Allocate isolated UID ranges for app zygote and its children.

Introduce a new range of app-zygote isolated UIDs, [90000..98999].
For each app that uses an application Zygote, allocate a range of
100 isolated UIDs. The application Zygote for an app will get a
UID out of that range, and all other children that are forked
from that zygote will get a UID from the same range.

Bug:  111434506
Test: app Zygote and its children run in the new range of
      isolated UIDs (with SELinux disabled). New set of
      tests for UID allocators pass.

Change-Id: I7a6883a5ddb95683932c93ea77f4e52d8f37fa4f
diff --git a/core/java/android/os/AppZygote.java b/core/java/android/os/AppZygote.java
index 2275693..40cbaf7 100644
--- a/core/java/android/os/AppZygote.java
+++ b/core/java/android/os/AppZygote.java
@@ -34,6 +34,8 @@
 public class AppZygote {
     private static final String LOG_TAG = "AppZygote";
 
+    private final int mZygoteUid;
+
     private final Object mLock = new Object();
 
     /**
@@ -45,8 +47,9 @@
 
     private final ApplicationInfo mAppInfo;
 
-    public AppZygote(ApplicationInfo appInfo) {
+    public AppZygote(ApplicationInfo appInfo, int zygoteUid) {
         mAppInfo = appInfo;
+        mZygoteUid = zygoteUid;
     }
 
     /**
@@ -94,8 +97,8 @@
             mZygote = Process.zygoteProcess.startChildZygote(
                     "com.android.internal.os.AppZygoteInit",
                     mAppInfo.processName + "_zygote",
-                    mAppInfo.uid,
-                    mAppInfo.uid,
+                    mZygoteUid,
+                    mZygoteUid,
                     null,  // gids
                     0,  // runtimeFlags
                     "app_zygote",  // seInfo
diff --git a/core/java/android/os/Process.java b/core/java/android/os/Process.java
index 938b23c..ee56e3d 100644
--- a/core/java/android/os/Process.java
+++ b/core/java/android/os/Process.java
@@ -205,6 +205,24 @@
     public static final int LAST_APPLICATION_UID = 19999;
 
     /**
+     * First uid used for fully isolated sandboxed processes spawned from an app zygote
+     * @hide
+     */
+    public static final int FIRST_APP_ZYGOTE_ISOLATED_UID = 90000;
+
+    /**
+     * Number of UIDs we allocate per application zygote
+     * @hide
+     */
+    public static final int NUM_UIDS_PER_APP_ZYGOTE = 100;
+
+    /**
+     * Last uid used for fully isolated sandboxed processes spawned from an app zygote
+     * @hide
+     */
+    public static final int LAST_APP_ZYGOTE_ISOLATED_UID = 98999;
+
+    /**
      * First uid used for fully isolated sandboxed processes (with no permissions of their own)
      * @hide
      */
@@ -650,7 +668,8 @@
     /** {@hide} */
     public static final boolean isIsolated(int uid) {
         uid = UserHandle.getAppId(uid);
-        return uid >= FIRST_ISOLATED_UID && uid <= LAST_ISOLATED_UID;
+        return (uid >= FIRST_ISOLATED_UID && uid <= LAST_ISOLATED_UID)
+                || (uid >= FIRST_APP_ZYGOTE_ISOLATED_UID && uid <= LAST_APP_ZYGOTE_ISOLATED_UID);
     }
 
