Merge "Move fontchain_lint to build/core/tasks" into main
diff --git a/AconfigFlags.bp b/AconfigFlags.bp
index bd69385..59a1cbc 100644
--- a/AconfigFlags.bp
+++ b/AconfigFlags.bp
@@ -18,6 +18,7 @@
     ":android.content.pm.flags-aconfig-java{.generated_srcjars}",
     ":android.content.res.flags-aconfig-java{.generated_srcjars}",
     ":android.hardware.biometrics.flags-aconfig-java{.generated_srcjars}",
+    ":android.media.playback.flags-aconfig-java{.generated_srcjars}",
     ":android.net.vcn.flags-aconfig-java{.generated_srcjars}",
     ":android.nfc.flags-aconfig-java{.generated_srcjars}",
     ":android.os.flags-aconfig-java{.generated_srcjars}",
@@ -30,6 +31,25 @@
     // !!! KEEP THIS LIST ALPHABETICAL !!!
 ]
 
+stubs_defaults {
+    name: "framework-minus-apex-aconfig-declarations",
+    aconfig_declarations: [
+        "android.content.pm.flags-aconfig",
+        "android.content.res.flags-aconfig",
+        "android.hardware.biometrics.flags-aconfig",
+        "android.media.playback.flags-aconfig",
+        "android.net.vcn.flags-aconfig",
+        "android.nfc.flags-aconfig",
+        "android.os.flags-aconfig",
+        "android.security.flags-aconfig",
+        "com.android.hardware.camera2-aconfig",
+        "com.android.hardware.input.input-aconfig",
+        "com.android.window.flags.window-aconfig",
+        "com.android.text.flags-aconfig",
+        "com.android.net.flags-aconfig",
+    ],
+}
+
 filegroup {
     name: "framework-minus-apex-aconfig-srcjars",
     srcs: aconfig_srcjars,
diff --git a/api/Android.bp b/api/Android.bp
index 7dd13e3..7fb427e 100644
--- a/api/Android.bp
+++ b/api/Android.bp
@@ -310,6 +310,7 @@
 // classpath (or sources) somehow.
 stubs_defaults {
     name: "android-non-updatable-stubs-defaults",
+    defaults: ["framework-minus-apex-aconfig-declarations"],
     srcs: [":android-non-updatable-stub-sources"],
     sdk_version: "none",
     system_modules: "none",
diff --git a/core/java/android/security/flags.aconfig b/core/java/android/security/flags.aconfig
index 1994058..43163b3 100644
--- a/core/java/android/security/flags.aconfig
+++ b/core/java/android/security/flags.aconfig
@@ -58,3 +58,10 @@
     bug: "290312729"
     is_fixed_read_only: true
 }
+
+flag {
+  name: "report_primary_auth_attempts"
+  namespace: "biometrics"
+  description: "Report primary auth attempts from LockSettingsService"
+  bug: "285053096"
+}
diff --git a/core/java/com/android/internal/widget/ILockSettingsStateListener.aidl b/core/java/com/android/internal/widget/ILockSettingsStateListener.aidl
new file mode 100644
index 0000000..25e3003
--- /dev/null
+++ b/core/java/com/android/internal/widget/ILockSettingsStateListener.aidl
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.internal.widget;
+
+/**
+ * Callback interface between LockSettingService and other system services to be notified about the
+ * state of primary authentication (i.e. PIN/pattern/password).
+ * @hide
+ */
+oneway interface ILockSettingsStateListener {
+    /**
+     * Defines behavior in response to a successful authentication
+     * @param userId The user Id for the requested authentication
+     */
+    void onAuthenticationSucceeded(int userId);
+
+    /**
+     * Defines behavior in response to a failed authentication
+     * @param userId The user Id for the requested authentication
+     */
+    void onAuthenticationFailed(int userId);
+}
\ No newline at end of file
diff --git a/core/java/com/android/internal/widget/LockSettingsInternal.java b/core/java/com/android/internal/widget/LockSettingsInternal.java
index 8114e1f..627e877 100644
--- a/core/java/com/android/internal/widget/LockSettingsInternal.java
+++ b/core/java/com/android/internal/widget/LockSettingsInternal.java
@@ -166,4 +166,16 @@
      * Refreshes pending strong auth timeout with the latest admin requirement set by device policy.
      */
     public abstract void refreshStrongAuthTimeout(int userId);
+
+    /**
+     * Register a LockSettingsStateListener
+     * @param listener The listener to be registered
+     */
+    public abstract void registerLockSettingsStateListener(ILockSettingsStateListener listener);
+
+    /**
+     * Unregister a LockSettingsStateListener
+     * @param listener The listener to be unregistered
+     */
+    public abstract void unregisterLockSettingsStateListener(ILockSettingsStateListener listener);
 }
diff --git a/libs/hwui/RenderNode.cpp b/libs/hwui/RenderNode.cpp
index 1dd22cf..a733d17 100644
--- a/libs/hwui/RenderNode.cpp
+++ b/libs/hwui/RenderNode.cpp
@@ -218,7 +218,7 @@
  * stencil buffer may be needed. Views that use a functor to draw will be forced onto a layer.
  */
 void RenderNode::prepareTreeImpl(TreeObserver& observer, TreeInfo& info, bool functorsNeedLayer) {
-    if (mDamageGenerationId == info.damageGenerationId) {
+    if (mDamageGenerationId == info.damageGenerationId && mDamageGenerationId != 0) {
         // We hit the same node a second time in the same tree. We don't know the minimal
         // damage rect anymore, so just push the biggest we can onto our parent's transform
         // We push directly onto parent in case we are clipped to bounds but have moved position.
diff --git a/libs/hwui/RenderNode.h b/libs/hwui/RenderNode.h
index 572635a..4d03bf1 100644
--- a/libs/hwui/RenderNode.h
+++ b/libs/hwui/RenderNode.h
@@ -263,7 +263,7 @@
     DisplayList mDisplayList;
     DisplayList mStagingDisplayList;
 
