Re: [PATCH v2] leds: Introduce userspace leds driver

[David Lechner]

On 09/15/2016 09:54 AM, Jacek Anaszewski wrote:
> Hi Pavel,
>
> On 09/15/2016 03:01 PM, Pavel Machek wrote:
> > Hi!
> >
> > > > @@ -0,0 +1,23 @@
> > > > +/*
> > > > + * Userspace driver support for leds subsystem
> > > > + *
> > > > + * This program is free software; you can redistribute it and/or
> > > > modify
> > > > + * it under the terms of the GNU General Public License as
> > > > published by
> > > > + * the Free Software Foundation; either version 2 of the License, or
> > > > + * (at your option) any later version.
> > > > + *
> > > > + * This program is distributed in the hope that it will be useful,
> > > > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > > > + * GNU General Public License for more details.
> > > > + */
> > > > +#ifndef _UAPI__ULEDS_H_
> > > > +#define _UAPI__ULEDS_H_
> > > > +
> > > > +#define ULEDS_MAX_NAME_SIZE    80
> > > > +
> > > > +struct uleds_user_dev {
> > > > +    char name[ULEDS_MAX_NAME_SIZE];
> > > > +};
> >
> > We already have path component length limit somewhere, right? Just use
> > it?

As a matter of fact, in led_classdev_register(), the name is limited to 
64. This is hard-coded (no #define).

     char name[64];

The given name is truncated to this length in a call to 
led_classdev_next_name().

> > (And is struct with char array good idea at all? Perphaps it can just
> > use write() length up to something reasonable, and not bother with new
> > header file for userspace?)
>
> In fact in this case the addition of another public header can be
> avoided.