src/scratch_impl.h

	/***********************************************************************
	* Copyright (c) 2017 Andrew Poelstra *
	* Distributed under the MIT software license, see the accompanying *
	* file COPYING or https://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) {
	Taking true branch
	'scratch' is not equal to NULL
	if (secp256k1_memcmp_var(scratch->magic, "scratch", 8) != 0) {
	Taking false branch
	Assuming the condition is false
	secp256k1_callback_call(error_callback, "invalid scratch space");
	return;
	}
	VERIFY_CHECK(scratch->alloc_size == 0); /* all checkpoints should be applied */
	Loop condition is false. Exiting loop
	Taking false branch
	memset(scratch->magic, 0, sizeof(scratch->magic));
	free(scratch);
	Argument to free() is the address of the local variable 'local_scratch', which is not memory allocated by malloc()
	Argument to free() is the address of the local variable 'local_scratch', which is not memory allocated by malloc()
	}
	}

	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

secp256k1