To show a remerge diff, the merge needs to be recreated. For that to
work, the merge base(s) need to be found, which means that the commits'
parents have to be traversed until common ancestors are found (if any).
However, one optimization that hails all the way back to cb115748ec
(Some more memory leak avoidance, 2006-06-17) is to release the commit's
list of parents immediately after showing it _and to set that parent
list to `NULL`_. This can break the merge base computation.
This problem is most obvious when traversing the commits in reverse: In
that instance, if a parent of a merge commit has been shown as part of
the `git log` command, by the time the merge commit's diff needs to be
computed, that parent commit's list of parent commits will have been set
to `NULL` and as a result no merge base will be found (even if one
should be found).
Traversing commits in reverse is far from the only circumstance in which
this problem occurs, though. There are many avenues to traversing at
least one commit in the revision walk that will later be part of a merge
base computation, for example when not even walking any revisions in
`git show <merge1> <merge2>` where `<merge1>` is part of the commit
graph between the parents of `<merge2>`.
Another way to force a scenario where a commit is traversed before it
has to be traversed again as part of a merge base computation is to
start with two revisions (where the first one is reachable from the
second but not in a first-parent ancestry) and show the commit log with
`--topo-order` and `--first-parent`.
Let's fix this by special-casing the `remerge_diff` mode, similar to
what we did with reflogs in f35650dff6 (log: do not free parents when
walking reflog, 2017-07-07).
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Now that the default value for TEST_PASSES_SANITIZE_LEAK is `true` there
is no longer a need to have that variable declared in all of our tests.
Drop it.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
More leak fixes.
* ps/leakfixes-part-4: (22 commits)
builtin/diff: free symmetric diff members
diff: free state populated via options
builtin/log: fix leak when showing converted blob contents
userdiff: fix leaking memory for configured diff drivers
builtin/format-patch: fix various trivial memory leaks
diff: fix leak when parsing invalid ignore regex option
unpack-trees: clear index when not propagating it
sequencer: release todo list on error paths
merge-ort: unconditionally release attributes index
builtin/fast-export: plug leaking tag names
builtin/fast-export: fix leaking diff options
builtin/fast-import: plug trivial memory leaks
builtin/notes: fix leaking `struct notes_tree` when merging notes
builtin/rebase: fix leaking `commit.gpgsign` value
config: fix leaking comment character config
submodule-config: fix leaking name entry when traversing submodules
read-cache: fix leaking hashfile when writing index fails
bulk-checkin: fix leaking state TODO
object-name: fix leaking symlink paths in object context
object-file: fix memory leak when reading corrupted headers
...
The `objfind` and `anchors` members of `struct diff_options` are
populated via option parsing, but are never freed in `diff_free()`. Fix
this to plug those memory leaks.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When using "git-diff-tree" to get the tree diff for merge commits with
the diff format set to `remerge`, a bug is triggered as shown below:
$ git diff-tree -r --remerge-diff 363337e6eb363337e6eb
BUG: log-tree.c:1006: did a remerge diff without remerge_objdir?!?
This bug is reported by `log-tree.c:do_remerge_diff`, where a bug check
added in commit 7b90ab467a (log: clean unneeded objects during log
--remerge-diff, 2022-02-02) detects the absence of `remerge_objdir` when
attempting to clean up temporary objects generated during the remerge
process.
After some further digging, I find that the remerge-related diff options
were introduced in db757e8b8d (show, log: provide a --remerge-diff
capability, 2022-02-02), which also affect the setup of `rev_info` for
"git-diff-tree", but were not accounted for in the original
implementation (inferred from the commit message).
Elijah Newren, the author of the remerge diff feature, notes that other
callers of `log-tree.c:log_tree_commit` (the only caller of
`log-tree.c:do_remerge_diff`) also exist, but:
`builtin/am.c`: manually sets all flags; remerge_diff is not among them
`sequencer.c`: manually sets all flags; remerge_diff is not among them
so `builtin/diff-tree.c` really is the only caller that was overlooked
when remerge-diff functionality was added.
This commit resolves the crash by adding `remerge_objdir` setup logic to
`builtin/diff-tree.c`, mirroring `builtin/log.c:cmd_log_walk_no_free`.
It also includes the necessary cleanup for `remerge_objdir`.
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Xing Xin <xingxin.xx@bytedance.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Commit 95433eeed9 ("diff: add ability to insert additional headers for
paths", 2022-02-02) introduced the possibility of additional headers.
Because there could be conflicts with no content differences (e.g. a
modify/delete conflict resolved in favor of taking the modified file
as-is), that commit also modified the diff_queue_is_empty() and
diff_flush_patch() logic to ensure these headers were included even if
there was no associated content diff.
However, the added logic was a bit inconsistent between these two
functions. diff_queue_is_empty() overlooked the fact that the
additional headers strmap could be non-NULL and empty, which would cause
it to display commits that should have been filtered out.