-    int64_t mDamageGenerationId;
+    int64_t mDamageGenerationId = 0;
 
     friend class AnimatorManager;
     AnimatorManager mAnimatorManager;
diff --git a/services/core/java/com/android/server/locksettings/LockSettingsService.java b/services/core/java/com/android/server/locksettings/LockSettingsService.java
index ad09082..c81ce26 100644
--- a/services/core/java/com/android/server/locksettings/LockSettingsService.java
+++ b/services/core/java/com/android/server/locksettings/LockSettingsService.java
@@ -16,6 +16,7 @@
 
 package com.android.server.locksettings;
 
+import static android.security.Flags.reportPrimaryAuthAttempts;
 import static android.Manifest.permission.ACCESS_KEYGUARD_SECURE_STORAGE;
 import static android.Manifest.permission.MANAGE_BIOMETRIC;
 import static android.Manifest.permission.SET_AND_VERIFY_LOCKSCREEN_CREDENTIALS;
@@ -90,6 +91,7 @@
 import android.os.IBinder;
 import android.os.IProgressListener;
 import android.os.Process;
+import android.os.RemoteCallbackList;
 import android.os.RemoteException;
 import android.os.ResultReceiver;
 import android.os.ServiceManager;
@@ -135,6 +137,7 @@
 import com.android.internal.util.Preconditions;
 import com.android.internal.widget.ICheckCredentialProgressCallback;
 import com.android.internal.widget.ILockSettings;
+import com.android.internal.widget.ILockSettingsStateListener;
 import com.android.internal.widget.IWeakEscrowTokenActivatedListener;
 import com.android.internal.widget.IWeakEscrowTokenRemovedListener;
 import com.android.internal.widget.LockPatternUtils;
@@ -327,6 +330,9 @@
 
     private HashMap<UserHandle, UserManager> mUserManagerCache = new HashMap<>();
 
+    private final RemoteCallbackList<ILockSettingsStateListener> mLockSettingsStateListeners =
+            new RemoteCallbackList<>();
+
     // This class manages life cycle events for encrypted users on File Based Encryption (FBE)
     // devices. The most basic of these is to show/hide notifications about missing features until
     // the user unlocks the account and credential-encrypted storage is available.
@@ -2342,9 +2348,37 @@
                 requireStrongAuth(STRONG_AUTH_REQUIRED_AFTER_LOCKOUT, userId);
             }
         }
+        if (reportPrimaryAuthAttempts()) {
+            final boolean success =
+                    response.getResponseCode() == VerifyCredentialResponse.RESPONSE_OK;
+            notifyLockSettingsStateListeners(success, userId);
+        }
         return response;
     }
 
