[RFC/WIP PATCH 06/11] remote.h: add get_remote_capabilities, request_capabilities

[Stefan Beller <sbeller@google.com>]

Instead of calling get_remote_heads as a first command during the
protocol exchange, we need to have fine grained control over the
capability negotiation in version 2 of the protocol.

Introduce get_remote_capabilities, which will just listen to
capabilities of the remote and request_capabilities which will
tell the selection of capabilities to the remote.

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 connect.c | 48 +++++++++++++++++++++++++++++++++++++++++++++++-
 remote.h  |  3 +++
 2 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/connect.c b/connect.c
index c0144d8..bb17618 100644
--- a/connect.c
+++ b/connect.c
@@ -105,8 +105,54 @@ static void annotate_refs_with_symref_info(struct ref *ref)
 	string_list_clear(&symref, 0);
 }
 
+void get_remote_capabilities(int in, char *src_buf, size_t src_len)
+{
+	struct strbuf capabilities_string = STRBUF_INIT;
+	for (;;) {
+		int len;
+		char *line = packet_buffer;
+		const char *arg;
+
+		len = packet_read(in, &src_buf, &src_len,
+				  packet_buffer, sizeof(packet_buffer),
+				  PACKET_READ_GENTLE_ON_EOF |
+				  PACKET_READ_CHOMP_NEWLINE);
+		if (len < 0)
+			die_initial_contact(0);
+
+		if (!len)
+			break;
+
+		if (len > 4 && skip_prefix(line, "ERR ", &arg))
+			die("remote error: %s", arg);
+
+		if (starts_with(line, "capability:")) {
+			strbuf_addstr(&capabilities_string, line + strlen("capability:"));
+			strbuf_addch(&capabilities_string, ' ');
+		}
+	}
+	free(server_capabilities);
+	server_capabilities = xmalloc(capabilities_string.len + 1);
+	server_capabilities = strbuf_detach(&capabilities_string, NULL);
+
+	strbuf_release(&capabilities_string);
+}
+
+int request_capabilities(int out)
+{
+	fprintf(stderr, "request_capabilities\n");
+	// todo: send our capabilities
+	packet_write(out, "capability:foo");
+	packet_flush(out);
+}
+
 /*
- * Read all the refs from the other end
+ * Read all the refs from the other end,
+ * in is a file descriptor input stream
+ * src_buf and src_len may be an alternative way to specify the input.
+ * list is the output of refs
+ * extra_have is a list to store information learned about sha1 the other side has.
+ * shallow_points
  */
 struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
 			      struct ref **list, unsigned int flags,
diff --git a/remote.h b/remote.h
index 04e2310..7381ddf 100644
--- a/remote.h
+++ b/remote.h
@@ -146,6 +146,9 @@ int check_ref_type(const struct ref *ref, int flags);
 void free_refs(struct ref *ref);
 
 struct sha1_array;
+
+extern void get_remote_capabilities(int in, char *src_buf, size_t src_len);
+extern int request_capabilities(int out);
 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,
-- 
2.4.1.345.gab207b6.dirty