fmt_scaled.c revision 323136
1/* $OpenBSD: fmt_scaled.c,v 1.13 2017/03/11 23:37:23 djm 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((unsigned char)*p) && isspace((unsigned char)*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((unsigned char)*p) && 112 (isdigit((unsigned char)*p) || *p=='.'); ++p) { 113 if (*p == '.') { 114 if (fract_digits > 0) { /* oops, more than one '.' */ 115 errno = EINVAL; 116 return -1; 117 } 118 fract_digits = 1; 119 continue; 120 } 121 122 i = (*p) - '0'; /* whew! finally a digit we can use */ 123 if (fract_digits > 0) { 124 if (fract_digits >= MAX_DIGITS-1) 125 /* ignore extra fractional digits */ 126 continue; 127 fract_digits++; /* for later scaling */ 128 if (fpart >= LLONG_MAX / 10) { 129 errno = ERANGE; 130 return -1; 131 } 132 fpart *= 10; 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 whole += i; 145 } 146 } 147 148 if (sign) { 149 whole *= sign; 150 fpart *= sign; 151 } 152 153 /* If no scale factor given, we're done. fraction is discarded. */ 154 if (!*p) { 155 *result = whole; 156 return 0; 157 } 158 159 /* Validate scale factor, and scale whole and fraction by it. */ 160 for (i = 0; i < SCALE_LENGTH; i++) { 161 162 /* Are we there yet? */ 163 if (*p == scale_chars[i] || 164 *p == tolower((unsigned char)scale_chars[i])) { 165 166 /* If it ends with alphanumerics after the scale char, bad. */ 167 if (isalnum((unsigned char)*(p+1))) { 168 errno = EINVAL; 169 return -1; 170 } 171 scale_fact = scale_factors[i]; 172 173 if (whole >= LLONG_MAX / scale_fact) { 174 errno = ERANGE; 175 return -1; 176 } 177 178 /* scale whole part */ 179 whole *= scale_fact; 180 181 /* truncate fpart so it does't overflow. 182 * then scale fractional part. 183 */ 184 while (fpart >= LLONG_MAX / scale_fact) { 185 fpart /= 10; 186 fract_digits--; 187 } 188 fpart *= scale_fact; 189 if (fract_digits > 0) { 190 for (i = 0; i < fract_digits -1; i++) 191 fpart /= 10; 192 } 193 whole += fpart; 194 *result = whole; 195 return 0; 196 } 197 } 198 199 /* Invalid unit or character */ 200 errno = EINVAL; 201 return -1; 202} 203 204/* Format the given "number" into human-readable form in "result". 205 * Result must point to an allocated buffer of length FMT_SCALED_STRSIZE. 206 * Return 0 on success, -1 and errno set if error. 207 */ 208int 209fmt_scaled(long long number, char *result) 210{ 211 long long abval, fract = 0; 212 unsigned int i; 213 unit_type unit = NONE; 214 215 abval = llabs(number); 216 217 /* Not every negative long long has a positive representation. 218 * Also check for numbers that are just too darned big to format 219 */ 220 if (abval < 0 || abval / 1024 >= scale_factors[SCALE_LENGTH-1]) { 221 errno = ERANGE; 222 return -1; 223 } 224 225 /* scale whole part; get unscaled fraction */ 226 for (i = 0; i < SCALE_LENGTH; i++) { 227 if (abval/1024 < scale_factors[i]) { 228 unit = units[i]; 229 fract = (i == 0) ? 0 : abval % scale_factors[i]; 230 number /= scale_factors[i]; 231 if (i > 0) 232 fract /= scale_factors[i - 1]; 233 break; 234 } 235 } 236 237 fract = (10 * fract + 512) / 1024; 238 /* if the result would be >= 10, round main number */ 239 if (fract == 10) { 240 if (number >= 0) 241 number++; 242 else 243 number--; 244 fract = 0; 245 } 246 247 if (number == 0) 248 strlcpy(result, "0B", FMT_SCALED_STRSIZE); 249 else if (unit == NONE || number >= 100 || number <= -100) { 250 if (fract >= 5) { 251 if (number >= 0) 252 number++; 253 else 254 number--; 255 } 256 (void)snprintf(result, FMT_SCALED_STRSIZE, "%lld%c", 257 number, scale_chars[unit]); 258 } else 259 (void)snprintf(result, FMT_SCALED_STRSIZE, "%lld.%1lld%c", 260 number, fract, scale_chars[unit]); 261 262 return 0; 263} 264 265#ifdef MAIN 266/* 267 * This is the original version of the program in the man page. 268 * Copy-and-paste whatever you need from it. 269 */ 270int 271main(int argc, char **argv) 272{ 273 char *cinput = "1.5K", buf[FMT_SCALED_STRSIZE]; 274 long long ninput = 10483892, result; 275 276 if (scan_scaled(cinput, &result) == 0) 277 printf("\"%s\" -> %lld\n", cinput, result); 278 else 279 perror(cinput); 280 281 if (fmt_scaled(ninput, buf) == 0) 282 printf("%lld -> \"%s\"\n", ninput, buf); 283 else 284 fprintf(stderr, "%lld invalid (%s)\n", ninput, strerror(errno)); 285 286 return 0; 287} 288#endif 289 290#endif /* HAVE_FMT_SCALED */ 291