lib/human.c

   1 /* human.c -- print human readable file size
   2    Copyright (C) 1996, 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* Originally contributed by lm@sgi.com;
  19    --si, output block size selection, and large file support
  20    added by eggert@twinsun.com.  */
  21
  22 #if HAVE_CONFIG_H
  23 # include <config.h>
  24 #endif
  25
  26 #include <sys/types.h>
  27 #include <stdio.h>
  28
  29 #if HAVE_LIMITS_H
  30 # include <limits.h>
  31 #endif
  32
  33 #if HAVE_STRING_H
  34 # include <string.h>
  35 #else
  36 # include <strings.h>
  37 #endif
  38
  39 #ifndef CHAR_BIT
  40 # define CHAR_BIT 8
  41 #endif
  42 #if HAVE_STDLIB_H
  43 # include <stdlib.h>
  44 #endif
  45
  46 #if NEED_GETENV_DECL
  47 char *getenv ();
  48 #endif
  49
  50 #if ENABLE_NLS
  51 # include <libintl.h>
  52 # define _(Text) gettext (Text)
  53 #else
  54 # define _(Text) Text
  55 #endif
  56
  57 #include <argmatch.h>
  58 #include <error.h>
  59 #include <xstrtol.h>
  60
  61 #include "human.h"
  62
  63 static const char suffixes[] =
  64 {
  65   0,    /* not used */
  66   'k',  /* kilo */
  67   'M',  /* Mega */
  68   'G',  /* Giga */
  69   'T',  /* Tera */
  70   'P',  /* Peta */
  71   'E',  /* Exa */
  72   'Z',  /* Zetta */
  73   'Y'   /* Yotta */
  74 };
  75
  76 /* Like human_readable_inexact, except always round to even.  */
  77 char *
  78 human_readable (uintmax_t n, char *buf,
  79                 int from_block_size, int output_block_size)
  80 {
  81   return human_readable_inexact (n, buf, from_block_size, output_block_size,
  82                                  human_round_to_even);
  83 }
  84
  85 /* Convert N to a human readable format in BUF.
  86
  87    N is expressed in units of FROM_BLOCK_SIZE.  FROM_BLOCK_SIZE must
  88    be nonnegative.
  89
  90    If OUTPUT_BLOCK_SIZE is positive, use units of OUTPUT_BLOCK_SIZE in
  91    the output number.  OUTPUT_BLOCK_SIZE must be a multiple of
  92    FROM_BLOCK_SIZE or vice versa.
  93
  94    Use INEXACT_STYLE to determine whether to take the ceiling or floor
  95    of any result that cannot be expressed exactly.
  96
  97    If OUTPUT_BLOCK_SIZE is negative, use a format like "127k" if
  98    possible, using powers of -OUTPUT_BLOCK_SIZE; otherwise, use
  99    ordinary decimal format.  Normally -OUTPUT_BLOCK_SIZE is either
 100    1000 or 1024; it must be at least 2.  Most people visually process
 101    strings of 3-4 digits effectively, but longer strings of digits are
 102    more prone to misinterpretation.  Hence, converting to an
 103    abbreviated form usually improves readability.  Use a suffix
 104    indicating which power is being used.  For example, assuming
 105    -OUTPUT_BLOCK_SIZE is 1024, 8500 would be converted to 8.3k,
 106    133456345 to 127M, 56990456345 to 53G, and so on.  Numbers smaller
 107    than -OUTPUT_BLOCK_SIZE aren't modified.  */
 108
 109 char *
 110 human_readable_inexact (uintmax_t n, char *buf,
 111                         int from_block_size, int output_block_size,
 112                         enum human_inexact_style inexact_style)
 113 {
 114   uintmax_t amt;
 115   int base;
 116   int to_block_size;
 117   int tenths = 0;
 118   int power;
 119   char *p;
 120
 121   /* 0 means adjusted N == AMT.TENTHS;
 122      1 means AMT.TENTHS < adjusted N < AMT.TENTHS + 0.05;
 123      2 means adjusted N == AMT.TENTHS + 0.05;
 124      3 means AMT.TENTHS + 0.05 < adjusted N < AMT.TENTHS + 0.1.  */
 125   int rounding = 0;
 126
 127   if (output_block_size < 0)
 128     {
 129       base = -output_block_size;
 130       to_block_size = 1;
 131     }
 132   else
 133     {
 134       base = 0;
 135       to_block_size = output_block_size;
 136     }
 137
 138   p = buf + LONGEST_HUMAN_READABLE;
 139   *p = '\0';
 140
 141 #ifdef lint
 142   /* Suppress `used before initialized' warning.  */
 143   power = 0;
 144 #endif
 145
 146   /* Adjust AMT out of FROM_BLOCK_SIZE units and into TO_BLOCK_SIZE units.  */
 147
 148   if (to_block_size <= from_block_size)
 149     {
 150       int multiplier = from_block_size / to_block_size;
 151       amt = n * multiplier;
 152
 153       if (amt / multiplier != n)
 154         {
 155           /* Overflow occurred during multiplication.  We should use
 156              multiple precision arithmetic here, but we'll be lazy and
 157              resort to floating point.  This can yield answers that
 158              are slightly off.  In practice it is quite rare to
 159              overflow uintmax_t, so this is good enough for now.  */
 160
 161           double damt = n * (double) multiplier;
