[PATCH 0/6] loose-object fsck fixes/tightening

[Jeff King <peff@peff.net>]

On Fri, Jan 13, 2017 at 04:15:42AM -0500, John Szakmeister wrote:

> > I did notice another interesting case when looking at this. Fsck ends up
> > in fsck_loose(), which has the sha1 and path of the loose object. It
> > passes the sha1 to fsck_sha1(), and ignores the path entirely!
> >
> > So if you have a duplicate copy of the object in a pack, we'd actually
> > find and check the duplicate. This can happen, e.g., if you had a loose
> > object and fetched a thin-pack which made a copy of the loose object to
> > complete the pack).
> >
> > Probably fsck_loose() should be more picky about making sure we are
> > reading the data from the loose version we found.
> 
> Interesting find!  Thanks for the information Peff!

So I figured I would knock this out as a fun morning exercise. But
sheesh, it turned out to be a slog, because most of the functions rely
on map_sha1_file() to convert the sha1 to an object path at the lowest
level.

But I finally got something working, so here it is. I found another bug
on the way, along with a few cleanups. And then I did the trailing
garbage detection at the end, because by that point I knew right where
it needed to go. :)

  [1/6]: t1450: refactor loose-object removal
  [2/6]: sha1_file: fix error message for alternate objects
  [3/6]: t1450: test fsck of packed objects
  [4/6]: sha1_file: add read_loose_object() function
  [5/6]: fsck: parse loose object paths directly
  [6/6]: fsck: detect trailing garbage in all object types

 builtin/fsck.c  |  46 +++++++++++----
 cache.h         |  13 ++++
 sha1_file.c     | 180 +++++++++++++++++++++++++++++++++++++++++++++++++++-----
 t/t1450-fsck.sh |  86 +++++++++++++++++++++++----
 4 files changed, 284 insertions(+), 41 deletions(-)

-Peff