altosdroid: Check for closed before writing/reading bluetooth

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/altosdroid/src/org/altusmetrum/AltosDroid/AltosBluetooth.java b/altosdroid/src/org/altusmetrum/AltosDroid/AltosBluetooth.java
index 15efc0e2..51937b7f 100644
--- a/altosdroid/src/org/altusmetrum/AltosDroid/AltosBluetooth.java
+++ b/altosdroid/src/org/altusmetrum/AltosDroid/AltosBluetooth.java
@@ -199,6 +199,8 @@ public class AltosBluetooth extends AltosDroidLink {
 	}
 
 	int write(byte[] buffer, int len) {
+		if (output == null)
+			return -1;
 		try {
 			output.write(buffer, 0, len);
 		} catch (IOException ie) {
@@ -208,6 +210,8 @@ public class AltosBluetooth extends AltosDroidLink {
 	}
 
 	int read(byte[] buffer, int len) {
+		if (input == null)
+			return -1;
 		try {
 			return input.read(buffer, 0, len);
 		} catch (IOException ie) {