     /**
diff --git a/core/java/android/os/UserHandle.java b/core/java/android/os/UserHandle.java
index f8feb7b..ad8a4d5 100644
--- a/core/java/android/os/UserHandle.java
+++ b/core/java/android/os/UserHandle.java
@@ -138,8 +138,7 @@
      */
     public static boolean isIsolated(int uid) {
         if (uid > 0) {
-            final int appId = getAppId(uid);
-            return appId >= Process.FIRST_ISOLATED_UID && appId <= Process.LAST_ISOLATED_UID;
+            return Process.isIsolated(uid);
         } else {
             return false;
         }
@@ -294,9 +293,14 @@
             sb.append('u');
             sb.append(getUserId(uid));
             final int appId = getAppId(uid);
-            if (appId >= Process.FIRST_ISOLATED_UID && appId <= Process.LAST_ISOLATED_UID) {
-                sb.append('i');
-                sb.append(appId - Process.FIRST_ISOLATED_UID);
+            if (isIsolated(appId)) {
+                if (appId > Process.FIRST_ISOLATED_UID) {
+                    sb.append('i');
+                    sb.append(appId - Process.FIRST_ISOLATED_UID);
+                } else {
+                    sb.append("ai");
+                    sb.append(appId - Process.FIRST_APP_ZYGOTE_ISOLATED_UID);
+                }
             } else if (appId >= Process.FIRST_APPLICATION_UID) {
                 sb.append('a');
                 sb.append(appId - Process.FIRST_APPLICATION_UID);
@@ -330,9 +334,14 @@
             pw.print('u');
             pw.print(getUserId(uid));
             final int appId = getAppId(uid);
-            if (appId >= Process.FIRST_ISOLATED_UID && appId <= Process.LAST_ISOLATED_UID) {
-                pw.print('i');
-                pw.print(appId - Process.FIRST_ISOLATED_UID);
+            if (isIsolated(appId)) {
+                if (appId > Process.FIRST_ISOLATED_UID) {
+                    pw.print('i');
+                    pw.print(appId - Process.FIRST_ISOLATED_UID);
+                } else {
+                    pw.print("ai");
+                    pw.print(appId - Process.FIRST_APP_ZYGOTE_ISOLATED_UID);
+                }
             } else if (appId >= Process.FIRST_APPLICATION_UID) {
                 pw.print('a');
                 pw.print(appId - Process.FIRST_APPLICATION_UID);
diff --git a/core/java/com/android/internal/os/WebViewZygoteInit.java b/core/java/com/android/internal/os/WebViewZygoteInit.java
index 2c8e66d..0b329d7 100644
--- a/core/java/com/android/internal/os/WebViewZygoteInit.java
+++ b/core/java/com/android/internal/os/WebViewZygoteInit.java
@@ -121,7 +121,6 @@
 
     public static void main(String argv[]) {
         Log.i(TAG, "Starting WebViewZygoteInit");
-
         WebViewZygoteServer server = new WebViewZygoteServer();
         ChildZygoteInit.runZygoteServer(server, argv);
     }
diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index e171736..bc21610 100644
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -1943,7 +1943,8 @@
             synchronized (this) {
                 ProcessRecord app = mProcessList.newProcessRecordLocked(info, info.processName,
                         false,
-                        0);
+                        0,
+                        false);
                 app.setPersistent(true);
                 app.pid = MY_PID;
                 app.getWindowProcessController().setPid(MY_PID);
@@ -7407,7 +7408,7 @@
         }
 
         if (app == null) {
-            app = mProcessList.newProcessRecordLocked(info, customProcess, isolated, 0);
+            app = mProcessList.newProcessRecordLocked(info, customProcess, isolated, 0, false);
             mProcessList.updateLruProcessLocked(app, false, null);
             updateOomAdjLocked();
         }
diff --git a/services/core/java/com/android/server/am/ProcessList.java b/services/core/java/com/android/server/am/ProcessList.java
index 896452b..9898d06 100644
--- a/services/core/java/com/android/server/am/ProcessList.java
+++ b/services/core/java/com/android/server/am/ProcessList.java
@@ -19,8 +19,6 @@
 import static android.app.ActivityManager.PROCESS_STATE_CACHED_ACTIVITY;
 import static android.app.ActivityThread.PROC_START_SEQ_IDENT;
 import static android.content.pm.PackageManager.MATCH_DIRECT_BOOT_AUTO;
-import static android.os.Process.FIRST_ISOLATED_UID;
-import static android.os.Process.LAST_ISOLATED_UID;
 import static android.os.Process.SYSTEM_UID;
 import static android.os.Process.THREAD_PRIORITY_BACKGROUND;
 import static android.os.Process.getFreeMemory;
@@ -83,6 +81,7 @@
 import android.util.LongSparseArray;
 import android.util.Slog;
 import android.util.SparseArray;
+import android.util.SparseBooleanArray;
 import android.util.StatsLog;
 import android.view.Display;
 
@@ -112,6 +111,7 @@
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.BitSet;
 import java.util.List;
 
 /**
@@ -368,11 +368,126 @@
     final ArrayMap<AppZygote, ArrayList<ProcessRecord>> mAppZygoteProcesses =
             new ArrayMap<AppZygote, ArrayList<ProcessRecord>>();
 
