1/*	$NetBSD: kern_subr.c,v 1.199 2009/04/02 17:25:24 drochner Exp $	*/
2
3/*-
4 * Copyright (c) 1997, 1998, 1999, 2002, 2007, 2008 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Luke Mewburn.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33__KERNEL_RCSID(0, "$NetBSD$");
34
35#include <sys/types.h>
36#include <sys/systm.h>
37
38/*
39 * snprintf() `bytes' into `buf', reformatting it so that the number,
40 * plus a possible `x' + suffix extension) fits into len bytes (including
41 * the terminating NUL).
42 * Returns the number of bytes stored in buf, or -1 if there was a problem.
43 * E.g, given a len of 9 and a suffix of `B':
44 *	bytes		result
45 *	-----		------
46 *	99999		`99999 B'
47 *	100000		`97 kB'
48 *	66715648	`65152 kB'
49 *	252215296	`240 MB'
50 */
51int
52humanize_number(char *buf, size_t len, uint64_t bytes, const char *suffix,
53    int divisor)
54{
55       	/* prefixes are: (none), kilo, Mega, Giga, Tera, Peta, Exa */
56	const char *prefixes;
57	int		r;
58	uint64_t	umax;
59	size_t		i, suffixlen;
60
61	if (buf == NULL || suffix == NULL)
62		return (-1);
63	if (len > 0)
64		buf[0] = '\0';
65	suffixlen = strlen(suffix);
66	/* check if enough room for `x y' + suffix + `\0' */
67	if (len < 4 + suffixlen)
68		return (-1);
69
70	if (divisor == 1024) {
71		/*
72		 * binary multiplies
73		 * XXX IEC 60027-2 recommends Ki, Mi, Gi...
74		 */
75		prefixes = " KMGTPE";
76	} else
77		prefixes = " kMGTPE"; /* SI for decimal multiplies */
78
79	umax = 1;
80	for (i = 0; i < len - suffixlen - 3; i++) {
81		umax *= 10;
82		if (umax > bytes)
83			break;
84	}
85	for (i = 0; bytes >= umax && prefixes[i + 1]; i++)
86		bytes /= divisor;
87
88	r = snprintf(buf, len, "%qu%s%c%s", (unsigned long long)bytes,
89	    i == 0 ? "" : " ", prefixes[i], suffix);
90
91	return (r);
92}
93
94int
95format_bytes(char *buf, size_t len, uint64_t bytes)
96{
97	int	rv;
98	size_t	nlen;
99
100	rv = humanize_number(buf, len, bytes, "B", 1024);
101	if (rv != -1) {
102			/* nuke the trailing ` B' if it exists */
103		nlen = strlen(buf) - 2;
104		if (strcmp(&buf[nlen], " B") == 0)
105			buf[nlen] = '\0';
106	}
107	return (rv);
108}
109