Merge "Implement the launcher side permission." into nyc-dev
diff --git a/api/current.txt b/api/current.txt
index 9e0af76..c04debf 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -9454,6 +9454,7 @@
     method public int getShortcutIconResId(android.content.pm.ShortcutInfo, android.os.UserHandle);
     method public java.util.List<android.content.pm.ShortcutInfo> getShortcutInfo(java.lang.String, java.util.List<java.lang.String>, android.os.UserHandle);
     method public java.util.List<android.content.pm.ShortcutInfo> getShortcuts(android.content.pm.LauncherApps.ShortcutQuery, android.os.UserHandle);
+    method public boolean hasShortcutHostPermission();
     method public boolean isActivityEnabled(android.content.ComponentName, android.os.UserHandle);
     method public boolean isPackageEnabled(java.lang.String, android.os.UserHandle);
     method public void pinShortcuts(java.lang.String, java.util.List<java.lang.String>, android.os.UserHandle);
diff --git a/api/system-current.txt b/api/system-current.txt
index 00cf357..d242e2f 100644
--- a/api/system-current.txt
+++ b/api/system-current.txt
@@ -9788,6 +9788,7 @@
     method public int getShortcutIconResId(android.content.pm.ShortcutInfo, android.os.UserHandle);
     method public java.util.List<android.content.pm.ShortcutInfo> getShortcutInfo(java.lang.String, java.util.List<java.lang.String>, android.os.UserHandle);
     method public java.util.List<android.content.pm.ShortcutInfo> getShortcuts(android.content.pm.LauncherApps.ShortcutQuery, android.os.UserHandle);
+    method public boolean hasShortcutHostPermission();
     method public boolean isActivityEnabled(android.content.ComponentName, android.os.UserHandle);
     method public boolean isPackageEnabled(java.lang.String, android.os.UserHandle);
     method public void pinShortcuts(java.lang.String, java.util.List<java.lang.String>, android.os.UserHandle);
diff --git a/api/test-current.txt b/api/test-current.txt
index 9aed5e9..78bdf16 100644
--- a/api/test-current.txt
+++ b/api/test-current.txt
@@ -9463,6 +9463,7 @@
     method public int getShortcutIconResId(android.content.pm.ShortcutInfo, android.os.UserHandle);
     method public java.util.List<android.content.pm.ShortcutInfo> getShortcutInfo(java.lang.String, java.util.List<java.lang.String>, android.os.UserHandle);
     method public java.util.List<android.content.pm.ShortcutInfo> getShortcuts(android.content.pm.LauncherApps.ShortcutQuery, android.os.UserHandle);
+    method public boolean hasShortcutHostPermission();
     method public boolean isActivityEnabled(android.content.ComponentName, android.os.UserHandle);
     method public boolean isPackageEnabled(java.lang.String, android.os.UserHandle);
     method public void pinShortcuts(java.lang.String, java.util.List<java.lang.String>, android.os.UserHandle);
diff --git a/core/java/android/content/pm/ILauncherApps.aidl b/core/java/android/content/pm/ILauncherApps.aidl
index b1d3f20..7b57872 100644
--- a/core/java/android/content/pm/ILauncherApps.aidl
+++ b/core/java/android/content/pm/ILauncherApps.aidl
@@ -58,4 +58,6 @@
     int getShortcutIconResId(String callingPackage, in ShortcutInfo shortcut, in UserHandle user);
     ParcelFileDescriptor getShortcutIconFd(String callingPackage, in ShortcutInfo shortcut,
             in UserHandle user);
+
+    boolean hasShortcutHostPermission(String callingPackage);
 }
diff --git a/core/java/android/content/pm/LauncherApps.java b/core/java/android/content/pm/LauncherApps.java
index a6a732e..8d43c44 100644
--- a/core/java/android/content/pm/LauncherApps.java
+++ b/core/java/android/content/pm/LauncherApps.java
@@ -16,11 +16,9 @@
 
 package android.content.pm;
 
-import android.Manifest.permission;
 import android.annotation.IntDef;
 import android.annotation.NonNull;
 import android.annotation.Nullable;
-import android.annotation.RequiresPermission;
 import android.content.ComponentName;
 import android.content.Context;
 import android.content.Intent;
@@ -30,7 +28,6 @@
 import android.os.Handler;
 import android.os.Looper;
 import android.os.Message;
-import android.os.Parcel;
 import android.os.ParcelFileDescriptor;
 import android.os.RemoteException;
 import android.os.UserHandle;
@@ -159,6 +156,9 @@
          * Indicates that one or more shortcuts (which may be dynamic and/or pinned)
          * have been added, updated or removed.
          *
+         * <p>Only the applications that are allowed to access the shortcut information,
+         * as defined in {@link #hasShortcutHostPermission()}, will receive it.
+         *
          * @param packageName The name of the package that has the shortcuts.
          * @param shortcuts all shortcuts from the package (dynamic and/or pinned).
          * @param user The UserHandle of the profile that generated the change.
@@ -395,16 +395,34 @@
     }
 
