Dogcows Code - chaz/tar/blob - 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 #ifndef HAVE_DECL_GETENV
  47 "this configure-time declaration test was not run"
  48 #endif
  49 #if !HAVE_DECL_GETENV
  50 char *getenv ();
  51 #endif
  52
  53 #if ENABLE_NLS
  54 # include <libintl.h>
  55 # define _(Text) gettext (Text)
  56 #else
  57 # define _(Text) Text
  58 #endif
  59
  60 #include <argmatch.h>
  61 #include <error.h>
  62 #include <xstrtol.h>
  63
  64 #include "human.h"
  65
  66 static const char suffixes[] =
  67 {
  68   0,    /* not used */
  69   'k',  /* kilo */
  70   'M',  /* Mega */
  71   'G',  /* Giga */
  72   'T',  /* Tera */
  73   'P',  /* Peta */
  74   'E',  /* Exa */
  75   'Z',  /* Zetta */
  76   'Y'   /* Yotta */
  77 };
  78
  79 /* Like human_readable_inexact, except always round to even.  */
  80 char *
  81 human_readable (uintmax_t n, char *buf,
  82                 int from_block_size, int output_block_size)
  83 {
  84   return human_readable_inexact (n, buf, from_block_size, output_block_size,
  85                                  human_round_to_even);
  86 }
  87
  88 /* Convert N to a human readable format in BUF.
  89
  90    N is expressed in units of FROM_BLOCK_SIZE.  FROM_BLOCK_SIZE must
  91    be nonnegative.
  92
  93    If OUTPUT_BLOCK_SIZE is positive, use units of OUTPUT_BLOCK_SIZE in
  94    the output number.  OUTPUT_BLOCK_SIZE must be a multiple of
  95    FROM_BLOCK_SIZE or vice versa.
  96
  97    Use INEXACT_STYLE to determine whether to take the ceiling or floor
  98    of any result that cannot be expressed exactly.
  99
 100    If OUTPUT_BLOCK_SIZE is negative, use a format like "127k" if
 101    possible, using powers of -OUTPUT_BLOCK_SIZE; otherwise, use
 102    ordinary decimal format.  Normally -OUTPUT_BLOCK_SIZE is either
 103    1000 or 1024; it must be at least 2.  Most people visually process
 104    strings of 3-4 digits effectively, but longer strings of digits are
 105    more prone to misinterpretation.  Hence, converting to an
 106    abbreviated form usually improves readability.  Use a suffix
 107    indicating which power is being used.  For example, assuming
 108    -OUTPUT_BLOCK_SIZE is 1024, 8500 would be converted to 8.3k,
 109    133456345 to 127M, 56990456345 to 53G, and so on.  Numbers smaller
 110    than -OUTPUT_BLOCK_SIZE aren't modified.  */
 111
 112 char *
 113 human_readable_inexact (uintmax_t n, char *buf,
 114                         int from_block_size, int output_block_size,
 115                         enum human_inexact_style inexact_style)
 116 {
 117   uintmax_t amt;
 118   int base;
 119   int to_block_size;
 120   int tenths = 0;
 121   int power;
 122   char *p;
 123
 124   /* 0 means adjusted N == AMT.TENTHS;
 125      1 means AMT.TENTHS < adjusted N < AMT.TENTHS + 0.05;
 126      2 means adjusted N == AMT.TENTHS + 0.05;
 127      3 means AMT.TENTHS + 0.05 < adjusted N < AMT.TENTHS + 0.1.  */
 128   int rounding = 0;
 129
 130   if (output_block_size < 0)
 131     {
 132       base = -output_block_size;
 133       to_block_size = 1;
 134     }
 135   else
 136     {
 137       base = 0;
 138       to_block_size = output_block_size;
 139     }
 140
 141   p = buf + LONGEST_HUMAN_READABLE;
 142   *p = '\0';
 143
 144 #ifdef lint
 145   /* Suppress `used before initialized' warning.  */
 146   power = 0;
 147 #endif
 148
 149   /* Adjust AMT out of FROM_BLOCK_SIZE units and into TO_BLOCK_SIZE units.  */
 150
 151   if (to_block_size <= from_block_size)
 152     {
 153       int multiplier = from_block_size / to_block_size;
 154       amt = n * multiplier;
 155
 156       if (amt / multiplier != n)
 157         {
 158           /* Overflow occurred during multiplication.  We should use
 159              multiple precision arithmetic here, but we'll be lazy and
 160              resort to floating point.  This can yield answers that
 161              are slightly off.  In practice it is quite rare to
 162              overflow uintmax_t, so this is good enough for now.  */
 163
 164           double damt = n * (double) multiplier;
 165
 166           if (! base)
 167             sprintf (buf, "%.0f", damt);
 168           else
 169             {
 170               double e = 1;
 171               power = 0;
 172
 173               do
 174                 {
 175                   e *= base;
