1 /*	$OpenBSD: fmt_scaled.c,v 1.19 2020/10/12 22:08:34 deraadt Exp $	*/
2 
3 /*
4  * Copyright (c) 2001, 2002, 2003 Ian F. Darwin.  All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  * 3. The name of the author may not be used to endorse or promote products
15  *    derived from this software without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27  */
28 
29 /*
30  * fmt_scaled: Format numbers scaled for human comprehension
31  * scan_scaled: Scan numbers in this format.
32  *
33  * "Human-readable" output uses 4 digits max, and puts a unit suffix at
34  * the end.  Makes output compact and easy-to-read esp. on huge disks.
35  * Formatting code was originally in OpenBSD "df", converted to library routine.
36  * Scanning code written for OpenBSD libutil.
37  */
38 
39 #include "compat.h"
40 
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <errno.h>
44 #include <string.h>
45 #include <ctype.h>
46 #include <limits.h>
47 
48 typedef enum {
49 	NONE = 0, KILO = 1, MEGA = 2, GIGA = 3, TERA = 4, PETA = 5, EXA = 6
50 } unit_type;
51 
52 /* These three arrays MUST be in sync!  XXX make a struct */
53 static const unit_type units[] = { NONE, KILO, MEGA, GIGA, TERA, PETA, EXA };
54 static const char scale_chars[] = "BKMGTPE";
55 static const long long scale_factors[] = {
56 	1LL,
57 	1024LL,
58 	1024LL*1024,
59 	1024LL*1024*1024,
60 	1024LL*1024*1024*1024,
61 	1024LL*1024*1024*1024*1024,
62 	1024LL*1024*1024*1024*1024*1024,
63 };
64 #define	SCALE_LENGTH (sizeof(units)/sizeof(units[0]))
65 
66 #define MAX_DIGITS (SCALE_LENGTH * 3)	/* XXX strlen(sprintf("%lld", -1)? */
67 
68 /* Format the given "number" into human-readable form in "result".
69  * Result must point to an allocated buffer of length FMT_SCALED_STRSIZE.
70  * Return 0 on success, -1 and errno set if error.
71  */
72 int
73 fmt_scaled(long long number, char *result)
74 {
75 	long long abval, fract = 0;
76 	unsigned int i;
77 	unit_type unit = NONE;
78 
79 	/* Not every negative long long has a positive representation. */
80 	if (number == LLONG_MIN) {
81 		errno = ERANGE;
82 		return -1;
83 	}
84 
85 	abval = llabs(number);
86 
87 	/* Also check for numbers that are just too darned big to format. */
88 	if (abval / 1024 >= scale_factors[SCALE_LENGTH-1]) {
89 		errno = ERANGE;
90 		return -1;
91 	}
92 
93 	/* scale whole part; get unscaled fraction */
94 	for (i = 0; i < SCALE_LENGTH; i++) {
95 		if (abval/1024 < scale_factors[i]) {
96 			unit = units[i];
97 			fract = (i == 0) ? 0 : abval % scale_factors[i];
98 			number /= scale_factors[i];
99 			if (i > 0)
100 				fract /= scale_factors[i - 1];
101 			break;
102 		}
103 	}
104 
105 	fract = (10 * fract + 512) / 1024;
106 	/* if the result would be >= 10, round main number */
107 	if (fract >= 10) {
108 		if (number >= 0)
109 			number++;
110 		else
111 			number--;
112 		fract = 0;
113 	} else if (fract < 0) {
114 		/* shouldn't happen */
115 		fract = 0;
116 	}
117 
118 	if (number == 0)
119 		strlcpy(result, "0B", FMT_SCALED_STRSIZE);
120 	else if (unit == NONE || number >= 100 || number <= -100) {
121 		if (fract >= 5) {
122 			if (number >= 0)
123 				number++;
124 			else
125 				number--;
126 		}
127 		(void)snprintf(result, FMT_SCALED_STRSIZE, "%lld%c",
128 			number, scale_chars[unit]);
129 	} else
130 		(void)snprintf(result, FMT_SCALED_STRSIZE, "%lld.%1lld%c",
131 			number, fract, scale_chars[unit]);
132 
133 	return 0;
134 }
135 
136 #ifdef	MAIN
137 /*
138  * This is the original version of the program in the man page.
139  * Copy-and-paste whatever you need from it.
140  */
141 int
142 main(int argc, char **argv)
143 {
144 	char *cinput = "1.5K", buf[FMT_SCALED_STRSIZE];
145 	long long ninput = 10483892, result;
146 
147 	if (scan_scaled(cinput, &result) == 0)
148 		printf("\"%s\" -> %lld\n", cinput, result);
149 	else
150 		perror(cinput);
151 
152 	if (fmt_scaled(ninput, buf) == 0)
153 		printf("%lld -> \"%s\"\n", ninput, buf);
154 	else
155 		fprintf(stderr, "%lld invalid (%s)\n", ninput, strerror(errno));
156 
157 	return 0;
158 }
159 #endif