     /**
+     * Returns whether the caller can access the shortcut information.
+     *
+     * <p>Only the default launcher can access the shortcut information.
+     *
+     * <p>Note when this method returns {@code false}, that may be a temporary situation because
+     * the user is trying a new launcher application.  The user may decide to change the default
+     * launcher to the calling application again, so even if a launcher application loses
+     * this permission, it does <b>not</b> have to purge pinned shortcut information.
+     */
+    public boolean hasShortcutHostPermission() {
+        try {
+            return mService.hasShortcutHostPermission(mContext.getPackageName());
+        } catch (RemoteException re) {
+            throw re.rethrowFromSystemServer();
+        }
+    }
+
+    /**
      * Returns the IDs of {@link ShortcutInfo}s that match {@code query}.
      *
-     * <p>Callers mut have the {@link permission#BIND_APPWIDGET} permission.
+     * <p>Callers must be allowed to access the shortcut information, as defined in {@link
+     * #hasShortcutHostPermission()}.
      *
      * @param query result includes shortcuts matching this query.
      * @param user The UserHandle of the profile.
      *
      * @return the IDs of {@link ShortcutInfo}s that match the query.
      */
-    @RequiresPermission(permission.BIND_APPWIDGET)
     @Nullable
     public List<ShortcutInfo> getShortcuts(@NonNull ShortcutQuery query,
             @NonNull UserHandle user) {
@@ -420,7 +438,8 @@
     /**
      * Returns {@link ShortcutInfo}s with the given IDs from a package.
      *
-     * <p>Callers mut have the {@link permission#BIND_APPWIDGET} permission.
+     * <p>Callers must be allowed to access the shortcut information, as defined in {@link
+     * #hasShortcutHostPermission()}.
      *
      * @param packageName The target package.
      * @param ids IDs of the shortcuts to retrieve.
@@ -428,7 +447,6 @@
      *
      * @return list of {@link ShortcutInfo} associated with the package.
      */
-    @RequiresPermission(permission.BIND_APPWIDGET)
     @Nullable
     public List<ShortcutInfo> getShortcutInfo(@NonNull String packageName,
             @NonNull List<String> ids, @NonNull UserHandle user) {
@@ -447,13 +465,13 @@
      * <p>This API is <b>NOT</b> cumulative; this will replace all pinned shortcuts for the package.
      * However, different launchers may have different set of pinned shortcuts.
      *
-     * <p>Callers must have the {@link permission#BIND_APPWIDGET} permission.
+     * <p>Callers must be allowed to access the shortcut information, as defined in {@link
+     * #hasShortcutHostPermission()}.
      *
      * @param packageName The target package name.
      * @param shortcutIds The IDs of the shortcut to be pinned.
      * @param user The UserHandle of the profile.
      */
-    @RequiresPermission(permission.BIND_APPWIDGET)
     public void pinShortcuts(@NonNull String packageName, @NonNull List<String> shortcutIds,
             @NonNull UserHandle user) {
         try {
@@ -467,12 +485,12 @@
      * Return the icon resource ID, if {@code shortcut} has one
      * (i.e. when {@link ShortcutInfo#hasIconResource()} returns {@code true}).
      *
-     * <p>Callers mut have the {@link permission#BIND_APPWIDGET} permission.
+     * <p>Callers must be allowed to access the shortcut information, as defined in {@link
+     * #hasShortcutHostPermission()}.
      *
      * @param shortcut The target shortcut.
      * @param user The UserHandle of the profile.
      */
-    @RequiresPermission(permission.BIND_APPWIDGET)
     public int getShortcutIconResId(@NonNull ShortcutInfo shortcut, @NonNull UserHandle user) {
         try {
             return mService.getShortcutIconResId(mContext.getPackageName(), shortcut, user);
@@ -485,12 +503,12 @@
      * Return the icon as {@link ParcelFileDescriptor}, when it's stored as a file
      * (i.e. when {@link ShortcutInfo#hasIconFile()} returns {@code true}).
      *
-     * <p>Callers mut have the {@link permission#BIND_APPWIDGET} permission.
+     * <p>Callers must be allowed to access the shortcut information, as defined in {@link
+     * #hasShortcutHostPermission()}.
      *
      * @param shortcut The target shortcut.
      * @param user The UserHandle of the profile.
      */
-    @RequiresPermission(permission.BIND_APPWIDGET)
     public ParcelFileDescriptor getShortcutIconFd(
             @NonNull ShortcutInfo shortcut, @NonNull UserHandle user) {
         try {
@@ -503,7 +521,8 @@
     /**
      * Launches a shortcut.
      *
-     * <p>Callers mut have the {@link permission#BIND_APPWIDGET} permission.
+     * <p>Callers must be allowed to access the shortcut information, as defined in {@link
+     * #hasShortcutHostPermission()}.
      *
      * @param packageName The target shortcut package name.
      * @param shortcutId The target shortcut ID.
@@ -513,7 +532,6 @@
      * @return {@code false} when the shortcut is no longer valid (e.g. the creator application
      *   has been uninstalled). {@code true} when the shortcut is still valid.
      */
-    @RequiresPermission(permission.BIND_APPWIDGET)
     public boolean startShortcut(@NonNull String packageName, @NonNull String shortcutId,
             @Nullable Rect sourceBounds, @Nullable Bundle startActivityOptions,
             @NonNull UserHandle user) {
diff --git a/core/java/android/content/pm/PackageManagerInternal.java b/core/java/android/content/pm/PackageManagerInternal.java
index 89f2fc4..13ebb82 100644
--- a/core/java/android/content/pm/PackageManagerInternal.java
+++ b/core/java/android/content/pm/PackageManagerInternal.java
@@ -16,6 +16,7 @@
 
