added some more tests and improved C error handling

uinput_test.go

@@ -24,3 +24,47 @@ func TestBasicVKeyboard(t *testing.T) {
 		t.Fatalf("Failed to close device. Last error was: %s\n", err)
 	}
 }
+
+// This test will confirm that a proper error code is returned if an invalid uinput path is
+// passed to the library
+func TestInvalidDevicePath(t *testing.T) {
+	devId, err := CreateVKeyboardDevice("/invalid/path")
+
+	if err == nil {
+		// this usually shouldn't happen, but if the device is created, we need to close it
+		CloseDevice(devId)
+		t.Fatalf("Expected error code,but received %s instead.\n", err)
+	}
+}
+
+// This test will confirm that a proper error code is returned if an invalid keycode is 
+// passed to the library
+func TestInvalidKeycode(t *testing.T) {
+	devId, err := CreateVKeyboardDevice("/dev/uinput")
+
+	if err != nil {
+		t.Fatalf("Failed to create the virtual keyboard. Last error was: %s\n", err)
+	}
+
+	err = SendBtnEvent(devId, 4711, 1)
+
+	if err == nil {
+		t.Fatalf("Sending an invalid keycode did not trigger an error. Got: %d.\n")
+	}
+}
+
+// This test will confirm that a proper error code is returned if an invalid button state is 
+// passed to the library
+func TestInvalidBtnState(t *testing.T) {
+	devId, err := CreateVKeyboardDevice("/dev/uinput")
+
+	if err != nil {
+		t.Fatalf("Failed to create the virtual keyboard. Last error was: %s\n", err)
+	}
+
+	err = SendBtnEvent(devId, KEY_1, 3)
+
+	if err == nil {
+		t.Fatalf("Sending an invalid btnState did not trigger an error. Got: %d.\n")
+	}
+}

uinputwrapper.c

@@ -30,8 +30,8 @@ int initVKeyboardDevice(char* uinputPath) {
                 deviceHandle = -1;
             }
         } else {
-			// register key events
-            for(i=0; i<255; i++) {
+			// register key events - only values from 1 to 255 are valid
+            for(i=1; i<256; i++) {
                 ioctl(deviceHandle, UI_SET_KEYBIT, i);
             }
 
@@ -59,6 +59,16 @@ int initVKeyboardDevice(char* uinputPath) {
 }
 
 int sendBtnEvent(int deviceHandle, int key, int btnState) {
+	// check whether the keycode is valid and return -1 on error
+	if (key < 1 || key > 255) {
+		return -1;
+	}
+
+	// btnState should only be either 0 or 1
+	if (btnState < 0 || btnState > 1) {
+		return -1;
+	}
+
     struct input_event ev;
     memset(&ev, 0, sizeof(ev));