+    private void notifyLockSettingsStateListeners(boolean success, int userId) {
+        int i = mLockSettingsStateListeners.beginBroadcast();
+        try {
+            while (i > 0) {
+                i--;
+                try {
+                    if (success) {
+                        mLockSettingsStateListeners.getBroadcastItem(i)
+                                .onAuthenticationSucceeded(userId);
+                    } else {
+                        mLockSettingsStateListeners.getBroadcastItem(i)
+                                .onAuthenticationFailed(userId);
+                    }
+                } catch (RemoteException e) {
+                    Slog.e(TAG, "Exception while notifying LockSettingsStateListener:"
+                            + " success = " + success + ", userId = " + userId, e);
+                }
+            }
+        } finally {
+            mLockSettingsStateListeners.finishBroadcast();
+        }
+    }
+
     @Override
     public VerifyCredentialResponse verifyTiedProfileChallenge(LockscreenCredential credential,
             int userId, @LockPatternUtils.VerifyFlag int flags) {
@@ -3662,6 +3696,18 @@
         public void refreshStrongAuthTimeout(int userId) {
             mStrongAuth.refreshStrongAuthTimeout(userId);
         }
+
+        @Override
+        public void registerLockSettingsStateListener(
+                @NonNull ILockSettingsStateListener listener) {
+            mLockSettingsStateListeners.register(listener);
+        }
+
+        @Override
+        public void unregisterLockSettingsStateListener(
+                @NonNull ILockSettingsStateListener listener) {
+            mLockSettingsStateListeners.unregister(listener);
+        }
     }
 
     private class RebootEscrowCallbacks implements RebootEscrowManager.Callbacks {
diff --git a/services/tests/servicestests/src/com/android/server/locksettings/LockSettingsServiceTests.java b/services/tests/servicestests/src/com/android/server/locksettings/LockSettingsServiceTests.java
index 5a62d92..5081198 100644
--- a/services/tests/servicestests/src/com/android/server/locksettings/LockSettingsServiceTests.java
+++ b/services/tests/servicestests/src/com/android/server/locksettings/LockSettingsServiceTests.java
@@ -16,6 +16,8 @@
 
 package com.android.server.locksettings;
 
+import static android.security.Flags.FLAG_REPORT_PRIMARY_AUTH_ATTEMPTS;
+
 import static com.android.internal.widget.LockPatternUtils.CREDENTIAL_TYPE_NONE;
 import static com.android.internal.widget.LockPatternUtils.CREDENTIAL_TYPE_PASSWORD;
 import static com.android.internal.widget.LockPatternUtils.CREDENTIAL_TYPE_PATTERN;
@@ -30,25 +32,30 @@
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.reset;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
 import android.app.PropertyInvalidatedCache;
+import android.os.IBinder;
 import android.os.RemoteException;
 import android.platform.test.annotations.Presubmit;
+import android.platform.test.flag.junit.SetFlagsRule;
 import android.service.gatekeeper.GateKeeperResponse;
 import android.text.TextUtils;
 
 import androidx.test.filters.SmallTest;
 import androidx.test.runner.AndroidJUnit4;
 
+import com.android.internal.widget.ILockSettingsStateListener;
 import com.android.internal.widget.LockPatternUtils;
 import com.android.internal.widget.LockscreenCredential;
 import com.android.internal.widget.VerifyCredentialResponse;
 
 import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
@@ -59,6 +66,7 @@
 @Presubmit
 @RunWith(AndroidJUnit4.class)
 public class LockSettingsServiceTests extends BaseLockSettingsServiceTests {
+    @Rule public final SetFlagsRule mSetFlagsRule = new SetFlagsRule();
 
