connect: discover protocol version outside of get_remote_heads

In order to prepare for the addition of protocol_v2 push the protocol
version discovery outside of 'get_remote_heads()'.  This will allow for
keeping the logic for processing the reference advertisement for
protocol_v1 and protocol_v0 separate from the logic for protocol_v2.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/fetch-pack.c

@@ -4,6 +4,7 @@
 #include "remote.h"
 #include "connect.h"
 #include "sha1-array.h"
+#include "protocol.h"
 
 static const char fetch_pack_usage[] =
 "git fetch-pack [--all] [--stdin] [--quiet | -q] [--keep | -k] [--thin] "
@@ -52,6 +53,7 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
 	struct fetch_pack_args args;
 	struct oid_array shallow = OID_ARRAY_INIT;
 	struct string_list deepen_not = STRING_LIST_INIT_DUP;
+	struct packet_reader reader;
 
 	packet_trace_identity("fetch-pack");
 
@@ -193,7 +195,19 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
 		if (!conn)
 			return args.diag_url ? 0 : 1;
 	}
-	get_remote_heads(fd[0], NULL, 0, &ref, 0, NULL, &shallow);
+
+	packet_reader_init(&reader, fd[0], NULL, 0,
+			   PACKET_READ_CHOMP_NEWLINE |
+			   PACKET_READ_GENTLE_ON_EOF);
+
+	switch (discover_version(&reader)) {
+	case protocol_v1:
+	case protocol_v0:
+		get_remote_heads(&reader, &ref, 0, NULL, &shallow);
+		break;
+	case protocol_unknown_version:
+		BUG("unknown protocol version");
+	}
 
 	ref = fetch_pack(&args, fd, conn, ref, dest, sought, nr_sought,
 			 &shallow, pack_lockfile_ptr);

builtin/send-pack.c

@@ -14,6 +14,7 @@
 #include "sha1-array.h"
 #include "gpg-interface.h"
 #include "gettext.h"
+#include "protocol.h"
 
 static const char * const send_pack_usage[] = {
 	N_("git send-pack [--all | --mirror] [--dry-run] [--force] "
@@ -154,6 +155,7 @@ int cmd_send_pack(int argc, const char **argv, const char *prefix)
 	int progress = -1;
 	int from_stdin = 0;
 	struct push_cas_option cas = {0};
+	struct packet_reader reader;
 
 	struct option options[] = {
 		OPT__VERBOSITY(&verbose),
@@ -256,8 +258,19 @@ int cmd_send_pack(int argc, const char **argv, const char *prefix)
 			args.verbose ? CONNECT_VERBOSE : 0);
 	}
 
-	get_remote_heads(fd[0], NULL, 0, &remote_refs, REF_NORMAL,
-			 &extra_have, &shallow);
+	packet_reader_init(&reader, fd[0], NULL, 0,
+			   PACKET_READ_CHOMP_NEWLINE |
+			   PACKET_READ_GENTLE_ON_EOF);
+
+	switch (discover_version(&reader)) {
+	case protocol_v1:
+	case protocol_v0:
+		get_remote_heads(&reader, &remote_refs, REF_NORMAL,
+				 &extra_have, &shallow);
+		break;
+	case protocol_unknown_version:
+		BUG("unknown protocol version");
+	}
 
 	transport_verify_remote_names(nr_refspecs, refspecs);
 

connect.c

@@ -62,7 +62,7 @@ static void die_initial_contact(int unexpected)
 		      "and the repository exists."));
 }
 
-static enum protocol_version discover_version(struct packet_reader *reader)
+enum protocol_version discover_version(struct packet_reader *reader)
 {
 	enum protocol_version version = protocol_unknown_version;
 
@@ -233,7 +233,7 @@ enum get_remote_heads_state {
 /*
  * Read all the refs from the other end
  */
-struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
+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)
@@ -241,24 +241,17 @@ struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
 	struct ref **orig_list = list;
 	int len = 0;
 	enum get_remote_heads_state state = EXPECTING_FIRST_REF;
-	struct packet_reader reader;
 	const char *arg;
 
