- [ ] Have you followed the [guidelines for contributing](https://github.com/snapcore/snapcraft/blob/master/CONTRIBUTING.md)? - [ ] Have you signed the [CLA](http://www.ubuntu.com/legal/contributors/)? - [ ] Have you successfully run `./runtests.sh static`? - [ ] Have you successfully run `./runtests.sh tests/unit`? ----- This is still a work in progress, and somewhat duplicates the current `ldd` based dependency checking code. It is currently not hooked up to anything, and I'm not quite sure where it would make most sense to run the check. With a single pass over all files in the snap, it performs the following checks: 1. check for unused shared libraries, using the non-libraries as a starting point and recursively following dependencies. 2. check that all dependencies in the set of used elf files are met by either the snap itself or its base. This includes checking that required symbol versions are defined (e.g. to catch executables requiring newer glibc). 3. check whether libraries in the snap duplicate those in the base snap. We only generate a warning if the library from the base snap defines all the symbol versions required by the elf files in the snap. For (1), I'm defining non-libraries as ELF files without a soname. I intended this to cover both executables and "plugin" type shared object files. Unfortunately my testing showed up a number of cases where plugins have sonames, so perhaps it needs to take the file path into account too. Here is an example of the current output: ``` >>> from snapcraft.internal import elf >>> dep = elf.DependencyChecker() >>> dep.add_base_libs('/snap/core18/current') >>> for w in dep.check('/snap/lxd/current'): print(w) ... library lib/liblxcfs.so in snap is unused library lib/libmnl.so.0.2.0 in snap duplicates /snap/core18/current/lib/x86_64-linux-gnu/libmnl.so.0.2.0 from base snap library lib/libseccomp.so.2.5.1 in snap duplicates /snap/core18/current/lib/x86_64-linux-gnu/libseccomp.so.2.4.3 from base snap library lib/libsqlite3.so.0.8.6 in snap duplicates /snap/core18/current/usr/lib/x86_64-linux-gnu/libsqlite3.so.0.8.6 from base snap library lib/x86_64-linux-gnu/ceph/compressor/libceph_snappy.so.2.0.0 in snap is unused library lib/x86_64-linux-gnu/ceph/compressor/libceph_zlib.so.2.0.0 in snap is unused library lib/x86_64-linux-gnu/ceph/compressor/libceph_zstd.so.2.0.0 in snap is unused library lib/x86_64-linux-gnu/ceph/crypto/libceph_crypto_isal.so.1.0.0 in snap is unused library lib/x86_64-linux-gnu/device-mapper/libdevmapper-event-lvm2mirror.so in snap is unused library lib/x86_64-linux-gnu/device-mapper/libdevmapper-event-lvm2raid.so in snap is unused library lib/x86_64-linux-gnu/device-mapper/libdevmapper-event-lvm2snapshot.so in snap is unused library lib/x86_64-linux-gnu/device-mapper/libdevmapper-event-lvm2thin.so in snap is unused library lib/x86_64-linux-gnu/libdb-5.3.so in snap duplicates /snap/core18/current/usr/lib/x86_64-linux-gnu/libdb-5.3.so from base snap library lib/x86_64-linux-gnu/libdevmapper-event-lvm2.so.2.02 in snap is unused library lib/x86_64-linux-gnu/liblvm2app.so.2.2 in snap is unused library lib/x86_64-linux-gnu/liblvm2cmd.so.2.02 in snap is unused library lib/x86_64-linux-gnu/libsnappy.so.1.1.7 in snap is unused library lib/x86_64-linux-gnu/libusbredirhost.so.1.0.0 in snap is unused library lib/x86_64-linux-gnu/nss/libfreeblpriv3.so in snap is unused library lib/x86_64-linux-gnu/nss/libsoftokn3.so in snap is unused library libebt_802_3.so required by bin/ebtables is missing library libebt_among.so required by bin/ebtables is missing library libebt_arp.so required by bin/ebtables is missing library libebt_arpreply.so required by bin/ebtables is missing library libebt_ip.so required by bin/ebtables is missing library libebt_ip6.so required by bin/ebtables is missing library libebt_limit.so required by bin/ebtables is missing library libebt_log.so required by bin/ebtables is missing library libebt_mark.so required by bin/ebtables is missing library libebt_mark_m.so required by bin/ebtables is missing library libebt_nat.so required by bin/ebtables is missing library libebt_nflog.so required by bin/ebtables is missing library libebt_pkttype.so required by bin/ebtables is missing library libebt_redirect.so required by bin/ebtables is missing library libebt_standard.so required by bin/ebtables is missing library libebt_stp.so required by bin/ebtables is missing library libebt_ulog.so required by bin/ebtables is missing library libebt_vlan.so required by bin/ebtables is missing library libebtable_broute.so required by bin/ebtables is missing library libebtable_filter.so required by bin/ebtables is missing library libebtable_nat.so required by bin/ebtables is missing library zfs-2.0/lib/libzfsbootenv.so.1.0.0 in snap is unused library zfs-2.0/lib/libzpool.so.4.0.0 in snap is unused ``` While this shows up a few libraries that could be removed from the snap, there it also exposes a few problems with the checks: * the ceph and device-mapper plugins are listed as unused libraries, which has knock-on effects for other libraries in the snap. They should be treated as non-libraries despite having a soname. * the `libebt_*.so` libraries are reported as missing. It turns out the files exist but have no soname set so were incorrectly excluded from the library set. So perhaps doing a path based check is a better approach for distinguishing libraries from executables/plugins. Perhaps checking that the file's dirname ends with `/lib` or `/lib/${any_arch_triplet}` would be appropriate?