Re: [PATCH v2] param: add error check to __dev_add_param()

[Masahiro Yamada <yamada.m@jp.panasonic.com>]

Hi Sascha,

On Thu, 29 Jan 2015 10:32:12 +0100
Sascha Hauer <s.hauer@pengutronix.de> wrote:

> On Thu, Jan 29, 2015 at 06:21:39PM +0900, Masahiro Yamada wrote:
> > Hi Sascha,
> > 
> > On Thu, 29 Jan 2015 10:06:22 +0100
> > Sascha Hauer <s.hauer@pengutronix.de> wrote:
> > 
> > > On Thu, Jan 29, 2015 at 11:46:53AM +0900, Masahiro Yamada wrote:
> > > > If the argument, name is given with NULL, it would be probably
> > > > unexpected behavior.  It should fail rather than register the
> > > > NULL-named parameter.
> > > > 
> > > > If strdup() fails with out-of-memory, it should also fail
> > > > with -ENOMEM.
> > > > 
> > > > Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
> > > > ---
> > > > 
> > > > Changes in v2:
> > > >   - Fix the condition of returning -ENOMEM
> > > > 
> > > >  lib/parameter.c | 8 +++++++-
> > > >  1 file changed, 7 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git a/lib/parameter.c b/lib/parameter.c
> > > > index 71262c4..02a89bb 100644
> > > > --- a/lib/parameter.c
> > > > +++ b/lib/parameter.c
> > > > @@ -130,6 +130,13 @@ static int __dev_add_param(struct param_d *param, struct device_d *dev, const ch
> > > >  	if (get_param_by_name(dev, name))
> > > >  		return -EEXIST;
> > > >  
> > > > +	if (!name)
> > > > +		return -EINVAL;
> > > 
> > > Name is used already two lines above so barebox will already be crashed
> > > before this triggers.
> > > 
> > > Besides, I normally don't like these checks. dereferencing NULL pointers
> > > means you get a backtrace showing you what went wrong. Returning an error
> > > means adding code which in this case makes dev_add_param just fail
> > > silently because the return value often is not checked.
> > > 
> > 
> > OK, then how about dropping this -EINVAL check?
> 
> Yes, please.


I did that in v3.


> > 
> > I think the -ENOMEM check below is still useful.
> > ( strdup() returns NULL also when NULL is passed,
> > but in that case this line cannot be reached.
> > The problem is that is not apparent at a glance..)
> 
> Note we also have xstrdup which crashes barebox on out of memory. This
> is usually the right thing to do when it's known that the allocation is
> small.
> 

I stopped and I have been thinking about it.
I hesitate a bit to replace it with xstrdup().  I feel like being lazy.

So, I did not do this in v3.



Best Regards
Masahiro Yamada


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