1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
24 * Copyright 2017 Jason king
25 */
26
27 #include <stdio.h>
28 #include <string.h>
29 #include <sys/types.h>
30 #include <sys/debug.h>
31 #include "libcmdutils.h"
32
33 /* The largest suffix that can fit, aka an exabyte (2^60 / 10^18) */
34 #define INDEX_MAX (6)
35
36 /* Verify INDEX_MAX fits */
37 CTASSERT(INDEX_MAX * 10 < sizeof (uint64_t) * 8);
38
39 void
nicenum_scale(uint64_t n,size_t units,char * buf,size_t buflen,uint32_t flags)40 nicenum_scale(uint64_t n, size_t units, char *buf, size_t buflen,
41 uint32_t flags)
42 {
43 uint64_t divamt = 1024;
44 uint64_t divisor = 1;
45 int index = 0;
46 int rc = 0;
47 char u;
48
49 if (units == 0)
50 units = 1;
51
52 if (n > 0) {
53 n *= units;
54 if (n < units)
55 goto overflow;
56 }
57
58 if (flags & NN_DIVISOR_1000)
59 divamt = 1000;
60
61 /*
62 * This tries to find the suffix S(n) such that
63 * S(n) <= n < S(n+1), where S(n) = 2^(n*10) | 10^(3*n)
64 * (i.e. 1024/1000, 1,048,576/1,000,000, etc). Stop once S(n)
65 * is the largest prefix supported (i.e. don't bother computing
66 * and checking S(n+1). Since INDEX_MAX should be the largest
67 * suffix that fits (currently an exabyte), S(INDEX_MAX + 1) is
68 * never checked as it would overflow.
69 */
70 while (index < INDEX_MAX) {
71 uint64_t newdiv = divisor * divamt;
72
73 /* CTASSERT() guarantee these never trip */
74 VERIFY3U(newdiv, >=, divamt);
75 VERIFY3U(newdiv, >=, divisor);
76
77 if (n < newdiv)
78 break;
79
80 divisor = newdiv;
81 index++;
82 }
83
84 u = " KMGTPE"[index];
85
86 if (index == 0) {
87 rc = snprintf(buf, buflen, "%llu", n);
88 } else if (n % divisor == 0) {
89 /*
90 * If this is an even multiple of the base, always display
91 * without any decimal precision.
92 */
93 rc = snprintf(buf, buflen, "%llu%c", n / divisor, u);
94 } else {
95 /*
96 * We want to choose a precision that reflects the best choice
97 * for fitting in 5 characters. This can get rather tricky
98 * when we have numbers that are very close to an order of
99 * magnitude. For example, when displaying 10239 (which is
100 * really 9.999K), we want only a single place of precision
101 * for 10.0K. We could develop some complex heuristics for
102 * this, but it's much easier just to try each combination
103 * in turn.
104 */
105 int i;
106 for (i = 2; i >= 0; i--) {
107 if ((rc = snprintf(buf, buflen, "%.*f%c", i,
108 (double)n / divisor, u)) <= 5)
109 break;
110 }
111 }
112
113 if (rc + 1 > buflen || rc < 0)
114 goto overflow;
115
116 return;
117
118 overflow:
119 /* prefer a more verbose message if possible */
120 if (buflen > 10)
121 (void) strlcpy(buf, "<overflow>", buflen);
122 else
123 (void) strlcpy(buf, "??", buflen);
124 }
125
126 void
nicenum(uint64_t num,char * buf,size_t buflen)127 nicenum(uint64_t num, char *buf, size_t buflen)
128 {
129 nicenum_scale(num, 1, buf, buflen, 0);
130 }
131