1 /*	$OpenBSD: fmt_scaled.c,v 1.22 2022/03/11 09:04:59 dtucker 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 /* Convert the given input string "scaled" into numeric in "result".
69  * Return 0 on success, -1 and errno set on error.
70  */
71 int
72 scan_scaled(char *scaled, long long *result)
73 {
74 	char *p = scaled;
75 	int sign = 0;
76 	unsigned int i, ndigits = 0, fract_digits = 0;
77 	long long scale_fact = 1, whole = 0, fpart = 0;
78 
79 	/* Skip leading whitespace */
80 	while (isascii((unsigned char)*p) && isspace((unsigned char)*p))
81 		++p;
82 
83 	/* Then at most one leading + or - */
84 	while (*p == '-' || *p == '+') {
85 		if (*p == '-') {
86 			if (sign) {
87 				errno = EINVAL;
88 				return -1;
89 			}
90 			sign = -1;
91 			++p;
92 		} else if (*p == '+') {
93 			if (sign) {
94 				errno = EINVAL;
95 				return -1;
96 			}
97 			sign = +1;
98 			++p;
99 		}
100 	}
101 
102 	/* Main loop: Scan digits, find decimal point, if present.
103 	 * We don't allow exponentials, so no scientific notation
104 	 * (but note that E for Exa might look like e to some!).
105 	 * Advance 'p' to end, to get scale factor.
106 	 */
107 	for (; isascii((unsigned char)*p) &&
108 	    (isdigit((unsigned char)*p) || *p=='.'); ++p) {
109 		if (*p == '.') {
110 			if (fract_digits > 0) {	/* oops, more than one '.' */
111 				errno = EINVAL;
112 				return -1;
113 			}
114 			fract_digits = 1;
115 			continue;
116 		}
117 
118 		i = (*p) - '0';			/* whew! finally a digit we can use */
119 		if (fract_digits > 0) {
120 			if (fract_digits >= MAX_DIGITS-1)
121 				/* ignore extra fractional digits */
122 				continue;
123 			fract_digits++;		/* for later scaling */
124 			if (fpart > LLONG_MAX / 10) {
125 				errno = ERANGE;
126 				return -1;
127 			}
128 			fpart *= 10;
129 			if (i > LLONG_MAX - fpart) {
130 				errno = ERANGE;
131 				return -1;
132 			}
133 			fpart += i;
134 		} else {				/* normal digit */
135 			if (++ndigits >= MAX_DIGITS) {
136 				errno = ERANGE;
137 				return -1;
138 			}
139 			if (whole > LLONG_MAX / 10) {
140 				errno = ERANGE;
141 				return -1;
142 			}
143 			whole *= 10;
144 			if (i > LLONG_MAX - whole) {
145 				errno = ERANGE;
146 				return -1;
147 			}
148 			whole += i;
149 		}
150 	}
151 
152 	if (sign)
153 		whole *= sign;
154 
155 	/* If no scale factor given, we're done. fraction is discarded. */
156 	if (!*p) {
157 		*result = whole;
158 		return 0;
159 	}
160 
161 	/* Validate scale factor, and scale whole and fraction by it. */
162 	for (i = 0; i < SCALE_LENGTH; i++) {
163 
164 		/* Are we there yet? */
165 		if (*p == scale_chars[i] ||
166 			*p == tolower((unsigned char)scale_chars[i])) {
167 
168 			/* If it ends with alphanumerics after the scale char, bad. */
169 			if (isalnum((unsigned char)*(p+1))) {
170 				errno = EINVAL;
171 				return -1;
172 			}
173 			scale_fact = scale_factors[i];
174 
175 			/* check for overflow and underflow after scaling */
176 			if (whole > LLONG_MAX / scale_fact ||
177 			    whole < LLONG_MIN / scale_fact) {
178 				errno = ERANGE;
179 				return -1;
180 			}
181 
182 			/* scale whole part */
183 			whole *= scale_fact;
184 
185 			/* truncate fpart so it does't overflow.
