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100 lines
3.6 KiB
C
100 lines
3.6 KiB
C
/***********************************************************************
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* Copyright (c) 2017 Andrew Poelstra *
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* Distributed under the MIT software license, see the accompanying *
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* file COPYING or https://www.opensource.org/licenses/mit-license.php.*
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***********************************************************************/
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#ifndef SECP256K1_SCRATCH_IMPL_H
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#define SECP256K1_SCRATCH_IMPL_H
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#include "util.h"
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#include "scratch.h"
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static secp256k1_scratch* secp256k1_scratch_create(const secp256k1_callback* error_callback, size_t size) {
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const size_t base_alloc = ROUND_TO_ALIGN(sizeof(secp256k1_scratch));
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void *alloc = checked_malloc(error_callback, base_alloc + size);
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secp256k1_scratch* ret = (secp256k1_scratch *)alloc;
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if (ret != NULL) {
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memset(ret, 0, sizeof(*ret));
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memcpy(ret->magic, "scratch", 8);
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ret->data = (void *) ((char *) alloc + base_alloc);
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ret->max_size = size;
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}
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return ret;
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}
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static void secp256k1_scratch_destroy(const secp256k1_callback* error_callback, secp256k1_scratch* scratch) {
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if (scratch != NULL) {
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if (secp256k1_memcmp_var(scratch->magic, "scratch", 8) != 0) {
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secp256k1_callback_call(error_callback, "invalid scratch space");
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return;
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}
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VERIFY_CHECK(scratch->alloc_size == 0); /* all checkpoints should be applied */
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memset(scratch->magic, 0, sizeof(scratch->magic));
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free(scratch);
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}
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}
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static size_t secp256k1_scratch_checkpoint(const secp256k1_callback* error_callback, const secp256k1_scratch* scratch) {
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if (secp256k1_memcmp_var(scratch->magic, "scratch", 8) != 0) {
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secp256k1_callback_call(error_callback, "invalid scratch space");
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return 0;
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}
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return scratch->alloc_size;
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}
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static void secp256k1_scratch_apply_checkpoint(const secp256k1_callback* error_callback, secp256k1_scratch* scratch, size_t checkpoint) {
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if (secp256k1_memcmp_var(scratch->magic, "scratch", 8) != 0) {
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secp256k1_callback_call(error_callback, "invalid scratch space");
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return;
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}
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if (checkpoint > scratch->alloc_size) {
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secp256k1_callback_call(error_callback, "invalid checkpoint");
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return;
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}
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scratch->alloc_size = checkpoint;
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}
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static size_t secp256k1_scratch_max_allocation(const secp256k1_callback* error_callback, const secp256k1_scratch* scratch, size_t objects) {
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if (secp256k1_memcmp_var(scratch->magic, "scratch", 8) != 0) {
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secp256k1_callback_call(error_callback, "invalid scratch space");
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return 0;
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}
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/* Ensure that multiplication will not wrap around */
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if (ALIGNMENT > 1 && objects > SIZE_MAX/(ALIGNMENT - 1)) {
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return 0;
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}
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if (scratch->max_size - scratch->alloc_size <= objects * (ALIGNMENT - 1)) {
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return 0;
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}
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return scratch->max_size - scratch->alloc_size - objects * (ALIGNMENT - 1);
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}
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static void *secp256k1_scratch_alloc(const secp256k1_callback* error_callback, secp256k1_scratch* scratch, size_t size) {
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void *ret;
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size_t rounded_size;
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rounded_size = ROUND_TO_ALIGN(size);
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/* Check that rounding did not wrap around */
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if (rounded_size < size) {
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return NULL;
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}
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size = rounded_size;
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if (secp256k1_memcmp_var(scratch->magic, "scratch", 8) != 0) {
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secp256k1_callback_call(error_callback, "invalid scratch space");
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return NULL;
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}
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if (size > scratch->max_size - scratch->alloc_size) {
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return NULL;
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}
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ret = (void *) ((char *) scratch->data + scratch->alloc_size);
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memset(ret, 0, size);
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scratch->alloc_size += size;
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return ret;
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}
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#endif
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