git/t/t5318-commit-graph.sh, branch v2.30.2

commit-graph: use the "hash version" byte

2020-08-17T23:45:14Z

The commit-graph format reserved a byte among the header of the file to store a "hash version". During the SHA-256 work, this was not modified because file formats are not necessarily intended to work across hash versions. If a repository has SHA-256 as its hash algorithm, it automatically up-shifts the lengths of object names in all necessary formats. However, since we have this byte available for adjusting the version, we can make the file formats more obviously incompatible instead of relying on other context from the repository. Update the oid_version() method in commit-graph.c to add a new value, 2, for sha-256. This automatically writes the new value in a SHA-256 repository _and_ verifies the value is correct. This is a breaking change relative to the current 'master' branch since 092b677 (Merge branch 'bc/sha-256-cvs-svn-updates', 2020-08-13) but it is not breaking relative to any released version of Git. The test impact is relatively minor: the output of 'test-tool read-graph' lists the header information, so those instances of '1' need to be replaced with a variable determined by GIT_TEST_DEFAULT_HASH. A more careful test is added that specifically creates a repository of each type then swaps the commit-graph files. The important value here is that the "git log" command succeeds while writing a message to stderr. Helped-by: brian m. carlson Signed-off-by: Derrick Stolee Reviewed-by: brian m. carlson Signed-off-by: Junio C Hamano

Merge branch 'bc/sha-256-part-3'

2020-08-12T01:04:11Z

The final leg of SHA-256 transition. * bc/sha-256-part-3: (39 commits) t: remove test_oid_init in tests docs: add documentation for extensions.objectFormat ci: run tests with SHA-256 t: make SHA1 prerequisite depend on default hash t: allow testing different hash algorithms via environment t: add test_oid option to select hash algorithm repository: enable SHA-256 support by default setup: add support for reading extensions.objectformat bundle: add new version for use with SHA-256 builtin/verify-pack: implement an --object-format option http-fetch: set up git directory before parsing pack hashes t0410: mark test with SHA1 prerequisite t5308: make test work with SHA-256 t9700: make hash size independent t9500: ensure that algorithm info is preserved in config t9350: make hash size independent t9301: make hash size independent t9300: use $ZERO_OID instead of hard-coded object ID t9300: abstract away SHA-1-specific constants t8011: make hash size independent ...

Merge branch 'ds/commit-graph-bloom-updates' into master

2020-07-30T20:20:31Z

Updates to the changed-paths bloom filter. * ds/commit-graph-bloom-updates: commit-graph: check all leading directories in changed path Bloom filters revision: empty pathspecs should not use Bloom filters revision.c: fix whitespace commit-graph: check chunk sizes after writing commit-graph: simplify chunk writes into loop commit-graph: unify the signatures of all write_graph_chunk_*() functions commit-graph: persist existence of changed-paths bloom: fix logic in get_bloom_filter() commit-graph: change test to die on parse, not load commit-graph: place bloom_settings in context

Merge branch 'sg/commit-graph-cleanups' into master

2020-07-30T20:20:30Z

The changed-path Bloom filter is improved using ideas from an independent implementation. * sg/commit-graph-cleanups: commit-graph: simplify write_commit_graph_file() #2 commit-graph: simplify write_commit_graph_file() #1 commit-graph: simplify parse_commit_graph() #2 commit-graph: simplify parse_commit_graph() #1 commit-graph: clean up #includes diff.h: drop diff_tree_oid() & friends' return value commit-slab: add a function to deep free entries on the slab commit-graph-format.txt: all multi-byte numbers are in network byte order commit-graph: fix parsing the Chunk Lookup table tree-walk.c: don't match submodule entries for 'submod/anything'

t: remove test_oid_init in tests

2020-07-30T16:16:49Z

Now that we call test_oid_init in the setup for all test scripts, there's no point in calling it individually. Remove all of the places where we've done so to help keep tests tidy. Signed-off-by: brian m. carlson Reviewed-by: Eric Sunshine Signed-off-by: Junio C Hamano

commit-graph: change test to die on parse, not load

2020-06-24T00:12:08Z

43d3561 (commit-graph write: don't die if the existing graph is corrupt, 2019-03-25) introduced the GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD environment variable. This was created to verify that commit-graph was not loaded when writing a new non-incremental commit-graph. An upcoming change wants to load a commit-graph in some valuable cases, but we want to maintain that we don't trust the commit-graph data when writing our new file. Instead of dying on load, instead die if we ever try to parse a commit from the commit-graph. This functionally verifies the same intended behavior, but allows a more advanced feature in the next change. Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano

Merge branch 'tb/t5318-cleanup'

2020-06-18T04:54:01Z

Code cleanup. * tb/t5318-cleanup: t5318: test that '--stdin-commits' respects '--[no-]progress' t5318: use 'test_must_be_empty'

Merge branch 'tb/commit-graph-no-check-oids'

2020-06-09T01:06:27Z

Clean-up the commit-graph codepath. * tb/commit-graph-no-check-oids: commit-graph: drop COMMIT_GRAPH_WRITE_CHECK_OIDS flag t5318: reorder test below 'graph_read_expect' commit-graph.c: simplify 'fill_oids_from_commits' builtin/commit-graph.c: dereference tags in builtin builtin/commit-graph.c: extract 'read_one_commit()' commit-graph.c: peel refs in 'add_ref_to_set' commit-graph.c: show progress of finding reachable commits commit-graph.c: extract 'refs_cb_data'

commit-graph: simplify parse_commit_graph() #1

2020-06-08T19:28:49Z

While we iterate over all entries of the Chunk Lookup table we make sure that we don't attempt to read past the end of the mmap-ed commit-graph file, and check in each iteration that the chunk ID and offset we are about to read is still within the mmap-ed memory region. However, these checks in each iteration are not really necessary, because the number of chunks in the commit-graph file is already known before this loop from the just parsed commit-graph header. So let's check that the commit-graph file is large enough for all entries in the Chunk Lookup table before we start iterating over those entries, and drop those per-iteration checks. While at it, take into account the size of everything that is necessary to have a valid commit-graph file, i.e. the size of the header, the size of the mandatory OID Fanout chunk, and the size of the signature in the trailer as well. Note that this necessitates the change of the error message as well, and, consequently, have to update the 'detect incorrect chunk count' test in 't5318-commit-graph.sh' as well. Signed-off-by: SZEDER Gábor Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano

commit-graph: fix parsing the Chunk Lookup table

2020-06-08T19:28:48Z

The commit-graph file format specifies that the chunks may be in any order. However, if the OID Lookup chunk happens to be the last one in the file, then any command attempting to access the commit-graph data will fail with: fatal: invalid commit position. commit-graph is likely corrupt In this case the error is wrong, the commit-graph file does conform to the specification, but the parsing of the Chunk Lookup table is a bit buggy, and leaves the field holding the number of commits in the commit-graph zero-initialized. The number of commits in the commit-graph is determined while parsing the Chunk Lookup table, by dividing the size of the OID Lookup chunk with the hash size. However, the Chunk Lookup table doesn't actually store the size of the chunks, but it stores their starting offset. Consequently, the size of a chunk can only be calculated by subtracting the starting offsets of that chunk from the offset of the subsequent chunk, or in case of the last chunk from the offset recorded in the terminating label. This is currenly implemented in a bit complicated way: as we iterate over the entries of the Chunk Lookup table, we check the ID of each chunk and store its starting offset, then we check the ID of the last seen chunk and calculate its size using its previously saved offset if necessary (at the moment it's only necessary for the OID Lookup chunk). Alas, while parsing the Chunk Lookup table we only interate through the "real" chunks, but never look at the terminating label, thus don't even check whether it's necessary to calulate the size of the last chunk. Consequently, if the OID Lookup chunk is the last one, then we don't calculate its size and turn don't run the piece of code determining the number of commits in the commit graph, leaving the field holding that number unchanged (i.e. zero-initialized), eventually triggering the sanity check in load_oid_from_graph(). Fix this by iterating through all entries in the Chunk Lookup table, including the terminating label. Note that this is the minimal fix, suitable for the maintenance track. A better fix would be to simplify how the chunk sizes are calculated, but that is a more invasive change, less suitable for 'maint', so that will be done in later patches. This additional flexibility of scanning more chunks breaks a test for "git commit-graph verify" so alter that test to mutate the commit-graph to have an even lower chunk count. Signed-off-by: SZEDER Gábor Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano