prepare_commit_graft: treat non-repository as a noop

The parse_commit_buffer() function consults lookup_commit_graft()
to see if we need to rewrite parents. The latter will look
at $GIT_DIR/info/grafts. If you're outside of a repository,
then this will trigger a BUG() as of b1ef400eec (setup_git_env:
avoid blind fall-back to ".git", 2016-10-20).

It's probably uncommon to actually parse a commit outside of
a repository, but you can see it in action with:

cd /not/a/git/repo
git index-pack --strict /some/file.pack

This works fine without --strict, but the fsck checks will
try to parse any commits, triggering the BUG(). We can fix
that by teaching the graft code to behave as if there are no
grafts when we aren't in a repository.

Arguably index-pack (and fsck) are wrong to consider grafts
at all. So another solution is to disable grafts entirely
for those commands. But given that the graft feature is
deprecated anyway, it's not worth even thinking through the
ramifications that might have.

There is one other corner case I considered here. What
should:

cd /not/a/git/repo
export GIT_GRAFT_FILE=/file/with/grafts
git index-pack --strict /some/file.pack

do? We don't have a repository, but the user has pointed us
directly at a graft file, which we could respect. I believe
this case did work that way prior to b1ef400eec. However,
fixing it now would be pretty invasive. Back then we would
just call into setup_git_env() even without a repository.
But these days it actually takes a git_dir argument. So
there would be a fair bit of refactoring of the setup code
involved.

Given the obscurity of this case, plus the fact that grafts
are deprecated and probably shouldn't work under index-pack
anyway, it's not worth pursuing further. This patch at least
un-breaks the common case where you're _not_ using grafts,
but we BUG() anyway trying to even find that out.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/commit.c b/commit.c
index 00c99c7272badc2d5a8f16c29db7d4040f5eb4d3..9e49c221ed4726008f06882c4d1ea69d47a2f623 100644 (file)
--- a/commit.c
+++ b/commit.c
@@ -196,6 +196,9 @@ static void prepare_commit_graft(void)
 
        if (commit_graft_prepared)
                return;
+       if (!startup_info->have_repository)
+               return;
+
        graft_file = get_graft_file();
        read_graft_file(graft_file);
        /* make sure shallows are read */

diff --git a/t/t5300-pack-object.sh b/t/t5300-pack-object.sh
index 9c68b992511b7098df0570ca37e0add468a8a093..88ec5d78489ee3394e9c719f851546d7ae12e320 100755 (executable)
--- a/t/t5300-pack-object.sh
+++ b/t/t5300-pack-object.sh
@@ -421,6 +421,12 @@ test_expect_success 'index-pack <pack> works in non-repo' '
        test_path_is_file foo.idx
 '
 
+test_expect_success 'index-pack --strict <pack> works in non-repo' '
+       rm -f foo.idx &&
+       nongit git index-pack --strict ../foo.pack &&
+       test_path_is_file foo.idx
+'
+
 test_expect_success !PTHREADS,C_LOCALE_OUTPUT 'index-pack --threads=N or pack.threads=N warns when no pthreads' '
        test_must_fail git index-pack --threads=2 2>err &&
        grep ^warning: err >warnings &&