dbus cの例

先日C++下のapi呼び出しインスタンスを整理しましたが、ついでにCの呼び出しインスタンスを整理します.
コードはdbusの参照コードで、直接copyで使われ、基本的にdbusはcの下で使われています.
自分で読むことができるほど興味があります.

/*
* Example low-level D-Bus code.
* Written by Matthew Johnson 
*
* This code has been released into the Public Domain.
* You may do whatever you like with it.
*/
#include 
#include 
#include 
#include 
#include 
/**
* Connect to the DBUS bus and send a broadcast signal
*/
void sendsignal(char* sigvalue)
{
	DBusMessage* msg;
	DBusMessageIter args;
	DBusConnection* conn;
	DBusError err;
	int ret;
	dbus_uint32_t serial = 0;
	printf("Sending signal with value %s
", sigvalue);
	// initialise the error value
	dbus_error_init(&err);
	// connect to the DBUS system bus, and check for errors
	conn = dbus_bus_get(DBUS_BUS_SESSION, &err);
	if (dbus_error_is_set(&err)) {
	fprintf(stderr, "Connection Error (%s)
", err.message);
	dbus_error_free(&err);
	}
	if (NULL == conn) {
	exit(1);
	}
// register our name on the bus, and check for errors
	ret	=dbus_bus_request_name(conn,"test.signal.source",\
	DBUS_NAME_FLAG_REPLACE_EXISTING , &err);
	if (dbus_error_is_set(&err)) {
	fprintf(stderr, "Name Error (%s)
", err.message);
	dbus_error_free(&err);
	}
	if (DBUS_REQUEST_NAME_REPLY_PRIMARY_OWNER != ret) {
	exit(1);
	}
// create a signal & check for errors
	msg = dbus_message_new_signal("/test/signal/Object", // object name of the signal
	"test.signal.Type", // interface name of the signal
	"Test");
	// name of the signal
	if (NULL == msg)
	{
	fprintf(stderr, "Message Null
");
	exit(1);
	}
// append arguments onto signal
	dbus_message_iter_init_append(msg, &args);
	if (!dbus_message_iter_append_basic(&args, DBUS_TYPE_STRING, &sigvalue)) {
	fprintf(stderr, "Out Of Memory!
");
	exit(1);
	}
	// send the message and flush the connection
	if (!dbus_connection_send(conn, msg, &serial)) {
	fprintf(stderr, "Out Of Memory!
");
	exit(1);
	}
	dbus_connection_flush(conn);
	printf("Signal Sent
");
	// free the message
	dbus_message_unref(msg);
}


/**
* Call a method on a remote object
*/
void query(char* param)
{
	DBusMessage* msg;
	DBusMessageIter args;
	DBusConnection* conn;
	DBusError err;
	DBusPendingCall* pending;
	int ret;
	bool stat;
	dbus_uint32_t level;
	printf("Calling remote method with %s
", param);
	// initialiset the errors
	dbus_error_init(&err);
	// connect to the system bus and check for errors
	conn = dbus_bus_get(DBUS_BUS_SESSION, &err);
	if (dbus_error_is_set(&err)) {
	fprintf(stderr, "Connection Error (%s)
", err.message);
	dbus_error_free(&err);
	}
	if (NULL == conn) {
	exit(1);
	}
	// request our name on the bus
	ret
	=
	dbus_bus_request_name(conn,"test.method.caller",\
	DBUS_NAME_FLAG_REPLACE_EXISTING , &err);
	if (dbus_error_is_set(&err)) {
	fprintf(stderr, "Name Error (%s)
", err.message);
	dbus_error_free(&err);
	}
	if (DBUS_REQUEST_NAME_REPLY_PRIMARY_OWNER != ret) {
	exit(1);
	}
"test.method.caller",
// create a new method call and check for errors
	msg = dbus_message_new_method_call("test.method.server",// target for the method call
	"/test/method/Object", // object to call on
	"test.method.Type", // interface to call on
	"Method");
	// method name
	if (NULL == msg) {
	fprintf(stderr, "Message Null
");
	exit(1);
	}
	// append arguments
	dbus_message_iter_init_append(msg, &args);
	if (!dbus_message_iter_append_basic(&args, DBUS_TYPE_STRING, ¶m)) {
	fprintf(stderr, "Out Of Memory!
