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 * Copyright 2019, Joyent, Inc.
26 */
27
28 #include <stdio.h>
29 #include <string.h>
30 #include <sys/types.h>
31 #include <sys/debug.h>
32 #include "libcmdutils.h"
33
34 /* The largest suffix that can fit, aka an exabyte (2^60 / 10^18) */
35 #define INDEX_MAX (6)
36
37 /* Verify INDEX_MAX fits */
38 CTASSERT(INDEX_MAX * 10 < sizeof (uint64_t) * 8);
39
40 void
nicenum_scale(uint64_t n,size_t units,char * buf,size_t buflen,uint32_t flags)41 nicenum_scale(uint64_t n, size_t units, char *buf, size_t buflen,
42 uint32_t flags)
43 {
44 uint64_t divamt = 1024;
45 uint64_t divisor = 1;
46 int index = 0;
47 int rc = 0;
48 const char *spc = "";
49 char u;
50
51 if (flags & NN_UNIT_SPACE) {
52 spc = " ";
53 }
54
55 if (units == 0)
56 units = 1;
57
58 if (n > 0) {
59 n *= units;
60 if (n < units)
61 goto overflow;
62 }
63
64 if (flags & NN_DIVISOR_1000)
65 divamt = 1000;
66
67 /*
68 * This tries to find the suffix S(n) such that
69 * S(n) <= n < S(n+1), where S(n) = 2^(n*10) | 10^(3*n)
70 * (i.e. 1024/1000, 1,048,576/1,000,000, etc). Stop once S(n)
71 * is the largest prefix supported (i.e. don't bother computing
72 * and checking S(n+1). Since INDEX_MAX should be the largest
73 * suffix that fits (currently an exabyte), S(INDEX_MAX + 1) is
74 * never checked as it would overflow.
75 */
76 while (index < INDEX_MAX) {
77 uint64_t newdiv = divisor * divamt;
78
79 /* CTASSERT() guarantee these never trip */
80 VERIFY3U(newdiv, >=, divamt);
81 VERIFY3U(newdiv, >=, divisor);
82
83 if (n < newdiv)
84 break;
85
86 divisor = newdiv;
87 index++;
88 }
89
90 u = " KMGTPE"[index];
91
92 if (index == 0) {
93 rc = snprintf(buf, buflen, "%llu%s", n, spc);
94 } else if (n % divisor == 0) {
95 /*
96 * If this is an even multiple of the base, always display
97 * without any decimal precision.
98 */
99 rc = snprintf(buf, buflen, "%llu%s%c", n / divisor, spc, u);
100 } else {
101 /*
102 * We want to choose a precision that reflects the best choice
103 * for fitting in the buffer. This can get rather tricky
104 * when we have numbers that are very close to an order of
105 * magnitude. For example, when displaying 10239 (which is
106 * really 9.999K), we want only a single place of precision
107 * for 10.0K. We could develop some complex heuristics for
108 * this, but it's much easier just to try each combination
109 * in turn.
110 */
111 int i;
112 for (i = 2; i >= 0; i--) {
113 if ((rc = snprintf(buf, buflen, "%.*f%s%c", i,
114 (double)n / divisor, spc, u)) <= (buflen - 1))
115 break;
116 }
117 }
118
119 if (rc + 1 > buflen || rc < 0)
120 goto overflow;
121
122 return;
123
124 overflow:
125 /* prefer a more verbose message if possible */
126 if (buflen > 10)
127 (void) strlcpy(buf, "<overflow>", buflen);
128 else
129 (void) strlcpy(buf, "??", buflen);
130 }
131
132 void
nicenum(uint64_t num,char * buf,size_t buflen)133 nicenum(uint64_t num, char *buf, size_t buflen)
134 {
135 nicenum_scale(num, 1, buf, buflen, 0);
136 }
137