1/*-
2 * Copyright (c) 2020 The FreeBSD Foundation
3 *
4 * This software was developed by Emmanuel Vadot under sponsorship
5 * from the FreeBSD Foundation.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 *
28 * $FreeBSD: stable/11/sys/compat/linuxkpi/common/include/linux/overflow.h 363792 2020-08-03 09:15:38Z hselasky $
29 */
30
31#ifndef __LINUX_OVERFLOW_H__
32#define	__LINUX_OVERFLOW_H__
33
34#include <sys/stdint.h>
35#include <sys/types.h>
36
37#ifndef	__has_builtin
38#define	__has_builtin(x)	0
39#endif
40
41#if __has_builtin(__builtin_add_overflow)
42#define check_add_overflow(a, b, c)		\
43	__builtin_add_overflow(a, b, c)
44#else
45#error "Compiler does not support __builtin_add_overflow"
46#endif
47
48#if __has_builtin(__builtin_mul_overflow)
49#define check_mul_overflow(a, b, c)	\
50	__builtin_mul_overflow(a, b, c)
51
52static inline size_t
53array_size(size_t x, size_t y)
54{
55	size_t retval;
56
57	if (__builtin_mul_overflow(x, y, &retval))
58		retval = SIZE_MAX;
59	return (retval);
60}
61#else
62#error "Compiler does not support __builtin_mul_overflow"
63#endif
64
65#endif	/* __LINUX_OVERFLOW_H__ */
66