");
	exit(1);
	}
	// send message and get a handle for a reply
	if (!dbus_connection_send_with_reply (conn, msg, &pending, -1)) { // -1 is default timeout
	fprintf(stderr, "Out Of Memory!
");
	exit(1);
	}
	if (NULL == pending) {
	fprintf(stderr, "Pending Call Null
");
	exit(1);
	}
	dbus_connection_flush(conn);
	printf("Request Sent
");
	// free message
	dbus_message_unref(msg);
	// block until we recieve a reply
	dbus_pending_call_block(pending);
	// get the reply message
	msg = dbus_pending_call_steal_reply(pending);
	if (NULL == msg) {
	fprintf(stderr, "Reply Null
");
	exit(1);
	}
	// free the pending message handle
	dbus_pending_call_unref(pending);
	// read the parameters
	if (!dbus_message_iter_init(msg, &args))
	fprintf(stderr, "Message has no arguments!
");
	else if (DBUS_TYPE_BOOLEAN != dbus_message_iter_get_arg_type(&args))
	fprintf(stderr, "Argument is not boolean!
");
	else
	dbus_message_iter_get_basic(&args, &stat);
	if (!dbus_message_iter_next(&args))
	fprintf(stderr, "Message has too few arguments!
");
	else if (DBUS_TYPE_UINT32 != dbus_message_iter_get_arg_type(&args))
	fprintf(stderr, "Argument is not int!
");
	else
	dbus_message_iter_get_basic(&args, &level);
	printf("Got Reply: %d, %d
", stat, level);
	// free reply
	dbus_message_unref(msg);
}
void reply_to_method_call(DBusMessage* msg, DBusConnection* conn)
{
	DBusMessage* reply;
	DBusMessageIter args;
	bool stat = true;
	dbus_uint32_t level = 21614;
	dbus_uint32_t serial = 0;
	char* param = "";
	// read the arguments
	if (!dbus_message_iter_init(msg, &args))
	fprintf(stderr, "Message has no arguments!
");
	else if (DBUS_TYPE_STRING != dbus_message_iter_get_arg_type(&args))
	fprintf(stderr, "Argument is not string!
");
	else
	dbus_message_iter_get_basic(&args, ¶m);
	printf("Method called with %s
", param);
	// create a reply from the message
	reply = dbus_message_new_method_return(msg);
	// add the arguments to the reply
	dbus_message_iter_init_append(reply, &args);
	if (!dbus_message_iter_append_basic(&args, DBUS_TYPE_BOOLEAN, &stat)) {
	fprintf(stderr, "Out Of Memory!
");
	exit(1);
	}
	if (!dbus_message_iter_append_basic(&args, DBUS_TYPE_UINT32, &level)) {
	fprintf(stderr, "Out Of Memory!
");
	exit(1);
	}
	// send the reply && flush the connection
	if (!dbus_connection_send(conn, reply, &serial)) {
	fprintf(stderr, "Out Of Memory!
