Do not call `byteArrayToWritableMap` with a null byte array

Version

Tell us which versions you are using:

• react-native-ble-manager v6.4.0
• react-native v0.52.3
• Android v7.1.1

Expected behaviour

My log should not constantly get these errors:

01:57 W/System.err: java.lang.NullPointerException: Attempt to get length of null array
01:57 W/System.err: 	at android.util.Base64.encode(Base64.java:494)
01:57 W/System.err: 	at android.util.Base64.encodeToString(Base64.java:456)
01:57 W/System.err: 	at it.innove.Peripheral.byteArrayToWritableMap(Peripheral.java:257)
01:57 W/System.err: 	at it.innove.Peripheral.asWritableMap(Peripheral.java:158)
01:57 W/System.err: 	at it.innove.BleManager.getConnectedPeripherals(BleManager.java:480)
01:57 W/System.err: 	at java.lang.reflect.Method.invoke(Native Method)
01:57 W/System.err: 	at com.facebook.react.bridge.JavaMethodWrapper.invoke(JavaMethodWrapper.java:374)
01:57 W/System.err: 	at com.facebook.react.bridge.JavaModuleWrapper.invoke(JavaModuleWrapper.java:162)
01:57 W/System.err: 	at com.facebook.react.bridge.queue.NativeRunnable.run(Native Method)
01:57 W/System.err: 	at android.os.Handler.handleCallback(Handler.java:751)
01:57 W/System.err: 	at android.os.Handler.dispatchMessage(Handler.java:95)
01:57 W/System.err: 	at com.facebook.react.bridge.queue.MessageQueueThreadHandler.dispatchMessage(MessageQueueThreadHandler.java:31)
01:57 W/System.err: 	at android.os.Looper.loop(Looper.java:154)
01:57 W/System.err: 	at com.facebook.react.bridge.queue.MessageQueueThreadImpl$3.run(MessageQueueThreadImpl.java:194)
01:57 W/System.err: 	at java.lang.Thread.run(Thread.java:762)

Actual behaviour

I am constantly getting errors about trying to encode a null byte array. I believe the issue is in Peripheral.java, line 179 – it should be checking the result of entry.getValue() and only call byteArrayToWritableMap if the value is non-null.

[Sean-Brown]

I experimented with initializing the advertisingDataBytes to an empty array and it seems to avoid the error, i.e. on line 48 do private byte[] advertisingDataBytes = new byte[0], or initialize it in the third constructor on line 81

[Sean-Brown]

Yes I’m still seeing the error:

01:55 W/System.err: java.lang.NullPointerException: Attempt to get length of null array
01:55 W/System.err: 	at android.util.Base64.encode(Base64.java:494)
01:55 W/System.err: 	at android.util.Base64.encodeToString(Base64.java:456)
01:55 W/System.err: 	at it.innove.Peripheral.byteArrayToWritableMap(Peripheral.java:264)
01:55 W/System.err: 	at it.innove.Peripheral.asWritableMap(Peripheral.java:164)
01:55 W/System.err: 	at it.innove.BleManager.getConnectedPeripherals(BleManager.java:480)
01:55 W/System.err: 	at java.lang.reflect.Method.invoke(Native Method)
01:55 W/System.err: 	at com.facebook.react.bridge.JavaMethodWrapper.invoke(JavaMethodWrapper.java:374)
01:55 W/System.err: 	at com.facebook.react.bridge.JavaModuleWrapper.invoke(JavaModuleWrapper.java:162)
01:55 W/System.err: 	at com.facebook.react.bridge.queue.NativeRunnable.run(Native Method)
01:55 W/System.err: 	at android.os.Handler.handleCallback(Handler.java:751)
01:55 W/System.err: 	at android.os.Handler.dispatchMessage(Handler.java:95)
01:55 W/System.err: 	at com.facebook.react.bridge.queue.MessageQueueThreadHandler.dispatchMessage(MessageQueueThreadHandler.java:31)
01:55 W/System.err: 	at android.os.Looper.loop(Looper.java:154)
01:55 W/System.err: 	at com.facebook.react.bridge.queue.MessageQueueThreadImpl$3.run(MessageQueueThreadImpl.java:194)
01:55 W/System.err: 	at java.lang.Thread.run(Thread.java:762)

Looking at the code I can’t imagine how the getConnectedPeripherals method in the BleManager.java file could work. It constructs a new peripheral object but calls the constructor that won’t initialize the advertisingDataBytes attribute. Then it calls the asWritableMap method on the new peripheral, which will call byteArrayToWritableMap with the advertisingDataBytes member as an argument, but I don’t see how this member will ever be non-null. I’m not sure what the correct solution would be but a couple come to mind:

• Initialize advertisingDataBytes to an empty array
• Do a null-check on advertisingDataBytes before calling byteArrayToWritableMap

What I don’t fully understand is how this would impact the caller (BleManager.getConnectedPeripherals)