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

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

[Uwe Kleine-König]

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@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;
+	}
+
+	return pos;
 
 out:
 	if (ret)
-- 
2.11.0


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

[Sascha Hauer]

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@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.

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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

[Uwe Kleine-König]

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@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.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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Re: [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@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


-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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