Re: [PATCH v2] i2c-tools: Allow passing device file paths

["Gero Schwäricke" <gero.schwaericke@sevenlab.de>]

Hi Brigham,

On Thu Mar 12, 2026 at 9:18 AM CET, Brigham Campbell wrote:
> I've tested these changes using i2cdetect, i2cget, and i2cset. However,
> I still consider this v2 a work-in-progress. In particular, I don't like
> that the code copies the path from argv into filename for two reasons:
> 1.  It's needless and 2. it introduces another potential edge case in
> the case that the user passes in a path longer than PATH_MAX.
>
> I'm looking for comments and feedback. I'm interested to know whether or
> not you maintainers believe I'm on the right track with these changes
> and what you might suggest. I sense that some slightly more invasive
> changes may help clean up the code.

I see that you're struggling to find a good way to pass the device
information between lookup_i2c_bus() and open_i2c_dev(). How about we
lookup and open the device in one go? Exit paths will have to close the
file, but the rest should stay the same. It's worth to take a look at
how libgpio does the same, see gpiod_chip_open_lookup().

Also, to keep things backward compatible, we should presumably do the
path lookup only after bus number parsing and bus name lookup failed.

Symlink support would be welcome as well.

Best,
Gero


-- 


sevenlab engineering GmbH <https://sevenlab.de>
serious engineering.

Geschäftsführer: Christian J. Pereira
Amtsgericht Köln, HRB 121730
Anschrift: Hansaring 20, 50670 Köln