186 			 * then scale fractional part.
187 			 */
188 			while (fpart >= LLONG_MAX / scale_fact) {
189 				fpart /= 10;
190 				fract_digits--;
191 			}
192 			fpart *= scale_fact;
193 			if (fract_digits > 0) {
194 				for (i = 0; i < fract_digits -1; i++)
195 					fpart /= 10;
196 			}
197 			if (sign == -1)
198 				whole -= fpart;
199 			else
200 				whole += fpart;
201 			*result = whole;
202 			return 0;
203 		}
204 	}
205 
206 	/* Invalid unit or character */
207 	errno = EINVAL;
208 	return -1;
209 }
210 
211 /* Format the given "number" into human-readable form in "result".
212  * Result must point to an allocated buffer of length FMT_SCALED_STRSIZE.
213  * Return 0 on success, -1 and errno set if error.
214  */
215 int
216 fmt_scaled(long long number, char *result)
217 {
218 	long long abval, fract = 0;
219 	unsigned int i;
220 	unit_type unit = NONE;
221 
222 	/* Not every negative long long has a positive representation. */
223 	if (number == LLONG_MIN) {
224 		errno = ERANGE;
225 		return -1;
226 	}
227 
228 	abval = llabs(number);
229 
230 	/* Also check for numbers that are just too darned big to format. */
231 	if (abval / 1024 >= scale_factors[SCALE_LENGTH-1]) {
232 		errno = ERANGE;
233 		return -1;
234 	}
235 
236 	/* scale whole part; get unscaled fraction */
237 	for (i = 0; i < SCALE_LENGTH; i++) {
238 		if (abval/1024 < scale_factors[i]) {
239 			unit = units[i];
240 			fract = (i == 0) ? 0 : abval % scale_factors[i];
241 			number /= scale_factors[i];
242 			if (i > 0)
243 				fract /= scale_factors[i - 1];
244 			break;
245 		}
246 	}
247 
248 	fract = (10 * fract + 512) / 1024;
249 	/* if the result would be >= 10, round main number */
250 	if (fract >= 10) {
251 		if (number >= 0)
252 			number++;
253 		else
254 			number--;
255 		fract = 0;
256 	} else if (fract < 0) {
257 		/* shouldn't happen */
258 		fract = 0;
259 	}
260 
261 	if (number == 0)
262 		strlcpy(result, "0B", FMT_SCALED_STRSIZE);
263 	else if (unit == NONE || number >= 100 || number <= -100) {
264 		if (fract >= 5) {
265 			if (number >= 0)
266 				number++;
267 			else
268 				number--;
269 		}
270 		(void)snprintf(result, FMT_SCALED_STRSIZE, "%lld%c",
271 			number, scale_chars[unit]);
272 	} else
273 		(void)snprintf(result, FMT_SCALED_STRSIZE, "%lld.%1lld%c",
274 			number, fract, scale_chars[unit]);
275 
276 	return 0;
277 }
278 
279 #ifdef	MAIN
280 /*
281  * This is the original version of the program in the man page.
282  * Copy-and-paste whatever you need from it.
283  */
284 int
285 main(int argc, char **argv)
286 {
287 	char *cinput = "1.5K", buf[FMT_SCALED_STRSIZE];
288 	long long ninput = 10483892, result;
289 
290 	if (scan_scaled(cinput, &result) == 0)
291 		printf("\"%s\" -> %lld\n", cinput, result);
292 	else
293 		perror(cinput);
294 
295 	if (fmt_scaled(ninput, buf) == 0)
296 		printf("%lld -> \"%s\"\n", ninput, buf);
297 	else
298 		fprintf(stderr, "%lld invalid (%s)\n", ninput, strerror(errno));
299 
300 	return 0;
301 }
302 #endif