1/*	$OpenBSD: fmt_scaled.c,v 1.9 2007/03/20 03:42:52 tedu 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/* OPENBSD ORIGINAL: lib/libutil/fmt_scaled.c */
30
31/*
32 * fmt_scaled: Format numbers scaled for human comprehension
33 * scan_scaled: Scan numbers in this format.
34 *
35 * "Human-readable" output uses 4 digits max, and puts a unit suffix at
36 * the end.  Makes output compact and easy-to-read esp. on huge disks.
37 * Formatting code was originally in OpenBSD "df", converted to library routine.
38 * Scanning code written for OpenBSD libutil.
39 */
40
41#include "includes.h"
42
43#ifndef HAVE_FMT_SCALED
44
45#include <stdio.h>
46#include <stdlib.h>
47#include <errno.h>
48#include <string.h>
49#include <ctype.h>
50#include <limits.h>
51
52typedef enum {
53	NONE = 0, KILO = 1, MEGA = 2, GIGA = 3, TERA = 4, PETA = 5, EXA = 6
54} unit_type;
55
56/* These three arrays MUST be in sync!  XXX make a struct */
57static unit_type units[] = { NONE, KILO, MEGA, GIGA, TERA, PETA, EXA };
58static char scale_chars[] = "BKMGTPE";
59static long long scale_factors[] = {
60	1LL,
61	1024LL,
62	1024LL*1024,
63	1024LL*1024*1024,
64	1024LL*1024*1024*1024,
65	1024LL*1024*1024*1024*1024,
66	1024LL*1024*1024*1024*1024*1024,
67};
68#define	SCALE_LENGTH (sizeof(units)/sizeof(units[0]))
69
70#define MAX_DIGITS (SCALE_LENGTH * 3)	/* XXX strlen(sprintf("%lld", -1)? */
71
72/** Convert the given input string "scaled" into numeric in "result".
73 * Return 0 on success, -1 and errno set on error.
74 */
75int
76scan_scaled(char *scaled, long long *result)
77{
78	char *p = scaled;
79	int sign = 0;
80	unsigned int i, ndigits = 0, fract_digits = 0;
81	long long scale_fact = 1, whole = 0, fpart = 0;
82
83	/* Skip leading whitespace */
84	while (isascii(*p) && isspace(*p))
85		++p;
86
87	/* Then at most one leading + or - */
88	while (*p == '-' || *p == '+') {
89		if (*p == '-') {
90			if (sign) {
91				errno = EINVAL;
92				return -1;
93			}
94			sign = -1;
95			++p;
96		} else if (*p == '+') {
97			if (sign) {
98				errno = EINVAL;
99				return -1;
100			}
101			sign = +1;
102			++p;
103		}
104	}
105
106	/* Main loop: Scan digits, find decimal point, if present.
107	 * We don't allow exponentials, so no scientific notation
108	 * (but note that E for Exa might look like e to some!).
109	 * Advance 'p' to end, to get scale factor.
110	 */
111	for (; isascii(*p) && (isdigit(*p) || *p=='.'); ++p) {
112		if (*p == '.') {
113			if (fract_digits > 0) {	/* oops, more than one '.' */
114				errno = EINVAL;
115				return -1;
116			}
117			fract_digits = 1;
118			continue;
119		}
120
121		i = (*p) - '0';			/* whew! finally a digit we can use */
122		if (fract_digits > 0) {
123			if (fract_digits >= MAX_DIGITS-1)
124				/* ignore extra fractional digits */
125				continue;
126			fract_digits++;		/* for later scaling */
127			fpart *= 10;
128			fpart += i;
129		} else {				/* normal digit */
130			if (++ndigits >= MAX_DIGITS) {
131				errno = ERANGE;
132				return -1;
133			}
134			whole *= 10;
135			whole += i;
136		}
137	}
138
139	if (sign) {
140		whole *= sign;
141		fpart *= sign;
142	}
143
144	/* If no scale factor given, we're done. fraction is discarded. */
145	if (!*p) {
146		*result = whole;
147		return 0;
148	}
149
150	/* Validate scale factor, and scale whole and fraction by it. */
151	for (i = 0; i < SCALE_LENGTH; i++) {
152
153		/** Are we there yet? */
154		if (*p == scale_chars[i] ||
155			*p == tolower(scale_chars[i])) {
156
157			/* If it ends with alphanumerics after the scale char, bad. */
158			if (isalnum(*(p+1))) {
159				errno = EINVAL;
160				return -1;
161			}
162			scale_fact = scale_factors[i];
163
164			/* scale whole part */
165			whole *= scale_fact;
166
167			/* truncate fpart so it does't overflow.
