MidiService: update listener with current status when registered

This will give an app an opportunity to learn whether an input port is busy
before the user tries to connect and then fails.

Bug: 22825043
Change-Id: Ifede60f166dfe66ea15453044fce06f4a8452b18
Signed-off-by: Phil Burk <philburk@google.com>
(cherry picked from commit b2355940e3e697deeecd1b6511cd5094f9dc553a)

1 files changed, 21 insertions, 0 deletions

diff --git a/services/midi/java/com/android/server/midi/MidiService.java b/services/midi/java/com/android/server/midi/MidiService.java
index 3ecfd55..701e07f 100644
--- a/services/midi/java/com/android/server/midi/MidiService.java
+++ b/services/midi/java/com/android/server/midi/MidiService.java
@@ -575,6 +575,8 @@ public class MidiService extends IMidiManager.Stub {
         Client client = getClient(token);
         if (client == null) return;
         client.addListener(listener);
+        // Let listener know whether any ports are already busy.
+        updateStickyDeviceStatus(client.mUid, listener);
     }
 
     @Override
@@ -584,6 +586,25 @@ public class MidiService extends IMidiManager.Stub {
         client.removeListener(listener);
     }
 
+    // Inform listener of the status of all known devices.
+    private void updateStickyDeviceStatus(int uid, IMidiDeviceListener listener) {
+        synchronized (mDevicesByInfo) {
+            for (Device device : mDevicesByInfo.values()) {
+                // ignore private devices that our client cannot access
+                if (device.isUidAllowed(uid)) {
+                    try {
+                        MidiDeviceStatus status = device.getDeviceStatus();
+                        if (status != null) {
+                            listener.onDeviceStatusChanged(status);
+                        }
+                    } catch (RemoteException e) {
+                        Log.e(TAG, "remote exception", e);
+                    }
+                }
+            }
+        }
+    }
+
     private static final MidiDeviceInfo[] EMPTY_DEVICE_INFO_ARRAY = new MidiDeviceInfo[0];
 
     public MidiDeviceInfo[] getDevices() {