rev-list: detect broken root trees

peff · gitster · commit 97dd512af7ce · 2019-04-10T12:59:39.000+09:00
When the traversal machinery sees a commit without a root tree, it
assumes that the tree was part of a BOUNDARY commit, and quietly ignores
the tree. But it could also be caused by a commit whose root tree is
broken or missing.

Instead, let's die() when we see a NULL root tree. We can differentiate
it from the BOUNDARY case by seeing if the commit was actually parsed.
This covers that case, plus future-proofs us against any others where we
might try to show an unparsed commit.

Signed-off-by: Jeff King &lt;peff@peff.net&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
diff --git a/list-objects.c b/list-objects.c
@@ -374,6 +374,9 @@ static void do_traverse(struct traversal_context *ctx)
 			struct tree *tree = get_commit_tree(commit);
 			tree->object.flags |= NOT_USER_GIVEN;
 			add_pending_tree(ctx->revs, tree);
+		} else if (commit->object.parsed) {
+			die(_("unable to load root tree for commit %s"),
+			      oid_to_hex(&commit->object.oid));
 		}
 		ctx->show_commit(commit, ctx->show_data);
 
diff --git a/t/t6102-rev-list-unexpected-objects.sh b/t/t6102-rev-list-unexpected-objects.sh
@@ -67,8 +67,10 @@ test_expect_success 'traverse unexpected non-tree root (lone)' '
 	test_must_fail git rev-list --objects $broken_commit
 '
 
-test_expect_failure 'traverse unexpected non-tree root (seen)' '
-	test_must_fail git rev-list --objects $blob $broken_commit
+test_expect_success 'traverse unexpected non-tree root (seen)' '
+	test_must_fail git rev-list --objects $blob $broken_commit \
+		>output 2>&1 &&
+	test_i18ngrep "not a tree" output
 '
 
 test_expect_success 'setup unexpected non-commit tag' '

Original file line number	Diff line number	Diff line change
`@@ -374,6 +374,9 @@ static void do_traverse(struct traversal_context *ctx)`
`374`	`374`	`struct tree *tree = get_commit_tree(commit);`
`375`	`375`	`tree->object.flags \|= NOT_USER_GIVEN;`
`376`	`376`	`add_pending_tree(ctx->revs, tree);`
	`377`	`+ } else if (commit->object.parsed) {`
	`378`	`+ die(_("unable to load root tree for commit %s"),`
	`379`	`+ oid_to_hex(&commit->object.oid));`
`377`	`380`	`}`
`378`	`381`	`ctx->show_commit(commit, ctx->show_data);`
`379`	`382`
Original file line number	Diff line number	Diff line change
`@@ -67,8 +67,10 @@ test_expect_success 'traverse unexpected non-tree root (lone)' '`
`67`	`67`	`test_must_fail git rev-list --objects $broken_commit`
`68`	`68`	`'`
`69`	`69`
`70`		`-test_expect_failure 'traverse unexpected non-tree root (seen)' '`
`71`		`- test_must_fail git rev-list --objects $blob $broken_commit`
	`70`	`+test_expect_success 'traverse unexpected non-tree root (seen)' '`
	`71`	`+ test_must_fail git rev-list --objects $blob $broken_commit \`
	`72`	`+ >output 2>&1 &&`
	`73`	`+ test_i18ngrep "not a tree" output`
`72`	`74`	`'`
`73`	`75`
`74`	`76`	`test_expect_success 'setup unexpected non-commit tag' '`