[SOLVED] Unable to access x11-utils in snap

snapcraft
1

I’m creating an Electron app that calls out to xprops to gather information from the WM.

I’ve included x11-utils in stage-packages. I’ve tried to add -usr/bin/xprop to app.stage, and I’ve tried to add a bind / symlink in layouts from /usr/bin/xprop to $SNAP/usr/bin/xprop.

Nothing works - the Node.js code in Electron is saying “spawn xprop ENOENT”, which means xprop isn’t found. I’ve looked in /usr/bin at runtime and it’s just not there.

My snapcraft.yaml is here: https://pastebin.com/27MJyE7j

Any help would be appreciated!

2

Hi,

I’m new here so I hope I’m not saying anything stupid but:

  1. How do you “call out to xprops” in your Electron app?
  2. How do you “look in /usr/bin at runtime”?
  3. I don’t see a layout in your snapcraft.yaml file:
    layout:
    /usr/bin/xprops:
        bind-file: $SNAP/usr/bin/xprops
3

Thanks Dimitri.

  1. We use child_process.execFile. I’ve tried with exec() as well

  2. child_process.exec("ls -l /usr/bin/x*", ...). With bind-file, it outputs:

    lrwxrwxrwx 1 root root 7 Apr 9 11:46 /usr/bin/x86_64 -> setarch
    -rwxr-xr-x 1 root root 71896 Nov 5 2017 /usr/bin/xargs
    -rwxr-xr-x 1 root root 38 Mar 10 22:46 /usr/bin/xdg-open
    -rwxr-xr-x 1 root root 886 Mar 10 22:46 /usr/bin/xdg-settings
    -rwxr-xr-x 1 root root 0 Apr 9 11:49 /usr/bin/xprop
    -rwxr-xr-x 1 root root 18552 Jun 6 2019 /usr/bin/xxd

With symlinks, I get instead:

lrwxrwxrwx 1 root root    30 Apr  9 11:54 /usr/bin/xprop -> /snap/tandem/x15/usr/bin/xprop
  1. I’ve tried bind, symlink, and bind-file in the layouts section, they all do something but none of them seem to work.
4

-rwxr-xr-x 1 root root 0 Apr 9 11:49 /usr/bin/xprop

Isn’t the size of the file 0?

-rwxr-xr-x 1 root root 38 Mar 10 22:46 /usr/bin/xdg-open

The size of xdg-open is suspiciously small too.

5

Yeah, I don’t think it exists in $SNAP/usr/bin - seems like maybe the stage-packages process isn’t working properly?

6

Yes, this seems wrong. The xprops file should be visible as /snap/tandem/current/usr/bin/xprops. What if you run ls /snap/tandem/current/usr/bin/xprops from the command line?

7

Hmm… /snap/tandem/current/usr/bin doesn’t exist, either from within the app, or on my file system.

8

Whatever directory the snap is installed into. On which system do you install the snap?

9

I’m using Ubuntu 18 for development and testing. The app works fine outside of the snap, and via other distribution methods (e.g. deb, AppImage).

Should /snap/tandem/current/usr/bin exist? only usr/lib exists.

10

You’re trying to run /usr/bin/xprop. It must be made available in the snap, typically like the following:

layout:
    /usr/bin/xprop:
        bind-file: $SNAP/usr/bin/xprop

In the above case xprop is expected in $SNAP/usr/bin/xprop → /snap/tandem/current/usr/bin/xprop. However xprop could be stored elsewehere for example in $SNAP/lib/alternative/location/xprop → /snap/tandem/current/lib/alternative/location/xprop:

layout:
    /usr/bin/xprop:
        bind-file: $SNAP/lib/alternative/location/xprop

Now you have added xprop by including x11-utils in stage-packages, so I would expect xprop to have been installed as $SNAP/usr/bin/xprop.

11

The problem is that you add some stuff with stage-packages and then remove most of it under stage.

For example you remove all of $SNAP/usr/bin:

    stage:
      [...]
      - -usr/bin
      [...]

My guess is that you have misunderstood the the meaning of the initial - (dash). The syntax of stage is similar to the syntax of filesets. I suggest you remove stage completely - and put it back later on if really needed.

12

Amazing! I was able to get it working after that. Had no clue that the - would strip that folder. Thank you Dimitri