1 /* $OpenBSD: fmt_scaled.c,v 1.6 2005/03/09 09:27:57 otto 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 #if defined(LIBC_SCCS) && !defined(lint)
40 static const char ident[] = "$OpenBSD: fmt_scaled.c,v 1.6 2005/03/09 09:27:57 otto Exp $";
41 #endif /* LIBC_SCCS and not lint */
42
43 #include <stdio.h>
44 #include <stdlib.h>
45 #include <errno.h>
46 #include <string.h>
47 #include <ctype.h>
48 #include <limits.h>
49
50 #include "util.h"
51
52 typedef 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 */
57 static unit_type units[] = { NONE, KILO, MEGA, GIGA, TERA, PETA, EXA };
58 static char scale_chars[] = "BKMGTPE";
59 static 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 */
75 int
scan_scaled(char * scaled,long long * result)76 scan_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 if (p == NULL || result == NULL) {
84 errno = EFAULT;
85 return -1;
86 }
87
88 /* Skip leading whitespace */
89 while (*p && isascii(*p) && isspace(*p))
90 ++p;
91
92 /* Then at most one leading + or - */
93 while (*p == '-' || *p == '+') {
94 if (*p == '-') {
95 if (sign) {
96 errno = EINVAL;
97 return -1;
98 }
99 sign = -1;
100 ++p;
101 } else if (*p == '+') {
102 if (sign) {
103 errno = EINVAL;
104 return -1;
105 }
106 sign = +1;
107 ++p;
108 }
109 }
110
111 /* Main loop: Scan digits, find decimal point, if present.
112 * We don't allow exponentials, so no scientific notation
113 * (but note that E for Exa might look like e to some!).
114 * Advance 'p' to end, to get scale factor.
115 */
116 for (; *p && isascii(*p) && (isdigit(*p) || *p=='.'); ++p) {
117 if (*p == '.') {
118 if (fract_digits > 0) { /* oops, more than one '.' */
119 errno = EINVAL;
120 return -1;
121 }
122 fract_digits = 1;
123 continue;
124 }
125
126 i = (*p) - '0'; /* whew! finally a digit we can use */
127 if (fract_digits > 0) {
128 if (fract_digits >= MAX_DIGITS-1)
129 /* ignore extra fractional digits */
130 continue;
131 fract_digits++; /* for later scaling */
132 fpart *= 10;
133 fpart += i;
134 } else { /* normal digit */
135 if (++ndigits >= MAX_DIGITS) {
136 errno = ERANGE;
137 return -1;
138 }
139 whole *= 10;
140 whole += i;
141 }
142 }
143
144 if (sign) {
145 whole *= sign;
146 fpart *= sign;
147 }
148
149 /* If no scale factor given, we're done. fraction is discarded. */
150 if (!*p) {
151 *result = whole;
152 return 0;
153 }
154
155 /* Validate scale factor, and scale whole and fraction by it. */
156 for (i = 0; i < SCALE_LENGTH; i++) {
157
158 /** Are we there yet? */
159 if (*p == scale_chars[i] ||
160 *p == tolower(scale_chars[i])) {
161
162 /* If it ends with alphanumerics after the scale char, bad. */
163 if (*(p+1) != '\0' && isalnum(*(p+1))) {
164 errno = EINVAL;
165 return -1;
166 }
167 scale_fact = scale_factors[i];
168
169 /* scale whole part */
170 whole *= scale_fact;
171
172 /* truncate fpart so it does't overflow.
173 * then scale fractional part.
174 */
175 while (fpart >= LLONG_MAX / scale_fact) {
176 fpart /= 10;
177 fract_digits--;
178 }
179 fpart *= scale_fact;
180 if (fract_digits > 0) {
181 for (i = 0; i < fract_digits -1; i++)
182 fpart /= 10;
183 }
184 whole += fpart;
185 *result = whole;
186 return 0;
187 }
188 }
189 errno = ERANGE;
190 return -1;
191 }
192
193 /* Format the given "number" into human-readable form in "result".
194 * Result must point to an allocated buffer of length FMT_SCALED_STRSIZE.
195 * Return 0 on success, -1 and errno set if error.
196 */
197 int
fmt_scaled(long long number,char * result)198 fmt_scaled(long long number, char *result)
199 {
200 long long abval, fract = 0;
201 unsigned int i;
202 unit_type unit = NONE;
203
204 if (result == NULL) {
205 errno = EFAULT;
206 return -1;
207 }
208
209 abval = (number < 0LL) ? -number : number; /* no long long_abs yet */
210
211 /* Not every negative long long has a positive representation.
212 * Also check for numbers that are just too darned big to format
213 */
214 if (abval < 0 || abval / 1024 >= scale_factors[SCALE_LENGTH-1]) {
215 errno = ERANGE;
216 return -1;
217 }
218
219 /* scale whole part; get unscaled fraction */
220 for (i = 0; i < SCALE_LENGTH; i++) {
221 if (abval/1024 < scale_factors[i]) {
222 unit = units[i];
223 fract = (i == 0) ? 0 : abval % scale_factors[i];
224 number /= scale_factors[i];
225 if (i > 0)
226 fract /= scale_factors[i - 1];
227 break;
228 }
229 }
230
231 fract = (10 * fract + 512) / 1024;
232 /* if the result would be >= 10, round main number */
233 if (fract == 10) {
234 if (number >= 0)
235 number++;
236 else
237 number--;
238 fract = 0;
239 }
240
241 if (number == 0)
242 strlcpy(result, "0B", FMT_SCALED_STRSIZE);
243 else if (unit == NONE || number >= 100 || number <= -100) {
244 if (fract >= 5) {
245 if (number >= 0)
246 number++;
247 else
248 number--;
249 }
250 (void)snprintf(result, FMT_SCALED_STRSIZE, "%lld%c",
251 number, scale_chars[unit]);
252 } else
253 (void)snprintf(result, FMT_SCALED_STRSIZE, "%lld.%1lld%c",
254 number, fract, scale_chars[unit]);
255
256 return 0;
257 }
258
259 #ifdef MAIN
260 /*
261 * This is the original version of the program in the man page.
262 * Copy-and-paste whatever you need from it.
263 */
264 int
main(int argc,char ** argv)265 main(int argc, char **argv)
266 {
267 char *cinput = "1.5K", buf[FMT_SCALED_STRSIZE];
268 long long ninput = 10483892, result;
269
270 if (scan_scaled(cinput, &result) == 0)
271 printf("\"%s\" -> %lld\n", cinput, result);
272 else
273 perror(cinput);
274
275 if (fmt_scaled(ninput, buf) == 0)
276 printf("%lld -> \"%s\"\n", ninput, buf);
277 else
278 fprintf(stderr, "%lld invalid (%s)\n", ninput, strerror(errno));
279
280 return 0;
281 }
282 #endif
283