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/**********************************************************************
* Copyright (c) 2017 Andrew Poelstra *
* Distributed under the MIT software license, see the accompanying *
* file COPYING or http://www.opensource.org/licenses/mit-license.php.*
**********************************************************************/
#ifndef _SECP256K1_SCRATCH_IMPL_H_
#define _SECP256K1_SCRATCH_IMPL_H_
#include "util.h"
#include "scratch.h"
static secp256k1_scratch* secp256k1_scratch_create(const secp256k1_callback* error_callback, size_t size) {
const size_t base_alloc = ROUND_TO_ALIGN(sizeof(secp256k1_scratch));
void *alloc = checked_malloc(error_callback, base_alloc + size);
secp256k1_scratch* ret = (secp256k1_scratch *)alloc;
if (ret != NULL) {
memset(ret, 0, sizeof(*ret));
memcpy(ret->magic, "scratch", 8);
ret->data = (void *) ((char *) alloc + base_alloc);
ret->max_size = size;
}
return ret;
}
static void secp256k1_scratch_destroy(const secp256k1_callback* error_callback, secp256k1_scratch* scratch) {
if (scratch != NULL) {
VERIFY_CHECK(scratch->alloc_size == 0); /* all checkpoints should be applied */
if (secp256k1_memcmp_var(scratch->magic, "scratch", 8) != 0) {
secp256k1_callback_call(error_callback, "invalid scratch space");
return;
}
memset(scratch->magic, 0, sizeof(scratch->magic));
free(scratch);
}
}
static size_t secp256k1_scratch_checkpoint(const secp256k1_callback* error_callback, const secp256k1_scratch* scratch) {
if (secp256k1_memcmp_var(scratch->magic, "scratch", 8) != 0) {
secp256k1_callback_call(error_callback, "invalid scratch space");
return 0;
}
return scratch->alloc_size;
}
static void secp256k1_scratch_apply_checkpoint(const secp256k1_callback* error_callback, secp256k1_scratch* scratch, size_t checkpoint) {
if (secp256k1_memcmp_var(scratch->magic, "scratch", 8) != 0) {
secp256k1_callback_call(error_callback, "invalid scratch space");
return;
}
if (checkpoint > scratch->alloc_size) {
secp256k1_callback_call(error_callback, "invalid checkpoint");
return;
}
scratch->alloc_size = checkpoint;
}
static size_t secp256k1_scratch_max_allocation(const secp256k1_callback* error_callback, const secp256k1_scratch* scratch, size_t objects) {
if (secp256k1_memcmp_var(scratch->magic, "scratch", 8) != 0) {
secp256k1_callback_call(error_callback, "invalid scratch space");
return 0;
}
/* Ensure that multiplication will not wrap around */
if (ALIGNMENT > 1 && objects > SIZE_MAX/(ALIGNMENT - 1)) {
return 0;
}
if (scratch->max_size - scratch->alloc_size <= objects * (ALIGNMENT - 1)) {
return 0;
}
return scratch->max_size - scratch->alloc_size - objects * (ALIGNMENT - 1);
}
static void *secp256k1_scratch_alloc(const secp256k1_callback* error_callback, secp256k1_scratch* scratch, size_t size) {
void *ret;
size_t rounded_size;
rounded_size = ROUND_TO_ALIGN(size);
/* Check that rounding did not wrap around */
if (rounded_size < size) {
return NULL;
}
size = rounded_size;
if (secp256k1_memcmp_var(scratch->magic, "scratch", 8) != 0) {
secp256k1_callback_call(error_callback, "invalid scratch space");
return NULL;
}
if (size > scratch->max_size - scratch->alloc_size) {
return NULL;
}
ret = (void *) ((char *) scratch->data + scratch->alloc_size);
memset(ret, 0, size);
scratch->alloc_size += size;
return ret;
}
#endif
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