serve: introduce git-serve

Introduce git-serve, the base server for protocol version 2.

Protocol version 2 is intended to be a replacement for Git's current
wire protocol.  The intention is that it will be a simpler, less
wasteful protocol which can evolve over time.

Protocol version 2 improves upon version 1 by eliminating the initial
ref advertisement.  In its place a server will export a list of
capabilities and commands which it supports in a capability
advertisement.  A client can then request that a particular command be
executed by providing a number of capabilities and command specific
parameters.  At the completion of a command, a client can request that
another command be executed or can terminate the connection by sending a
flush packet.

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

builtin/serve.c

@@ -0,0 +1,30 @@
+#include "cache.h"
+#include "builtin.h"
+#include "parse-options.h"
+#include "serve.h"
+
+static char const * const serve_usage[] = {
+	N_("git serve [<options>]"),
+	NULL
+};
+
+int cmd_serve(int argc, const char **argv, const char *prefix)
+{
+	struct serve_options opts = SERVE_OPTIONS_INIT;
+
+	struct option options[] = {
+		OPT_BOOL(0, "stateless-rpc", &opts.stateless_rpc,
+			 N_("quit after a single request/response exchange")),
+		OPT_BOOL(0, "advertise-capabilities", &opts.advertise_capabilities,
+			 N_("exit immediately after advertising capabilities")),
+		OPT_END()
+	};
+
+	/* ignore all unknown cmdline switches for now */
+	argc = parse_options(argc, argv, prefix, options, serve_usage,
+			     PARSE_OPT_KEEP_DASHDASH |
+			     PARSE_OPT_KEEP_UNKNOWN);
+	serve(&opts);
+
+	return 0;
+}