 package android.content.pm;
 
+import android.content.ComponentName;
 import android.content.pm.PackageManager.NameNotFoundException;
 
 import java.util.List;
@@ -140,4 +141,10 @@
      *             found on the system.
      */
     public abstract ApplicationInfo getApplicationInfo(String packageName, int userId);
+
+    /**
+     * Interface to {@link com.android.server.pm.PackageManagerService#getHomeActivitiesAsUser}.
+     */
+    public abstract ComponentName getHomeActivitiesAsUser(List<ResolveInfo> allHomeCandidates,
+            int userId);
 }
diff --git a/core/java/android/content/pm/ShortcutServiceInternal.java b/core/java/android/content/pm/ShortcutServiceInternal.java
index 918c763..7c764aa 100644
--- a/core/java/android/content/pm/ShortcutServiceInternal.java
+++ b/core/java/android/content/pm/ShortcutServiceInternal.java
@@ -63,4 +63,6 @@
 
     public abstract ParcelFileDescriptor getShortcutIconFd(@NonNull String callingPackage,
             @NonNull ShortcutInfo shortcut, int userId);
+
+    public abstract boolean hasShortcutHostPermission(@NonNull String callingPackage, int userId);
 }
diff --git a/services/core/java/com/android/server/pm/LauncherAppsService.java b/services/core/java/com/android/server/pm/LauncherAppsService.java
index b7cd318..6cc0544 100644
--- a/services/core/java/com/android/server/pm/LauncherAppsService.java
+++ b/services/core/java/com/android/server/pm/LauncherAppsService.java
@@ -99,6 +99,15 @@
             mShortcutServiceInternal.addListener(mPackageMonitor);
         }
 
+        @VisibleForTesting
+        int injectBinderCallingUid() {
+            return getCallingUid();
+        }
+
+        private int getCallingUserId() {
+            return UserHandle.getUserId(injectBinderCallingUid());
+        }
+
         /*
          * @see android.content.pm.ILauncherApps#addOnAppsChangedListener(
          *          android.content.pm.IOnAppsChangedListener)
@@ -296,17 +305,21 @@
             }
         }
 
-        private void enforceShortcutPermission(UserHandle user) {
+        private void ensureShortcutPermission(@NonNull String callingPackage, UserHandle user) {
+            verifyCallingPackage(callingPackage);
             ensureInUserProfiles(user, "Cannot start activity for unrelated profile " + user);
-            // STOPSHIP Implement it
+
+            if (!mShortcutServiceInternal.hasShortcutHostPermission(callingPackage,
+                    user.getIdentifier())) {
+                throw new SecurityException("Caller can't access shortcut information");
+            }
         }
 
         @Override
         public ParceledListSlice getShortcuts(String callingPackage, long changedSince,
                 String packageName, ComponentName componentName, int flags, UserHandle user)
                 throws RemoteException {
-            enforceShortcutPermission(user);
-            verifyCallingPackage(callingPackage);
+            ensureShortcutPermission(callingPackage, user);
 
             return new ParceledListSlice<>(
                     mShortcutServiceInternal.getShortcuts(callingPackage, changedSince, packageName,
@@ -316,8 +329,7 @@
         @Override
         public ParceledListSlice getShortcutInfo(String callingPackage, String packageName,
                 List<String> ids, UserHandle user) throws RemoteException {
-            enforceShortcutPermission(user);
-            verifyCallingPackage(callingPackage);
+            ensureShortcutPermission(callingPackage, user);
 
