[buildd-tools-devel] Recent changes

[Roger Leigh]

I committed two large changes into sbuild.git today:

1) Exception handling.  The build code now uses exceptions to
   propagate errors, making the code somewhat cleaner and more
   robust.  Currently there is a set of top-level handlers in
   run() functions which cascade down on failure and run all
   cleanup actions.  This replaces the use of a set of precisely-
   ordered gotos which had to be jumped to in the correct order or
   else cleanup didn't work.  Now it all nests cleanly so if you
   throw an exception at any point it will be trapped and trigger all
   the cleanup needed as control passes back up the call stack.  As
   exception support is added to more of the code, any fatal error
   will just throw an exception and it will trigger all the correct
   cleanup actions.

2) sbuild user and privilege separation.  A wrapper, sbuild-schroot,
   is used to invoke schroot as the "sbuild" system user.  Builds now
   use the sbuild user, and all files in the build environment are
   owned by sbuild:sbuild.  This is the first stage of removing direct
   access to the chroot by the user invoking sbuild, mainly to
   eventually remove all root access to the chroot from users, for
   security and preventing tampering.  The rest of the job is for
   another day though--it will require splitting sbuild into two parts
   to run in different user and sbuild contexts, and is a much larger
   job.

Changes on my current TODO list for the next day or so:

- log filtering; filter out build-specific paths e.g. replacing
  /build/rleigh-dadadodo_1.04-3.1-amd64-xubcGh
  with /dadadodo to reduce the noise when diffing build logs,
  and to make them more readable.
- reduce path length of build dir.  Can cause issues on some arches,
  particularly WRT SYSV shm/sem.  Since we have a random part in
  /build/rleigh-dadadodo_1.04-3.1-amd64-xubcGh we could remove some
  of the extra information and reduce it e.g. to
  /build/dadadodo-xubcGh (or even just /build/xubcGh since the
  actual dadadodo build dir is inside).
- improve SIGTERM error handling.  Currently does some rather
  complex stuff and does not clean up the chroot.  Now we have
  exception support, we can just set an abort flag in the build
  object and kill dpkg-buildpackage if running, and have a
  function in the build object to poll the flag and throw an
  exception if set.  This will make it run all the usual cleanup so
  hitting ctrl-c won't require cleaning up the mess left in the
  chroot with e.g. debfoster.
- more user-friendly documentation.  Probably the hardest task!
  Any pointers as to what's difficult when setting up and using
  sbuild/schroot as a beginner would be appreciated!
- re-enable version checks after package unpack (currently parses
  debian/changelog but then doesn't use the information!)
- Apt and Aptitude resolvers don't need to use Dpkg::Deps; now in
  ResolverBase.
- Continue working on the db schema.  My latest work is on importing
  the current archive state from the InRelease file down to the sources
  and packages files, all with gpg verification from archive keys
  stored in the db.  I'll push this onto a git branch once it's fit
  for public consumption.
- Completely drop WannaBuild given that it's been in a separate
  repo for some time now?


As always, comments appreciated, as are wishlist bug reports for any
feature requests.


Regards,
Roger

-- 
  .''`.  Roger Leigh
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