From e05eef8449e5314c1bd0278b1484130c170a379a Mon Sep 17 00:00:00 2001
From: Jean-Michel Trivi <jmtrivi@google.com>
Date: Thu, 8 Mar 2018 18:56:34 -0800
Subject: [PATCH] AudioService: prevent muting of alarm / accessibility

STREAM_ACCESSIBILITY / ALARM min volume is index 1

Prevent a11y stream volume to be 0 when used separately from
  media.
Prevent setting a volume index above min value.

Bug: 72403580
Bug: 74985293
Test: verify media vol can go to 0 ; enable Talkback verify
    a11y volume can't be muted with vol keys or UI

Change-Id: Id46506d4c407f42fe3aca463055b0973e1a7c4dc
---
 .../android/server/audio/AudioService.java    | 38 ++++++++++++++++---
 1 file changed, 33 insertions(+), 5 deletions(-)

diff --git a/services/core/java/com/android/server/audio/AudioService.java b/services/core/java/com/android/server/audio/AudioService.java
index c8b6b5056ebbe..3e82c25836a89 100644
--- a/services/core/java/com/android/server/audio/AudioService.java
+++ b/services/core/java/com/android/server/audio/AudioService.java
@@ -320,13 +320,13 @@ public class AudioService extends IAudioService.Stub
         0,  // STREAM_SYSTEM
         0,  // STREAM_RING
         0,  // STREAM_MUSIC
-        0,  // STREAM_ALARM
+        1,  // STREAM_ALARM
         0,  // STREAM_NOTIFICATION
         0,  // STREAM_BLUETOOTH_SCO
         0,  // STREAM_SYSTEM_ENFORCED
         0,  // STREAM_DTMF
         0,  // STREAM_TTS
-        0   // STREAM_ACCESSIBILITY
+        1   // STREAM_ACCESSIBILITY
     };
 
     /* mStreamVolumeAlias[] indicates for each stream if it uses the volume settings
@@ -1208,6 +1208,8 @@ public class AudioService extends IAudioService.Stub
                             System.VOLUME_SETTINGS_INT[a11yStreamAlias];
                     mStreamStates[AudioSystem.STREAM_ACCESSIBILITY].setAllIndexes(
                             mStreamStates[a11yStreamAlias], caller);
+                    mStreamStates[AudioSystem.STREAM_ACCESSIBILITY].refreshRange(
+                            mStreamVolumeAlias[AudioSystem.STREAM_ACCESSIBILITY]);
                 }
             }
             if (sIndependentA11yVolume) {
@@ -1389,7 +1391,15 @@ public class AudioService extends IAudioService.Stub
     }
 
     private int rescaleIndex(int index, int srcStream, int dstStream) {
-        return (index * mStreamStates[dstStream].getMaxIndex() + mStreamStates[srcStream].getMaxIndex() / 2) / mStreamStates[srcStream].getMaxIndex();
+        final int rescaled =
+                (index * mStreamStates[dstStream].getMaxIndex()
+                        + mStreamStates[srcStream].getMaxIndex() / 2)
+                / mStreamStates[srcStream].getMaxIndex();
+        if (rescaled < mStreamStates[dstStream].getMinIndex()) {
+            return mStreamStates[dstStream].getMinIndex();
+        } else {
+            return rescaled;
+        }
     }
 
     ///////////////////////////////////////////////////////////////////////////
@@ -4602,8 +4612,8 @@ public class AudioService extends IAudioService.Stub
     //  4       VolumeStreamState.class
     public class VolumeStreamState {
         private final int mStreamType;
-        private final int mIndexMin;
-        private final int mIndexMax;
+        private int mIndexMin;
+        private int mIndexMax;
 
         private boolean mIsMuted;
         private String mVolumeIndexSettingName;
@@ -4888,6 +4898,24 @@ public class AudioService extends IAudioService.Stub
             return mIndexMin;
         }
 
+        /**
+         * Updates the min/max index values from another stream. Use this when changing the alias
+         * for the current stream type.
+         * @param sourceStreamType
+         */
+        // must be sync'd on mSettingsLock before VolumeStreamState.class
+        @GuardedBy("VolumeStreamState.class")
+        public void refreshRange(int sourceStreamType) {
+            mIndexMin = MIN_STREAM_VOLUME[sourceStreamType] * 10;
+            mIndexMax = MAX_STREAM_VOLUME[sourceStreamType] * 10;
+            // verify all current volumes are within bounds
+            for (int i = 0 ; i < mIndexMap.size(); i++) {
+                final int device = mIndexMap.keyAt(i);
+                final int index = mIndexMap.valueAt(i);
+                mIndexMap.put(device, getValidIndex(index));
+            }
+        }
+
         /**
          * Copies all device/index pairs from the given VolumeStreamState after initializing
          * them with the volume for DEVICE_OUT_DEFAULT. No-op if the source VolumeStreamState