Review for Package: protobuf-c

[Summary]
MIR team ACK under the constraint to resolve the below listed
required TODOs and as much as possible having a look at the
recommended TODOs.

This does need a security review, so I'll assign ubuntu-security

List of specific binary packages to be promoted to main: protobuf-c-compiler
Specific binary packages built, but NOT to be promoted to main: libprotobuf-c1 (at least not needed for the current case, but should be ok to promote if needed later)

Notes:
- Needed in fwupd due to https://github.com/fwupd/fwupd/pull/3609

Required TODOs:
- please add a debian/watch file to help auto-detecting new versions
Recommended TODOs:
- consider adding an autopkgtest, at least running the self-tests in
  autopkgtest or better some use case using the lib/compiler
- have a look at the compiler warnings if we could help upstream to fix those

[Duplication]
This is rather interesting in this case, as there are many users and
implementations of protobuf in general. The "main" src:protobuf is the core
project and provides c++, python, ruby, java, ... bindings.
https://developers.google.com/protocol-buffers
But no "C" in that, so protobuf-c exists.
But TBH also several other projects. Of the 6 listed by upstream:
https://github.com/protocolbuffers/protobuf/blob/master/docs/third_party.md
Only two are packaged upb and protobuf-c, both in universe.
Also - as outlined in the report - formerly protobuf-c was in main.
So there is similarity, but no duplication problem here.

[Dependencies]
OK:
- no other Dependencies to MIR due to this

Problems: None

[Embedded sources and static linking]
OK:
- no embedded source present
- no static linking
- does not have odd Built-Using entries
- not a go package, no extra constraints to consider in that regard

Problems: None

[Security]
OK:
- history of CVEs does not look concerning
- does not run a daemon as root
- does not use webkit1,2
- does not use lib*v8 directly
- does not open a port/socket
- does not process arbitrary web content
- does not use centralized online accounts
- does not integrate arbitrary javascript into the desktop
- does not deal with system authentication (eg, pam), etc)
- does not deal with security attestation (secure boot, tpm, signatures)

Problems:
- does parse data formats

Depending on where it is used that could be from external sources.
Also the current reason for the MIR is the use to update firmware which usually
runs with high privilege, so being able to inject some protobuf data on the
download could then - if it breaks in the handling - cause quite some issues.
I think a security review is needed here.
Also confirmed by the fact that the more common lib "protobuf" also had a bunch
of CVEs in the past.

[Common blockers]
OK:
- does not FTBFS currently
- does have a test suite that runs at build time
  - test suite fails will fail the build upon error.
- if special HW does prevent build/autopkgtest is there a test plan, code,
  log provided?
- if a non-trivial test on this level does not make sense (the lib alone
  is only doing rather simple things), is the overall solution (app+libs)
  extensively covered i.e. via end to end autopkgtest ?
- no new python2 dependency

Problems:
- does not have a non-trivial test suite that runs as autopkgtest

[Packaging red flags]
OK:
- Ubuntu does not carry a delta
- symbols tracking is in place
- Upstream update history is slow but ok
- Debian/Ubuntu update history is as slow as upstream
- the current release is packaged
- promoting this does not seem to cause issues for MOTUs that so far
  maintained the package
- no massive Lintian warnings
- d/rules is rather clean
- It is not on the lto-disabled list

Problems:
- d/watch is present and looks ok (if needed, e.g. non-native)

[Upstream red flags]
RULE: flag common issues:
RULE: - if you see anything else odd, speak up and ask for clarification

OK:
- no incautious use of malloc/sprintf (as far as we can check it)
- no use of sudo, gksu, pkexec, or LD_LIBRARY_PATH (usage is OK inside
  tests)
- no use of user nobody
- no use of setuid
- no important open bugs (crashers, etc) in Debian or Ubuntu
- no dependency on webkit, qtwebkit, seed or libgoa-*
- not part of the UI for extra checks
- no translation present, but none needed for this case (user visible)?

Problems: None
- Errors/warnings during the build - nothing severe, but there are some
  -Wdeclaration-after-statement and -Wc99-c11-compat which we all know are
  informational now, but could be a problem later on.