commit 539c27c9d417e2c2df07078c0089e2c7525b0287
author Arthur Ishiguro <arthuri@google.com> Mon Apr 13 09:47:59 2020 -0700
committer Arthur Ishiguro <arthuri@google.com> Wed Apr 22 08:49:52 2020 -0700
tree defb0d8bd76bafc4c5c26134e74ef62d434b0656
parent 538eebb1557d97b47bdc40fe307080606eca6bbc

Disable sensors when an app goes to background v2

This change is a revision of a previous version of the
implementation in ag/10737391. In this version, we
perform the book-keeping of backgrounded apps in the
SensorDevice.cpp (rather than SensorEventConnection.cpp),
to avoid unintended problems with the locking assumptions
in the Sensor Service code.

Bug: 74395023
Test: 1) Subscribe to sensor on sensorlogger
      2) Put app to background and wait
      3) Verify subscription is disabled once app is idle
      4) Put app to foreground and verify app can receive sensor samples
Test: Verify above test while a_sns_test streaming samples
Test: Verify above test with sensor service restrict and privacy mode
Change-Id: Ic44058e606868a665d5aa88a75211d1eba8d4950

services/sensorservice/SensorService.cpp

diff --git a/services/sensorservice/SensorService.cpp b/services/sensorservice/SensorService.cpp
index 5fdc74f..a5dafd5 100644
--- a/services/sensorservice/SensorService.cpp
+++ b/services/sensorservice/SensorService.cpp
@@ -299,11 +299,13 @@
     }
 }
 
-void SensorService::setSensorAccess(uid_t uid, bool hasAccess) {
+void SensorService::onUidStateChanged(uid_t uid, UidState state) {
+    SensorDevice& dev(SensorDevice::getInstance());
+
     ConnectionSafeAutolock connLock = mConnectionHolder.lock(mLock);
     for (const sp<SensorEventConnection>& conn : connLock.getActiveConnections()) {
         if (conn->getUid() == uid) {
-            conn->setSensorAccess(hasAccess);
+            dev.setUidStateForConnection(conn.get(), state);
         }
     }
 }
@@ -1234,9 +1236,8 @@
             (packageName == "") ? String8::format("unknown_package_pid_%d", pid) : packageName;
     String16 connOpPackageName =
             (opPackageName == String16("")) ? String16(connPackageName) : opPackageName;
-    bool hasSensorAccess = mUidPolicy->isUidActive(uid);
     sp<SensorEventConnection> result(new SensorEventConnection(this, uid, connPackageName,
-            requestedMode == DATA_INJECTION, connOpPackageName, hasSensorAccess));
+            requestedMode == DATA_INJECTION, connOpPackageName));
     if (requestedMode == DATA_INJECTION) {
         mConnectionHolder.addEventConnectionIfNotPresent(result);
         // Add the associated file descriptor to the Looper for polling whenever there is data to
@@ -1921,7 +1922,7 @@
     }
     sp<SensorService> service = mService.promote();
     if (service != nullptr) {
-        service->setSensorAccess(uid, true);
+        service->onUidStateChanged(uid, UID_STATE_ACTIVE);
     }
 }
 
@@ -1936,7 +1937,7 @@
     if (deleted) {
         sp<SensorService> service = mService.promote();
         if (service != nullptr) {
-            service->setSensorAccess(uid, false);
+            service->onUidStateChanged(uid, UID_STATE_IDLE);
         }
     }
 }
@@ -1964,7 +1965,7 @@
     if (wasActive != isActive) {
         sp<SensorService> service = mService.promote();
         if (service != nullptr) {
-            service->setSensorAccess(uid, isActive);
+            service->onUidStateChanged(uid, isActive ? UID_STATE_ACTIVE : UID_STATE_IDLE);
         }
     }
 }
@@ -1990,6 +1991,10 @@
     return mActiveUids.find(uid) != mActiveUids.end();
 }
 
+bool SensorService::isUidActive(uid_t uid) {
+    return mUidPolicy->isUidActive(uid);
+}
+
 void SensorService::SensorPrivacyPolicy::registerSelf() {
     SensorPrivacyManager spm;
     mSensorPrivacyEnabled = spm.isSensorPrivacyEnabled();