xref: /src/lib/libc/stdlib/aligned_alloc.c

/* $NetBSD: aligned_alloc.c,v 1.3 2024/08/18 18:47:20 riastradh Exp $ */

/*-
 * Copyright (C) 2015 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Niclas Rosenvik.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice(s), this list of conditions and the following disclaimer as
 *    the first lines of this file unmodified other than the possible
 *    addition of one or more copyright notices.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice(s), this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__RCSID("$NetBSD: aligned_alloc.c,v 1.3 2024/08/18 18:47:20 riastradh Exp $");

#include <errno.h>
#include <stdlib.h>

void *
aligned_alloc(size_t alignment, size_t size)
{
        void *memptr;
        int err;

        /*
         * Check that alignment is a power of 2.
         */
        if (alignment == 0 || ((alignment - 1) & alignment) != 0) {
                errno = EINVAL;
                return NULL;
        }

        /*
         * Adjust alignment to satisfy posix_memalign,
         * larger alignments satisfy smaller alignments.
         */
        while (alignment < sizeof(void *)) {
                alignment <<= 1;
        }

        err = posix_memalign(&memptr, alignment, size);
        if (err) {
                errno = err;
                return NULL;
        }

        return memptr;
}