     @Before
     public void setUp() {
@@ -399,6 +407,60 @@
     }
 
     @Test
+    public void testVerifyCredential_notifyLockSettingsStateListeners_whenGoodPassword()
+            throws Exception {
+        mSetFlagsRule.enableFlags(FLAG_REPORT_PRIMARY_AUTH_ATTEMPTS);
+        final LockscreenCredential password = newPassword("password");
+        setCredential(PRIMARY_USER_ID, password);
+        final ILockSettingsStateListener listener = mockLockSettingsStateListener();
+        mLocalService.registerLockSettingsStateListener(listener);
+
+        assertEquals(VerifyCredentialResponse.RESPONSE_OK,
+                mService.verifyCredential(password, PRIMARY_USER_ID, 0 /* flags */)
+                        .getResponseCode());
+
+        verify(listener).onAuthenticationSucceeded(PRIMARY_USER_ID);
+    }
+
+    @Test
+    public void testVerifyCredential_notifyLockSettingsStateListeners_whenBadPassword()
+            throws Exception {
+        mSetFlagsRule.enableFlags(FLAG_REPORT_PRIMARY_AUTH_ATTEMPTS);
+        final LockscreenCredential password = newPassword("password");
+        setCredential(PRIMARY_USER_ID, password);
+        final LockscreenCredential badPassword = newPassword("badPassword");
+        final ILockSettingsStateListener listener = mockLockSettingsStateListener();
+        mLocalService.registerLockSettingsStateListener(listener);
+
+        assertEquals(VerifyCredentialResponse.RESPONSE_ERROR,
+                mService.verifyCredential(badPassword, PRIMARY_USER_ID, 0 /* flags */)
+                        .getResponseCode());
+
+        verify(listener).onAuthenticationFailed(PRIMARY_USER_ID);
+    }
+
+    @Test
+    public void testLockSettingsStateListener_registeredThenUnregistered() throws Exception {
+        mSetFlagsRule.enableFlags(FLAG_REPORT_PRIMARY_AUTH_ATTEMPTS);
+        final LockscreenCredential password = newPassword("password");
+        setCredential(PRIMARY_USER_ID, password);
+        final LockscreenCredential badPassword = newPassword("badPassword");
+        final ILockSettingsStateListener listener = mockLockSettingsStateListener();
+
+        mLocalService.registerLockSettingsStateListener(listener);
+        assertEquals(VerifyCredentialResponse.RESPONSE_OK,
+                mService.verifyCredential(password, PRIMARY_USER_ID, 0 /* flags */)
+                        .getResponseCode());
+        verify(listener).onAuthenticationSucceeded(PRIMARY_USER_ID);
+
+        mLocalService.unregisterLockSettingsStateListener(listener);
+        assertEquals(VerifyCredentialResponse.RESPONSE_ERROR,
+                mService.verifyCredential(badPassword, PRIMARY_USER_ID, 0 /* flags */)
+                        .getResponseCode());
+        verify(listener, never()).onAuthenticationFailed(PRIMARY_USER_ID);
+    }
+
+    @Test
     public void testSetCredentialNotPossibleInSecureFrpModeDuringSuw() {
         setUserSetupComplete(false);
         setSecureFrpMode(true);
@@ -537,4 +599,12 @@
             assertNotEquals(0, mGateKeeperService.getSecureUserId(userId));
         }
     }
+
+    private ILockSettingsStateListener mockLockSettingsStateListener() {
+        ILockSettingsStateListener listener = mock(ILockSettingsStateListener.Stub.class);
+        IBinder binder = mock(IBinder.class);
+        when(binder.isBinderAlive()).thenReturn(true);
+        when(listener.asBinder()).thenReturn(binder);
+        return listener;
+    }
 }
diff --git a/tools/aapt2/cmd/Link.cpp b/tools/aapt2/cmd/Link.cpp
index cf4dd79..24699bf 100644
--- a/tools/aapt2/cmd/Link.cpp
+++ b/tools/aapt2/cmd/Link.cpp
@@ -56,6 +56,7 @@
 #include "java/JavaClassGenerator.h"
 #include "java/ManifestClassGenerator.h"
 #include "java/ProguardRules.h"
+#include "link/FeatureFlagsFilter.h"
 #include "link/Linkers.h"
 #include "link/ManifestFixer.h"
 #include "link/NoDefaultResourceRemover.h"
@@ -1986,6 +1987,19 @@
     context_->SetNameManglerPolicy(NameManglerPolicy{context_->GetCompilationPackage()});
     context_->SetSplitNameDependencies(app_info_.split_name_dependencies);
 
