Implement a sanity check of settings so that if onboot is selected,

foreground is forced.

app/src/main/java/org/galexander/sshd/Settings.java

@@ -1,11 +1,49 @@
 package org.galexander.sshd;
 
+import android.os.Build;
 import android.os.Bundle;
+import android.preference.CheckBoxPreference;
+import android.preference.Preference;
 import android.preference.PreferenceActivity;
+import android.widget.Toast;
 
 public class Settings extends PreferenceActivity {
+	private CheckBoxPreference pref_onboot, pref_foreground;
+
 	public void onCreate(Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
 		addPreferencesFromResource(R.xml.preferences);
+
+		pref_onboot = (CheckBoxPreference)findPreference("onboot");
+		pref_foreground =
+			(CheckBoxPreference)findPreference("foreground");
+
+		Preference.OnPreferenceChangeListener l = 
+			new Preference.OnPreferenceChangeListener() {
+				public boolean onPreferenceChange(Preference p,
+					Object v_) {
+					boolean v =((Boolean)v_).booleanValue();
+					((CheckBoxPreference)p).setChecked(v);
+					check();
+					return false;
+				} };
+		pref_onboot.setOnPreferenceChangeListener(l);
+		pref_foreground.setOnPreferenceChangeListener(l);
+	}
+
+	public void onResume() {
+                super.onResume();
+		check();
+	}
+
+	private void check() {
+		if ((Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) &&
+		    pref_onboot.isChecked() &&
+		    !pref_foreground.isChecked()) {
+			pref_foreground.setChecked(true);
+			Toast.makeText(this,
+"Android Oreo will not start a background service at boot. Forcing foreground.",
+                                        Toast.LENGTH_LONG).show();
+		}
 	}
 }