[PATCH] lseek: ensure errno is set on failure and return -1

[Sascha Hauer]

On Sat, Feb 25, 2017 at 09:14:34PM +0100, Uwe Kleine-König wrote:
> Hello Sascha,
> 
> On Fri, Feb 24, 2017 at 08:45:13AM +0100, Sascha Hauer wrote:
> > On Thu, Feb 23, 2017 at 10:28:41PM +0100, Uwe Kleine-König wrote:
> > > All error paths before calling the driver's lseek callback return -1 and
> > > set errno. Do the same if the callback returns an error.
> > > 
> > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig at pengutronix.de>
> > > ---
> > >  fs/fs.c | 8 +++++++-
> > >  1 file changed, 7 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/fs/fs.c b/fs/fs.c
> > > index 2b4659cfbb76..e7b696591433 100644
> > > --- a/fs/fs.c
> > > +++ b/fs/fs.c
> > > @@ -926,7 +926,13 @@ loff_t lseek(int fildes, loff_t offset, int whence)
> > >  		goto out;
> > >  	}
> > >  
> > > -	return fsdrv->lseek(&f->fsdev->dev, f, pos);
> > > +	pos = fsdrv->lseek(&f->fsdev->dev, f, pos);
> > > +	if (pos < 0) {
> > > +		errno = -pos;
> > > +		return -1;
> > > +	}
> > 
> > Before calling into the drivers lseek checks if the position is within
> > the bounds of the file. So when fsdrv->lseek() returns successfully then
> > the position must be the same that was passed in. I think we can just
> > let fsdrv->lseek() return an error code rather than the file position.
> 
> This is a separate and orthogonal change however that doesn't make my
> patch wrong.

Right. Applied.

Sascha


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