Re: [PATCH 7/7] commit-graph.c: introduce '--[no-]check-oids'

[Taylor Blau <me@ttaylorr.com>]

Whoops. I sent the wrong version of this patch. It should be the below:

--- >8 ---

Subject: [PATCH] shallow.c: use 'reset_repository_shallow' when appropriate

In bd0b42aed3 (fetch-pack: do not take shallow lock unnecessarily,
2019-01-10), the author noted that 'is_repository_shallow' produces
visible side-effect(s) by setting 'is_shallow' and 'shallow_stat'.

This is a problem for e.g., fetching with '--update-shallow' in a
shallow repsoitory with 'fetch.writeCommitGraph' enabled, since the
update to '.git/shallow' will cause Git to think that the repository
*isn't* shallow when it is, thereby circumventing the commit-graph
compatability check.

This causes problems in shallow repositories with at least shallow refs
that have at least one ancestor (since the client won't have those
object(s), and therefore can't take the reachability closure over
commits to be written to the commit-graph).

Address this by introducing 'reset_repository_shallow()', and calling it
when the shallow file is updated, forcing 'is_repository_shallow' to
re-evaluate whether the repository is still shallow after fetching in
the above scenario.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 commit.h     |  1 +
 fetch-pack.c |  1 +
 shallow.c    | 15 ++++++++-------
 3 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/commit.h b/commit.h
index 008a0fa4a0..ee1ba139d4 100644
--- a/commit.h
+++ b/commit.h
@@ -251,6 +251,7 @@ int register_shallow(struct repository *r, const struct object_id *oid);
 int unregister_shallow(const struct object_id *oid);
 int for_each_commit_graft(each_commit_graft_fn, void *);
 int is_repository_shallow(struct repository *r);
+void reset_repository_shallow(struct repository *r);
 struct commit_list *get_shallow_commits(struct object_array *heads,
 					int depth, int shallow_flag, int not_shallow_flag);
 struct commit_list *get_shallow_commits_by_rev_list(
diff --git a/fetch-pack.c b/fetch-pack.c
index 1734a573b0..051902ef6d 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -1630,6 +1630,7 @@ static void update_shallow(struct fetch_pack_args *args,
 		if (*alternate_shallow_file == '\0') { /* --unshallow */
 			unlink_or_warn(git_path_shallow(the_repository));
 			rollback_lock_file(&shallow_lock);
+			reset_repository_shallow(the_repository);
 		} else
 			commit_lock_file(&shallow_lock);
 		alternate_shallow_file = NULL;
diff --git a/shallow.c b/shallow.c
index 7fd04afed1..fac383dec9 100644
--- a/shallow.c
+++ b/shallow.c
@@ -40,13 +40,6 @@ int register_shallow(struct repository *r, const struct object_id *oid)

 int is_repository_shallow(struct repository *r)
 {
-	/*
-	 * NEEDSWORK: This function updates
-	 * r->parsed_objects->{is_shallow,shallow_stat} as a side effect but
-	 * there is no corresponding function to clear them when the shallow
-	 * file is updated.
-	 */
-
 	FILE *fp;
 	char buf[1024];
 	const char *path = r->parsed_objects->alternate_shallow_file;
@@ -79,6 +72,12 @@ int is_repository_shallow(struct repository *r)
 	return r->parsed_objects->is_shallow;
 }

+void reset_repository_shallow(struct repository *r)
+{
+	r->parsed_objects->is_shallow = -1;
+	stat_validity_clear(r->parsed_objects->shallow_stat);
+}
+
 /*
  * TODO: use "int" elemtype instead of "int *" when/if commit-slab
  * supports a "valid" flag.
@@ -362,6 +361,7 @@ void setup_alternate_shallow(struct lock_file *shallow_lock,
 		 * shallow file".
 		 */
 		*alternate_shallow_file = "";
+	reset_repository_shallow(the_repository);
 	strbuf_release(&sb);
 }

@@ -411,6 +411,7 @@ void prune_shallow(unsigned options)
 			die_errno("failed to write to %s",
 				  get_lock_file_path(&shallow_lock));
 		commit_lock_file(&shallow_lock);
+		reset_repository_shallow(the_repository);
 	} else {
 		unlink(git_path_shallow(the_repository));
 		rollback_lock_file(&shallow_lock);
--
2.26.0.106.g9fadedd637