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
|
#ifndef SECP256K1_PREALLOCATED_H
#define SECP256K1_PREALLOCATED_H
#include "secp256k1.h"
#ifdef __cplusplus
extern "C" {
#endif
/* The module provided by this header file is intended for settings in which it
* is not possible or desirable to rely on dynamic memory allocation. It provides
* functions for creating, cloning, and destroying secp256k1 context objects in a
* contiguous fixed-size block of memory provided by the caller.
*
* Context objects created by functions in this module can be used like contexts
* objects created by functions in secp256k1.h, i.e., they can be passed to any
* API function that expects a context object (see secp256k1.h for details). The
* only exception is that context objects created by functions in this module
* must be destroyed using secp256k1_context_preallocated_destroy (in this
* module) instead of secp256k1_context_destroy (in secp256k1.h).
*
* It is guaranteed that functions in this module will not call malloc or its
* friends realloc, calloc, and free.
*/
/** Determine the memory size of a secp256k1 context object to be created in
* caller-provided memory.
*
* The purpose of this function is to determine how much memory must be provided
* to secp256k1_context_preallocated_create.
*
* Returns: the required size of the caller-provided memory block
* In: flags: which parts of the context to initialize.
*/
SECP256K1_API size_t secp256k1_context_preallocated_size(
unsigned int flags
) SECP256K1_WARN_UNUSED_RESULT;
/** Create a secp256k1 context object in caller-provided memory.
*
* The caller must provide a pointer to a rewritable contiguous block of memory
* of size at least secp256k1_context_preallocated_size(flags) bytes, suitably
* aligned to hold an object of any type.
*
* The block of memory is exclusively owned by the created context object during
* the lifetime of this context object, which begins with the call to this
* function and ends when a call to secp256k1_context_preallocated_destroy
* (which destroys the context object again) returns. During the lifetime of the
* context object, the caller is obligated not to access this block of memory,
* i.e., the caller may not read or write the memory, e.g., by copying the memory
* contents to a different location or trying to create a second context object
* in the memory. In simpler words, the prealloc pointer (or any pointer derived
* from it) should not be used during the lifetime of the context object.
*
* Returns: a newly created context object.
* In: prealloc: a pointer to a rewritable contiguous block of memory of
* size at least secp256k1_context_preallocated_size(flags)
* bytes, as detailed above.
* flags: which parts of the context to initialize.
*
* See secp256k1_context_create (in secp256k1.h) for further details.
*
* See also secp256k1_context_randomize (in secp256k1.h)
* and secp256k1_context_preallocated_destroy.
*/
SECP256K1_API secp256k1_context* secp256k1_context_preallocated_create(
void* prealloc,
unsigned int flags
) SECP256K1_ARG_NONNULL(1) SECP256K1_WARN_UNUSED_RESULT;
/** Determine the memory size of a secp256k1 context object to be copied into
* caller-provided memory.
*
* Returns: the required size of the caller-provided memory block.
* In: ctx: an existing context to copy.
*/
SECP256K1_API size_t secp256k1_context_preallocated_clone_size(
const secp256k1_context* ctx
) SECP256K1_ARG_NONNULL(1) SECP256K1_WARN_UNUSED_RESULT;
/** Copy a secp256k1 context object into caller-provided memory.
*
* The caller must provide a pointer to a rewritable contiguous block of memory
* of size at least secp256k1_context_preallocated_size(flags) bytes, suitably
* aligned to hold an object of any type.
*
* The block of memory is exclusively owned by the created context object during
* the lifetime of this context object, see the description of
* secp256k1_context_preallocated_create for details.
*
* Cloning secp256k1_context_static is not possible, and should not be emulated by
* the caller (e.g., using memcpy). Create a new context instead.
*
* Returns: a newly created context object.
* Args: ctx: an existing context to copy (not secp256k1_context_static).
* In: prealloc: a pointer to a rewritable contiguous block of memory of
* size at least secp256k1_context_preallocated_size(flags)
* bytes, as detailed above.
*/
SECP256K1_API secp256k1_context* secp256k1_context_preallocated_clone(
const secp256k1_context* ctx,
void* prealloc
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_WARN_UNUSED_RESULT;
/** Destroy a secp256k1 context object that has been created in
* caller-provided memory.
*
* The context pointer may not be used afterwards.
*
* The context to destroy must have been created using
* secp256k1_context_preallocated_create or secp256k1_context_preallocated_clone.
* If the context has instead been created using secp256k1_context_create or
* secp256k1_context_clone, the behaviour is undefined. In that case,
* secp256k1_context_destroy must be used instead.
*
* If required, it is the responsibility of the caller to deallocate the block
* of memory properly after this function returns, e.g., by calling free on the
* preallocated pointer given to secp256k1_context_preallocated_create or
* secp256k1_context_preallocated_clone.
*
* Args: ctx: an existing context to destroy, constructed using
* secp256k1_context_preallocated_create or
* secp256k1_context_preallocated_clone
* (i.e., not secp256k1_context_static).
*/
SECP256K1_API void secp256k1_context_preallocated_destroy(
secp256k1_context* ctx
) SECP256K1_ARG_NONNULL(1);
#ifdef __cplusplus
}
#endif
#endif /* SECP256K1_PREALLOCATED_H */
|
