improve gdb_init() sequence

Rework gdb_init to create flexible APIs (gdb_target_add_{one,all}) and
static helper (gdb_target_start) for starting GDB services.  Eliminates
duplicated code and provides general mechanisms for adding GDB services.
The 'init' command is updated to call the new API, and later patches can
decouple its policy of adding all targets therein.

Provides the new capability to use both piped and TCP servers when
multiple targets are defined.  The first target fills the pipe, and
others will be started on TCP ports (unless disabled, i.e. gdb_port=0).

src/openocd.c

@@ -154,7 +154,7 @@ COMMAND_HANDLER(handle_init_command)
 
 	/* initialize telnet subsystem */
 	telnet_init("Open On-Chip Debugger");
-	gdb_init();
+	gdb_target_add_all(all_targets);
 	tcl_init(); /* allows tcl to just connect without going thru telnet */
 
 	target_register_event_callback(log_target_callback_event_handler, CMD_CTX);

src/server/gdb_server.c

@@ -2189,55 +2189,68 @@ int gdb_input(struct connection *connection)
 	return ERROR_OK;
 }
 
-int gdb_init(void)
+static int gdb_target_start(struct target *target, uint16_t port)
 {
-	struct gdb_service *gdb_service;
-	struct target *target = all_targets;
+	bool use_pipes = 0 == port;
+	struct gdb_service *gdb_service = malloc(sizeof(struct gdb_service));
+	if (NULL == gdb_service)
+		return -ENOMEM;
 
-	if (!target)
-	{
-		LOG_WARNING("no gdb ports allocated as no target has been specified");
-		return ERROR_OK;
-	}
+	gdb_service->target = target;
 
+	add_service("gdb", use_pipes ? CONNECTION_PIPE : CONNECTION_TCP,
+			port, 1, &gdb_new_connection, &gdb_input,
+			&gdb_connection_closed, gdb_service);
+
+	const char *name = target_name(target);
+	if (use_pipes)
+		LOG_DEBUG("gdb service for target '%s' using pipes", name);
+	else
+		LOG_DEBUG("gdb service for target '%s' on TCP port %u", name, port);
+	return ERROR_OK;
+}
+
+int gdb_target_add_one(struct target *target)
+{
 	if (gdb_port == 0 && server_use_pipes == 0)
 	{
 		LOG_INFO("gdb port disabled");
 		return ERROR_OK;
 	}
 
-	if (server_use_pipes)
+	bool use_pipes = server_use_pipes;
+	static bool server_started_with_pipes = false;
+	if (server_started_with_pipes)
 	{
-		/* only a single gdb connection when using a pipe */
+		LOG_WARNING("gdb service permits one target when using pipes");
+		if (0 == gdb_port)
+			return ERROR_OK;
 
-		gdb_service = malloc(sizeof(struct gdb_service));
-		gdb_service->target = target;
-
-		add_service("gdb", CONNECTION_PIPE, 0, 1, gdb_new_connection, gdb_input, gdb_connection_closed, gdb_service);
-
-		LOG_DEBUG("gdb service for target %s using pipes",
-				target_name(target));
+		use_pipes = false;
 	}
-	else
+
+	int e = gdb_target_start(target, use_pipes ? 0 : gdb_port++);
+	if (ERROR_OK == e)
+		server_started_with_pipes |= use_pipes;
+
+	return e;
+}
+
+int gdb_target_add_all(struct target *target)
+{
+	if (NULL == target)
 	{
-		unsigned short port = gdb_port;
+		LOG_WARNING("gdb services need one or more targets defined");
+		return ERROR_OK;
+	}
 
-		while (target)
-		{
-			gdb_service = malloc(sizeof(struct gdb_service));
-			gdb_service->target = target;
+	while (NULL != target)
+	{
+		int retval = gdb_target_add_one(target);
+		if (ERROR_OK != retval)
+			return retval;
 
-			add_service("gdb", CONNECTION_TCP,
-					port, 1,
-					gdb_new_connection, gdb_input,
-					gdb_connection_closed, gdb_service);
-
-			LOG_DEBUG("gdb service for target %s at TCP port %i",
-					target_name(target),
-					port);
-			target = target->next;
-			port++;
-		}
+		target = target->next;
 	}
 
 	return ERROR_OK;

src/server/gdb_server.h

@@ -52,7 +52,8 @@ struct gdb_service
 	struct target *target;
 };
 
-int gdb_init(void);
+int gdb_target_add_one(struct target *target);
+int gdb_target_add_all(struct target *target);
 int gdb_register_commands(struct command_context *command_context);
 
 #define ERROR_GDB_BUFFER_TOO_SMALL (-800)