Re: [vox-tech] files with holes in them

[Peter Jay Salzman <p@bMAPSelial.ucdavis.edu>]

i'm not sure i follow.

so du -k returns allocated disk space in kilobyte blocks.

10000.003 kb of data can't fit in 24 kb of allocated disk space.  what am
i missing?

if anything, i'd expect st_blocks (in kb) >= st_size (in kb).

pete


On Fri, 17 Nov 2000 jdnewmil@dcn.davis.ca.us wrote:

> On Fri, 17 Nov 2000, Peter Jay Salzman wrote:
> 
> > i was playing around with creating files with holes in them:
> > 
> >     % ls -l holy_file
> >     -rw-------    1 p        p        10000003 Nov 17 19:59 holy_file
> > 
> >     % du -k holy_file
> >     24      holy_file
> > 
> > the program i wrote to generate this file looks more or less like:
> > 
> >     if((fd = open("holy_file", O_WRONLY|O_CREAT)) < 0)
> >             exit(0);
> > 
> >     write(fd, string1, strlen(string1));
> >     lseek(fd, 99999, SEEK_SET);
> >     write(fd, string2, strlen(string2));
> > 
> > ls gets its info from stat.  i did an strace on du, and it also calls stat.
> > i'm curious about the discrepency in file size.  does anyone know why the
> > two programs report different file sizes?
> 
> Because by design du looks at allocated disk space, and ls looks at the
> recorded file size.  From "man stat", I gather the former comes from
> st_blocks and the latter comes from st_size.