             return new ParceledListSlice<>(
                     mShortcutServiceInternal.getShortcutInfo(callingPackage, packageName,
@@ -327,8 +339,7 @@
         @Override
         public void pinShortcuts(String callingPackage, String packageName, List<String> ids,
                 UserHandle user) throws RemoteException {
-            enforceShortcutPermission(user);
-            verifyCallingPackage(callingPackage);
+            ensureShortcutPermission(callingPackage, user);
 
             mShortcutServiceInternal.pinShortcuts(callingPackage, packageName,
                     ids, user.getIdentifier());
@@ -337,8 +348,7 @@
         @Override
         public int getShortcutIconResId(String callingPackage, ShortcutInfo shortcut,
                 UserHandle user) {
-            enforceShortcutPermission(user);
-            verifyCallingPackage(callingPackage);
+            ensureShortcutPermission(callingPackage, user);
 
             return mShortcutServiceInternal.getShortcutIconResId(callingPackage, shortcut,
                     user.getIdentifier());
@@ -347,19 +357,24 @@
         @Override
         public ParcelFileDescriptor getShortcutIconFd(String callingPackage, ShortcutInfo shortcut,
                 UserHandle user) {
-            enforceShortcutPermission(user);
-            verifyCallingPackage(callingPackage);
+            ensureShortcutPermission(callingPackage, user);
 
             return mShortcutServiceInternal.getShortcutIconFd(callingPackage, shortcut,
                     user.getIdentifier());
         }
 
         @Override
+        public boolean hasShortcutHostPermission(String callingPackage) throws RemoteException {
+            verifyCallingPackage(callingPackage);
+            return mShortcutServiceInternal.hasShortcutHostPermission(callingPackage,
+                    getCallingUserId());
+        }
+
+        @Override
         public boolean startShortcut(String callingPackage, String packageName, String shortcutId,
                 Rect sourceBounds, Bundle startActivityOptions, UserHandle user)
                 throws RemoteException {
-            enforceShortcutPermission(user);
-            verifyCallingPackage(callingPackage);
+            ensureShortcutPermission(callingPackage, user);
 
             final Intent intent = mShortcutServiceInternal.createShortcutIntent(callingPackage,
                     packageName, shortcutId, user.getIdentifier());
@@ -656,6 +671,9 @@
                     IOnAppsChangedListener listener = mListeners.getBroadcastItem(i);
                     UserHandle listeningUser = (UserHandle) mListeners.getBroadcastCookie(i);
                     if (!isEnabledProfileOf(user, listeningUser, "onShortcutChanged")) continue;
+
+                    // STOPSHIP Skip if the receiver doesn't have the permission.
+
                     try {
                         listener.onShortcutChanged(user, packageName,
                                 new ParceledListSlice<>(shortcuts));
diff --git a/services/core/java/com/android/server/pm/PackageManagerService.java b/services/core/java/com/android/server/pm/PackageManagerService.java
index 9a1ecd7..b624087 100644
--- a/services/core/java/com/android/server/pm/PackageManagerService.java
+++ b/services/core/java/com/android/server/pm/PackageManagerService.java
@@ -16456,14 +16456,17 @@
 
     @Override
     public ComponentName getHomeActivities(List<ResolveInfo> allHomeCandidates) {
+        return getHomeActivitiesAsUser(allHomeCandidates, UserHandle.getCallingUserId());
+    }
+
+    ComponentName getHomeActivitiesAsUser(List<ResolveInfo> allHomeCandidates,
+            int userId) {
         Intent intent = new Intent(Intent.ACTION_MAIN);
         intent.addCategory(Intent.CATEGORY_HOME);
-
-        final int callingUserId = UserHandle.getCallingUserId();
         List<ResolveInfo> list = queryIntentActivitiesInternal(intent, null,
-                PackageManager.GET_META_DATA, callingUserId);
+                PackageManager.GET_META_DATA, userId);
         ResolveInfo preferred = findPreferredActivity(intent, null, 0, list, 0,
-                true, false, false, callingUserId);
+                true, false, false, userId);
 
         allHomeCandidates.clear();
         if (list != null) {
@@ -19252,6 +19255,12 @@
         public ApplicationInfo getApplicationInfo(String packageName, int userId) {
             return PackageManagerService.this.getApplicationInfo(packageName, 0 /*flags*/, userId);
         }
+
+        @Override
+        public ComponentName getHomeActivitiesAsUser(List<ResolveInfo> allHomeCandidates,
+                int userId) {
+            return PackageManagerService.this.getHomeActivitiesAsUser(allHomeCandidates, userId);
+        }
     }
 