+    final class IsolatedUidRange {
+        @VisibleForTesting
+        public final int mFirstUid;
+        @VisibleForTesting
+        public final int mLastUid;
+
+        @GuardedBy("ProcessList.this.mService")
+        private final SparseBooleanArray mUidUsed = new SparseBooleanArray();
+
+        @GuardedBy("ProcessList.this.mService")
+        private int mNextUid;
+
+        IsolatedUidRange(int firstUid, int lastUid) {
+            mFirstUid = firstUid;
+            mLastUid = lastUid;
+            mNextUid = firstUid;
+        }
+
+        @GuardedBy("ProcessList.this.mService")
+        int allocateIsolatedUidLocked(int userId) {
+            int uid;
+            int stepsLeft = (mLastUid - mFirstUid + 1);
+            for (int i = 0; i < stepsLeft; ++i) {
+                if (mNextUid < mFirstUid || mNextUid > mLastUid) {
+                    mNextUid = mFirstUid;
+                }
+                uid = UserHandle.getUid(userId, mNextUid);
+                mNextUid++;
+                if (!mUidUsed.get(uid, false)) {
+                    mUidUsed.put(uid, true);
+                    return uid;
+                }
+            }
+            return -1;
+        }
+
+        @GuardedBy("ProcessList.this.mService")
+        void freeIsolatedUidLocked(int uid) {
+            // Strip out userId
+            final int appId = UserHandle.getAppId(uid);
+            mUidUsed.delete(appId);
+        }
+    };
+
     /**
-     * Counter for assigning isolated process uids, to avoid frequently reusing the
-     * same ones.
+     * A class that allocates ranges of isolated UIDs per application, and keeps track of them.
      */
-    int mNextIsolatedProcessUid = 0;
+    final class IsolatedUidRangeAllocator {
+        private final int mFirstUid;
+        private final int mNumUidRanges;
+        private final int mNumUidsPerRange;
+        /**
+         * We map the uid range [mFirstUid, mFirstUid + mNumUidRanges * mNumUidsPerRange)
+         * back to an underlying bitset of [0, mNumUidRanges) and allocate out of that.
+         */
+        @GuardedBy("ProcessList.this.mService")
+        private final BitSet mAvailableUidRanges;
+        @GuardedBy("ProcessList.this.mService")
+        private final ProcessMap<IsolatedUidRange> mAppRanges = new ProcessMap<IsolatedUidRange>();
+
+        IsolatedUidRangeAllocator(int firstUid, int lastUid, int numUidsPerRange) {
+            mFirstUid = firstUid;
+            mNumUidsPerRange = numUidsPerRange;
+            mNumUidRanges = (lastUid - firstUid + 1) / numUidsPerRange;
+            mAvailableUidRanges = new BitSet(mNumUidRanges);
+            // Mark all as available
+            mAvailableUidRanges.set(0, mNumUidRanges);
+        }
+
+        @GuardedBy("ProcessList.this.mService")
+        IsolatedUidRange getIsolatedUidRangeLocked(ApplicationInfo info) {
+            return mAppRanges.get(info.processName, info.uid);
+        }
+
+        @GuardedBy("ProcessList.this.mService")
+        IsolatedUidRange getOrCreateIsolatedUidRangeLocked(ApplicationInfo info) {
+            IsolatedUidRange range = getIsolatedUidRangeLocked(info);
+            if (range == null) {
+                int uidRangeIndex = mAvailableUidRanges.nextSetBit(0);
+                if (uidRangeIndex < 0) {
+                    // No free range
+                    return null;
+                }
+                mAvailableUidRanges.clear(uidRangeIndex);
+                int actualUid = mFirstUid + uidRangeIndex * mNumUidsPerRange;
+                range = new IsolatedUidRange(actualUid, actualUid + mNumUidsPerRange - 1);
+                mAppRanges.put(info.processName, info.uid, range);
+            }
+            return range;
+        }
+
+        @GuardedBy("ProcessList.this.mService")
+        void freeUidRangeLocked(ApplicationInfo info) {
+            // Find the UID range
+            IsolatedUidRange range = mAppRanges.get(info.processName, info.uid);
+            if (range != null) {
+                // Map back to starting uid
+                final int uidRangeIndex = (range.mFirstUid - mFirstUid) / mNumUidsPerRange;
+                // Mark it as available in the underlying bitset
+                mAvailableUidRanges.set(uidRangeIndex);
+                // And the map
+                mAppRanges.remove(info.processName, info.uid);
+            }
+        }
+    }
+
+    /**
+     * The available isolated UIDs for processes that are not spawned from an application zygote.
+     */
+    @VisibleForTesting
+    IsolatedUidRange mGlobalIsolatedUids = new IsolatedUidRange(Process.FIRST_ISOLATED_UID,
+            Process.LAST_ISOLATED_UID);
+
+    /**
+     * An allocator for isolated UID ranges for apps that use an application zygote.
+     */
+    @VisibleForTesting
+    IsolatedUidRangeAllocator mAppIsolatedUidRangeAllocator =
+            new IsolatedUidRangeAllocator(Process.FIRST_APP_ZYGOTE_ISOLATED_UID,
+                    Process.LAST_APP_ZYGOTE_ISOLATED_UID, Process.NUM_UIDS_PER_APP_ZYGOTE);
 
