coreutils/lib/fileblocks.c

/* Convert file size to number of blocks on System V-like machines.
   Copyright (C) 1990 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

/* Written by Brian L. Matthews, blm@6sceng.UUCP. */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#if !defined (HAVE_ST_BLOCKS) && !defined(_POSIX_VERSION)
# include <sys/types.h>
# include <sys/param.h>

# ifndef NINDIR
/* Some SysV's, like Irix, seem to lack these.  Hope they're correct. */
/* Size of a indirect block, in bytes. */
#  ifndef BSIZE
#   define BSIZE 1024
#  endif

/* Number of inode pointers per indirect block. */
#  define NINDIR (BSIZE/sizeof(daddr_t))
# endif /* !NINDIR */

/* Number of direct block addresses in an inode. */
# define NDIR	10

/* Return the number of 512-byte blocks in a file of SIZE bytes. */

long
st_blocks (size)
     long size;
{
  long datablks = (size + 512 - 1) / 512;
  long indrblks = 0;

  if (datablks > NDIR)
    {
      indrblks = (datablks - NDIR - 1) / NINDIR + 1;

      if (datablks > NDIR + NINDIR)
	{
	  indrblks += (datablks - NDIR - NINDIR - 1) / (NINDIR * NINDIR) + 1;

	  if (datablks > NDIR + NINDIR + NINDIR * NINDIR)
	    indrblks++;
	}
    }

  return datablks + indrblks;
}
#else
/* This declaration is solely to ensure that after preprocessing
   this file is never empty.  */
extern int textutils_fileblocks_unused;
#endif