     @Override
diff --git a/services/core/java/com/android/server/pm/ShortcutService.java b/services/core/java/com/android/server/pm/ShortcutService.java
index 0b0f7ab..f3c63ee 100644
--- a/services/core/java/com/android/server/pm/ShortcutService.java
+++ b/services/core/java/com/android/server/pm/ShortcutService.java
@@ -28,7 +28,9 @@
 import android.content.pm.LauncherApps.ShortcutQuery;
 import android.content.pm.PackageManager;
 import android.content.pm.PackageManager.NameNotFoundException;
+import android.content.pm.PackageManagerInternal;
 import android.content.pm.ParceledListSlice;
+import android.content.pm.ResolveInfo;
 import android.content.pm.ShortcutInfo;
 import android.content.pm.ShortcutServiceInternal;
 import android.content.pm.ShortcutServiceInternal.ShortcutChangeListener;
@@ -71,6 +73,7 @@
 import com.android.server.SystemService;
 
 import libcore.io.IoUtils;
+import libcore.util.Objects;
 
 import org.xmlpull.v1.XmlPullParser;
 import org.xmlpull.v1.XmlPullParserException;
@@ -88,7 +91,6 @@
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.List;
-import java.util.Map;
 import java.util.function.Predicate;
 
 /**
@@ -112,7 +114,7 @@
 public class ShortcutService extends IShortcutService.Stub {
     static final String TAG = "ShortcutService";
 
-    static final boolean DEBUG = false; // STOPSHIP if true
+    static final boolean DEBUG = true; // STOPSHIP if true
     static final boolean DEBUG_LOAD = false; // STOPSHIP if true
 
     @VisibleForTesting
@@ -156,6 +158,7 @@
     static final String TAG_INTENT_EXTRAS = "intent-extras";
     static final String TAG_EXTRAS = "extras";
     static final String TAG_SHORTCUT = "shortcut";
+    static final String TAG_LAUNCHER = "launcher";
 
     static final String ATTR_VALUE = "value";
     static final String ATTR_NAME = "name";
@@ -251,10 +254,13 @@
     private CompressFormat mIconPersistFormat;
     private int mIconPersistQuality;
 
+    private final PackageManagerInternal mPackageManagerInternal;
+
     public ShortcutService(Context context) {
         mContext = Preconditions.checkNotNull(context);
         LocalServices.addService(ShortcutServiceInternal.class, new LocalService());
         mHandler = new Handler(BackgroundThread.get().getLooper());
+        mPackageManagerInternal = LocalServices.getService(PackageManagerInternal.class);
     }
 
     /**
@@ -460,6 +466,11 @@
         writeTagValue(out, tag, Long.toString(value));
     }
 
+    static void writeTagValue(XmlSerializer out, String tag, ComponentName name) throws IOException {
+        if (name == null) return;
+        writeTagValue(out, tag, name.flattenToString());
+    }
+
     static void writeTagExtra(XmlSerializer out, String tag, PersistableBundle bundle)
             throws IOException, XmlPullParserException {
         if (bundle == null) return;
@@ -658,7 +669,7 @@
     }
 
     // TODO Actually make it async.
-    private void scheduleSaveUser(@UserIdInt int userId) {
+    void scheduleSaveUser(@UserIdInt int userId) {
         synchronized (mLock) {
             saveUserLocked(userId);
         }
@@ -1289,6 +1300,87 @@
         Slog.i(TAG, "ShortcutManager: throttling counter reset");
     }
 
