How to create content interface that shares a C-level library

snapcraft
1

Hey,

the documentation for content interfaces lists sharing C-level library as TBD. So, how to create such as interface, is it even possible or still needs implementation on snapd/snapcraft side?

Thanks,
K

1 Like
2

I can’t find information on this either.
For example, I wonder where are the header files supposed to be stored? From one side, they are not going to be inside snap - headers useless on target. From other, .h and the .so files should be tied together somehow, since .h corresponds to particular version of the library

3

I’m still working on this and still need some help in getting it fly.

I have used mir-libs-snap and mir-kiosk as the examples of producer and consumer respectively. Based on them I have following declarations:

producer:

slots:
  tpm2-libs:
    interface: content
    content: tpm2-libs
    read:
      - lib
      - usr/lib

consumer:

plugs:
  tpm2-libs:
    interface: content
    content: tpm2-libs
    target: $SNAP/tpm2-libs
    default-provider: tpm2-libs

Now, as I understand the documentation here are the rules:

  1. content must match between producer and consumer
  2. default-provider is important for auto-connection and should match the producer:slot
  3. target is where the “content” coming from producer will be mounted at the consumer side
  4. read is a path to expose, relative to /snap/$SNAP_NAME/current

However clearly I have something wrong because still whenever I try to use it I get:

/snap/tpm2-tools/x1/sbin/tpm2_listpcrs: error while loading shared
libraries: libtcti-socket.so.0: cannot open shared object file: No such
file or directory

For the reference the tpm2-tools snap that I use here for testing is basically the tmp2 snap without lib directory of tpm2-tss part being primed.

How can I debug this efficiently?

4

Also for the record, I’m running core v16-2.28.1

5

Have you adjusted the LD_LIBRARY_PATH environment variable to include your tpm2 library’s path as seen from the view of your consumer snap? e.g. have you included $SNAP/tpm2-libs in the list?