mirror of https://github.com/openssl/openssl.git
68 lines
2.1 KiB
C
68 lines
2.1 KiB
C
/*
|
|
* Copyright 2024-2025 The OpenSSL Project Authors. All Rights Reserved.
|
|
*
|
|
* Licensed under the Apache License 2.0 (the "License"). You may not use
|
|
* this file except in compliance with the License. You can obtain a copy
|
|
* in the file LICENSE in the source distribution or at
|
|
* https://www.openssl.org/source/license.html
|
|
*/
|
|
|
|
#include "internal/e_os.h"
|
|
#include "internal/cryptlib.h"
|
|
#include "internal/mem_alloc_utils.h"
|
|
#include "crypto/cryptlib.h"
|
|
#include <stdlib.h>
|
|
|
|
void *ossl_malloc_align(size_t num, size_t alignment, void **freeptr,
|
|
const char *file, int line)
|
|
{
|
|
size_t alloc_bytes;
|
|
void *ret;
|
|
|
|
*freeptr = NULL;
|
|
|
|
/* Ensure that alignment is a power of two */
|
|
if (alignment == 0 || (alignment & (alignment - 1)) != 0) {
|
|
ossl_report_alloc_err_inv(file, line);
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Note: Windows supports an _aligned_malloc call, but we choose
|
|
* not to use it here, because allocations from that function
|
|
* require that they be freed via _aligned_free. Given that
|
|
* we can't differentiate plain malloc blocks from blocks obtained
|
|
* via _aligned_malloc, just avoid its use entirely
|
|
*/
|
|
|
|
if (ossl_unlikely(!ossl_size_add(num, alignment, &alloc_bytes, file, line)))
|
|
return NULL;
|
|
|
|
/*
|
|
* Step 1: Allocate an amount of memory that is <alignment>
|
|
* bytes bigger than requested
|
|
*/
|
|
*freeptr = CRYPTO_malloc(alloc_bytes, file, line);
|
|
if (*freeptr == NULL)
|
|
return NULL;
|
|
|
|
/*
|
|
* Step 2: Add <alignment - 1> bytes to the pointer
|
|
* This will cross the alignment boundary that is
|
|
* requested
|
|
*/
|
|
ret = (void *)((char *)*freeptr + (alignment - 1));
|
|
|
|
/*
|
|
* Step 3: Use the alignment as a mask to translate the
|
|
* least significant bits of the allocation at the alignment
|
|
* boundary to 0. ret now holds a pointer to the memory
|
|
* buffer at the requested alignment
|
|
* NOTE: It is a documented requirement that alignment be a
|
|
* power of 2, which is what allows this to work
|
|
*/
|
|
ret = (void *)((uintptr_t)ret & (uintptr_t)(~(alignment - 1)));
|
|
|
|
return ret;
|
|
}
|