linux-kernel - Re: st_size of a symlink

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Message-ID: <20120723231333.GA1299@gaara.hadrons.org>
Date:	Tue, 24 Jul 2012 01:13:33 +0200
From:	Guillem Jover <guillem@...rons.org>
To:	Richard Weinberger <richard@....at>
Cc:	Jesper Juhl <jj@...osbits.net>, Al Viro <viro@...IV.linux.org.uk>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-fsdevel@...r.kernel.org, linux-man@...r.kernel.org
Subject: Re: st_size of a symlink

On Tue, 2012-07-24 at 00:07:48 +0200, Richard Weinberger wrote:
> On 23.07.2012 22:47, Jesper Juhl wrote:
> >>Fix it _how_?
> >
> >By returning the size as the number of bytes in the name the link is
> >currently pointing at.
> 
> This is not easy.
> procfs has no clue where the link pointing at.
> The information is generated while accessing the link.
> tmpfs on the other hand has this information because symlinks get
> only changed through tmpfs...

Well, can't the link be accessed when getting the stat information
then?

> >>  By retrying readlink() with bigger buffer.
> >>With procfs there's just a few more ways the readlink() output can
> >>change, that's all.
> >>
> >Still not a good reason to just return 0 IMHO.
> 
> IMHO the lstat() and readlink() manpages have to be more precise
> about st_size.

They document what POSIX says:

  <http://pubs.opengroup.org/onlinepubs/009695399/basedefs/sys/stat.h.html>

regards,
guillem
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