In order to talk with service manager, we need following things:
1. an unique id for the service we are going to build. It is a string16
2. add permission for our service to service manager.
For the point 1, I create an uint16 array like
uint16_t svcmgr_id16[] = {
'B','i','n','d','e','r','.','T','e','s','t','.','I','B','i','n',
'd','e','r','t','e','s','t'
};
for the point 2, I'm kind of lazy, I add a new item to the allowd[] in servicemanager. It looks like this:
{10001, "Binder.Test.IBindertest"}
Ok, lets get something real, we need to do following steps to make everything to work:
1. connect to the binder by calling binder_open function. The binder_open function creates a shared memory with /dev/binder. I copied service manager code to create a 128K shared memory.
2.create an io block through bio_init function to talk with service manager through binder. You need to provide a buff to bio_init. I use an integer array with size of 128
3. fill in the target (servicemanager) and source(Binder.Test.IBindertest) by calling bio_put_string16_x
4. call binder_call with command SVC_MGR_ADD_SERVICE. It is a blocking call. You need to provide a binder_io object for the result.
5. if binder_call returns 0, call binder_loop with a message handler callback function to process messages sent from service client.
The message processing callback function:
The prototype of the message processing callback functions is:
static int binder_handler(struct binder_state *bs,
struct binder_txn *txn,
struct binder_io *msg,
struct binder_io *reply)
In the callback function, we at least need to handle INTERFACE_TRANSACTION so that our service client can find our service.
switch(txn->code) {
case INTERFACE_TRANSACTION:
bio_put_string16(reply,svcmgr_id16);
break;
case
default:
error handling.