+    FeatureFlagsFilterOptions flags_filter_options;
+    if (context_->GetMinSdkVersion() > SDK_UPSIDE_DOWN_CAKE) {
+      // For API version > U, PackageManager will dynamically read the flag values and disable
+      // manifest elements accordingly when parsing the manifest.
+      // For API version <= U, we remove disabled elements from the manifest with the filter.
+      flags_filter_options.remove_disabled_elements = false;
+      flags_filter_options.flags_must_have_value = false;
+    }
+    FeatureFlagsFilter flags_filter(options_.feature_flag_values, flags_filter_options);
+    if (!flags_filter.Consume(context_, manifest_xml.get())) {
+      return 1;
+    }
+
     // Override the package ID when it is "android".
     if (context_->GetCompilationPackage() == "android") {
       context_->SetPackageId(kAndroidPackageId);
@@ -2530,7 +2544,7 @@
   }
 
   for (const std::string& arg : all_feature_flags_args) {
-    if (ParseFeatureFlagsParameter(arg, context.GetDiagnostics(), &options_.feature_flag_values)) {
+    if (!ParseFeatureFlagsParameter(arg, context.GetDiagnostics(), &options_.feature_flag_values)) {
       return 1;
     }
   }
diff --git a/tools/aapt2/cmd/Link.h b/tools/aapt2/cmd/Link.h
index 26713fd..dc18b1c 100644
--- a/tools/aapt2/cmd/Link.h
+++ b/tools/aapt2/cmd/Link.h
@@ -330,7 +330,11 @@
             "should only be used together with the --static-lib flag.",
         &options_.merge_only);
     AddOptionalSwitch("-v", "Enables verbose logging.", &verbose_);
-    AddOptionalFlagList("--feature-flags", "Placeholder, to be implemented.", &feature_flags_args_);
+    AddOptionalFlagList("--feature-flags",
+                        "Specify the values of feature flags. The pairs in the argument\n"
+                        "are separated by ',' and the name is separated from the value by '='.\n"
+                        "Example: \"flag1=true,flag2=false,flag3=\" (flag3 has no given value).",
+                        &feature_flags_args_);
   }
 
   int Action(const std::vector<std::string>& args) override;
diff --git a/tools/aapt2/cmd/Link_test.cpp b/tools/aapt2/cmd/Link_test.cpp
index 725a1b8..7ceb351 100644
--- a/tools/aapt2/cmd/Link_test.cpp
+++ b/tools/aapt2/cmd/Link_test.cpp
@@ -16,11 +16,10 @@
 
 #include "Link.h"
 
-#include <android-base/file.h>
-
-#include "AppInfo.h"
 #include "Diagnostics.h"
 #include "LoadedApk.h"
+#include "android-base/file.h"
+#include "android-base/stringprintf.h"
 #include "test/Test.h"
 
 using testing::Eq;
@@ -993,4 +992,213 @@
   ASSERT_FALSE(Link(link_args, &diag));
 }
 
