From 2a6552ed502cfa60fec71a9d41a11faa1e4be963 Mon Sep 17 00:00:00 2001
From: Paul Lawrence <paullawrence@google.com>
Date: Thu, 14 May 2015 15:49:08 -0700
Subject: [PATCH] Disable back button on crypto screen

The back button cannot do anything from this activity as it is
only ever launched first thing at boot. So do not permit going back.

Note that screens launched from here (emergency dialer, keyboard config)
still work and their back buttons still work.

Bug: 20730074
Change-Id: I939e05450e5fbd61d12890325c4afe9dcad35c1e
---
 src/com/android/settings/CryptKeeper.java | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/src/com/android/settings/CryptKeeper.java b/src/com/android/settings/CryptKeeper.java
index b4f19ddd723..45b4ff134e3 100644
--- a/src/com/android/settings/CryptKeeper.java
+++ b/src/com/android/settings/CryptKeeper.java
@@ -116,7 +116,6 @@ public class CryptKeeper extends Activity implements TextView.OnEditorActionList
     /** If gone bad, should we show encryption failed (false) or corrupt (true)*/
     private boolean mCorrupt;
     /** A flag to indicate when the back event should be ignored */
-    private boolean mIgnoreBack = false;
     /** When set, blocks unlocking. Set every COOL_DOWN_ATTEMPTS attempts, only cleared
         by power cycling phone. */
     private boolean mCooldown = false;
@@ -390,15 +389,11 @@ public class CryptKeeper extends Activity implements TextView.OnEditorActionList
     }
 
     /**
-     * Ignore back events after the user has entered the decrypt screen and while the device is
-     * encrypting.
+     * Ignore back events from this activity always - there's nowhere to go back
+     * to
      */
     @Override
     public void onBackPressed() {
-        // In the rare case that something pressed back even though we were disabled.
-        if (mIgnoreBack)
-            return;
-        super.onBackPressed();
     }
 
     @Override
@@ -516,6 +511,8 @@ public class CryptKeeper extends Activity implements TextView.OnEditorActionList
 
                     passwordEntryInit();
 
+                    findViewById(android.R.id.content).setSystemUiVisibility(View.STATUS_BAR_DISABLE_BACK);
+
                     if (mLockPatternView != null) {
                         mLockPatternView.setInStealthMode(!pattern_visible);
                     }
@@ -694,7 +691,6 @@ public class CryptKeeper extends Activity implements TextView.OnEditorActionList
      * @param isEnabled true if back is enabled, false otherwise.
      */
     private final void setBackFunctionality(boolean isEnabled) {
-        mIgnoreBack = !isEnabled;
         if (isEnabled) {
             mStatusBar.disable(sWidgetsToDisable);
         } else {