168			 * then scale fractional part.
169			 */
170			while (fpart >= LLONG_MAX / scale_fact) {
171				fpart /= 10;
172				fract_digits--;
173			}
174			fpart *= scale_fact;
175			if (fract_digits > 0) {
176				for (i = 0; i < fract_digits -1; i++)
177					fpart /= 10;
178			}
179			whole += fpart;
180			*result = whole;
181			return 0;
182		}
183	}
184	errno = ERANGE;
185	return -1;
186}
187
188/* Format the given "number" into human-readable form in "result".
189 * Result must point to an allocated buffer of length FMT_SCALED_STRSIZE.
190 * Return 0 on success, -1 and errno set if error.
191 */
192int
193fmt_scaled(long long number, char *result)
194{
195	long long abval, fract = 0;
196	unsigned int i;
197	unit_type unit = NONE;
198
199	abval = (number < 0LL) ? -number : number;	/* no long long_abs yet */
200
201	/* Not every negative long long has a positive representation.
202	 * Also check for numbers that are just too darned big to format
203	 */
204	if (abval < 0 || abval / 1024 >= scale_factors[SCALE_LENGTH-1]) {
205		errno = ERANGE;
206		return -1;
207	}
208
209	/* scale whole part; get unscaled fraction */
210	for (i = 0; i < SCALE_LENGTH; i++) {
211		if (abval/1024 < scale_factors[i]) {
212			unit = units[i];
213			fract = (i == 0) ? 0 : abval % scale_factors[i];
214			number /= scale_factors[i];
215			if (i > 0)
216				fract /= scale_factors[i - 1];
217			break;
218		}
219	}
220
221	fract = (10 * fract + 512) / 1024;
222	/* if the result would be >= 10, round main number */
223	if (fract == 10) {
224		if (number >= 0)
225			number++;
226		else
227			number--;
228		fract = 0;
229	}
230
231	if (number == 0)
232		strlcpy(result, "0B", FMT_SCALED_STRSIZE);
233	else if (unit == NONE || number >= 100 || number <= -100) {
234		if (fract >= 5) {
235			if (number >= 0)
236				number++;
237			else
238				number--;
239		}
240		(void)snprintf(result, FMT_SCALED_STRSIZE, "%lld%c",
241			number, scale_chars[unit]);
242	} else
243		(void)snprintf(result, FMT_SCALED_STRSIZE, "%lld.%1lld%c",
244			number, fract, scale_chars[unit]);
245
246	return 0;
247}
248
249#ifdef	MAIN
250/*
251 * This is the original version of the program in the man page.
252 * Copy-and-paste whatever you need from it.
253 */
254int
255main(int argc, char **argv)
256{
257	char *cinput = "1.5K", buf[FMT_SCALED_STRSIZE];
258	long long ninput = 10483892, result;
259
260	if (scan_scaled(cinput, &result) == 0)
261		printf("\"%s\" -> %lld\n", cinput, result);
262	else
263		perror(cinput);
264
265	if (fmt_scaled(ninput, buf) == 0)
266		printf("%lld -> \"%s\"\n", ninput, buf);
267	else
268		fprintf(stderr, "%lld invalid (%s)\n", ninput, strerror(errno));
269
270	return 0;
271}
272#endif
273
274#endif /* HAVE_FMT_SCALED */
275