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From: "Han-Wen Nienhuys via GitGitGadget" <gitgitgadget@gmail.com>
To: git@vger.kernel.org
Cc: Han-Wen Nienhuys <hanwen@google.com>,
	Han-Wen Nienhuys <hanwenn@gmail.com>,
	Han-Wen Nienhuys <hanwen@google.com>
Subject: [PATCH v3 4/7] reftable: avoid writing empty keys at the block layer
Date: Mon, 21 Feb 2022 18:46:07 +0000	[thread overview]
Message-ID: <a9372cacd1b7f62530df948c0ba99cf276d34cad.1645469170.git.gitgitgadget@gmail.com> (raw)
In-Reply-To: <pull.1185.v3.git.git.1645469170.gitgitgadget@gmail.com>

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

The public interface (reftable_writer) already ensures that keys are
written in strictly increasing order, and an empty key by definition
fails this check.

However, by also enforcing this at the block layer, it is easier to
verify that records (which are written into blocks) never have to
consider the possibility of empty keys.

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 2170748c5e9..34d4d073692 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)
@@ -332,6 +334,9 @@ 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)
@@ -358,6 +363,8 @@ 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 REFTABLE_FORMAT_ERROR;
 
 	return 0;
 }
diff --git a/reftable/block_test.c b/reftable/block_test.c
index fa2ee092ec0..cb88af4a563 100644
--- a/reftable/block_test.c
+++ b/reftable/block_test.c
@@ -42,6 +42,11 @@ static void test_block_read_write(void)
 	block_writer_init(&bw, BLOCK_TYPE_REF, block.data, block_size,
 			  header_off, hash_size(GIT_SHA1_FORMAT_ID));
 
+	rec.u.ref.refname = "";
+	rec.u.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 944c2329ab5..d54215a50dc 100644
--- a/reftable/writer.c
+++ b/reftable/writer.c
@@ -240,14 +240,13 @@ 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;
-- 
gitgitgadget


  parent reply	other threads:[~2022-02-21 18:46 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-12 18:07 [PATCH 0/7] reftable: avoid reading and writing empty keys Han-Wen Nienhuys via GitGitGadget
2022-01-12 18:07 ` [PATCH 1/7] Documentation: object_id_len goes up to 31 Han-Wen Nienhuys via GitGitGadget
2022-01-12 18:07 ` [PATCH 2/7] reftable: reject 0 object_id_len Han-Wen Nienhuys via GitGitGadget
2022-01-12 18:07 ` [PATCH 3/7] reftable: add a test that verifies that writing empty keys fails Han-Wen Nienhuys via GitGitGadget
2022-01-12 18:07 ` [PATCH 4/7] reftable: avoid writing empty keys at the block layer Han-Wen Nienhuys via GitGitGadget
2022-01-14  1:26   ` Junio C Hamano
2022-01-17 13:10     ` Han-Wen Nienhuys
2022-01-17 19:11       ` Junio C Hamano
2022-01-12 18:07 ` [PATCH 5/7] reftable: ensure that obj_id_len is >= 2 on writing Han-Wen Nienhuys via GitGitGadget
2022-01-12 18:07 ` [PATCH 6/7] reftable: add test for length of disambiguating prefix Han-Wen Nienhuys via GitGitGadget
2022-01-12 18:07 ` [PATCH 7/7] reftable: rename writer_stats to reftable_writer_stats Han-Wen Nienhuys via GitGitGadget
2022-02-17 13:55 ` [PATCH v2 0/7] reftable: avoid reading and writing empty keys Han-Wen Nienhuys via GitGitGadget
2022-02-17 13:55   ` [PATCH v2 1/7] Documentation: object_id_len goes up to 31 Han-Wen Nienhuys via GitGitGadget
2022-02-17 13:55   ` [PATCH v2 2/7] reftable: reject 0 object_id_len Han-Wen Nienhuys via GitGitGadget
2022-02-18  0:32     ` Junio C Hamano
2022-02-17 13:55   ` [PATCH v2 3/7] reftable: add a test that verifies that writing empty keys fails Han-Wen Nienhuys via GitGitGadget
2022-02-17 13:55   ` [PATCH v2 4/7] reftable: avoid writing empty keys at the block layer Han-Wen Nienhuys via GitGitGadget
2022-02-17 23:55     ` Junio C Hamano
2022-02-21 14:32       ` Han-Wen Nienhuys
2022-02-17 13:55   ` [PATCH v2 5/7] reftable: ensure that obj_id_len is >= 2 on writing Han-Wen Nienhuys via GitGitGadget
2022-02-18  0:01     ` Junio C Hamano
2022-02-17 13:55   ` [PATCH v2 6/7] reftable: add test for length of disambiguating prefix Han-Wen Nienhuys via GitGitGadget
2022-02-17 13:55   ` [PATCH v2 7/7] reftable: rename writer_stats to reftable_writer_stats Han-Wen Nienhuys via GitGitGadget
2022-02-18  0:02   ` [PATCH v2 0/7] reftable: avoid reading and writing empty keys Junio C Hamano
2022-02-21 18:46   ` [PATCH v3 " Han-Wen Nienhuys via GitGitGadget
2022-02-21 18:46     ` [PATCH v3 1/7] Documentation: object_id_len goes up to 31 Han-Wen Nienhuys via GitGitGadget
2022-02-21 18:46     ` [PATCH v3 2/7] reftable: reject 0 object_id_len Han-Wen Nienhuys via GitGitGadget
2022-02-21 18:46     ` [PATCH v3 3/7] reftable: add a test that verifies that writing empty keys fails Han-Wen Nienhuys via GitGitGadget
2022-02-21 18:46     ` Han-Wen Nienhuys via GitGitGadget [this message]
2022-02-21 18:46     ` [PATCH v3 5/7] reftable: ensure that obj_id_len is >= 2 on writing Han-Wen Nienhuys via GitGitGadget
2022-02-21 18:46     ` [PATCH v3 6/7] reftable: add test for length of disambiguating prefix Han-Wen Nienhuys via GitGitGadget
2022-02-21 18:46     ` [PATCH v3 7/7] reftable: rename writer_stats to reftable_writer_stats Han-Wen Nienhuys via GitGitGadget
2022-02-23 21:37     ` [PATCH v3 0/7] reftable: avoid reading and writing empty keys Junio C Hamano

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