+static void BuildSDKWithFeatureFlagAttr(const std::string& apk_path, const std::string& java_path,
+                                        CommandTestFixture* fixture, android::IDiagnostics* diag) {
+  const std::string android_values =
+      R"(<resources>
+          <staging-public-group type="attr" first-id="0x01fe0063">
+            <public name="featureFlag" />
+          </staging-public-group>
+          <attr name="featureFlag" format="string" />
+         </resources>)";
+
+  SourceXML source_xml{.res_file_path = "/res/values/values.xml", .file_contents = android_values};
+  BuildSDK({source_xml}, apk_path, java_path, fixture, diag);
+}
+
+TEST_F(LinkTest, FeatureFlagDisabled_SdkAtMostUDC) {
+  StdErrDiagnostics diag;
+  const std::string android_apk = GetTestPath("android.apk");
+  const std::string android_java = GetTestPath("android-java");
+  BuildSDKWithFeatureFlagAttr(android_apk, android_java, this, &diag);
+
+  const std::string manifest_contents = android::base::StringPrintf(
+      R"(<uses-sdk android:minSdkVersion="%d" />"
+          <permission android:name="FOO" android:featureFlag="flag" />)",
+      SDK_UPSIDE_DOWN_CAKE);
+  auto app_manifest = ManifestBuilder(this)
+                          .SetPackageName("com.example.app")
+                          .AddContents(manifest_contents)
+                          .Build();
+
+  auto app_link_args = LinkCommandBuilder(this)
+                           .SetManifestFile(app_manifest)
+                           .AddParameter("-I", android_apk)
+                           .AddParameter("--feature-flags", "flag=false");
+
+  const std::string app_apk = GetTestPath("app.apk");
+  BuildApk({}, app_apk, std::move(app_link_args), this, &diag);
+
+  // Permission element should be removed if flag is disabled
+  auto apk = LoadedApk::LoadApkFromPath(app_apk, &diag);
+  ASSERT_THAT(apk, NotNull());
+  auto apk_manifest = apk->GetManifest();
+  ASSERT_THAT(apk_manifest, NotNull());
+  auto root = apk_manifest->root.get();
+  ASSERT_THAT(root, NotNull());
+  auto maybe_removed = root->FindChild({}, "permission");
+  ASSERT_THAT(maybe_removed, IsNull());
+}
+
+TEST_F(LinkTest, FeatureFlagEnabled_SdkAtMostUDC) {
+  StdErrDiagnostics diag;
+  const std::string android_apk = GetTestPath("android.apk");
+  const std::string android_java = GetTestPath("android-java");
+  BuildSDKWithFeatureFlagAttr(android_apk, android_java, this, &diag);
+
+  const std::string manifest_contents = android::base::StringPrintf(
+      R"(<uses-sdk android:minSdkVersion="%d" />"
+          <permission android:name="FOO" android:featureFlag="flag" />)",
+      SDK_UPSIDE_DOWN_CAKE);
+  auto app_manifest = ManifestBuilder(this)
+                          .SetPackageName("com.example.app")
+                          .AddContents(manifest_contents)
+                          .Build();
+
+  auto app_link_args = LinkCommandBuilder(this)
+                           .SetManifestFile(app_manifest)
+                           .AddParameter("-I", android_apk)
+                           .AddParameter("--feature-flags", "flag=true");
+
+  const std::string app_apk = GetTestPath("app.apk");
+  BuildApk({}, app_apk, std::move(app_link_args), this, &diag);
+
+  // Permission element should be kept if flag is enabled
+  auto apk = LoadedApk::LoadApkFromPath(app_apk, &diag);
+  ASSERT_THAT(apk, NotNull());
+  auto apk_manifest = apk->GetManifest();
+  ASSERT_THAT(apk_manifest, NotNull());
+  auto root = apk_manifest->root.get();
+  ASSERT_THAT(root, NotNull());
+  auto maybe_removed = root->FindChild({}, "permission");
+  ASSERT_THAT(maybe_removed, NotNull());
+}
+
+TEST_F(LinkTest, FeatureFlagWithNoValue_SdkAtMostUDC) {
+  StdErrDiagnostics diag;
+  const std::string android_apk = GetTestPath("android.apk");
+  const std::string android_java = GetTestPath("android-java");
+  BuildSDKWithFeatureFlagAttr(android_apk, android_java, this, &diag);
+
+  const std::string manifest_contents = android::base::StringPrintf(
+      R"(<uses-sdk android:minSdkVersion="%d" />"
+          <permission android:name="FOO" android:featureFlag="flag" />)",
+      SDK_UPSIDE_DOWN_CAKE);
+  auto app_manifest = ManifestBuilder(this)
+                          .SetPackageName("com.example.app")
+                          .AddContents(manifest_contents)
+                          .Build();
+
+  auto app_link_args = LinkCommandBuilder(this)
+                           .SetManifestFile(app_manifest)
+                           .AddParameter("-I", android_apk)
+                           .AddParameter("--feature-flags", "flag=");
+
+  // Flags must have values if <= UDC
+  const std::string app_apk = GetTestPath("app.apk");
+  ASSERT_FALSE(Link(app_link_args.Build(app_apk), &diag));
