[PATCH 5/5] refs/reftable: add fsck check for incorrect update index

From

Karthik Nayak <karthik.188@gmail.com>

Date

Aug 19, 2025, 12:21 UTC

Message-ID

<20250819-228-reftable-introduce-consistency-checks-v1-5-8b8f6879fa9e@gmail.com>

In-Reply-To

<20250819-228-reftable-introduce-consistency-checks-v1-0-8b8f6879fa9e@gmail.com>

Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
---
 Documentation/fsck-msgids.adoc |  3 ++
 fsck.h                         |  1 +
 refs/reftable-backend.c        |  3 ++
 reftable/fsck.c                | 14 +++++++++-
 reftable/reftable-fsck.h       |  2 ++
 t/t0614-reftable-fsck.sh       | 62 ++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 84 insertions(+), 1 deletion(-)

diff --git a/Documentation/fsck-msgids.adoc b/Documentation/fsck-msgids.adoc
index 1432b1de06..982d51876c 100644
--- a/Documentation/fsck-msgids.adoc
+++ b/Documentation/fsck-msgids.adoc
@@ -47,6 +47,9 @@
 `badReftableTableName`::
 	(ERROR) A reftable table has an invalid name.
 
+`badReftableUpdateIndex`::
+	(ERROR) Incorrect update index found for table.
+
 `badTagName`::
 	(INFO) A tag has an invalid format.
 
diff --git a/fsck.h b/fsck.h
index 33432bae79..60e9b84183 100644
--- a/fsck.h
+++ b/fsck.h
@@ -37,6 +37,7 @@ enum fsck_msg_type {
 	FUNC(BAD_REFTABLE_STACK_COUNT, ERROR)                      \
 	FUNC(BAD_REFTABLE_STACK_LIST_NEWLINE, ERROR)               \
 	FUNC(BAD_REFTABLE_TABLE_NAME, ERROR)                       \
+	FUNC(BAD_REFTABLE_UPDATE_INDEX, ERROR)                     \
 	FUNC(BAD_REF_CONTENT, ERROR)                               \
 	FUNC(BAD_REF_FILETYPE, ERROR)                              \
 	FUNC(BAD_REF_NAME, ERROR)                                  \
diff --git a/refs/reftable-backend.c b/refs/reftable-backend.c
index 0087afa3ac..d5993238db 100644
--- a/refs/reftable-backend.c
+++ b/refs/reftable-backend.c
@@ -2701,6 +2701,9 @@ static int reftable_fsck_error_handler(struct reftable_fsck_info info,
 	case REFTABLE_FSCK_ERROR_STACK_LIST_MISSING_NEWLINE:
 		msg_id = FSCK_MSG_BAD_REFTABLE_STACK_LIST_NEWLINE;
 		break;
+	case REFTABLE_FSCK_ERROR_UPDATE_INDEX:
+		msg_id = FSCK_MSG_BAD_REFTABLE_UPDATE_INDEX;
+		break;
 	default:
 		BUG("unknown fsck error: %d", info.error);
 	}
diff --git a/reftable/fsck.c b/reftable/fsck.c
index b4898fd2cd..a6551b9a3c 100644
--- a/reftable/fsck.c
+++ b/reftable/fsck.c
@@ -53,8 +53,8 @@ int reftable_fsck_check(struct reftable_stack *stack,
 			reftable_fsck_verbose_fn verbose_fn,
 			void *cb_data)
 {
+	uint64_t min, max, prev_max = 0;
 	char **names = NULL;
-	uint64_t min, max;
 	int err = 0;
 
 	if (stack == NULL)
@@ -85,9 +85,21 @@ int reftable_fsck_check(struct reftable_stack *stack,
 			err = report_fn(info, cb_data);
 		}
 
