From 14e3485272a2ca28764d916e266e17311943c245 Mon Sep 17 00:00:00 2001
From: Jean-Michel Trivi <jmtrivi@google.com>
Date: Thu, 9 Apr 2020 08:19:26 -0700
Subject: [PATCH] AudioService: better mic muting API behavior with errors

 If an error is reported when changing the microphone mute state,
log it but still fire ACTION_MICROPHONE_MUTE_CHANGED intent.
 Make AudioManager.isMicrophoneMute() return the "real" mute
state, not the intended mute state, by returning the cache
of the state returned by AudioSystem whenever a change is
attempted.

Bug: 153103117
Test: atest AudioServiceTest
Change-Id: I102f6b379eace7b396860b6f24024720fb465382
---
 .../android/server/audio/AudioService.java    | 32 +++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/services/core/java/com/android/server/audio/AudioService.java b/services/core/java/com/android/server/audio/AudioService.java
index f55249e1d6f55..c7fac44077029 100644
--- a/services/core/java/com/android/server/audio/AudioService.java
+++ b/services/core/java/com/android/server/audio/AudioService.java
@@ -574,6 +574,8 @@ public class AudioService extends IAudioService.Stub
     private boolean mMicMuteFromSwitch;
     private boolean mMicMuteFromApi;
     private boolean mMicMuteFromRestrictions;
+    // caches the value returned by AudioSystem.isMicrophoneMuted()
+    private boolean mMicMuteFromSystemCached;
 
     @GuardedBy("mSettingsLock")
     private int mAssistantUid;
@@ -934,6 +936,7 @@ public class AudioService extends IAudioService.Stub
 
         onIndicateSystemReady();
 
+        mMicMuteFromSystemCached = AudioSystem.isMicrophoneMuted();
         setMicMuteFromSwitchInput();
     }
 
@@ -1127,6 +1130,7 @@ public class AudioService extends IAudioService.Stub
         sendMsg(mAudioHandler, MSG_DISPATCH_AUDIO_SERVER_STATE,
                 SENDMSG_QUEUE, 1, 0, null, 0);
 
+        setMicrophoneMuteNoCallerCheck(getCurrentUserId()); // will also update the mic mute cache
         setMicMuteFromSwitchInput();
     }
 
@@ -3223,12 +3227,20 @@ public class AudioService extends IAudioService.Stub
         }
     }
 
+    /**
+     * Returns the microphone mute state as seen from the native audio system
+     * @return true if microphone is reported as muted by primary HAL
+     */
     public boolean isMicrophoneMuted() {
+        return mMicMuteFromSystemCached;
+    }
+
+    private boolean isMicrophoneSupposedToBeMuted() {
         return mMicMuteFromSwitch || mMicMuteFromRestrictions || mMicMuteFromApi;
     }
 
     private void setMicrophoneMuteNoCallerCheck(int userId) {
-        final boolean muted = isMicrophoneMuted();
+        final boolean muted = isMicrophoneSupposedToBeMuted();
         if (DEBUG_VOL) {
             Log.d(TAG, String.format("Mic mute %b, user=%d", muted, userId));
         }
@@ -3236,7 +3248,7 @@ public class AudioService extends IAudioService.Stub
         if (getCurrentUserId() == userId || userId == android.os.Process.SYSTEM_UID) {
             final boolean currentMute = AudioSystem.isMicrophoneMuted();
             final long identity = Binder.clearCallingIdentity();
-            AudioSystem.muteMicrophone(muted);
+            final int ret = AudioSystem.muteMicrophone(muted);
 
             new MediaMetrics.Item(mAnalyticsId + "setMicrophoneMuteNoCallerCheck")
                     .setUid(userId)
@@ -3244,7 +3256,19 @@ public class AudioService extends IAudioService.Stub
                     .putInt("currentMute", currentMute ? 1 : 0)
                     .putLong("identity", identity)
                     .record();
+
+            // update cache with the real state independently from what was set
+            mMicMuteFromSystemCached = AudioSystem.isMicrophoneMuted();
+            if (ret != AudioSystem.AUDIO_STATUS_OK) {
+                Log.e(TAG, "Error changing mic mute state to " + muted + " current:"
+                        + mMicMuteFromSystemCached);
+            }
             try {
+                // send the intent even if there was a failure to change the actual mute state:
+                // the AudioManager.setMicrophoneMute API doesn't have a return value to
+                // indicate if the call failed to successfully change the mute state, and receiving
+                // the intent may be the only time an application can resynchronize its mic mute
+                // state with the actual system mic mute state
                 if (muted != currentMute) {
                     sendMsg(mAudioHandler, MSG_BROADCAST_MICROPHONE_MUTE,
                                 SENDMSG_NOOP, 0, 0, null, 0);
@@ -7154,6 +7178,10 @@ public class AudioService extends IAudioService.Stub
         pw.print("  mHdmiTvClient="); pw.println(mHdmiTvClient);
         pw.print("  mHdmiSystemAudioSupported="); pw.println(mHdmiSystemAudioSupported);
         pw.print("  mIsCallScreeningModeSupported="); pw.println(mIsCallScreeningModeSupported);
+        pw.print("  mic mute FromSwitch=" + mMicMuteFromSwitch
+                        + " FromRestrictions=" + mMicMuteFromRestrictions
+                        + " FromApi=" + mMicMuteFromApi
+                        + " from system=" + mMicMuteFromSystemCached);
 
         dumpAudioPolicies(pw);
         mDynPolicyLogger.dump(pw);