1/*	$NetBSD: humanize_number.c,v 1.19 2024/01/20 14:52:47 christos Exp $	*/
2
3/*
4 * Copyright (c) 1997, 1998, 1999, 2002 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
9 * NASA Ames Research Center, by Luke Mewburn and by Tomas Svensson.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 */
32
33#include <sys/cdefs.h>
34#if defined(LIBC_SCCS) && !defined(lint)
35__RCSID("$NetBSD: humanize_number.c,v 1.19 2024/01/20 14:52:47 christos Exp $");
36#endif /* LIBC_SCCS and not lint */
37
38#include "namespace.h"
39#include <assert.h>
40#include <inttypes.h>
41#include <stdio.h>
42#include <stdlib.h>
43#include <string.h>
44#include <locale.h>
45
46int
47humanize_number(char *buf, size_t len, int64_t bytes,
48    const char *suffix, int scale, int flags)
49{
50	const char *prefixes, *sep;
51	int	b, i, r, s1, s2, sign;
52	int64_t	divisor, max, post = 1;
53	size_t	baselen;
54	int	maxscale;
55
56	_DIAGASSERT(buf != NULL);
57	_DIAGASSERT(scale >= 0);
58
59	if (suffix == NULL)
60		suffix = "";
61
62	if (flags & HN_DIVISOR_1000) {
63		/* SI for decimal multiplies */
64		divisor = 1000;
65		if (flags & HN_B)
66			prefixes = "B\0k\0M\0G\0T\0P\0E";
67		else
68			prefixes = "\0\0k\0M\0G\0T\0P\0E";
69	} else {
70		/*
71		 * binary multiplies
72		 * XXX IEC 60027-2 recommends Ki, Mi, Gi...
73		 */
74		divisor = 1024;
75		if (flags & HN_B)
76			prefixes = "B\0K\0M\0G\0T\0P\0E";
77		else
78			prefixes = "\0\0K\0M\0G\0T\0P\0E";
79	}
80
81#define	SCALE2PREFIX(scale)	(&prefixes[(scale) << 1])
82	maxscale = 6;
83
84	if (scale < 0 || (scale > maxscale &&
85	    (scale & (HN_AUTOSCALE | HN_GETSCALE)) == 0))
86		return (-1);
87
88	if (buf == NULL)
89		return (-1);
90
91	if (len > 0)
92		buf[0] = '\0';
93
94	if (bytes < 0) {
95		sign = -1;
96		baselen = 3;		/* sign, digit, prefix */
97		if (-bytes < INT64_MAX / 100)
98			bytes *= -100;
99		else {
100			bytes = -bytes;
101			post = 100;
102			baselen += 2;
103		}
104	} else {
105		sign = 1;
106		baselen = 2;		/* digit, prefix */
107		if (bytes < INT64_MAX / 100)
108			bytes *= 100;
109		else {
110			post = 100;
111			baselen += 2;
112		}
113	}
114	if (flags & HN_NOSPACE)
115		sep = "";
116	else {
117		sep = " ";
118		baselen++;
119	}
120	baselen += strlen(suffix);
121
122	/* Check if enough room for `x y' + suffix + `\0' */
123	if (len < baselen + 1)
124		return (-1);
125
126	if (scale & (HN_AUTOSCALE | HN_GETSCALE)) {
127		/*
128		 * 19 is number of digits in biggest possible int64_t
129		 * If we don't do this, the calc of max just below can
130		 * overflow, leading to absurd results.   If the buffer
131		 * is big enough for the number, simply use it, no scaling.
132		 */
133		if (len - baselen > 19)
134			i = 0;
135		else {
136			size_t j;
137			/* See if there are additional columns to be used. */
138			for (max = 100, j = len - baselen; j-- > 0;)
139				max *= 10;
140
141			/*
142			 * Divide the number until it fits the avail buffer.
143			 * If there will be an overflow by the rounding below,
144			 * (the "-50") divide once more.
145			 */
146			for (i = 0; bytes >= max - 50 && i < maxscale; i++)
147				bytes /= divisor;
148		}
149		if (scale & HN_GETSCALE) {
150			_DIAGASSERT(__type_fit(int, i));
151			return i;
152		}
153	} else {
154		/* XXX
155		 * we already know scale <= maxscale, so
156		 * i < scale ==> i < maxscale
157		 */
158		for (i = 0; i < scale && i < maxscale; i++)
159			bytes /= divisor;
160	}
161
162	if (i == 0) {
163		/*
164		 * Cannot go the bytes *= post route, as
165		 * that can cause overflow of bytes
166		 *
167		 * but if we already scaled up, undo that.
168		 */
169		if (post == 1)
170			bytes /= 100;
171
172		r = snprintf(buf, len, "%" PRId64 "%s%s%s",
173		    sign * bytes, sep, SCALE2PREFIX(0), suffix);
174	} else {
175		/*
176		 * Here this is safe, as if i > 0, we have already
177		 * divided bytes by at least 1000, post <= 100, so ...
178		 */
179		bytes *= post;
180
181		/* If a value <= 9.9 after rounding and ... */
182		if (bytes < 995 && i > 0 && flags & HN_DECIMAL) {
183			/* baselen + \0 + .N */
184			if (len < baselen + 1 + 1 +
185			    strlen(localeconv()->decimal_point))
186				return (-1);
187			b = ((int)bytes + 5) / 10;
188			s1 = b / 10;
189			s2 = b % 10;
190			r = snprintf(buf, len, "%d%s%d%s%s%s",
191			    sign * s1, localeconv()->decimal_point, s2,
192			    sep, SCALE2PREFIX(i), suffix);
193		} else
194			r = snprintf(buf, len, "%" PRId64 "%s%s%s",
195			    sign * ((bytes + 50) / 100),
196			    sep, SCALE2PREFIX(i), suffix);
197	}
198
199	if ((size_t)r > len)
200		r = -1;
201
202	return (r);
203}
204