[PATCH 2/7] reftable: reject 0 object_id_len

["Han-Wen Nienhuys via GitGitGadget" <gitgitgadget@gmail.com>]

From: Han-Wen Nienhuys <hanwen@google.com>

The spec says 2 <= object_id_len <= 31. We are lenient and allow 1,
but we forbid 0, so we can we can be sure that we never read a
0-length key.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
---
 reftable/reader.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/reftable/reader.c b/reftable/reader.c
index 006709a645a..21843f5e935 100644
--- a/reftable/reader.c
+++ b/reftable/reader.c
@@ -155,6 +155,11 @@ static int parse_footer(struct reftable_reader *r, uint8_t *footer,
 	r->log_offsets.is_present = (first_block_typ == BLOCK_TYPE_LOG ||
 				     r->log_offsets.offset > 0);
 	r->obj_offsets.is_present = r->obj_offsets.offset > 0;
+	if (r->obj_offsets.is_present && !r->object_id_len) {
+		err = REFTABLE_FORMAT_ERROR;
+		goto done;
+	}
+
 	err = 0;
 done:
 	return err;
-- 
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