 176                   power++;
 177                 }
 178               while (e * base <= damt && power < sizeof suffixes - 1);
 179
 180               damt /= e;
 181
 182               sprintf (buf, "%.1f%c", damt, suffixes[power]);
 183               if (4 < strlen (buf))
 184                 sprintf (buf, "%.0f%c", damt, suffixes[power]);
 185             }
 186
 187           return buf;
 188         }
 189     }
 190   else if (from_block_size == 0)
 191     amt = 0;
 192   else
 193     {
 194       int divisor = to_block_size / from_block_size;
 195       int r10 = (n % divisor) * 10;
 196       int r2 = (r10 % divisor) * 2;
 197       amt = n / divisor;
 198       tenths = r10 / divisor;
 199       rounding = r2 < divisor ? 0 < r2 : 2 + (divisor < r2);
 200     }
 201
 202
 203   /* Use power of BASE notation if adjusted AMT is large enough.  */
 204
 205   if (base && base <= amt)
 206     {
 207       power = 0;
 208
 209       do
 210         {
 211           int r10 = (amt % base) * 10 + tenths;
 212           int r2 = (r10 % base) * 2 + (rounding >> 1);
 213           amt /= base;
 214           tenths = r10 / base;
 215           rounding = (r2 < base
 216                       ? 0 < r2 + rounding
 217                       : 2 + (base < r2 + rounding));
 218           power++;
 219         }
 220       while (base <= amt && power < sizeof suffixes - 1);
 221
 222       *--p = suffixes[power];
 223
 224       if (amt < 10)
 225         {
 226           if (2 * (1 - (int) inexact_style)
 227               < rounding + (tenths & (inexact_style == human_round_to_even)))
 228             {
 229               tenths++;
 230               rounding = 0;
 231
 232               if (tenths == 10)
 233                 {
 234                   amt++;
 235                   tenths = 0;
 236                 }
 237             }
 238
 239           if (amt < 10)
 240             {
 241               *--p = '0' + tenths;
 242               *--p = '.';
 243               tenths = rounding = 0;
 244             }
 245         }
 246     }
 247
 248   if (inexact_style == human_ceiling
 249       ? 0 < tenths + rounding
 250       : inexact_style == human_round_to_even
 251       ? 5 < tenths + (2 < rounding + (amt & 1))
 252       : /* inexact_style == human_floor */ 0)
 253     {
 254       amt++;
 255
 256       if (amt == base && power < sizeof suffixes - 1)
 257         {
 258           *p = suffixes[power + 1];
 259           *--p = '0';
 260           *--p = '.';
 261           amt = 1;
 262         }
 263     }
 264
 265   do
 266     *--p = '0' + (int) (amt % 10);
 267   while ((amt /= 10) != 0);
 268
 269   return p;
 270 }
 271
 272
 273 /* The default block size used for output.  This number may change in
 274    the future as disks get larger.  */
 275 #ifndef DEFAULT_BLOCK_SIZE
 276 # define DEFAULT_BLOCK_SIZE 1024
 277 #endif
 278
 279 static char const *const block_size_args[] = { "human-readable", "si", 0 };
 280 static int const block_size_types[] = { -1024, -1000 };
 281
 282 static int
 283 default_block_size (void)
 284 {
 285   return getenv ("POSIXLY_CORRECT") ? 512 : DEFAULT_BLOCK_SIZE;
 286 }
 287
 288 static strtol_error
 289 humblock (char const *spec, int *block_size)
 290 {
 291   int i;
 292
 293   if (! spec && ! (spec = getenv ("BLOCK_SIZE")))
 294     *block_size = default_block_size ();
 295   else if (0 <= (i = ARGMATCH (spec, block_size_args, block_size_types)))
 296     *block_size = block_size_types[i];
 297   else
 298     {
 299       char *ptr;
 300       unsigned long val;
 301       strtol_error e = xstrtoul (spec, &ptr, 0, &val, "eEgGkKmMpPtTyYzZ0");
 302       if (e != LONGINT_OK)
 303         return e;
 304       if (*ptr)
 305         return LONGINT_INVALID_SUFFIX_CHAR;
 306       if ((int) val < 0 || val != (int) val)
 307         return LONGINT_OVERFLOW;
 308       *block_size = (int) val;
 309     }
 310
 311   return LONGINT_OK;
 312 }
 313
 314 void
 315 human_block_size (char const *spec, int report_errors, int *block_size)
 316 {
 317   strtol_error e = humblock (spec, block_size);
 318   if (*block_size == 0)
 319     {
 320       *block_size = default_block_size ();
 321       e = LONGINT_INVALID;
 322     }
 323   if (e != LONGINT_OK && report_errors)
 324     STRTOL_FATAL_ERROR (spec, _("block size"), e);
 325 }