summaryrefslogtreecommitdiffstats
path: root/lib/adds.h
blob: 6544ce5fe540c17d5220a0225e724f6ab38456f9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
// SPDX-FileCopyrightText: 2023, Alejandro Colomar <alx@kernel.org>
// SPDX-License-Identifier: BSD-3-Clause


#ifndef SHADOW_INCLUDE_LIB_ADDS_H_
#define SHADOW_INCLUDE_LIB_ADDS_H_


#include <config.h>

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

#include "sizeof.h"


#define addsl(a, b, ...)                                                      \
({                                                                            \
	long  addend_[] = {a, b, __VA_ARGS__};                                \
                                                                              \
	addslN(NITEMS(addend_), addend_);                                     \
})


inline long addsl2(long a, long b);
inline long addslN(size_t n, long addend[n]);

inline int cmpl(const void *p1, const void *p2);


inline long
addsl2(long a, long b)
{
	if (a > 0 && b > LONG_MAX - a) {
		errno = EOVERFLOW;
		return LONG_MAX;
	}
	if (a < 0 && b < LONG_MIN - a) {
		errno = EOVERFLOW;
		return LONG_MIN;
	}
	return a + b;
}


inline long
addslN(size_t n, long addend[n])
{
	int   e;

	if (n == 0) {
		errno = EDOM;
		return 0;
	}

	e = errno;
	while (n > 1) {
		qsort(addend, n, sizeof(addend[0]), cmpl);

		errno = 0;
		addend[0] = addsl2(addend[0], addend[--n]);
		if (errno == EOVERFLOW)
			return addend[0];
	}
	errno = e;
	return addend[0];
}


inline int
cmpl(const void *p1, const void *p2)
{
	const long  *l1 = p1;
	const long  *l2 = p2;

	if (*l1 < *l2)
		return -1;
	if (*l1 > *l2)
		return +1;
	return 0;
}


#endif  // include guard