Fix the diff_queue_is_empty() logic to also account for
additional_path_headers being empty.
Reported-by: Philippe Blain <levraiphilippeblain@gmail.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Commit 95433eeed9 ("diff: add ability to insert additional headers for
paths", 2022-02-02) introduced the possibility of additional headers.
Because there could be conflicts with no content differences (e.g. a
modify/delete conflict resolved in favor of taking the modified file
as-is), that commit also modified the diff_queue_is_empty() and
diff_flush_patch() logic to ensure these headers were included even if
there was no associated content diff.
However, when the pickaxe is active, we really only want the remerge
conflict headers to be shown when there is an associated content diff.
Adjust the logic in these two functions accordingly.
This also removes the TEST_PASSES_SANITIZE_LEAK=true declaration from
t4069, as there is apparently some kind of memory leak with the pickaxe
code.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Commit 95433eeed9 ("diff: add ability to insert additional headers for
paths", 2022-02-02) introduced the possibility of additional headers,
created in create_filepairs_for_header_only_notifications(). These are
represented by inserting additional pairs in diff_queued_diff which
always have a mode of 0 and a null_oid. When these were added, one
code path was noted to assume that at least one of the diff_filespecs
in the pair were valid, and that codepath was corrected.
The submodule_format handling is another codepath with the same issue;
it would operate on these additional headers and attempt to display them
as submodule changes. Prevent that by explicitly checking for "phoney"
filepairs (i.e. filepairs with both modes being 0).
Reported-by: Philippe Blain <levraiphilippeblain@gmail.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fix a memory leak in code added in 5d7eeee2ac (git-show: grok blobs,
trees and tags, too, 2006-12-14). As we iterate over a "<revision>..."
command-line and encounter ad OBJ_COMMIT we want to use our "struct
rev_info", but with a "pending" array of one element: the one commit
we're showing in the loop.
To do this 5d7eeee2ac saved away a pointer to rev.pending.objects and
rev.pending.nr for its iteration. We'd then clobber those (and alloc)
when we needed to show an OBJ_COMMIT.
We'd therefore leak the "rev.pending" we started out with, and only
free the new "rev.pending" in the "OBJ_COMMIT" case arm as
prepare_revision_walk() would draw it down.
Let's fix this memory leak. Now when we encounter an OBJ_COMMIT we
save away the "rev.pending" before clearing it. We then add a single
commit to it, which our indirect invocation of prepare_revision_walk()
will remove. After that we restore the "rev.pending".
Our "rev.pending" will then get free'd by the release_revisions()
added in f6bfea0ad0 (revisions API users: use release_revisions() in
builtin/log.c, 2022-04-13)
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Doing diffs for merges are special; they should typically avoid history
simplification. For example, with
git log --diff-merges=first-parent -- path
the default history simplification would remove merge commits from
consideration if the file "path" matched the second parent. That is
counter to what the user wants when looking for first-parent diffs.
Similar comments can be made for --diff-merges=separate (which diffs
against both parents) and --diff-merges=remerge (which diffs against a
remerge of the merge commit).
However, history simplification still makes sense if not doing diffing
merges, and it also makes sense for the combined and dense-combined
forms of diffing merges (because both of those are defined to only show
a diff when the merge result at the relevant paths differs from *both*
parents).
So, for separate, first-parent, and remerge styles of diff-merges, turn
off history simplification.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Conflicts such as modify/delete, rename/rename, or file/directory are
not representable via content conflict markers, and the normal output
messages notifying users about these were dropped with --remerge-diff.
While we don't want these messages randomly shown before the commit
and diff headers, we do want them to still be shown; include them as
part of the diff headers instead.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When this option is specified, we remerge all (two parent) merge commits
and diff the actual merge commit to the automatically created version,
in order to show how users removed conflict markers, resolved the
different conflict versions, and potentially added new changes outside
of conflict regions in order to resolve semantic merge problems (or,
possibly, just to hide other random changes).
This capability works by creating a temporary object directory and
marking it as the primary object store. This makes it so that any blobs
or trees created during the automatic merge are easily removable
afterwards by just deleting all objects from the temporary object
directory.
There are a few ways that this implementation is suboptimal:
* `log --remerge-diff` becomes slow, because the temporary object
directory can fill with many loose objects while running
* the log output can be muddied with misplaced "warning: cannot merge
binary files" messages, since ll-merge.c unconditionally writes those
messages to stderr while running instead of allowing callers to
manage them.
* important conflict and warning messages are simply dropped; thus for
conflicts like modify/delete or rename/rename or file/directory which
are not representable with content conflict markers, there may be no
way for a user of --remerge-diff to know that there had been a
conflict which was resolved (and which possibly motivated other
changes in the merge commit).
* when fixing the previous issue, note that some unimportant conflict
and warning messages might start being included. We should instead
make sure these remain dropped.
Subsequent commits will address these issues.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Junio C Hamano