[yocto] Set linux capabilities on binary on a recipe in meta-oe layer

[Uwe Geuder]

On Mon, Nov 12, 2018 at 3:09 PM Markus W markus4dev-at-gmail.com wrote:
>
> Thanks Uwe!
>
> I tried the global approach by adding the following to my local.conf file:
>
> ROOTFS_POSTPROCESS_COMMAND += "my_setcap_function"
>
> my_setcap_function() {
>     setcap cap_net_raw+eip ${IMAGE_ROOTFS}/usr/bin/node
> }
>
> But got the following warning:
> WARNING: core-image-full-cmdline-1.0-r0 do_rootfs: Function my_setcap_function doesn't exist
>
> I have tried to add the function into a recipe but this doesn't work either. Where should the function be defined?
>

As I wrote

>> This is done in your image recipe.

At least this is where I do it and it works for me.

My use of "global" was probably not so lucky, I did not mean bitbake
configuration.  I just meant that it is done in the image recipe and not
in the node recipe.

You can always use "bitbake -e" to check variable and recipe function
definitions if you are wondering what is really going on. I often
understand problems when looking at the listing produced by this
command. In your case "bitbake -e core-image-full-cmdline"

There are also other functions in the value of ROOTFS_POSTPROCESS_COMMAND so as


On Tue, Nov 13, 2018 at 4:09 AM Mike Looijmans mike.looijmans-at-topic.nl wrote:
>
> Also, there's a semicolon missing:
> ROOTFS_POSTPROCESS_COMMAND += "my_setcap_function;"
>

The final value of ROOTFS_POSTPROCESS_COMMAND as shown by "bitbake -e"
should be list of function names separated by semicolons.

My previous link was broken, hopefully this time it survives intact...

https://www.yoctoproject.org/docs/2.5.1/mega-manual/mega-manual.html#var-ROOTFS_POSTPROCESS_COMMAND

> Sometimes the problem is that parts of the underscored function name are seen
> as overrides, so you should try using "mysetcapfunction" instead as a name.
>

That has never happened to me and I use underscores in my function
names. But I could imagine that it's possible in some case. I would
strongly expect to see such issue in the output of "bitbake -e", too.


Regards,

Uwe Geuder
Neuro Event Labs Oy
Tampere, Finland
uwe.gexder at neuroeventlabs.com (Bot check: fix one obvious typo)