connect.c: teach get_remote_heads to parse "shallow" lines

No callers pass a non-empty pointer as shallow_points at this
stage. As a result, all clients still refuse to talk to shallow
repository on the other end.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/fetch-pack.c

@@ -150,7 +150,7 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
 				   args.verbose ? CONNECT_VERBOSE : 0);
 	}
 
-	get_remote_heads(fd[0], NULL, 0, &ref, 0, NULL);
+	get_remote_heads(fd[0], NULL, 0, &ref, 0, NULL, NULL);
 
 	ref = fetch_pack(&args, fd, conn, ref, dest,
 			 sought, nr_sought, pack_lockfile_ptr);

builtin/send-pack.c

@@ -232,7 +232,7 @@ 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);
+	get_remote_heads(fd[0], NULL, 0, &remote_refs, REF_NORMAL, &extra_have, NULL);
 
 	transport_verify_remote_names(nr_refspecs, refspecs);
 

connect.c

@@ -116,7 +116,8 @@ static void annotate_refs_with_symref_info(struct ref *ref)
  */
 struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
 			      struct ref **list, unsigned int flags,
-			      struct sha1_array *extra_have)
+			      struct sha1_array *extra_have,
+			      struct sha1_array *shallow_points)
 {
 	struct ref **orig_list = list;
 	int got_at_least_one_head = 0;
@@ -142,6 +143,15 @@ struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
 		if (len > 4 && !prefixcmp(buffer, "ERR "))
 			die("remote error: %s", buffer + 4);
 
+		if (len == 48 && !prefixcmp(buffer, "shallow ")) {
+			if (get_sha1_hex(buffer + 8, old_sha1))
+				die("protocol error: expected shallow sha-1, got '%s'", buffer + 8);
+			if (!shallow_points)
+				die("repository on the other end cannot be shallow");
+			sha1_array_append(shallow_points, old_sha1);
+			continue;
+		}
+
 		if (len < 42 || get_sha1_hex(buffer, old_sha1) || buffer[40] != ' ')
 			die("protocol error: expected sha/ref, got '%s'", buffer);
 		name = buffer + 41;

remote-curl.c

@@ -107,7 +107,7 @@ 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);
+			 for_push ? REF_NORMAL : 0, NULL, NULL);
 	return list;
 }
 

remote.h

@@ -140,7 +140,8 @@ void free_refs(struct ref *ref);
 struct sha1_array;
 extern struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
 				     struct ref **list, unsigned int flags,
-				     struct sha1_array *extra_have);
+				     struct sha1_array *extra_have,
+				     struct sha1_array *shallow);
 
 int resolve_remote_symref(struct ref *ref, struct ref *list);
 int ref_newer(const unsigned char *new_sha1, const unsigned char *old_sha1);

transport.c

@@ -512,7 +512,7 @@ static struct ref *get_refs_via_connect(struct transport *transport, int for_pus
 
 	connect_setup(transport, for_push, 0);
 	get_remote_heads(data->fd[0], NULL, 0, &refs,
-			 for_push ? REF_NORMAL : 0, &data->extra_have);
+			 for_push ? REF_NORMAL : 0, &data->extra_have, NULL);
 	data->got_remote_heads = 1;
 
 	return refs;
@@ -542,7 +542,8 @@ static int fetch_refs_via_pack(struct transport *transport,
 
 	if (!data->got_remote_heads) {
 		connect_setup(transport, 0, 0);
-		get_remote_heads(data->fd[0], NULL, 0, &refs_tmp, 0, NULL);
+		get_remote_heads(data->fd[0], NULL, 0, &refs_tmp, 0,
+				 NULL, NULL);
 		data->got_remote_heads = 1;
 	}
 
@@ -806,7 +807,7 @@ static int git_transport_push(struct transport *transport, struct ref *remote_re
 		struct ref *tmp_refs;
 		connect_setup(transport, 1, 0);
 
-		get_remote_heads(data->fd[0], NULL, 0, &tmp_refs, REF_NORMAL, NULL);
+		get_remote_heads(data->fd[0], NULL, 0, &tmp_refs, REF_NORMAL, NULL, NULL);
 		data->got_remote_heads = 1;
 	}