[PATCH 4/7] reftable: avoid writing empty keys at the block layer

From

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

Date

Jan 12, 2022, 18:07 UTC

Message-ID

<e4c1cc58265ca7ae7b32b9faf41324883011d1a6.1642010868.git.gitgitgadget@gmail.com>

In-Reply-To

<pull.1185.git.git.1642010868.gitgitgadget@gmail.com>

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

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
---
 reftable/block.c      | 27 +++++++++++++++++----------
 reftable/block_test.c |  5 +++++
 reftable/writer.c     |  3 +--
 3 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/reftable/block.c b/reftable/block.c
index 855e3f5c947..8725eaaf64f 100644
--- a/reftable/block.c
+++ b/reftable/block.c
@@ -88,8 +88,9 @@ uint8_t block_writer_type(struct block_writer *bw)
 	return bw->buf[bw->header_off];
 }
 
-/* adds the reftable_record to the block. Returns -1 if it does not fit, 0 on
-   success */
+/* Adds the reftable_record to the block. Returns -1 if it does not fit, 0 on
+   success. Returns REFTABLE_API_ERROR if attempting to write a record with
+   empty key. */
 int block_writer_add(struct block_writer *w, struct reftable_record *rec)
 {
 	struct strbuf empty = STRBUF_INIT;
@@ -105,8 +106,14 @@ int block_writer_add(struct block_writer *w, struct reftable_record *rec)
 	int is_restart = 0;
 	struct strbuf key = STRBUF_INIT;
 	int n = 0;
+	int err = -1;
 
 	reftable_record_key(rec, &key);
+	if (!key.len) {
+		err = REFTABLE_API_ERROR;
+		goto done;
+	}
+
 	n = reftable_encode_key(&is_restart, out, last, key,
 				reftable_record_val_type(rec));
 	if (n < 0)
@@ -118,16 +125,11 @@ int block_writer_add(struct block_writer *w, struct reftable_record *rec)
 		goto done;
 	string_view_consume(&out, n);
 
-	if (block_writer_register_restart(w, start.len - out.len, is_restart,
-					  &key) < 0)
-		goto done;
-
-	strbuf_release(&key);
-	return 0;
-
+	err = block_writer_register_restart(w, start.len - out.len, is_restart,
+					    &key);
 done:
 	strbuf_release(&key);
-	return -1;
+	return err;
 }
 
 int block_writer_finish(struct block_writer *w)
@@ -324,6 +326,9 @@ int block_iter_next(struct block_iter *it, struct reftable_record *rec)
 	if (n < 0)
 		return -1;
 
+	if (!key.len)
+		return REFTABLE_FORMAT_ERROR;
+
 	string_view_consume(&in, n);
 	n = reftable_record_decode(rec, key, extra, in, it->br->hash_size);
 	if (n < 0)
@@ -350,6 +355,8 @@ int block_reader_first_key(struct block_reader *br, struct strbuf *key)
 	int n = reftable_decode_key(key, &extra, empty, in);
 	if (n < 0)
 		return n;
+	if (!key->len)
+		return -1;
 
 	return 0;
 }
diff --git a/reftable/block_test.c b/reftable/block_test.c
index 4b3ea262dcb..5112ddbf468 100644
--- a/reftable/block_test.c
+++ b/reftable/block_test.c
@@ -42,6 +42,11 @@ static void test_block_read_write(void)
 			  header_off, hash_size(GIT_SHA1_FORMAT_ID));
 	reftable_record_from_ref(&rec, &ref);
 
+	ref.refname = "";
+	ref.value_type = REFTABLE_REF_DELETION;
+	n = block_writer_add(&bw, &rec);
+	EXPECT(n == REFTABLE_API_ERROR);
+
 	for (i = 0; i < N; i++) {
 		char name[100];
 		uint8_t hash[GIT_SHA1_RAWSZ];
diff --git a/reftable/writer.c b/reftable/writer.c
index 35c8649c9b7..e3c042b9d84 100644
--- a/reftable/writer.c
+++ b/reftable/writer.c
@@ -238,14 +238,13 @@ static int writer_add_record(struct reftable_writer *w,
 
 	writer_reinit_block_writer(w, reftable_record_type(rec));
 	err = block_writer_add(w->block_writer, rec);
-	if (err < 0) {
+	if (err == -1) {
 		/* we are writing into memory, so an error can only mean it
 		 * doesn't fit. */
 		err = REFTABLE_ENTRY_TOO_BIG_ERROR;
 		goto done;
 	}
 
-	err = 0;
 done:
 	strbuf_release(&key);
 	return err;

-- 
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