Re: more fun with procfs (netfilter)

H. Peter Anvin (hpa@zytor.com)
19 Nov 2001 11:18:46 -0800

Followup to: <Pine.GSO.4.21.0111190419250.17210-100000@weyl.math.psu.edu>
By author: Alexander Viro <viro@math.psu.edu>
In newsgroup: linux.dev.kernel
>
> Some shells (pdksh 5.2.14-1, bash 2.04 as shipped by SuSE) are trying to be
> smart if stdin is from regular file - they hope that third argument of
> lseek() is in bytes and is consistent with read() return value.
>

Not just hope... they have a legitimate reason to expect that
guarantee from anything that advertises itself as S_IFREG. I really
think procfs files should advertise themselves as S_IFCHR if they
can't fully obey the semantics of S_IFREG files (including having a
working length in stat()!)

Such S_IFCHR devices can return 0 in st_rdev to signal userspace that
this is a device node keyed by special filesystem semantics rather
than by device number.

-hpa

-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
http://www.zytor.com/~hpa/puzzle.txt	<amsp@zytor.com>
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