git/commit.c, branch v2.28.1

Merge branch 'tb/fix-persistent-shallow' into master

2020-07-09T21:00:44Z

When "fetch.writeCommitGraph" configuration is set in a shallow repository and a fetch moves the shallow boundary, we wrote out broken commit-graph files that do not match the reality, which has been corrected. * tb/fix-persistent-shallow: commit.c: don't persist substituted parents when unshallowing

commit.c: don't persist substituted parents when unshallowing

2020-07-08T23:13:46Z

Since 37b9dcabfc (shallow.c: use '{commit,rollback}_shallow_file', 2020-04-22), Git knows how to reset stat-validity checks for the $GIT_DIR/shallow file, allowing it to change between a shallow and non-shallow state in the same process (e.g., in the case of 'git fetch --unshallow'). However, when $GIT_DIR/shallow changes, Git does not alter or remove any grafts (nor substituted parents) in memory. This comes up in a "git fetch --unshallow" with fetch.writeCommitGraph set to true. Ordinarily in a shallow repository (and before 37b9dcabfc, even in this case), commit_graph_compatible() would return false, indicating that the repository should not be used to write a commit-graphs (since commit-graph files cannot represent a shallow history). But since 37b9dcabfc, in an --unshallow operation that check succeeds. Thus even though the repository isn't shallow any longer (that is, we have all of the objects), the in-core representation of those objects still has munged parents at the shallow boundaries. When the commit-graph write proceeds, we use the incorrect parentage, producing wrong results. There are two ways for a user to work around this: either (1) set 'fetch.writeCommitGraph' to 'false', or (2) drop the commit-graph after unshallowing. One way to fix this would be to reset the parsed object pool entirely (flushing the cache and thus preventing subsequent reads from modifying their parents) after unshallowing. That would produce a problem when callers have a now-stale reference to the old pool, and so this patch implements a different approach. Instead, attach a new bit to the pool, 'substituted_parent', which indicates if the repository *ever* stored a commit which had its parents modified (i.e., the shallow boundary prior to unshallowing). This bit needs to be sticky because all reads subsequent to modifying a commit's parents are unreliable when unshallowing. Modify the check in 'commit_graph_compatible' to take this bit into account, and correctly avoid generating commit-graphs in this case, thus solving the bug. Helped-by: Derrick Stolee Helped-by: Jonathan Nieder Reported-by: Jay Conrod Reviewed-by: Jonathan Nieder Signed-off-by: Taylor Blau Signed-off-by: Junio C Hamano

commit-graph: minimize commit_graph_data_slab access

2020-06-17T21:37:52Z

In an earlier patch, multiple struct acccesses to `graph_pos` and `generation` were auto-converted to multiple method calls. Since the values are fixed and commit-slab access costly, we would be better off with storing the values as a local variable and reusing it. Signed-off-by: Abhishek Kumar Signed-off-by: Junio C Hamano

commit: move members graph_pos, generation to a slab

2020-06-17T21:37:30Z

We remove members `graph_pos` and `generation` from the struct commit. The default assignments in init_commit_node() are no longer valid, which is fine as the slab helpers return appropriate default values and the assignments are removed. We will replace existing use of commit->generation and commit->graph_pos by commit_graph_data_slab helpers using `contrib/coccinelle/commit.cocci'. Signed-off-by: Abhishek Kumar Signed-off-by: Junio C Hamano

object: drop parsed_object_pool->commit_count

2020-06-17T21:37:14Z

14ba97f8 (alloc: allow arbitrary repositories for alloc functions, 2018-05-15) introduced parsed_object_pool->commit_count to keep count of commits per repository and was used to assign commit->index. However, commit-slab code requires commit->index values to be unique and a global count would be correct, rather than a per-repo count. Let's introduce a static counter variable, `parsed_commits_count` to keep track of parsed commits so far. As commit_count has no use anymore, let's also drop it from the struct. Signed-off-by: Abhishek Kumar Signed-off-by: Junio C Hamano

Merge branch 'tb/shallow-cleanup'

2020-05-13T19:19:18Z

Code cleanup. * tb/shallow-cleanup: shallow: use struct 'shallow_lock' for additional safety shallow.h: document '{commit,rollback}_shallow_file' shallow: extract a header file for shallow-related functions commit: make 'commit_graft_pos' non-static

shallow: extract a header file for shallow-related functions

2020-04-30T21:19:13Z

There are many functions in commit.h that are more related to shallow repositories than they are to any sort of generic commit machinery. Likely this began when there were only a few shallow-related functions, and commit.h seemed a reasonable enough place to put them. But, now there are a good number of shallow-related functions, and placing them all in 'commit.h' doesn't make sense. This patch extracts a 'shallow.h', which takes all of the declarations from 'commit.h' for functions which already exist in 'shallow.c'. We will bring the remaining shallow-related functions defined in 'commit.c' in a subsequent patch. For now, move only the ones that already are implemented in 'shallow.c', and update the necessary includes. Signed-off-by: Taylor Blau Signed-off-by: Junio C Hamano

commit: make 'commit_graft_pos' non-static

2020-04-30T21:18:41Z

In the next patch, some functions will be moved from 'commit.c' to have prototypes in a new 'shallow.h' and their implementations in 'shallow.c'. Three functions in 'commit.c' use 'commit_graft_pos()' (they are 'register_commit_graft()', 'lookup_commit_graft()', and 'unregister_shallow()'). The first two of these will stay in 'commit.c', but the latter will move to 'shallow.c', and thus needs 'commit_graft_pos' to be non-static. Prepare for that by making 'commit_graft_pos' non-static so that it can be called from both 'commit.c' and 'shallow.c'. Signed-off-by: Taylor Blau Signed-off-by: Junio C Hamano

Merge branch 'at/rebase-fork-point-regression-fix'

2020-03-27T00:11:21Z

The "--fork-point" mode of "git rebase" regressed when the command was rewritten in C back in 2.20 era, which has been corrected. * at/rebase-fork-point-regression-fix: rebase: --fork-point regression fix

commit: use expected signature header for SHA-256

2020-02-24T17:33:30Z

The transition plan anticipates that we will allow signatures using multiple algorithms in a single commit. In order to do so, we need to use a different header per algorithm so that it will be obvious over which data to compute the signature. The transition plan specifies that we should use "gpgsig-sha256", so wire up the commit code such that it can write and parse the current algorithm, and it can remove the headers for any algorithm when creating a new commit. Add tests to ensure that we write using the right header and that git fsck doesn't reject these commits. Signed-off-by: brian m. carlson Signed-off-by: Junio C Hamano