[WIP 13/15] connect: request remote refs using v2

[Brandon Williams <bmwill@google.com>]

Teach the client to be able to request a remote's refs using protocol
v2.  This is done by having a client issue a 'ls-refs' request to a v2
server.

Signed-off-by: Brandon Williams <bmwill@google.com>
---
 connect.c              | 85 +++++++++++++++++++++++++++++++++++++++++++++++++-
 remote.h               |  2 ++
 t/t5701-protocol-v2.sh | 28 +++++++++++++++++
 transport.c            |  2 +-
 upload-pack.c          |  3 +-
 5 files changed, 117 insertions(+), 3 deletions(-)
 create mode 100755 t/t5701-protocol-v2.sh

diff --git a/connect.c b/connect.c
index 433f08649..b3c933fc1 100644
--- a/connect.c
+++ b/connect.c
@@ -15,6 +15,7 @@
 #include "protocol.h"
 
 static char *server_capabilities;
+static struct argv_array server_capabilities_v2 = ARGV_ARRAY_INIT;
 static const char *parse_feature_value(const char *, const char *, int *);
 
 static int check_ref(const char *name, unsigned int flags)
@@ -62,6 +63,30 @@ static void die_initial_contact(int unexpected)
 		      "and the repository exists."));
 }
 
+static int server_supports_v2(const char *c)
+{
+	int i;
+
+	for (i = 0; i < server_capabilities_v2.argc; i++) {
+		const char *out;
+		if (skip_prefix(server_capabilities_v2.argv[i], c, &out) &&
+		    (!*out || *out == '='))
+			return 1;
+	}
+
+	return 0;
+}
+
+static void process_capabilities_v2(struct packet_reader *reader)
+{
+	while (packet_reader_read(reader) == PACKET_READ_NORMAL) {
+		argv_array_push(&server_capabilities_v2, reader->line);
+	}
+
+	if (reader->status != PACKET_READ_FLUSH)
+		die("protocol error");
+}
+
 enum protocol_version discover_version(struct packet_reader *reader)
 {
 	enum protocol_version version = protocol_unknown_version;
@@ -85,7 +110,7 @@ enum protocol_version discover_version(struct packet_reader *reader)
 	/* Maybe process capabilities here, at least for v2 */
 	switch (version) {
 	case protocol_v2:
-		die("support for protocol v2 not implemented yet");
+		process_capabilities_v2(reader);
 		break;
 	case protocol_v1:
 		/* Read the peeked version line */
@@ -292,6 +317,64 @@ struct ref **get_remote_heads(struct packet_reader *reader,
 	return list;
 }
 
+static int process_ref_v2(const char *line, struct ref ***list)
+{
+	struct object_id old_oid;
+	const char *end_of_name;
+	struct ref *ref;
+
+	if (parse_oid_hex(line, &old_oid, &line))
+		return 0;
+	if (*line != ' ')
+		return 0;
+	line++;
+
+	end_of_name = strchr(line, ' ');
+
+	if (!end_of_name)
+		ref = alloc_ref(line);
+	else {
+		struct strbuf name = STRBUF_INIT;
+		/* symref info */
+		strbuf_add(&name, line, end_of_name - line);
+		ref = alloc_ref(name.buf);
+		ref->symref = xstrdup(end_of_name + 1);
+
+		strbuf_release(&name);
+	}
+
+	oidcpy(&ref->old_oid, &old_oid);
+	**list = ref;
+	*list = &ref->next;
+
+	return 1;
+}
+struct ref **get_remote_refs(int fd_out, struct packet_reader *reader,
+			     struct ref **list, unsigned int flags)
+{
+	*list = NULL;
+	/* Check that the server supports the ls-refs command */
+	if (!server_supports_v2("ls-refs"))
+		die("server doesn't support 'ls-refs' command");
+
+	/* Issue request for ls-refs */
+	packet_write_fmt(fd_out, "command=ls-refs");
+	packet_delim(fd_out);
+	packet_write_fmt(fd_out, "--symrefs");
+	packet_flush(fd_out);
+
+	/* Process response from server */
+	while (packet_reader_read(reader) == PACKET_READ_NORMAL) {
+		if (!process_ref_v2(reader->line, &list))
+			die("invalid ls-refs response: %s", reader->line);
+	}
+
+	if (reader->status != PACKET_READ_FLUSH)
+		die("protocol error");
+
+	return list;
+}
+
 static const char *parse_feature_value(const char *feature_list, const char *feature, int *lenp)
 {
 	int len;
diff --git a/remote.h b/remote.h
index af34e44a4..64d87bf5b 100644
--- a/remote.h
+++ b/remote.h
@@ -155,6 +155,8 @@ extern struct ref **get_remote_heads(struct packet_reader *reader,
 				     struct ref **list, unsigned int flags,
 				     struct oid_array *extra_have,
 				     struct oid_array *shallow_points);
+extern struct ref **get_remote_refs(int fd_out, struct packet_reader *reader,
+				    struct ref **list, unsigned int flags);
 
 int resolve_remote_symref(struct ref *ref, struct ref *list);
 int ref_newer(const struct object_id *new_oid, const struct object_id *old_oid);
diff --git a/t/t5701-protocol-v2.sh b/t/t5701-protocol-v2.sh
new file mode 100755
index 000000000..4bf4d61ac
--- /dev/null
+++ b/t/t5701-protocol-v2.sh
@@ -0,0 +1,28 @@
+#!/bin/sh
+
+test_description='test git wire-protocol version 2'
+
+TEST_NO_CREATE_REPO=1
+
+. ./test-lib.sh
+
+# Test protocol v2 with 'file://' transport
+#
+test_expect_success 'create repo to be served by file:// transport' '
+	git init file_parent &&
+	test_commit -C file_parent one
+'
+
+test_expect_success 'list refs with file:// using protocol v2' '
+	GIT_TRACE_PACKET=1 git -c protocol.version=2 \
+		ls-remote --symref "file://$(pwd)/file_parent" >actual 2>log &&
+
+	# Server responded using protocol v2
+	cat log &&
+	grep "git< version 2" log &&
+
+	git ls-remote --symref "file://$(pwd)/file_parent" >expect &&
+	test_cmp actual expect
+'
+
+test_done
diff --git a/transport.c b/transport.c
index 8a3735cf5..ddd0d6174 100644
--- a/transport.c
+++ b/transport.c
@@ -202,7 +202,7 @@ static struct ref *get_refs_via_connect(struct transport *transport, int for_pus
 	data->version = discover_version(&reader);
 	switch (data->version) {
 	case protocol_v2:
-		die("support for protocol v2 not implemented yet");
+		get_remote_refs(data->fd[1], &reader, &refs, for_push ? REF_NORMAL : 0);
 		break;
 	case protocol_v1:
 	case protocol_v0:
diff --git a/upload-pack.c b/upload-pack.c
index d706175e4..3296831f8 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -19,6 +19,7 @@
 #include "argv-array.h"
 #include "prio-queue.h"
 #include "protocol.h"
+#include "serve.h"
 
 static const char * const upload_pack_usage[] = {
 	N_("git upload-pack [<options>] <dir>"),
@@ -1106,7 +1107,7 @@ int cmd_upload_pack(int argc, const char **argv, const char *prefix)
 
 	switch (determine_protocol_version_server()) {
 	case protocol_v2:
-		die("support for protocol v2 not implemented yet");
+		serve();
 		break;
 	case protocol_v1:
 		/*
-- 
2.15.1.424.g9478a66081-goog