");
	exit(1);
	}
	dbus_connection_flush(conn);
	// free the reply
	dbus_message_unref(reply);
}
/**
* Server that exposes a method call and waits for it to be called
*/
void listen()
{
	DBusMessage* msg;
	DBusMessage* reply;
	DBusMessageIter args;
	DBusConnection* conn;
	DBusError err;
	int ret;
	char* param;
	printf("Listening for method calls
");
	// initialise the error
	dbus_error_init(&err);
	// connect to the bus and check for errors
	conn = dbus_bus_get(DBUS_BUS_SESSION, &err);
	if (dbus_error_is_set(&err)) {
	fprintf(stderr, "Connection Error (%s)
", err.message);
	dbus_error_free(&err);
	}
	if (NULL == conn) {
	fprintf(stderr, "Connection Null
");
	exit(1);
	}
	// request our name on the bus and check for errors
	ret = dbus_bus_request_name(conn, "test.method.server",
	DBUS_NAME_FLAG_REPLACE_EXISTING , &err);
	if (dbus_error_is_set(&err)) {
	fprintf(stderr, "Name Error (%s)
", err.message);
	dbus_error_free(&err);
	}
	if (DBUS_REQUEST_NAME_REPLY_PRIMARY_OWNER != ret) {
	fprintf(stderr, "Not Primary Owner (%d)
", ret);
	exit(1);
	}
	// loop, testing for new messages
	while (true) {
	// non blocking read of the next available message
	dbus_connection_read_write(conn, 0);
	msg = dbus_connection_pop_message(conn);
	// loop again if we haven't got a message
	if (NULL == msg) {
	sleep(1);
	continue;
	}
	// check this is a method call for the right interface & method
	if (dbus_message_is_method_call(msg, "test.method.Type", "Method"))
	reply_to_method_call(msg, conn);
	// free the message
	dbus_message_unref(msg);
}
}
/**
* Listens for signals on the bus
*/
void receive()
{
	DBusMessage* msg;
	DBusMessageIter args;
	DBusConnection* conn;
	DBusError err;
	int ret;
	char* sigvalue;
	printf("Listening for signals
");
	// initialise the errors
	dbus_error_init(&err);
	// connect to the bus and check for errors
	conn = dbus_bus_get(DBUS_BUS_SESSION, &err);
	if (dbus_error_is_set(&err)) {
	fprintf(stderr, "Connection Error (%s)
", err.message);
	dbus_error_free(&err);
	}
	if (NULL == conn) {
	exit(1);
	}
	// request our name on the bus and check for errors
	ret=dbus_bus_request_name(conn,"test.signal.sink",\
	DBUS_NAME_FLAG_REPLACE_EXISTING , &err);
	if (dbus_error_is_set(&err)) {
	fprintf(stderr, "Name Error (%s)
", err.message);
	dbus_error_free(&err);
	}
	if (DBUS_REQUEST_NAME_REPLY_PRIMARY_OWNER != ret) {
	exit(1);
	}
	"test.signal.sink",
	// add a rule for which messages we want to see
	dbus_bus_add_match(conn, "type='signal',interface='test.signal.Type'", &err); // see signals
										 //from the given interface
	dbus_connection_flush(conn);
	if (dbus_error_is_set(&err)) {
	fprintf(stderr, "Match Error (%s)
", err.message);
	exit(1);
	}
	printf("Match rule sent
");
	// loop listening for signals being emmitted
	while (true) {
	// non blocking read of the next available message
	dbus_connection_read_write(conn, 0);
	msg = dbus_connection_pop_message(conn);
	// loop again if we haven't read a message
	if (NULL == msg) {
	sleep(1);
	continue;
	}
	// check if the message is a signal from the correct interface and with the correct name
	if (dbus_message_is_signal(msg, "test.signal.Type", "Test")) {
	// read the parameters
	if (!dbus_message_iter_init(msg, &args))
	fprintf(stderr, "Message Has No Parameters
");
	else if (DBUS_TYPE_STRING != dbus_message_iter_get_arg_type(&args))
	fprintf(stderr, "Argument is not string!
");
	else
	dbus_message_iter_get_basic(&args, &sigvalue);
	printf("Got Signal with value %s
", sigvalue);
	}
	// free the message
	dbus_message_unref(msg);
	}
}

int main(int argc, char** argv)
{
	if (2 > argc) {
	printf ("Syntax: dbus-example [send|receive|listen|query] []
");
	return 1;
	}
	char* param = "no param";
	if (3 >= argc && NULL != argv[2]) param = argv[2];
	if (0 == strcmp(argv[1], "send"))
	sendsignal(param);
	else if (0 == strcmp(argv[1], "receive"))
	receive();
	else if (0 == strcmp(argv[1], "listen"))
	listen();
	else if (0 == strcmp(argv[1], "query"))
	query(param);else {
	printf ("Syntax: dbus-example [send|receive|listen|query] []
");
	return 1;
	}
	return 0;
}