[PATCH v3 4/4] fetch-pack: support protocol version 2

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

From: Jonathan Tan <jonathantanmy@google.com>

When the scaffolding for protocol version 2 was initially added in
8f6982b4e1 ("protocol: introduce enum protocol_version value
protocol_v2", 2018-03-14). As seen in:

    git log -p -G'support for protocol v2 not implemented yet' --full-diff --reverse v2.17.0..v2.20.0

Many of those scaffolding "die" placeholders were removed, but we
hadn't gotten around to fetch-pack yet.

The test here for "fetch refs from cmdline" is very minimal. There's
much better coverage when running the entire test suite under the WIP
GIT_TEST_PROTOCOL_VERSION=2 mode[1], we should ideally have better
coverage without needing to invoke a special test mode.

1. https://public-inbox.org/git/20181213155817.27666-1-avarab@gmail.com/

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 builtin/fetch-pack.c  |  9 ++++++---
 t/t5500-fetch-pack.sh | 22 +++++++++++++++-------
 2 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/builtin/fetch-pack.c b/builtin/fetch-pack.c
index 63e69a58011..f6a513495ea 100644
--- a/builtin/fetch-pack.c
+++ b/builtin/fetch-pack.c
@@ -55,6 +55,7 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
 	struct oid_array shallow = OID_ARRAY_INIT;
 	struct string_list deepen_not = STRING_LIST_INIT_DUP;
 	struct packet_reader reader;
+	enum protocol_version version;
 
 	fetch_if_missing = 0;
 
@@ -219,9 +220,11 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
 			   PACKET_READ_CHOMP_NEWLINE |
 			   PACKET_READ_GENTLE_ON_EOF);
 
-	switch (discover_version(&reader)) {
+	version = discover_version(&reader);
+	switch (version) {
 	case protocol_v2:
-		die("support for protocol v2 not implemented yet");
+		get_remote_refs(fd[1], &reader, &ref, 0, NULL, NULL);
+		break;
 	case protocol_v1:
 	case protocol_v0:
 		get_remote_heads(&reader, &ref, 0, NULL, &shallow);
@@ -231,7 +234,7 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
 	}
 
 	ref = fetch_pack(&args, fd, conn, ref, dest, sought, nr_sought,
-			 &shallow, pack_lockfile_ptr, protocol_v0);
+			 &shallow, pack_lockfile_ptr, version);
 	if (pack_lockfile) {
 		printf("lock %s\n", pack_lockfile);
 		fflush(stdout);
diff --git a/t/t5500-fetch-pack.sh b/t/t5500-fetch-pack.sh
index 086f2c40f68..49c540b1e1d 100755
--- a/t/t5500-fetch-pack.sh
+++ b/t/t5500-fetch-pack.sh
@@ -439,15 +439,23 @@ test_expect_success 'setup tests for the --stdin parameter' '
 	) >input.dup
 '
 
-test_expect_success 'fetch refs from cmdline' '
-	(
-		cd client &&
-		git fetch-pack --no-progress .. $(cat ../input)
-	) >output &&
-	cut -d " " -f 2 <output | sort >actual &&
-	test_cmp expect actual
+test_expect_success 'setup fetch refs from cmdline v[12]' '
+	cp -r client client1 &&
+	cp -r client client2
 '
 
+for version in '' 1 2
+do
+	test_expect_success "protocol.version=$version fetch refs from cmdline" "
+		(
+			cd client$version &&
+			GIT_TEST_PROTOCOL_VERSION=$version git fetch-pack --no-progress .. \$(cat ../input)
+		) >output &&
+		cut -d ' ' -f 2 <output | sort >actual &&
+		test_cmp expect actual
+	"
+done
+
 test_expect_success 'fetch refs from stdin' '
 	(
 		cd client &&
-- 
2.20.0.405.gbc1bbc6f85