Re: size of files in /proc

C. Scott Ananian (
Wed, 20 May 1998 16:59:28 -0400 (EDT)

On Tue, 19 May 1998 (Ton Hospel) wrote:

> But even then I'd like /proc to report the unknown sizes as 1, not 0.
> Because I like to be able to export /proc over NFS, and NFS doesn't even
> bother to read the file if the size is 0.
> A(nother) possibility is to cache the size from last time the file contents got
> generated. For most files that should be in the right ballpark.

This is exactly the Wrong Thing To Do. A file size of zero indicates that
the file is special in some way. Trying to guess the "right" value and
missing is Much Worse -- you're actually giving wrong information and
creating situations where programs work "most of the time" -- except for
that time when the guess is very wrong and everything breaks.

NFS needs fixing, not /proc. A zero-sized file is the best way to say "I
don't know."

[Note that silly mmap implementations of (for example) cp may have
problems with zero-length files, as well. They would have the same
troubles with 'finite but wrong' sized files, except the bugs would be
much more subtle.]
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