Re: [libgpiod v2][PATCH] misc: make gpiod_is_gpiochip_device() not set errno

[Kent Gibson <warthog618@xxxxxxxxx>]

On Fri, Jul 01, 2022 at 01:50:46PM +0200, Bartosz Golaszewski wrote:
> On Fri, Jul 1, 2022 at 1:43 PM Kent Gibson <warthog618@xxxxxxxxx> wrote:
> >
> > On Fri, Jul 01, 2022 at 01:00:56PM +0200, Bartosz Golaszewski wrote:
> > > This function should just report whether the file indicated by path is
> > > a GPIO chip or not. Let's rework it to not set errno. Failure to open a
> > > chip should still report errro numbers like before.
> > >
> >
> > This is will break my tool patch, for sure.
> > My gpiodetect uses the errno behaviour to give a clue as to why a chip
> > might not be available to a user, and that work was already done in
> > gpiod_is_gpiochip_device().
> > There might be other places the errno was propagated as well, but
> > whatever, I'll sort something out.
> >
> 
> Doesn't it make more sense to call gpiod_is_gpiochip_device() and then
> if it returns true, just try to open it and then report failure?
> 

Not for the case where the chip doesn't exist -
gpiod_is_gpiochip_device() has already worked that out.

But don't worry - I'll sort something out.

Cheers,
Kent.