &tramp);
147 void OPENSSL_SA_doall_arg(const OPENSSL_SA *sa,
148 void (*leaf)(ossl_uintmax_t, void *, void *),
152 sa_doall(sa, NULL, leaf, arg);
155 size_t OPENSSL_SA_num(const OPENSSL_SA *sa)
157 return sa == NULL ? 0 : sa->nelem;
160 void *OPENSSL_SA_get(const OPENSSL_SA *sa, ossl_uintmax_t n)
170 for (level = sa->levels - 1; p != NULL && level > 0; level--)
171 p = (void **)p[(n >> (OPENSSL_SA_BLOCK_BITS * level))
173 r = p == NULL ? NULL : p[n & SA_BLOCK_MASK];
178 static ossl_inline void **alloc_node(void)
180 return OPENSSL_zalloc(SA_BLOCK_MAX * sizeof(void *));
183 int OPENSSL_SA_set(OPENSSL_SA *sa, ossl_uintmax_t posn, void *val)
186 ossl_uintmax_t n = posn;
192 for (level = 1; level < SA_BLOCK_MAX_LEVELS; level++)
193 if ((n >>= OPENSSL_SA_BLOCK_BITS) == 0)
196 for (;sa->levels < level; sa->levels++) {
207 for (level = sa->levels - 1; level > 0; level--) {
208 i = (posn >> (OPENSSL_SA_BLOCK_BITS * level)) & SA_BLOCK_MASK;
209 if (p[i] == NULL && (p[i] = alloc_node()) == NULL)
213 p += posn & SA_BLOCK_MASK;
214 if (val == NULL && *p != NULL)
216 else if (val != NULL && *p == NULL)