lib/fileblocks.c

   1 /* Convert file size to number of blocks on System V-like machines.
   2    Copyright (C) 1990, 1997 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 /* Written by Brian L. Matthews, blm@6sceng.UUCP. */
  19 \f
  20 #ifdef HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 #if !HAVE_ST_BLOCKS && !defined _POSIX_SOURCE && defined BSIZE
  25 # include <sys/types.h>
  26 # include <sys/param.h>
  27
  28 # if HAVE_UNISTD_H
  29 #  include <unistd.h>
  30 # endif
  31
  32 # ifndef NINDIR
  33 /* Some SysV's, like Irix, seem to lack this.  Hope it's correct. */
  34 /* Number of inode pointers per indirect block. */
  35 #  define NINDIR (BSIZE/sizeof(daddr_t))
  36 # endif /* !NINDIR */
  37
  38 /* Number of direct block addresses in an inode. */
  39 # define NDIR   10
  40
  41 /* Return the number of 512-byte blocks in a file of SIZE bytes. */
  42
  43 off_t
  44 st_blocks (size)
  45      off_t size;
  46 {
  47   off_t datablks = size / 512 + (size % 512 != 0);
  48   off_t indrblks = 0;
  49
  50   if (datablks > NDIR)
  51     {
  52       indrblks = (datablks - NDIR - 1) / NINDIR + 1;
  53
  54       if (datablks > NDIR + NINDIR)
  55         {
  56           indrblks += (datablks - NDIR - NINDIR - 1) / (NINDIR * NINDIR) + 1;
  57
  58           if (datablks > NDIR + NINDIR + NINDIR * NINDIR)
  59             indrblks++;
  60         }
  61     }
  62
  63   return datablks + indrblks;
  64 }
  65 #else
  66 /* This declaration is solely to ensure that after preprocessing
  67    this file is never empty.  */
  68 extern int textutils_fileblocks_unused;
  69 #endif