1 /* $OpenBSD: fmt_scaled.c,v 1.12 2013/11/29 19:00:51 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 <stdio.h> 40 #include <stdlib.h> 41 #include <errno.h> 42 #include <string.h> 43 #include <ctype.h> 44 #include <limits.h> 45 46 #include "util.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 unit_type units[] = { NONE, KILO, MEGA, GIGA, TERA, PETA, EXA }; 54 static char scale_chars[] = "BKMGTPE"; 55 static 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 fpart *= 10; 125 fpart += i; 126 } else { /* normal digit */ 127 if (++ndigits >= MAX_DIGITS) { 128 errno = ERANGE; 129 return -1; 130 } 131 whole *= 10; 132 whole += i; 133 } 134 } 135 136 if (sign) { 137 whole *= sign; 138 fpart *= sign; 139 } 140 141 /* If no scale factor given, we're done. fraction is discarded. */ 142 if (!*p) { 143 *result = whole; 144 return 0; 145 } 146 147 /* Validate scale factor, and scale whole and fraction by it. */ 148 for (i = 0; i < SCALE_LENGTH; i++) { 149 150 /* Are we there yet? */ 151 if (*p == scale_chars[i] || 152 *p == tolower((unsigned char)scale_chars[i])) { 153 154 /* If it ends with alphanumerics after the scale char, bad. */ 155 if (isalnum((unsigned char)*(p+1))) { 156 errno = EINVAL; 157 return -1; 158 } 159 scale_fact = scale_factors[i]; 160 161 /* scale whole part */ 162 whole *= scale_fact; 163 164 /* truncate fpart so it does't overflow. 165 * then scale fractional part. 166 */ 167 while (fpart >= LLONG_MAX / scale_fact) { 168 fpart /= 10; 169 fract_digits--; 170 } 171 fpart *= scale_fact; 172 if (fract_digits > 0) { 173 for (i = 0; i < fract_digits -1; i++) 174 fpart /= 10; 175 } 176 whole += fpart; 177 *result = whole; 178 return 0; 179 } 180 } 181 182 /* Invalid unit or character */ 183 errno = EINVAL; 184 return -1; 185 } 186 187 /* Format the given "number" into human-readable form in "result". 188 * Result must point to an allocated buffer of length FMT_SCALED_STRSIZE. 189 * Return 0 on success, -1 and errno set if error. 190 */ 191 int 192 fmt_scaled(long long number, char *result) 193 { 194 long long abval, fract = 0; 195 unsigned int i; 196 unit_type unit = NONE; 197 198 abval = llabs(number); 199 200 /* Not every negative long long has a positive representation. 201 * Also check for numbers that are just too darned big to format 202 */ 203 if (abval < 0 || abval / 1024 >= scale_factors[SCALE_LENGTH-1]) { 204 errno = ERANGE; 205 return -1; 206 } 207 208 /* scale whole part; get unscaled fraction */ 209 for (i = 0; i < SCALE_LENGTH; i++) { 210 if (abval/1024 < scale_factors[i]) { 211 unit = units[i]; 212 fract = (i == 0) ? 0 : abval % scale_factors[i]; 213 number /= scale_factors[i]; 214 if (i > 0) 215 fract /= scale_factors[i - 1]; 216 break; 217 } 218 } 219 220 fract = (10 * fract + 512) / 1024; 221 /* if the result would be >= 10, round main number */ 222 if (fract == 10) { 223 if (number >= 0) 224 number++; 225 else 226 number--; 227 fract = 0; 228 } 229 230 if (number == 0) 231 strlcpy(result, "0B", FMT_SCALED_STRSIZE); 232 else if (unit == NONE || number >= 100 || number <= -100) { 233 if (fract >= 5) { 234 if (number >= 0) 235 number++; 236 else 237 number--; 238 } 239 (void)snprintf(result, FMT_SCALED_STRSIZE, "%lld%c", 240 number, scale_chars[unit]); 241 } else 242 (void)snprintf(result, FMT_SCALED_STRSIZE, "%lld.%1lld%c", 243 number, fract, scale_chars[unit]); 244 245 return 0; 246 } 247 248 #ifdef MAIN 249 /* 250 * This is the original version of the program in the man page. 251 * Copy-and-paste whatever you need from it. 252 */ 253 int 254 main(int argc, char **argv) 255 { 256 char *cinput = "1.5K", buf[FMT_SCALED_STRSIZE]; 257 long long ninput = 10483892, result; 258 259 if (scan_scaled(cinput, &result) == 0) 260 printf("\"%s\" -> %lld\n", cinput, result); 261 else 262 perror(cinput); 263 264 if (fmt_scaled(ninput, buf) == 0) 265 printf("%lld -> \"%s\"\n", ninput, buf); 266 else 267 fprintf(stderr, "%lld invalid (%s)\n", ninput, strerror(errno)); 268 269 return 0; 270 } 271 #endif 272