should not normally need to set this to `0`, but it may be
useful when trying to salvage data from a corrupted repository.
+`GIT_COMMIT_GRAPH_PARANOIA`::
+ When loading a commit object from the commit-graph, Git performs an
+ existence check on the object in the object database. This is done to
+ avoid issues with stale commit-graphs that contain references to
+ already-deleted commits, but comes with a performance penalty.
++
+The default is "true", which enables the aforementioned behavior.
+Setting this to "false" disables the existence check. This can lead to
+a performance improvement at the cost of consistency.
+
`GIT_ALLOW_PROTOCOL`::
If set to a colon-separated list of protocols, behave as if
`protocol.allow` is set to `never`, and each of the listed
struct commit *lookup_commit_in_graph(struct repository *repo, const struct object_id *id)
{
+ static int commit_graph_paranoia = -1;
struct commit *commit;
uint32_t pos;
+ if (commit_graph_paranoia == -1)
+ commit_graph_paranoia = git_env_bool(GIT_COMMIT_GRAPH_PARANOIA, 1);
+
if (!prepare_commit_graph(repo))
return NULL;
if (!search_commit_pos_in_graph(id, repo->objects->commit_graph, &pos))
return NULL;
- if (!has_object(repo, id, 0))
+ if (commit_graph_paranoia && !has_object(repo, id, 0))
return NULL;
commit = lookup_commit(repo, id);
#define GIT_TEST_COMMIT_GRAPH_DIE_ON_PARSE "GIT_TEST_COMMIT_GRAPH_DIE_ON_PARSE"
#define GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS "GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS"
+/*
+ * This environment variable controls whether commits looked up via the
+ * commit graph will be double checked to exist in the object database.
+ */
+#define GIT_COMMIT_GRAPH_PARANOIA "GIT_COMMIT_GRAPH_PARANOIA"
+
/*
* This method is only used to enhance coverage of the commit-graph
* feature in the test suite with the GIT_TEST_COMMIT_GRAPH and
)
'
+test_expect_success 'stale commit cannot be parsed when given directly' '
+ test_when_finished "rm -rf repo" &&
+ git init repo &&
+ (
+ cd repo &&
+ test_commit A &&
+ test_commit B &&
+ git commit-graph write --reachable &&
+
+ oid=$(git rev-parse B) &&
+ rm .git/objects/"$(test_oid_to_path "$oid")" &&
+
+ # Verify that it is possible to read the commit from the
+ # commit graph when not being paranoid, ...
+ GIT_COMMIT_GRAPH_PARANOIA=false git rev-list B &&
+ # ... but parsing the commit when double checking that
+ # it actually exists in the object database should fail.
+ test_must_fail git rev-list -1 B
+ )
+'
+
test_done