Hi,
While working on deploying layered commit-graphs at GitHub, I noticed
that I was able to trigger the mechanism to prevent merging
cross-alternate commit-graph layers in funny ways, like claiming that
"./objects" and "objects" were in different directories.
This resulted in removing all of the places in the commit-graph.c code
that use 'char *object_dir's with 'struct object_directory *'s instead.
This allows us to replace brittle string-based path comparisons with raw
pointer comparisons to check whether two commit-graphs belong to the
same object store or not.
This has a pleasant side effect in PATCH 5/6 of fixing an uninitialized
read as described in [1].
This series became a little bit longer than I was expecting it to be, so
here is the high-level structure:
- 1/6 fixes a bug in a test that would cause a subsequent failure if
unaddressed.
- 2/6 does the first half of the removal by using 'struct
object_directory *'s within the 'commit_graph' structure.
- 4/6 does the second half by removing 'char *object_dir' usage in the
'write_commit_graph_context' structure.
- 5/6 ties 2/6 and 4/6 together by removing all path normalization
completely, fixing the uninitialized read bug.
- And 6/6 cleans up.
We've been running a version of this series based on our fork (which is
in turn based on 2.24) for a few hours without issue.
Thanks in advance for your review.
[1]: https://lore.kernel.org/git/20191027042116.GA5801@xxxxxxxxxxxxxxxxxxxxx/
Taylor Blau (6):
t5318: don't pass non-object directory to '--object-dir'
commit-graph.h: store object directory in 'struct commit_graph'
builtin/commit-graph.c: die() with unknown '--object-dir'
commit-graph.h: store an odb in 'struct write_commit_graph_context'
commit-graph.c: remove path normalization, comparison
commit-graph.h: use odb in 'load_commit_graph_one_fd_st'
Documentation/git-commit-graph.txt | 5 +-
builtin/commit-graph.c | 25 ++++--
builtin/commit.c | 3 +-
builtin/fetch.c | 2 +-
builtin/gc.c | 2 +-
commit-graph.c | 135 +++++++++++++++--------------
commit-graph.h | 17 ++--
t/helper/test-read-graph.c | 8 +-
t/t5318-commit-graph.sh | 4 +-
9 files changed, 114 insertions(+), 87 deletions(-)
--
2.25.0.dirty
