openbsd-compat/fmt_scaled.c

   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
  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
  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         /* 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  */
 192 int
 193 fmt_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  */
 254 int
 255 main(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 */