Mounting new, empty filesystem on /tmp makes impossible to use mat2 for manipulating files stored there. Especially it breaks running tests while creating package and using /tmp as temporary builddir which is common setup in Arch Linux:
https://aur.archlinux.org/packages/mat2/#comment-721221
This mounts a new tmpfs on /tmp so any files residing there would be hidden
from the sandbox. Many programs store some files in there that might be useful
to an attacker. It also drops all capabilities incase it is ever run with
extra capabilities for whatever reason.
On some machines (like mine), `/proc` has to be mounted. Also, since
sandboxing with bubblewrap is best effort and assumes that an attacker doesn't
have control outside of the file to clean, it's safe to __try__ to enable some
bubblewrap features, and to silently fail otherwise.
This shouldn't make a big difference in the CLI/extension
usage, but might improve the performances of long-running
instances, or people misusing the API.
Rework the dependencies definition to include a 'required' flags, which
is passed by the check_dependencies helper to the callers, so that they
can distinguish between required and optional dependencies.
This help in two ways:
- The unit test for the dependencies was now failing when an optional
one was missing, due to a previous rework.
- Mat2's --check-dependencies was referring to "required dependencies"
and was misleading for the user as some of them could be optional.
Signed-off-by: Antoine Tenart <antoine.tenart@ack.tf>
