Use wiringPiSetupSys to avoid running as root

Question

Use wiringPiSetupSys to avoid running as root

RandScullard opened this issue 8 years ago · comments

I would love to be able to access the GPIO pins without root access, and apparently this is possible (at least in theory). According to this article: https://www.raspberrypi.org/forums/viewtopic.php?f=34&t=51265 the key is calling wiringPiSetupSys instead of wiringPiSetup. Would it be possible to have the raspi module work this way?

Bryan Hughes · Answer 1 · Wed Oct 26 2016 01:36:12 GMT+0800 (China Standard Time)

We could, but I'm against it for two reasons:

wiringPiSetypSys requires that the gpio interfaces be exported prior to the application starts...which is an operation that requires root privileges. Requiring that users do an operation by hand before using raspi-io is going to create a lot of confusion. My goal with raspi-io is for it to be as plug and play as possible, and wiringPiSetypSys goes against that.
This changes the pin numbering scheme and would require some architectural changes in raspi-io and raspi-board, and would also be a breaking change for everyone that uses raspi-io.

Does that make sense?

Rand Scullard · Answer 2 · Wed Oct 26 2016 02:09:39 GMT+0800 (China Standard Time)

I was thinking of it being an option, for exactly the reasons you stated. I agree that you definitely wouldn't want to change the current behavior for existing users of the module.

Bryan Hughes · Answer 3 · Wed Oct 26 2016 02:16:54 GMT+0800 (China Standard Time)

I was thinking of it being an option, for exactly the reasons you stated. I agree that you definitely wouldn't want to change the current behavior for existing users of the module.

🤔

Even as an option, there's still point number 2. Personally, I don't really want to implement it because I don't have much time I can dedicate to raspi-io these days, and this feature is a lot lower on my personal priority list than other things I want to implement (e.g. SPI, unit tests).

That said, this is a feature I wouldn't mind having if it were an option, and if someone (cough cough) were to submit a the necessary pull requests, I'd happily review it! Is this something you'd be interested in working on?

Rand Scullard · Answer 4 · Wed Oct 26 2016 02:29:19 GMT+0800 (China Standard Time)

I might be... I'm in the middle of a bunch of things right now, and by the time I'm done I may not care that I have to run these things as root. 😃

Bryan Hughes · Answer 5 · Sat Jun 03 2017 06:25:58 GMT+0800 (China Standard Time)

Raspi IO recently switched to using pigpio instead of Wiring Pi, so I'm going to go ahead and close this.

Rand Scullard · Answer 6 · Sat Jun 10 2017 21:59:49 GMT+0800 (China Standard Time)

@nebrius Can you explain briefly what drove your decision to move from Wiring Pi to pigpio? I have a project that currently uses Wiring Pi and I'm considering making the same move, so I'm very curious to know what your reasons were.

Bryan Hughes · Answer 7 · Tue Jun 13 2017 01:57:53 GMT+0800 (China Standard Time)

@RandScullard I don't know if this is the reason you're looking for, but check out nebrius/raspi-io#91.

tl;dr Wiring Pi in combination with some still unknown other factors flat out broke Raspi IO, and I was never able to figure out why, so I switched to pigpio so I could get Raspi IO functional again.

A nice side-effect though is that switching to pigpio allowed me to get rid of my own native build step, making Raspi IO 100% JavaScript.

Rand Scullard · Answer 8 · Tue Jun 13 2017 02:17:37 GMT+0800 (China Standard Time)

@nebrius Thanks for the info, I appreciate it!

I wonder if your issue nebrius/raspi-io#91 was caused by this: WiringPi/WiringPi-Node#70

I think I will go ahead and switch to pigpio as well, because of this issue as well as the apparent lack of active maintenance on WiringPi-Node.

Bryan Hughes · Answer 9 · Tue Jun 13 2017 03:14:50 GMT+0800 (China Standard Time)

Oh I remember that project, I briefly looked into it but decided maintaining my own native module was the better approach, although I can't remember exactly why off the top of my head.

EDIT: just in case in wasn't completely clear, Raspi IO did not use the WiringPi-Node project.

Rand Scullard · Answer 10 · Tue Jun 27 2017 05:04:01 GMT+0800 (China Standard Time)

Just in case anyone else can benefit from this info...

I looked into using pigpio for my own project, but then I realized that it requires root access, which I want to avoid (see above). This (finally) forced me to RTFM and understand how the /sys/class/gpio interface works, and I realized that I can just use file system APIs to read and write GPIO pins (no root access required). I threw together a simple wrapper module and dumped WiringPi-Node... which is what I should have done in the first place!

(Note that my project doesn't require anything fancy like PWM, just low-frequency reading and writing of GPIO pins.)

Bryan Hughes · Answer 11 · Tue Jun 27 2017 05:11:33 GMT+0800 (China Standard Time)

Thanks for the info, and I'm glad you figured out a workaround @RandScullard!