[PATCH v3 8/8] fetch-pack: implement ref-in-want

[Brandon Williams <bmwill@google.com>]

Implement ref-in-want on the client side so that when a server supports
the "ref-in-want" feature, a client will send "want-ref" lines for each
reference the client wants to fetch.

Signed-off-by: Brandon Williams <bmwill@google.com>
---
 fetch-pack.c                       | 35 +++++++++++++++++++++++++++---
 remote.c                           |  1 +
 remote.h                           |  1 +
 t/t5703-upload-pack-ref-in-want.sh |  4 ++--
 4 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/fetch-pack.c b/fetch-pack.c
index f1709e816..681b44061 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -1102,9 +1102,10 @@ static void add_shallow_requests(struct strbuf *req_buf,
 
 static void add_wants(const struct ref *wants, struct strbuf *req_buf)
 {
+	int use_ref_in_want = server_supports_feature("fetch", "ref-in-want", 0);
+
 	for ( ; wants ; wants = wants->next) {
 		const struct object_id *remote = &wants->old_oid;
-		const char *remote_hex;
 		struct object *o;
 
 		/*
@@ -1122,8 +1123,10 @@ static void add_wants(const struct ref *wants, struct strbuf *req_buf)
 			continue;
 		}
 
-		remote_hex = oid_to_hex(remote);
-		packet_buf_write(req_buf, "want %s\n", remote_hex);
+		if (!use_ref_in_want || wants->exact_oid)
+			packet_buf_write(req_buf, "want %s\n", oid_to_hex(remote));
+		else
+			packet_buf_write(req_buf, "want-ref %s\n", wants->name);
 	}
 }
 
@@ -1334,6 +1337,29 @@ static void receive_shallow_info(struct fetch_pack_args *args,
 	args->deepen = 1;
 }
 
+static void receive_wanted_refs(struct packet_reader *reader, struct ref *refs)
+{
+	process_section_header(reader, "wanted-refs", 0);
+	while (packet_reader_read(reader) == PACKET_READ_NORMAL) {
+		struct object_id oid;
+		const char *end;
+		struct ref *r = NULL;
+
+		if (parse_oid_hex(reader->line, &oid, &end) || *end++ != ' ')
+			die("expected wanted-ref, got '%s'", reader->line);
+
+		for (r = refs; r; r = r->next) {
+			if (!strcmp(end, r->name)) {
+				oidcpy(&r->old_oid, &oid);
+				break;
+			}
+		}
+	}
+
+	if (reader->status != PACKET_READ_DELIM)
+		die("error processing wanted refs: %d", reader->status);
+}
+
 enum fetch_state {
 	FETCH_CHECK_LOCAL = 0,
 	FETCH_SEND_REQUEST,
@@ -1408,6 +1434,9 @@ static struct ref *do_fetch_pack_v2(struct fetch_pack_args *args,
 			if (process_section_header(&reader, "shallow-info", 1))
 				receive_shallow_info(args, &reader);
 
+			if (process_section_header(&reader, "wanted-refs", 1))
+				receive_wanted_refs(&reader, ref);
+
 			/* get the pack */
 			process_section_header(&reader, "packfile", 0);
 			if (get_pack(args, fd, pack_lockfile))
diff --git a/remote.c b/remote.c
index abe80c139..2c2376fff 100644
--- a/remote.c
+++ b/remote.c
@@ -1735,6 +1735,7 @@ int get_fetch_map(const struct ref *remote_refs,
 		if (refspec->exact_sha1) {
 			ref_map = alloc_ref(name);
 			get_oid_hex(name, &ref_map->old_oid);
+			ref_map->exact_oid = 1;
 		} else {
 			ref_map = get_remote_ref(remote_refs, name);
 		}
diff --git a/remote.h b/remote.h
index 45ecc6cef..976292152 100644
--- a/remote.h
+++ b/remote.h
@@ -73,6 +73,7 @@ struct ref {
 		force:1,
 		forced_update:1,
 		expect_old_sha1:1,
+		exact_oid:1,
 		deletion:1;
 
 	enum {
diff --git a/t/t5703-upload-pack-ref-in-want.sh b/t/t5703-upload-pack-ref-in-want.sh
index 979ab6d03..b94a51380 100755
--- a/t/t5703-upload-pack-ref-in-want.sh
+++ b/t/t5703-upload-pack-ref-in-want.sh
@@ -204,7 +204,7 @@ test_expect_success 'server is initially ahead - no ref in want' '
 	grep "ERR upload-pack: not our ref" err
 '
 
-test_expect_failure 'server is initially ahead - ref in want' '
+test_expect_success 'server is initially ahead - ref in want' '
 	git -C "$REPO" config uploadpack.allowRefInWant true &&
 	rm -rf local &&
 	cp -r "$LOCAL_PRISTINE" local &&
@@ -228,7 +228,7 @@ test_expect_success 'server is initially behind - no ref in want' '
 	test_cmp expected actual
 '
 
-test_expect_failure 'server is initially behind - ref in want' '
+test_expect_success 'server is initially behind - ref in want' '
 	git -C "$REPO" config uploadpack.allowRefInWant true &&
 	rm -rf local &&
 	cp -r "$LOCAL_PRISTINE" local &&
-- 
2.18.0.rc1.244.gcf134e6275-goog