[uClibc]fseek(3) idempotency

[Matt Kraai]

On Mon, Sep 24, 2001 at 10:03:03AM -0600, Manuel Novoa III wrote:
> Matt,
> 
> On Mon, Sep 24, 2001 at 09:25:31AM -0600, Matt Kraai wrote:
> > The uClibc fseek(3) implementation clears the readahead buffer
> > before calling lseek(2).  If lseek(2) fails (e.g., it is called on
> > a pipe), the position is now off.
> 
> In my interpretation of the standards, if fseek() fails the error
> indicator for the stream is set and the associated file offset is
> undefined.  What's the problem?
> 
> >                 The following patch only resets
> > the readahead buffer if the lseek(2) call succeeds.
> 
> It looks to me like you're trying to deal with an application bug
> by introducing implementation-defined behavior to uClibc.

According to SUSv2,

	The behaviour of fseek() on devices which are incapable of
	seeking is implementation-dependent.

How can you determine if a device supports seeking?

Matt