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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 5/7] reftable: ensure that obj_id_len is >= 2 on writing
Date: Mon, 21 Feb 2022 18:46:08 +0000	[thread overview]
Message-ID: <0b8a42399dd7aa04fdc791d25969a3b085190c6f.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>

When writing the same hash many times, we might decide to use a
length-1 object ID prefix for the ObjectID => ref table, which is out
of spec.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
---
 reftable/readwrite_test.c | 37 +++++++++++++++++++++++++++++++++++++
 reftable/writer.c         |  4 +++-
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/reftable/readwrite_test.c b/reftable/readwrite_test.c
index fd5922e55f6..35142eb070e 100644
--- a/reftable/readwrite_test.c
+++ b/reftable/readwrite_test.c
@@ -667,6 +667,42 @@ static void test_write_empty_table(void)
 	strbuf_release(&buf);
 }
 
+static void test_write_object_id_min_length(void)
+{
+	struct reftable_write_options opts = {
+		.block_size = 75,
+	};
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_writer *w =
+		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+	uint8_t hash[GIT_SHA1_RAWSZ] = {42};
+	struct reftable_ref_record ref = {
+		.update_index = 1,
+		.value_type = REFTABLE_REF_VAL1,
+		.value.val1 = hash,
+	};
+	int err;
+	int i;
+
+	reftable_writer_set_limits(w, 1, 1);
+
+	/* Write the same hash in many refs. If there is only 1 hash, the
+	 * disambiguating prefix is length 0 */
+	for (i = 0; i < 256; i++) {
+		char name[256];
+		snprintf(name, sizeof(name), "ref%05d", i);
+		ref.refname = name;
+		err = reftable_writer_add_ref(w, &ref);
+		EXPECT_ERR(err);
+	}
+
+	err = reftable_writer_close(w);
+	EXPECT_ERR(err);
+	EXPECT(writer_stats(w)->object_id_len == 2);
+	reftable_writer_free(w);
+	strbuf_release(&buf);
+}
+
 static void test_write_empty_key(void)
 {
 	struct reftable_write_options opts = { 0 };
@@ -772,5 +808,6 @@ int readwrite_test_main(int argc, const char *argv[])
 	RUN_TEST(test_write_empty_key);
 	RUN_TEST(test_write_empty_table);
 	RUN_TEST(test_log_overflow);
+	RUN_TEST(test_write_object_id_min_length);
 	return 0;
 }
diff --git a/reftable/writer.c b/reftable/writer.c
index d54215a50dc..5e4e6e93416 100644
--- a/reftable/writer.c
+++ b/reftable/writer.c
@@ -515,7 +515,9 @@ static void object_record_free(void *void_arg, void *key)
 static int writer_dump_object_index(struct reftable_writer *w)
 {
 	struct write_record_arg closure = { .w = w };
-	struct common_prefix_arg common = { NULL };
+	struct common_prefix_arg common = {
+		.max = 1,		/* obj_id_len should be >= 2. */
+	};
 	if (w->obj_index_tree) {
 		infix_walk(w->obj_index_tree, &update_common, &common);
 	}
-- 
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     ` [PATCH v3 4/7] reftable: avoid writing empty keys at the block layer Han-Wen Nienhuys via GitGitGadget
2022-02-21 18:46     ` Han-Wen Nienhuys via GitGitGadget [this message]
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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