-	packet_reader_init(&reader, in, src_buf, src_len,
-			   PACKET_READ_CHOMP_NEWLINE |
-			   PACKET_READ_GENTLE_ON_EOF);
-
-	discover_version(&reader);
-
 	*list = NULL;
 
 	while (state != EXPECTING_DONE) {
-		switch (packet_reader_read(&reader)) {
+		switch (packet_reader_read(reader)) {
 		case PACKET_READ_EOF:
 			die_initial_contact(1);
 		case PACKET_READ_NORMAL:
-			len = reader.pktlen;
-			if (len > 4 && skip_prefix(reader.line, "ERR ", &arg))
+			len = reader->pktlen;
+			if (len > 4 && skip_prefix(reader->line, "ERR ", &arg))
 				die("remote error: %s", arg);
 			break;
 		case PACKET_READ_FLUSH:
@@ -270,22 +263,22 @@ struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
 
 		switch (state) {
 		case EXPECTING_FIRST_REF:
-			process_capabilities(reader.line, &len);
-			if (process_dummy_ref(reader.line)) {
+			process_capabilities(reader->line, &len);
+			if (process_dummy_ref(reader->line)) {
 				state = EXPECTING_SHALLOW;
 				break;
 			}
 			state = EXPECTING_REF;
 			/* fallthrough */
 		case EXPECTING_REF:
-			if (process_ref(reader.line, len, &list, flags, extra_have))
+			if (process_ref(reader->line, len, &list, flags, extra_have))
 				break;
 			state = EXPECTING_SHALLOW;
 			/* fallthrough */
 		case EXPECTING_SHALLOW:
-			if (process_shallow(reader.line, len, shallow_points))
+			if (process_shallow(reader->line, len, shallow_points))
 				break;
-			die("protocol error: unexpected '%s'", reader.line);
+			die("protocol error: unexpected '%s'", reader->line);
 		case EXPECTING_DONE:
 			break;
 		}

connect.h

@@ -13,4 +13,7 @@ extern int parse_feature_request(const char *features, const char *feature);
 extern const char *server_feature_value(const char *feature, int *len_ret);
 extern int url_is_local_not_ssh(const char *url);
 
+struct packet_reader;
+extern enum protocol_version discover_version(struct packet_reader *reader);
+
 #endif

remote-curl.c

@@ -1,6 +1,7 @@
 #include "cache.h"
 #include "config.h"
 #include "remote.h"
+#include "connect.h"
 #include "strbuf.h"
 #include "walker.h"
 #include "http.h"
@@ -13,6 +14,7 @@
 #include "credential.h"
 #include "sha1-array.h"
 #include "send-pack.h"
+#include "protocol.h"
 
 static struct remote *remote;
 /* always ends with a trailing slash */
@@ -176,8 +178,22 @@ static struct discovery *last_discovery;
 static struct ref *parse_git_refs(struct discovery *heads, int for_push)
 {
 	struct ref *list = NULL;
-	get_remote_heads(-1, heads->buf, heads->len, &list,
-			 for_push ? REF_NORMAL : 0, NULL, &heads->shallow);
+	struct packet_reader reader;
+
+	packet_reader_init(&reader, -1, heads->buf, heads->len,
+			   PACKET_READ_CHOMP_NEWLINE |
+			   PACKET_READ_GENTLE_ON_EOF);
+
+	switch (discover_version(&reader)) {
+	case protocol_v1:
+	case protocol_v0:
+		get_remote_heads(&reader, &list, for_push ? REF_NORMAL : 0,
+				 NULL, &heads->shallow);
+		break;
+	case protocol_unknown_version:
+		BUG("unknown protocol version");
+	}
+
 	return list;
 }
 

remote.h

@@ -150,10 +150,11 @@ int check_ref_type(const struct ref *ref, int flags);
 void free_refs(struct ref *ref);
 
 struct oid_array;
-extern struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
+struct packet_reader;
+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);
+				     struct oid_array *shallow_points);
 
 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);

transport.c

@@ -18,6 +18,7 @@
 #include "sha1-array.h"
 #include "sigchain.h"
 #include "transport-internal.h"
+#include "protocol.h"
 
 static void set_upstreams(struct transport *transport, struct ref *refs,
 	int pretend)
@@ -190,13 +191,26 @@ static int connect_setup(struct transport *transport, int for_push)
 static struct ref *get_refs_via_connect(struct transport *transport, int for_push)
 {
 	struct git_transport_data *data = transport->data;
-	struct ref *refs;
+	struct ref *refs = NULL;
+	struct packet_reader reader;
 
 	connect_setup(transport, for_push);
-	get_remote_heads(data->fd[0], NULL, 0, &refs,
-			 for_push ? REF_NORMAL : 0,
-			 &data->extra_have,
-			 &data->shallow);
+
+	packet_reader_init(&reader, data->fd[0], NULL, 0,
+			   PACKET_READ_CHOMP_NEWLINE |
+			   PACKET_READ_GENTLE_ON_EOF);
+
+	switch (discover_version(&reader)) {
+	case protocol_v1:
+	case protocol_v0:
+		get_remote_heads(&reader, &refs,
+				 for_push ? REF_NORMAL : 0,
+				 &data->extra_have,
+				 &data->shallow);
+		break;
+	case protocol_unknown_version:
+		BUG("unknown protocol version");
+	}
 	data->got_remote_heads = 1;
 
 	return refs;