+}
+
+TEST_F(LinkTest, FeatureFlagDisabled_SdkAfterUDC) {
+  StdErrDiagnostics diag;
+  const std::string android_apk = GetTestPath("android.apk");
+  const std::string android_java = GetTestPath("android-java");
+  BuildSDKWithFeatureFlagAttr(android_apk, android_java, this, &diag);
+
+  const std::string manifest_contents = android::base::StringPrintf(
+      R"(<uses-sdk android:minSdkVersion="%d" />"
+          <permission android:name="FOO" android:featureFlag="flag" />)",
+      SDK_CUR_DEVELOPMENT);
+  auto app_manifest = ManifestBuilder(this)
+                          .SetPackageName("com.example.app")
+                          .AddContents(manifest_contents)
+                          .Build();
+
+  auto app_link_args = LinkCommandBuilder(this)
+                           .SetManifestFile(app_manifest)
+                           .AddParameter("-I", android_apk)
+                           .AddParameter("--feature-flags", "flag=false");
+
+  const std::string app_apk = GetTestPath("app.apk");
+  BuildApk({}, app_apk, std::move(app_link_args), this, &diag);
+
+  // Permission element should be kept if > UDC, regardless of flag value
+  auto apk = LoadedApk::LoadApkFromPath(app_apk, &diag);
+  ASSERT_THAT(apk, NotNull());
+  auto apk_manifest = apk->GetManifest();
+  ASSERT_THAT(apk_manifest, NotNull());
+  auto root = apk_manifest->root.get();
+  ASSERT_THAT(root, NotNull());
+  auto maybe_removed = root->FindChild({}, "permission");
+  ASSERT_THAT(maybe_removed, NotNull());
+}
+
+TEST_F(LinkTest, FeatureFlagEnabled_SdkAfterUDC) {
+  StdErrDiagnostics diag;
+  const std::string android_apk = GetTestPath("android.apk");
+  const std::string android_java = GetTestPath("android-java");
+  BuildSDKWithFeatureFlagAttr(android_apk, android_java, this, &diag);
+
+  const std::string manifest_contents = android::base::StringPrintf(
+      R"(<uses-sdk android:minSdkVersion="%d" />"
+          <permission android:name="FOO" android:featureFlag="flag" />)",
+      SDK_CUR_DEVELOPMENT);
+  auto app_manifest = ManifestBuilder(this)
+                          .SetPackageName("com.example.app")
+                          .AddContents(manifest_contents)
+                          .Build();
+
+  auto app_link_args = LinkCommandBuilder(this)
+                           .SetManifestFile(app_manifest)
+                           .AddParameter("-I", android_apk)
+                           .AddParameter("--feature-flags", "flag=true");
+
+  const std::string app_apk = GetTestPath("app.apk");
+  BuildApk({}, app_apk, std::move(app_link_args), this, &diag);
+
+  // Permission element should be kept if > UDC, regardless of flag value
+  auto apk = LoadedApk::LoadApkFromPath(app_apk, &diag);
+  ASSERT_THAT(apk, NotNull());
+  auto apk_manifest = apk->GetManifest();
+  ASSERT_THAT(apk_manifest, NotNull());
+  auto root = apk_manifest->root.get();
+  ASSERT_THAT(root, NotNull());
+  auto maybe_removed = root->FindChild({}, "permission");
+  ASSERT_THAT(maybe_removed, NotNull());
+}
+
+TEST_F(LinkTest, FeatureFlagWithNoValue_SdkAfterUDC) {
+  StdErrDiagnostics diag;
+  const std::string android_apk = GetTestPath("android.apk");
+  const std::string android_java = GetTestPath("android-java");
+  BuildSDKWithFeatureFlagAttr(android_apk, android_java, this, &diag);
+
+  const std::string manifest_contents = android::base::StringPrintf(
+      R"(<uses-sdk android:minSdkVersion="%d" />"
+          <permission android:name="FOO" android:featureFlag="flag" />)",
+      SDK_CUR_DEVELOPMENT);
+  auto app_manifest = ManifestBuilder(this)
+                          .SetPackageName("com.example.app")
+                          .AddContents(manifest_contents)
+                          .Build();
+
+  auto app_link_args = LinkCommandBuilder(this)
+                           .SetManifestFile(app_manifest)
+                           .AddParameter("-I", android_apk)
+                           .AddParameter("--feature-flags", "flag=");
+
+  const std::string app_apk = GetTestPath("app.apk");
+  BuildApk({}, app_apk, std::move(app_link_args), this, &diag);
+
+  // Permission element should be kept if > UDC, regardless of flag value
+  auto apk = LoadedApk::LoadApkFromPath(app_apk, &diag);
+  ASSERT_THAT(apk, NotNull());
+  auto apk_manifest = apk->GetManifest();
+  ASSERT_THAT(apk_manifest, NotNull());
+  auto root = apk_manifest->root.get();
+  ASSERT_THAT(root, NotNull());
+  auto maybe_removed = root->FindChild({}, "permission");
+  ASSERT_THAT(maybe_removed, NotNull());
+}
+
 }  // namespace aapt
diff --git a/tools/aapt2/util/Files.cpp b/tools/aapt2/util/Files.cpp
index 93c1b61..02e4beae 100644
--- a/tools/aapt2/util/Files.cpp
+++ b/tools/aapt2/util/Files.cpp
@@ -251,10 +251,13 @@
     return false;
   }
 