     /**
      * Processes that are being forcibly torn down.
@@ -1527,12 +1642,20 @@
         if (zygoteProcesses.size() == 0) { // Only remove if no longer in use now
             mAppZygotes.remove(appInfo.processName, appInfo.uid);
             mAppZygoteProcesses.remove(appZygote);
+            mAppIsolatedUidRangeAllocator.freeUidRangeLocked(appInfo);
             appZygote.stopZygote();
         }
     }
 
     @GuardedBy("mService")
     private void removeProcessFromAppZygoteLocked(final ProcessRecord app) {
+        // Free the isolated uid for this process
+        final IsolatedUidRange appUidRange =
+                mAppIsolatedUidRangeAllocator.getIsolatedUidRangeLocked(app.info);
+        if (appUidRange != null) {
+            appUidRange.freeIsolatedUidLocked(app.uid);
+        }
+
         final AppZygote appZygote = mAppZygotes.get(app.info.processName, app.info.uid);
         if (appZygote != null) {
             ArrayList<ProcessRecord> zygoteProcesses = mAppZygoteProcesses.get(appZygote);
@@ -1550,7 +1673,12 @@
             AppZygote appZygote = mAppZygotes.get(app.info.processName, app.info.uid);
             final ArrayList<ProcessRecord> zygoteProcessList;
             if (appZygote == null) {
-                appZygote = new AppZygote(app.info);
+                final int userId = UserHandle.getUserId(app.info.uid);
+                final IsolatedUidRange uidRange =
+                        mAppIsolatedUidRangeAllocator.getIsolatedUidRangeLocked(app.info);
+                // Allocate an isolated UID out of this range for the Zygote itself
+                final int zygoteIsolatedUid = uidRange.allocateIsolatedUidLocked(userId);
+                appZygote = new AppZygote(app.info, zygoteIsolatedUid);
                 mAppZygotes.put(app.info.processName, app.info.uid, appZygote);
                 zygoteProcessList = new ArrayList<ProcessRecord>();
                 mAppZygoteProcesses.put(appZygote, zygoteProcessList);
@@ -1701,8 +1829,9 @@
                 ? hostingName.flattenToShortString() : null;
 
         if (app == null) {
+            final boolean fromAppZygote = "app_zygote".equals(hostingType);
             checkSlow(startTime, "startProcess: creating new process record");
-            app = newProcessRecordLocked(info, processName, isolated, isolatedUid);
+            app = newProcessRecordLocked(info, processName, isolated, isolatedUid, fromAppZygote);
             if (app == null) {
                 Slog.w(TAG, "Failed making new process record for "
                         + processName + "/" + info.uid + " isolated=" + isolated);
@@ -2075,29 +2204,31 @@
     }
 
     @GuardedBy("mService")
+    private IsolatedUidRange getOrCreateIsolatedUidRangeLocked(ApplicationInfo info,
+            boolean fromAppZygote) {
+        if (!fromAppZygote) {
+            // Allocate an isolated UID from the global range
+            return mGlobalIsolatedUids;
+        } else {
+            return mAppIsolatedUidRangeAllocator.getOrCreateIsolatedUidRangeLocked(info);
+        }
+    }
+
+    @GuardedBy("mService")
     final ProcessRecord newProcessRecordLocked(ApplicationInfo info, String customProcess,
-            boolean isolated, int isolatedUid) {
+            boolean isolated, int isolatedUid, boolean fromAppZygote) {
         String proc = customProcess != null ? customProcess : info.processName;
         final int userId = UserHandle.getUserId(info.uid);
         int uid = info.uid;
         if (isolated) {
             if (isolatedUid == 0) {
-                int stepsLeft = LAST_ISOLATED_UID - FIRST_ISOLATED_UID + 1;
-                while (true) {
-                    if (mNextIsolatedProcessUid < FIRST_ISOLATED_UID
-                            || mNextIsolatedProcessUid > LAST_ISOLATED_UID) {
-                        mNextIsolatedProcessUid = FIRST_ISOLATED_UID;
-                    }
-                    uid = UserHandle.getUid(userId, mNextIsolatedProcessUid);
-                    mNextIsolatedProcessUid++;
-                    if (mIsolatedProcesses.indexOfKey(uid) < 0) {
-                        // No process for this uid, use it.
-                        break;
-                    }
-                    stepsLeft--;
-                    if (stepsLeft <= 0) {
-                        return null;
-                    }
+                IsolatedUidRange uidRange = getOrCreateIsolatedUidRangeLocked(info, fromAppZygote);
+                if (uidRange == null) {
+                    return null;
+                }
+                uid = uidRange.allocateIsolatedUidLocked(userId);
+                if (uid == -1) {
+                    return null;
                 }
             } else {
                 // Special case for startIsolatedProcess (internal only), where
@@ -2165,9 +2296,10 @@
             old.uidRecord = null;
         }
         mIsolatedProcesses.remove(uid);
+        mGlobalIsolatedUids.freeIsolatedUidLocked(uid);
         // Remove the (expected) ProcessRecord from the app zygote
         final ProcessRecord record = expecting != null ? expecting : old;
-        if (record != null && record.isolated) {
+        if (record != null && record.appZygote) {
             removeProcessFromAppZygoteLocked(record);
         }
 