+    // We override this method in unit tests to do a simpler check.
+    boolean hasShortcutHostPermission(@NonNull String callingPackage, int userId) {
+        return hasShortcutHostPermissionInner(callingPackage, userId);
+    }
+
+    // This method is extracted so we can directly call this method from unit tests,
+    // even when hasShortcutPermission() is overridden.
+    @VisibleForTesting
+    boolean hasShortcutHostPermissionInner(@NonNull String callingPackage, int userId) {
+        synchronized (mLock) {
+            long start = 0;
+            if (DEBUG) {
+                start = System.currentTimeMillis();
+            }
+
+            final UserShortcuts user = getUserShortcutsLocked(userId);
+
+            final List<ResolveInfo> allHomeCandidates = new ArrayList<>();
+
+            // Default launcher from package manager.
+            final ComponentName defaultLauncher = injectPackageManagerInternal()
+                    .getHomeActivitiesAsUser(allHomeCandidates, userId);
+
+            ComponentName detected;
+            if (defaultLauncher != null) {
+                detected = defaultLauncher;
+                if (DEBUG) {
+                    Slog.v(TAG, "Default launcher from PM: " + detected);
+                }
+            } else {
+                detected = user.getLauncherComponent();
+
+                // TODO: Make sure it's still enabled.
+                if (DEBUG) {
+                    Slog.v(TAG, "Cached launcher: " + detected);
+                }
+            }
+
+            if (detected == null) {
+                // If we reach here, that means it's the first check since the user was created,
+                // and there's already multiple launchers and there's no default set.
+                // Find the system one with the highest priority.
+                // (We need to check the priority too because of FallbackHome in Settings.)
+                // If there's no system launcher yet, then no one can access shortcuts, until
+                // the user explicitly
+                final int size = allHomeCandidates.size();
+
+                int lastPriority = Integer.MIN_VALUE;
+                for (int i = 0; i < size; i++) {
+                    final ResolveInfo ri = allHomeCandidates.get(i);
+                    if (!ri.activityInfo.applicationInfo.isSystemApp()) {
+                        continue;
+                    }
+                    if (DEBUG) {
+                        Slog.d(TAG, String.format("hasShortcutPermissionInner: pkg=%s prio=%d",
+                                ri.activityInfo.getComponentName(), ri.priority));
+                    }
+                    if (ri.priority < lastPriority) {
+                        continue;
+                    }
+                    detected = ri.activityInfo.getComponentName();
+                    lastPriority = ri.priority;
+                }
+            }
+            if (DEBUG) {
+                long end = System.currentTimeMillis();
+                Slog.v(TAG, String.format("hasShortcutPermission took %d ms", end - start));
+            }
+            if (detected != null) {
+                if (DEBUG) {
+                    Slog.v(TAG, "Detected launcher: " + detected);
+                }
+                user.setLauncherComponent(this, detected);
+                return detected.getPackageName().equals(callingPackage);
+            } else {
+                // Default launcher not found.
+                return false;
+            }
+        }
+    }
+
     /**
      * Entry point from {@link LauncherApps}.
      */
@@ -1434,6 +1526,11 @@
                 }
             }
         }
+
+        @Override
+        public boolean hasShortcutHostPermission(@NonNull String callingPackage, int userId) {
+            return ShortcutService.this.hasShortcutHostPermission(callingPackage, userId);
+        }
     }
 
     // === Dump ===
@@ -1512,37 +1609,74 @@
         (new MyShellCommand()).exec(this, in, out, err, args, resultReceiver);
     }
 
+    static class CommandException extends Exception {
+        public CommandException(String message) {
+            super(message);
+        }
+    }
+
     /**
      * Handle "adb shell cmd".
      */
     private class MyShellCommand extends ShellCommand {
+
+        private int mUserId = UserHandle.USER_SYSTEM;
+
+        private void parseOptions(boolean takeUser)
+                throws CommandException {
+            String opt;
+            while ((opt = getNextOption()) != null) {
+                switch (opt) {
+                    case "--user":
+                        if (takeUser) {
+                            mUserId = UserHandle.parseUserArg(getNextArgRequired());
+                            break;
+                        }
+                        // fallthrough
+                    default:
+                        throw new CommandException("Unknown option: " + opt);
+                }
+            }
+        }
+
         @Override
         public int onCommand(String cmd) {
             if (cmd == null) {
                 return handleDefaultCommands(cmd);
             }
             final PrintWriter pw = getOutPrintWriter();
-            int ret = 1;
-            switch (cmd) {
-                case "reset-package-throttling":
-                    ret = handleResetPackageThrottling();
-                    break;
-                case "reset-throttling":
-                    ret = handleResetThrottling();
-                    break;
-                case "override-config":
-                    ret = handleOverrideConfig();
-                    break;
-                case "reset-config":
-                    ret = handleResetConfig();
-                    break;
-                default:
-                    return handleDefaultCommands(cmd);
+            try {
+                switch (cmd) {
+                    case "reset-package-throttling":
+                        handleResetPackageThrottling();
+                        break;
+                    case "reset-throttling":
+                        handleResetThrottling();
+                        break;
+                    case "override-config":
+                        handleOverrideConfig();
+                        break;
+                    case "reset-config":
+                        handleResetConfig();
+                        break;
+                    case "clear-default-launcher":
+                        handleClearDefaultLauncher();
+                        break;
+                    case "get-default-launcher":
+                        handleGetDefaultLauncher();
+                        break;
+                    case "refresh-default-launcher":
+                        handleRefreshDefaultLauncher();
+                        break;
+                    default:
+                        return handleDefaultCommands(cmd);
+                }
+            } catch (CommandException e) {
+                pw.println("Error: " + e.getMessage());
+                return 1;
             }
-            if (ret == 0) {
-                pw.println("Success");
-            }
-            return ret;
+            pw.println("Success");
+            return 0;
         }
 
         @Override
@@ -1562,6 +1696,15 @@
             pw.println("cmd shortcut reset-config");
             pw.println("    Reset the configuration set with \"update-config\"");
             pw.println();
+            pw.println("cmd shortcut clear-default-launcher [--user USER_ID]");
+            pw.println("    Clear the cached default launcher");
+            pw.println();
+            pw.println("cmd shortcut get-default-launcher [--user USER_ID]");
+            pw.println("    Show the cached default launcher");
+            pw.println();
+            pw.println("cmd shortcut refresh-default-launcher [--user USER_ID]");
+            pw.println("    Refresh the cached default launcher");
+            pw.println();
         }
 
         private int handleResetThrottling() {
@@ -1569,49 +1712,67 @@
             return 0;
         }
 
