lib/fileblocks.c

   1 /* Convert file size to number of blocks on System V-like machines.
   2
   3    Copyright (C) 1990, 1997-1999, 2004-2006, 2009-2024 Free Software
   4    Foundation, Inc.
   5
   6    This program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation, either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  18
  19 /* Written by Brian L. Matthews, blm@6sceng.UUCP. */
  20
  21 #include <config.h>
  22
  23 #include <sys/types.h>
  24
  25 #if HAVE_SYS_PARAM_H
  26 # include <sys/param.h>
  27 #endif
  28
  29 #if !HAVE_STRUCT_STAT_ST_BLOCKS && !defined _POSIX_SOURCE && defined BSIZE
  30
  31 # include <unistd.h>
  32
  33 # ifndef NINDIR
  34
  35 #  if defined __DJGPP__
  36 typedef long daddr_t; /* for disk address */
  37 #  endif
  38
  39 /* Some SysV's, like Irix, seem to lack this.  Hope it's correct. */
  40 /* Number of inode pointers per indirect block. */
  41 #  define NINDIR (BSIZE / sizeof (daddr_t))
  42 # endif /* !NINDIR */
  43
  44 /* Number of direct block addresses in an inode. */
  45 # define NDIR   10
  46
  47 /* Return the number of 512-byte blocks in a file of SIZE bytes. */
  48
  49 off_t
  50 st_blocks (off_t size)
  51 {
  52   off_t datablks = size / 512 + (size % 512 != 0);
  53   off_t indrblks = 0;
  54
  55   if (datablks > NDIR)
  56     {
  57       indrblks = (datablks - NDIR - 1) / NINDIR + 1;
  58
  59       if (datablks > NDIR + NINDIR)
  60         {
  61           indrblks += (datablks - NDIR - NINDIR - 1) / (NINDIR * NINDIR) + 1;
  62
  63           if (datablks > NDIR + NINDIR + NINDIR * NINDIR)
  64             indrblks++;
  65         }
  66     }
  67
  68   return datablks + indrblks;
  69 }
  70 #else
  71 /* This declaration is solely to ensure that after preprocessing
  72    this file is never empty.  */
  73 typedef int textutils_fileblocks_unused;
  74 #endif