Glen Choo <chooglen@xxxxxxxxxx> writes: > add_submodule_odb() is a hack - it adds a submodule's odb as an > alternate, allowing the submodule's objects to be read via > the_repository. Its last caller is submodule_has_commits(), which calls > add_submodule_odb() to prepare for check_has_commit(). This used to be > necessary because check_has_commit() used the_repository's odb, but this > is longer true as of 13a2f620b2 (submodule: pass repo to > check_has_commit(), 2021-10-08). > > Removing add_submodule_odb() reveals a bug in check_has_commit(), where > check_has_commit() will segfault if the submodule is missing (e.g. the > user has not init-ed the submodule). This happens because the > submodule's struct repository cannot be initialized, but > check_has_commit() tries to cleanup the uninitialized struct anyway. > This was masked by add_submodule_odb(), because add_submodule_odb() > fails when the submodule is missing, causing the caller to return early > and avoid calling check_has_commit(). > > Fix the bug and remove the call to add_submodule_odb(). Since > add_submodule_odb() has no more callers, remove it too. > > Note that submodule odbs can still by added as alternates via > add_submodule_odb_by_path(). > > Signed-off-by: Glen Choo <chooglen@xxxxxxxxxx> > --- > This bug only exists because we can't call repo_clear() twice on the > same struct repository. So instead of just fixing this site, an > alternative (and maybe better) fix would be to fix repo_clear(). If > others think that's a good idea, I'll do that instead. Reading the first paragraph of the commit message, I'm given the impression that this is the last site in which we attempt to add a submodule ODB as an alternate, but that is not true. This is indeed the last usage of add_submodule_odb(), but add_submodule_odb_by_path() still exists. I think the primary point of this commit is to fix a latent bug in check_has_commit(), and add_submodule_odb()'s role here is just hiding it. Its hacky behavior does not play a role. I would write the commit message like this: submodule: fix latent check_has_commit() bug check_has_commit() will attempt to clear a non-initialized struct repository if initialization fails. This bug is masked by its only caller, submodule_has_commits(), first calling add_submodule_odb(). The latter fails if the repo does not exist, making submodule_has_commits() exit early and not invoke check_has_commit() in a situation in which initialization would fail. Fix this bug, and because calling add_submodule_odb() is no longer necessary as of 13a2f620b2 (submodule: pass repo to check_has_commit(), 2021-10-08), remove that call too. This is the last caller of add_submodule_odb(), so remove that function. (Adding submodule ODBs as alternates is still present in the form of add_submodule_odb_by_path().)