-        private int handleResetPackageThrottling() {
-            final PrintWriter pw = getOutPrintWriter();
+        private void handleResetPackageThrottling() throws CommandException {
+            parseOptions(/* takeUser =*/ true);
 
-            int userId = UserHandle.USER_SYSTEM;
-            String opt;
-            while ((opt = getNextOption()) != null) {
-                switch (opt) {
-                    case "--user":
-                        userId = UserHandle.parseUserArg(getNextArgRequired());
-                        break;
-                    default:
-                        pw.println("Error: Unknown option: " + opt);
-                        return 1;
-                }
-            }
             final String packageName = getNextArgRequired();
 
             synchronized (mLock) {
-                getPackageShortcutsLocked(packageName, userId).resetRateLimitingForCommandLine();
-                saveUserLocked(userId);
+                getPackageShortcutsLocked(packageName, mUserId).resetRateLimitingForCommandLine();
+                saveUserLocked(mUserId);
             }
-
-            return 0;
         }
 
-        private int handleOverrideConfig() {
-            final PrintWriter pw = getOutPrintWriter();
+        private void handleOverrideConfig() throws CommandException {
             final String config = getNextArgRequired();
 
             synchronized (mLock) {
                 if (!updateConfigurationLocked(config)) {
-                    pw.println("override-config failed.  See logcat for details.");
-                    return 1;
+                    throw new CommandException("override-config failed.  See logcat for details.");
                 }
             }
-            return 0;
         }
 
-        private int handleResetConfig() {
+        private void handleResetConfig() {
             synchronized (mLock) {
                 loadConfigurationLocked();
             }
-            return 0;
+        }
+
+        private void clearLauncher() {
+            synchronized (mLock) {
+                getUserShortcutsLocked(mUserId).setLauncherComponent(
+                        ShortcutService.this, null);
+            }
+        }
+
+        private void showLauncher() {
+            synchronized (mLock) {
+                // This ensures to set the cached launcher.  Package name doesn't matter.
+                hasShortcutHostPermissionInner("-", mUserId);
+
+                getOutPrintWriter().println("Launcher: "
+                        + getUserShortcutsLocked(mUserId).getLauncherComponent());
+            }
+        }
+
+        private void handleClearDefaultLauncher() throws CommandException {
+            parseOptions(/* takeUser =*/ true);
+
+            clearLauncher();
+        }
+
+        private void handleGetDefaultLauncher() throws CommandException {
+            parseOptions(/* takeUser =*/ true);
+
+            showLauncher();
+        }
+
+        private void handleRefreshDefaultLauncher() throws CommandException {
+            parseOptions(/* takeUser =*/ true);
+
+            clearLauncher();
+            showLauncher();
         }
     }
 
@@ -1640,6 +1801,10 @@
         return ActivityManager.isLowRamDeviceStatic();
     }
 
+    PackageManagerInternal injectPackageManagerInternal() {
+        return mPackageManagerInternal;
+    }
+
     File getUserBitmapFilePath(@UserIdInt int userId) {
         return new File(injectUserDataPath(userId), DIRECTORY_BITMAPS);
     }
@@ -1687,6 +1852,9 @@
     }
 }
 
+/**
+ * Per-user information.
+ */
 class UserShortcuts {
     private static final String TAG = ShortcutService.TAG;
 
@@ -1695,6 +1863,8 @@
 
     private final ArrayMap<String, PackageShortcuts> mPackages = new ArrayMap<>();
 
+    private ComponentName mLauncherComponent;
+
     public UserShortcuts(int userId) {
         mUserId = userId;
     }
@@ -1706,11 +1876,11 @@
     public void saveToXml(XmlSerializer out) throws IOException, XmlPullParserException {
         out.startTag(null, ShortcutService.TAG_USER);
 
-        for (int i = 0; i < mPackages.size(); i++) {
-            final String packageName = mPackages.keyAt(i);
-            final PackageShortcuts packageShortcuts = mPackages.valueAt(i);
+        ShortcutService.writeTagValue(out, ShortcutService.TAG_LAUNCHER,
+                mLauncherComponent);
 
-            packageShortcuts.saveToXml(out);
+        for (int i = 0; i < mPackages.size(); i++) {
+            mPackages.valueAt(i).saveToXml(out);
         }
 
         out.endTag(null, ShortcutService.TAG_USER);
@@ -1730,6 +1900,10 @@
             final int depth = parser.getDepth();
             final String tag = parser.getName();
             switch (tag) {
+                case ShortcutService.TAG_LAUNCHER:
+                    ret.mLauncherComponent = ShortcutService.parseComponentNameAttribute(
+                            parser, ShortcutService.ATTR_VALUE);
+                    continue;
                 case ShortcutService.TAG_PACKAGE:
                     final PackageShortcuts shortcuts = PackageShortcuts.loadFromXml(parser, userId);
 
