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

[Sascha Hauer]

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 at 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 at 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 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.

Sascha

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