Incorrect behavior in df -P

[Toby Murray]

So I was hunting down a problem in cacti on a BSD server that didn't
happen on my linux cacti installation when I came across a difference
in the BSD and GNU versions of df and if I'm reading things correctly
I believe the GNU version is in error. Even comparing the actual
behavior to the man page seems to indicate a problem. So here is the
bug:

The -P option uses a block size of 1024 when it should be using 512
unless the block size is explicitly given. From the man page:

     -P     Output  in  six  columns, with heading `Filesystem N-blocks Used
             Available Capacity Mounted on' (with N=512, but N=1024 when  the
             -k option is given).

But when you run "df -P" the output says:
Filesystem         1024-blocks      Used Available Capacity Mounted on
/dev/hda3             76069416  37835316  38234100      50% /

In BSD it correctly uses a 512 block size.

This is evidently a long-standing bug because cacti is using the -P
option but expects 1024 block size to be returned. When df is
"correct" this of course causes cacti to report twice the actual size
of the disks.

I noticed the problem on my gentoo linux box with version 5.94-r1 of
the "coreutils" package. I have also verified that the behavior is the
same on Ubuntu with version 5.93.

Thanks,
Toby Murray