@@ -1742,12 +1916,30 @@
         return ret;
     }
 
+    public ComponentName getLauncherComponent() {
+        return mLauncherComponent;
+    }
+
+    public void setLauncherComponent(ShortcutService s, ComponentName launcherComponent) {
+        if (Objects.equal(mLauncherComponent, launcherComponent)) {
+            return;
+        }
+        mLauncherComponent = launcherComponent;
+        s.scheduleSaveUser(mUserId);
+    }
+
     public void dump(@NonNull ShortcutService s, @NonNull PrintWriter pw, @NonNull String prefix) {
-        pw.print("  ");
+        pw.print(prefix);
         pw.print("User: ");
         pw.print(mUserId);
         pw.println();
 
+        pw.print(prefix);
+        pw.print("  ");
+        pw.print("Default launcher: ");
+        pw.print(mLauncherComponent);
+        pw.println();
+
         for (int i = 0; i < mPackages.size(); i++) {
             mPackages.valueAt(i).dump(s, pw, prefix + "  ");
         }
diff --git a/services/tests/servicestests/src/com/android/server/pm/ShortcutManagerTest.java b/services/tests/servicestests/src/com/android/server/pm/ShortcutManagerTest.java
index f2c42db..caadbf9 100644
--- a/services/tests/servicestests/src/com/android/server/pm/ShortcutManagerTest.java
+++ b/services/tests/servicestests/src/com/android/server/pm/ShortcutManagerTest.java
@@ -16,6 +16,7 @@
 package com.android.server.pm;
 
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
 
 import android.annotation.NonNull;
 import android.annotation.UserIdInt;
@@ -27,6 +28,7 @@
 import android.content.pm.LauncherApps;
 import android.content.pm.LauncherApps.ShortcutQuery;
 import android.content.pm.PackageManager;
+import android.content.pm.PackageManagerInternal;
 import android.content.pm.ShortcutInfo;
 import android.content.pm.ShortcutManager;
 import android.content.pm.ShortcutServiceInternal;
@@ -191,6 +193,17 @@
         boolean injectIsLowRamDevice() {
             return mInjectdIsLowRamDevice;
         }
+
+        @Override
+        PackageManagerInternal injectPackageManagerInternal() {
+            return mMockPackageManagerInternal;
+        }
+
+        @Override
+        boolean hasShortcutHostPermission(@NonNull String callingPackage, int userId) {
+            // Sort of hack; do a simpler check.
+            return LAUNCHER_1.equals(callingPackage) || LAUNCHER_2.equals(callingPackage);
+        }
     }
 
     /** ShortcutManager with injection override methods. */
@@ -258,6 +271,7 @@
     private Map<String, Integer> mInjectedPackageUidMap;
 
     private PackageManager mMockPackageManager;
+    private PackageManagerInternal mMockPackageManagerInternal;
     private UserManager mMockUserManager;
 
     private static final String CALLING_PACKAGE_1 = "com.android.test.1";
@@ -298,6 +312,7 @@
         mClientContext = new ClientContext();
 
         mMockPackageManager = mock(PackageManager.class);
+        mMockPackageManagerInternal = mock(PackageManagerInternal.class);
         mMockUserManager = mock(UserManager.class);
 
         // Prepare injection values.
@@ -1889,6 +1904,9 @@
             assertEquals(2, mManager.getRemainingCallCount());
         });
 
+        mService.getShortcutsForTest().get(UserHandle.USER_SYSTEM).setLauncherComponent(
+                mService, new ComponentName("pkg1", "class"));
+
         // Restore.
         initService();
 
@@ -1918,6 +1936,9 @@
             assertEquals("title2-2", getCallerShortcut("s2").getTitle());
         });
 
+        assertEquals("pkg1", mService.getShortcutsForTest().get(UserHandle.USER_SYSTEM)
+                .getLauncherComponent().getPackageName());
+
         // Start another user
         mService.onStartUserLocked(USER_10);
 
@@ -1932,6 +1953,7 @@
             assertEquals("title10-1-1", getCallerShortcut("s1").getTitle());
             assertEquals("title10-1-2", getCallerShortcut("s2").getTitle());
         });
+        assertNull(mService.getShortcutsForTest().get(USER_10).getLauncherComponent());
 
         // Try stopping the user
         mService.onCleanupUserInner(USER_10);
@@ -1941,4 +1963,8 @@
 
         // TODO Check all other fields
     }
+
+    // TODO Detailed test for hasShortcutPermissionInner().
+
+    // TODO Add tests for the command line functions too.
 }