Merge branch 'bc/submodule-force-same-hash'

Adding a repository that uses a different hash function is a no-no,
but "git submodule add" did nt prevent it, which has been corrected.

* bc/submodule-force-same-hash:
  read-cache: drop submodule check from add_to_cache()
  object-file: disallow adding submodules of different hash algo

4 files changed, 56 insertions, 4 deletions

diff --git a/object-file.c b/object-file.c
index 4675c8ed6b..a7438b6205 100644
--- a/object-file.c
+++ b/object-file.c
@@ -1661,7 +1661,11 @@ int index_path(struct index_state *istate, struct object_id *oid,
 		strbuf_release(&sb);
 		break;
 	case S_IFDIR:
-		return repo_resolve_gitlink_ref(istate->repo, path, "HEAD", oid);
+		if (repo_resolve_gitlink_ref(istate->repo, path, "HEAD", oid))
+			return error(_("'%s' does not have a commit checked out"), path);
+		if (&hash_algos[oid->algo] != istate->repo->hash_algo)
+			return error(_("cannot add a submodule of a different hash algorithm"));
+		break;
 	default:
 		return error(_("%s: unsupported file type"), path);
 	}
diff --git a/read-cache.c b/read-cache.c
index 032480d0c7..990d4ead0d 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -706,7 +706,6 @@ int add_to_index(struct index_state *istate, const char *path, struct stat *st,
 	int add_option = (ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE|
 			  (intent_only ? ADD_CACHE_NEW_ONLY : 0));
 	unsigned hash_flags = pretend ? 0 : INDEX_WRITE_OBJECT;
-	struct object_id oid;
 
 	if (flags & ADD_CACHE_RENORMALIZE)
 		hash_flags |= INDEX_RENORMALIZE;
@@ -716,8 +715,6 @@ int add_to_index(struct index_state *istate, const char *path, struct stat *st,
 
 	namelen = strlen(path);
 	if (S_ISDIR(st_mode)) {
-		if (repo_resolve_gitlink_ref(the_repository, path, "HEAD", &oid) < 0)
-			return error(_("'%s' does not have a commit checked out"), path);
 		while (namelen && path[namelen-1] == '/')
 			namelen--;
 	}
diff --git a/t/t3700-add.sh b/t/t3700-add.sh
index df580a5806..af93e53c12 100755
--- a/t/t3700-add.sh
+++ b/t/t3700-add.sh
@@ -388,6 +388,7 @@ test_expect_success 'error on a repository with no commits' '
 	test_must_fail git add empty >actual 2>&1 &&
 	cat >expect <<-EOF &&
 	error: '"'empty/'"' does not have a commit checked out
+	error: unable to index file '"'empty/'"'
 	fatal: adding files failed
 	EOF
 	test_cmp expect actual
@@ -541,6 +542,31 @@ test_expect_success 'all statuses changed in folder if . is given' '
 	)
 '
 
+test_expect_success 'cannot add a submodule of a different algorithm' '
+	git init --object-format=sha256 sha256 &&
+	(
+		cd sha256 &&
+		test_commit abc &&
+		git init --object-format=sha1 submodule &&
+		test_commit -C submodule def &&
+		test_must_fail git add submodule 2>err &&
+		test_grep "cannot add a submodule of a different hash algorithm" err &&
+		git ls-files --stage >entries &&
+		test_grep ! ^160000 entries
+	) &&
+	git init --object-format=sha1 sha1 &&
+	(
+		cd sha1 &&
+		test_commit abc &&
+		git init --object-format=sha256 submodule &&
+		test_commit -C submodule def &&
+		test_must_fail git add submodule 2>err &&
+		test_grep "cannot add a submodule of a different hash algorithm" err &&
+		git ls-files --stage >entries &&
+		test_grep ! ^160000 entries
+	)
+'
+
 test_expect_success CASE_INSENSITIVE_FS 'path is case-insensitive' '
 	path="$(pwd)/BLUB" &&
 	touch "$path" &&
diff --git a/t/t7400-submodule-basic.sh b/t/t7400-submodule-basic.sh
index fd3e7e355e..e6b551daad 100755
--- a/t/t7400-submodule-basic.sh
+++ b/t/t7400-submodule-basic.sh
@@ -407,6 +407,31 @@ test_expect_success 'submodule add in subdirectory with relative path should fai
 	test_grep toplevel output.err
 '
 
+test_expect_success 'submodule add of a different algorithm fails' '
+	git init --object-format=sha256 sha256 &&
+	(
+		cd sha256 &&
+		test_commit abc &&
+		git init --object-format=sha1 submodule &&
+		test_commit -C submodule def &&
+		test_must_fail git submodule add "$submodurl" submodule 2>err &&
+		test_grep "cannot add a submodule of a different hash algorithm" err &&
+		git ls-files --stage >entries &&
+		test_grep ! ^160000 entries
+	) &&
+	git init --object-format=sha1 sha1 &&
+	(
+		cd sha1 &&
+		test_commit abc &&
+		git init --object-format=sha256 submodule &&
+		test_commit -C submodule def &&
+		test_must_fail git submodule add "$submodurl" submodule 2>err &&
+		test_grep "cannot add a submodule of a different hash algorithm" err &&
+		git ls-files --stage >entries &&
+		test_grep ! ^160000 entries
+	)
+'
+
 test_expect_success 'setup - add an example entry to .gitmodules' '
 	git config --file=.gitmodules submodule.example.url git://example.com/init.git
 '