-  for (StringPiece line : util::Tokenize(contents, ' ')) {
+  for (StringPiece line : util::Tokenize(contents, '\n')) {
     line = util::TrimWhitespace(line);
-    if (!line.empty()) {
-      out_arglist->emplace_back(line);
+    for (StringPiece arg : util::Tokenize(line, ' ')) {
+      arg = util::TrimWhitespace(arg);
+      if (!arg.empty()) {
+        out_arglist->emplace_back(arg);
+      }
     }
   }
   return true;
@@ -270,10 +273,13 @@
     return false;
   }
 
-  for (StringPiece line : util::Tokenize(contents, ' ')) {
+  for (StringPiece line : util::Tokenize(contents, '\n')) {
     line = util::TrimWhitespace(line);
-    if (!line.empty()) {
-      out_argset->emplace(line);
+    for (StringPiece arg : util::Tokenize(line, ' ')) {
+      arg = util::TrimWhitespace(arg);
+      if (!arg.empty()) {
+        out_argset->emplace(arg);
+      }
     }
   }
   return true;
diff --git a/tools/aapt2/util/Files_test.cpp b/tools/aapt2/util/Files_test.cpp
index 6c38080..618a3e0 100644
--- a/tools/aapt2/util/Files_test.cpp
+++ b/tools/aapt2/util/Files_test.cpp
@@ -25,6 +25,9 @@
 
 using ::android::base::StringPrintf;
 
+using ::testing::ElementsAre;
+using ::testing::UnorderedElementsAre;
+
 namespace aapt {
 namespace file {
 
@@ -34,9 +37,11 @@
 constexpr const char sTestDirSep = '/';
 #endif
 
-class FilesTest : public ::testing::Test {
+class FilesTest : public TestDirectoryFixture {
  public:
   void SetUp() override {
+    TestDirectoryFixture::SetUp();
+
     std::stringstream builder;
     builder << "hello" << sDirSep << "there";
     expected_path_ = builder.str();
@@ -66,6 +71,42 @@
   EXPECT_EQ(expected_path_, base);
 }
 
+TEST_F(FilesTest, AppendArgsFromFile) {
+  const std::string args_file = GetTestPath("args.txt");
+  WriteFile(args_file,
+            "  \n"
+            "arg1 arg2   arg3  \n"
+            "   arg4 arg5");
+  std::vector<std::string> args;
+  std::string error;
+  ASSERT_TRUE(AppendArgsFromFile(args_file, &args, &error));
+  EXPECT_THAT(args, ElementsAre("arg1", "arg2", "arg3", "arg4", "arg5"));
+}
+
+TEST_F(FilesTest, AppendArgsFromFile_InvalidFile) {
+  std::vector<std::string> args;
+  std::string error;
+  ASSERT_FALSE(AppendArgsFromFile(GetTestPath("not_found.txt"), &args, &error));
+}
+
+TEST_F(FilesTest, AppendSetArgsFromFile) {
+  const std::string args_file = GetTestPath("args.txt");
+  WriteFile(args_file,
+            "  \n"
+            "arg2 arg4   arg1  \n"
+            "   arg5 arg3");
+  std::unordered_set<std::string> args;
+  std::string error;
+  ASSERT_TRUE(AppendSetArgsFromFile(args_file, &args, &error));
+  EXPECT_THAT(args, UnorderedElementsAre("arg1", "arg2", "arg3", "arg4", "arg5"));
+}
+
+TEST_F(FilesTest, AppendSetArgsFromFile_InvalidFile) {
+  std::unordered_set<std::string> args;
+  std::string error;
+  ASSERT_FALSE(AppendSetArgsFromFile(GetTestPath("not_found.txt"), &args, &error));
+}
+
 #ifdef _WIN32
 TEST_F(FilesTest, WindowsMkdirsLongPath) {
   // Creating directory paths longer than the Windows maximum path length (260 charatcers) should