 162
 163           if (! base)
 164             sprintf (buf, "%.0f", damt);
 165           else
 166             {
 167               double e = 1;
 168               power = 0;
 169
 170               do
 171                 {
 172                   e *= base;
 173                   power++;
 174                 }
 175               while (e * base <= damt && power < sizeof suffixes - 1);
 176
 177               damt /= e;
 178
 179               sprintf (buf, "%.1f%c", damt, suffixes[power]);
 180               if (4 < strlen (buf))
 181                 sprintf (buf, "%.0f%c", damt, suffixes[power]);
 182             }
 183
 184           return buf;
 185         }
 186     }
 187   else if (from_block_size == 0)
 188     amt = 0;
 189   else
 190     {
 191       int divisor = to_block_size / from_block_size;
 192       int r10 = (n % divisor) * 10;
 193       int r2 = (r10 % divisor) * 2;
 194       amt = n / divisor;
 195       tenths = r10 / divisor;
 196       rounding = r2 < divisor ? 0 < r2 : 2 + (divisor < r2);
 197     }
 198
 199
 200   /* Use power of BASE notation if adjusted AMT is large enough.  */
 201
 202   if (base && base <= amt)
 203     {
 204       power = 0;
 205
 206       do
 207         {
 208           int r10 = (amt % base) * 10 + tenths;
 209           int r2 = (r10 % base) * 2 + (rounding >> 1);
 210           amt /= base;
 211           tenths = r10 / base;
 212           rounding = (r2 < base
 213                       ? 0 < r2 + rounding
 214                       : 2 + (base < r2 + rounding));
 215           power++;
 216         }
 217       while (base <= amt && power < sizeof suffixes - 1);
 218
 219       *--p = suffixes[power];
 220
 221       if (amt < 10)
 222         {
 223           if (2 * (1 - (int) inexact_style)
 224               < rounding + (tenths & (inexact_style == human_round_to_even)))
 225             {
 226               tenths++;
 227               rounding = 0;
 228
 229               if (tenths == 10)
 230                 {
 231                   amt++;
 232                   tenths = 0;
 233                 }
 234             }
 235
 236           if (amt < 10)
 237             {
 238               *--p = '0' + tenths;
 239               *--p = '.';
 240               tenths = rounding = 0;
 241             }
 242         }
 243     }
 244
 245   if (inexact_style == human_ceiling
 246       ? 0 < tenths + rounding
 247       : inexact_style == human_round_to_even
 248       ? 5 < tenths + (2 < rounding + (amt & 1))
 249       : /* inexact_style == human_floor */ 0)
 250     {
 251       amt++;
 252
 253       if (amt == base && power < sizeof suffixes - 1)
 254         {
 255           *p = suffixes[power + 1];
 256           *--p = '0';
 257           *--p = '.';
 258           amt = 1;
 259         }
 260     }
 261
 262   do
 263     *--p = '0' + (int) (amt % 10);
 264   while ((amt /= 10) != 0);
 265
 266   return p;
 267 }
 268
 269
 270 /* The default block size used for output.  This number may change in
 271    the future as disks get larger.  */
 272 #ifndef DEFAULT_BLOCK_SIZE
 273 # define DEFAULT_BLOCK_SIZE 1024
 274 #endif
 275
 276 static char const *const block_size_args[] = { "human-readable", "si", 0 };
 277 static int const block_size_types[] = { -1024, -1000 };
 278
 279 static int
 280 default_block_size (void)
 281 {
 282   return getenv ("POSIXLY_CORRECT") ? 512 : DEFAULT_BLOCK_SIZE;
 283 }
 284
 285 static strtol_error
 286 humblock (char const *spec, int *block_size)
 287 {
 288   int i;
 289
 290   if (! spec && ! (spec = getenv ("BLOCK_SIZE")))
 291     *block_size = default_block_size ();
 292   else if (0 <= (i = ARGMATCH (spec, block_size_args, block_size_types)))
 293     *block_size = block_size_types[i];
 294   else
 295     {
 296       char *ptr;
 297       unsigned long val;
 298       strtol_error e = xstrtoul (spec, &ptr, 0, &val, "eEgGkKmMpPtTyYzZ0");
 299       if (e != LONGINT_OK)
 300         return e;
 301       if (*ptr)
 302         return LONGINT_INVALID_SUFFIX_CHAR;
 303       if ((int) val < 0 || val != (int) val)
 304         return LONGINT_OVERFLOW;
 305       *block_size = (int) val;
 306     }
 307
 308   return LONGINT_OK;
 309 }
 310
 311 void
 312 human_block_size (char const *spec, int report_errors, int *block_size)
 313 {
 314   strtol_error e = humblock (spec, block_size);
 315   if (*block_size == 0)
 316     {
 317       *block_size = default_block_size ();
 318       e = LONGINT_INVALID;
 319     }
 320   if (e != LONGINT_OK && report_errors)
 321     STRTOL_FATAL_ERROR (spec, _("block size"), e);
 322 }