+		if (min != (prev_max + 1) || max < min) {
+			struct reftable_fsck_info info = {
+				.error = REFTABLE_FSCK_ERROR_UPDATE_INDEX,
+				.path = names[i],
+				.msg = "incorrect update index in table name"
+			};
+
+			err = report_fn(info, cb_data);
+		}
+
 		if (strcmp(tail, ".ref")) {
 			err = report_fn(info, cb_data);
 		}
+
+		prev_max = max;
 	}
 
 	verbose_fn("Checking trailing newline in stack list", cb_data);
diff --git a/reftable/reftable-fsck.h b/reftable/reftable-fsck.h
index 8e6cb6c7d2..49437280bb 100644
--- a/reftable/reftable-fsck.h
+++ b/reftable/reftable-fsck.h
@@ -10,6 +10,8 @@ enum reftable_fsck_error {
 	REFTABLE_FSCK_ERROR_STACK_COUNT = -2,
 	/* Newline missing at the end of the stack list */
 	REFTABLE_FSCK_ERROR_STACK_LIST_MISSING_NEWLINE = -3,
+	/* Incorrect update index for table */
+	REFTABLE_FSCK_ERROR_UPDATE_INDEX = -4,
 };
 
 /* Represents an individual error encounctered during the FSCK checks. */
diff --git a/t/t0614-reftable-fsck.sh b/t/t0614-reftable-fsck.sh
index 937c5dd37a..bdcbd65a9f 100755
--- a/t/t0614-reftable-fsck.sh
+++ b/t/t0614-reftable-fsck.sh
@@ -73,4 +73,66 @@ test_expect_success 'stack list must contain trailing newline' '
 	)
 '
 
+test_expect_success 'table update index should be sequential between tables' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		git commit --allow-empty -m initial &&
+
+		# Lock the existing table to disable auto-compaction
+		CUR_TABLE=$(cat .git/reftable/tables.list | tail -n1) &&
+		touch .git/reftable/${CUR_TABLE}.lock &&
+		git update-ref refs/heads/sample @ &&
+		rm .git/reftable/${CUR_TABLE}.lock &&
+
+		git refs verify 2>err &&
+		test_must_be_empty err &&
+
+		TABLE_NAME=$(cat .git/reftable/tables.list | tail -n1) &&
+		NEW_TABLE_NAME=$(echo ${TABLE_NAME} | sed "s/0003/0009/g") &&
+
+		sed "2s/.*/${NEW_TABLE_NAME}/" .git/reftable/tables.list >.git/reftable/tables.list.tmp &&
+		mv .git/reftable/tables.list.tmp .git/reftable/tables.list &&
+		mv .git/reftable/${TABLE_NAME} .git/reftable/${NEW_TABLE_NAME} &&
+
+		test_must_fail git refs verify 2>err &&
+		cat >expect <<-EOF &&
+		error: ${NEW_TABLE_NAME}: badReftableUpdateIndex: incorrect update index in table name
+		EOF
+		test_cmp expect err
+	)
+'
+
+test_expect_success 'table update index should be sequential within a table' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		git commit --allow-empty -m initial &&
+
+		# Lock the existing table to disable auto-compaction
+		CUR_TABLE=$(cat .git/reftable/tables.list | tail -n1) &&
+		touch .git/reftable/${CUR_TABLE}.lock &&
+		git update-ref refs/heads/sample @ &&
+		rm .git/reftable/${CUR_TABLE}.lock &&
+
+		git refs verify 2>err &&
+		test_must_be_empty err &&
+
+		TABLE_NAME=$(cat .git/reftable/tables.list | tail -n1) &&
+		NEW_TABLE_NAME=$(echo ${TABLE_NAME} | sed "s/\(.*\)0003/\10002/") &&
+
+		sed "2s/.*/${NEW_TABLE_NAME}/" .git/reftable/tables.list >.git/reftable/tables.list.tmp &&
+		mv .git/reftable/tables.list.tmp .git/reftable/tables.list &&
+		mv .git/reftable/${TABLE_NAME} .git/reftable/${NEW_TABLE_NAME} &&
+
+		test_must_fail git refs verify 2>err &&
+		cat >expect <<-EOF &&
+		error: ${NEW_TABLE_NAME}: badReftableUpdateIndex: incorrect update index in table name
+		EOF
+		test_cmp expect err
+	)
+'
+
 test_done

-- 
2.50.1