fsck: add ref name check for files backend

The git-fsck(1) only implicitly checks the reference, it does not fully
check refs with bad format name such as standalone "@".

However, a file ending with ".lock" should not be marked as having a bad
ref name. It is expected that concurrent writers may have such lock files.
We currently ignore this situation. But for bare ".lock" file, we will
report it as error.

In order to provide such checks, add a new fsck message id "badRefName"
with default ERROR type. Use existing "check_refname_format" to explicit
check the ref name. And add a new unit test to verify the functionality.

Mentored-by: Patrick Steinhardt <ps@pks.im>
Mentored-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: shejialuo <shejialuo@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/fsck-msgids.txt

@@ -22,6 +22,9 @@
 `badRefFiletype`::
 	(ERROR) A ref has a bad file type.
 
+`badRefName`::
+	(ERROR) A ref has an invalid format.
+
 `badTagName`::
 	(INFO) A tag has an invalid format.
 

fsck.h

@@ -32,6 +32,7 @@ enum fsck_msg_type {
 	FUNC(BAD_OBJECT_SHA1, ERROR) \
 	FUNC(BAD_PARENT_SHA1, ERROR) \
 	FUNC(BAD_REF_FILETYPE, ERROR) \
+	FUNC(BAD_REF_NAME, ERROR) \
 	FUNC(BAD_TIMEZONE, ERROR) \
 	FUNC(BAD_TREE, ERROR) \
 	FUNC(BAD_TREE_SHA1, ERROR) \

refs/files-backend.c

@@ -3419,6 +3419,36 @@ typedef int (*files_fsck_refs_fn)(struct ref_store *ref_store,
 				  const char *refs_check_dir,
 				  struct dir_iterator *iter);
 
+static int files_fsck_refs_name(struct ref_store *ref_store UNUSED,
+				struct fsck_options *o,
+				const char *refs_check_dir,
+				struct dir_iterator *iter)
+{
+	struct strbuf sb = STRBUF_INIT;
+	int ret = 0;
+
+	/*
+	 * Ignore the files ending with ".lock" as they may be lock files
+	 * However, do not allow bare ".lock" files.
+	 */
+	if (iter->basename[0] != '.' && ends_with(iter->basename, ".lock"))
+		goto cleanup;
+
+	if (check_refname_format(iter->basename, REFNAME_ALLOW_ONELEVEL)) {
+		struct fsck_ref_report report = { .path = NULL };
+
+		strbuf_addf(&sb, "%s/%s", refs_check_dir, iter->relative_path);
+		report.path = sb.buf;
+		ret = fsck_report_ref(o, &report,
+				      FSCK_MSG_BAD_REF_NAME,
+				      "invalid refname format");
+	}
+
+cleanup:
+	strbuf_release(&sb);
+	return ret;
+}
+
 static int files_fsck_refs_dir(struct ref_store *ref_store,
 			       struct fsck_options *o,
 			       const char *refs_check_dir,
@@ -3470,6 +3500,7 @@ static int files_fsck_refs(struct ref_store *ref_store,
 			   struct fsck_options *o)
 {
 	files_fsck_refs_fn fsck_refs_fn[]= {
+		files_fsck_refs_name,
 		NULL,
 	};
 

t/t0602-reffiles-fsck.sh

@@ -0,0 +1,92 @@
+#!/bin/sh
+
+test_description='Test reffiles backend consistency check'
+
+GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
+export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
+GIT_TEST_DEFAULT_REF_FORMAT=files
+export GIT_TEST_DEFAULT_REF_FORMAT
+TEST_PASSES_SANITIZE_LEAK=true
+
+. ./test-lib.sh
+
+test_expect_success 'ref name should be checked' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	branch_dir_prefix=.git/refs/heads &&
+	tag_dir_prefix=.git/refs/tags &&
+	cd repo &&
+
+	git commit --allow-empty -m initial &&
+	git checkout -b branch-1 &&
+	git tag tag-1 &&
+	git commit --allow-empty -m second &&
+	git checkout -b branch-2 &&
+	git tag tag-2 &&
+	git tag multi_hierarchy/tag-2 &&
+
+	cp $branch_dir_prefix/branch-1 $branch_dir_prefix/.branch-1 &&
+	test_must_fail git refs verify 2>err &&
+	cat >expect <<-EOF &&
+	error: refs/heads/.branch-1: badRefName: invalid refname format
+	EOF
+	rm $branch_dir_prefix/.branch-1 &&
+	test_cmp expect err &&
+
+	cp $branch_dir_prefix/branch-1 $branch_dir_prefix/@ &&
+	test_must_fail git refs verify 2>err &&
+	cat >expect <<-EOF &&
+	error: refs/heads/@: badRefName: invalid refname format
+	EOF
+	rm $branch_dir_prefix/@ &&
+	test_cmp expect err &&
+
+	cp $tag_dir_prefix/multi_hierarchy/tag-2 $tag_dir_prefix/multi_hierarchy/@ &&
+	test_must_fail git refs verify 2>err &&
+	cat >expect <<-EOF &&
+	error: refs/tags/multi_hierarchy/@: badRefName: invalid refname format
+	EOF
+	rm $tag_dir_prefix/multi_hierarchy/@ &&
+	test_cmp expect err &&
+
+	cp $tag_dir_prefix/tag-1 $tag_dir_prefix/tag-1.lock &&
+	git refs verify 2>err &&
+	rm $tag_dir_prefix/tag-1.lock &&
+	test_must_be_empty err &&
+
+	cp $tag_dir_prefix/tag-1 $tag_dir_prefix/.lock &&
+	test_must_fail git refs verify 2>err &&
+	cat >expect <<-EOF &&
+	error: refs/tags/.lock: badRefName: invalid refname format
+	EOF
+	rm $tag_dir_prefix/.lock &&
+	test_cmp expect err
+'
+
+test_expect_success 'ref name check should be adapted into fsck messages' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	branch_dir_prefix=.git/refs/heads &&
+	tag_dir_prefix=.git/refs/tags &&
+	cd repo &&
+	git commit --allow-empty -m initial &&
+	git checkout -b branch-1 &&
+	git tag tag-1 &&
+	git commit --allow-empty -m second &&
+	git checkout -b branch-2 &&
+	git tag tag-2 &&
+
+	cp $branch_dir_prefix/branch-1 $branch_dir_prefix/.branch-1 &&
+	git -c fsck.badRefName=warn refs verify 2>err &&
+	cat >expect <<-EOF &&
+	warning: refs/heads/.branch-1: badRefName: invalid refname format
+	EOF
+	rm $branch_dir_prefix/.branch-1 &&
+	test_cmp expect err &&
+
+	cp $branch_dir_prefix/branch-1 $branch_dir_prefix/@ &&
+	git -c fsck.badRefName=ignore refs verify 2>err &&
+	test_must_be_empty err
+'
+
+test_done