diff --git a/services/core/java/com/android/server/am/ProcessRecord.java b/services/core/java/com/android/server/am/ProcessRecord.java
index 6f0a562..0d0824a 100644
--- a/services/core/java/com/android/server/am/ProcessRecord.java
+++ b/services/core/java/com/android/server/am/ProcessRecord.java
@@ -76,6 +76,7 @@
     private final ActivityManagerService mService; // where we came from
     final ApplicationInfo info; // all about the first app in the process
     final boolean isolated;     // true if this is a special isolated process
+    final boolean appZygote;    // true if this is forked from the app zygote
     final int uid;              // uid of process; may be different from 'info' if isolated
     final int userId;           // user of process.
     final String processName;   // name of the process
@@ -559,6 +560,8 @@
         mService = _service;
         info = _info;
         isolated = _info.uid != _uid;
+        appZygote = (UserHandle.getAppId(_uid) >= Process.FIRST_APP_ZYGOTE_ISOLATED_UID
+                && UserHandle.getAppId(_uid) <= Process.LAST_APP_ZYGOTE_ISOLATED_UID);
         uid = _uid;
         userId = UserHandle.getUserId(_uid);
         processName = _processName;
diff --git a/services/tests/servicestests/src/com/android/server/am/ActivityManagerServiceTest.java b/services/tests/servicestests/src/com/android/server/am/ActivityManagerServiceTest.java
index ea0e095..6a10ff4 100644
--- a/services/tests/servicestests/src/com/android/server/am/ActivityManagerServiceTest.java
+++ b/services/tests/servicestests/src/com/android/server/am/ActivityManagerServiceTest.java
@@ -71,6 +71,8 @@
 import androidx.test.filters.SmallTest;
 
 import com.android.server.AppOpsService;
+import com.android.server.am.ProcessList.IsolatedUidRange;
+import com.android.server.am.ProcessList.IsolatedUidRangeAllocator;
 import com.android.server.wm.ActivityTaskManagerService;
 
 import org.junit.After;
@@ -294,6 +296,113 @@
         }
     }
 
+    private void validateAppZygoteIsolatedUidRange(IsolatedUidRange uidRange) {
+        assertNotNull(uidRange);
+        assertTrue(uidRange.mFirstUid >= Process.FIRST_APP_ZYGOTE_ISOLATED_UID
+                && uidRange.mFirstUid <= Process.LAST_APP_ZYGOTE_ISOLATED_UID);
+        assertTrue(uidRange.mLastUid >= Process.FIRST_APP_ZYGOTE_ISOLATED_UID
+                && uidRange.mLastUid <= Process.LAST_APP_ZYGOTE_ISOLATED_UID);
+        assertTrue(uidRange.mLastUid > uidRange.mFirstUid
+                && ((uidRange.mLastUid - uidRange.mFirstUid + 1)
+                     == Process.NUM_UIDS_PER_APP_ZYGOTE));
+    }
+
+    private void verifyUidRangesNoOverlap(IsolatedUidRange uidRange1, IsolatedUidRange uidRange2) {
+        IsolatedUidRange lowRange = uidRange1.mFirstUid <= uidRange2.mFirstUid ? uidRange1 : uidRange2;
+        IsolatedUidRange highRange = lowRange == uidRange1  ? uidRange2 : uidRange1;
+
+        assertTrue(highRange.mFirstUid > lowRange.mLastUid);
+    }
+
+    @Test
+    public void testIsolatedUidRangeAllocator() {
+        final IsolatedUidRangeAllocator allocator = mAms.mProcessList.mAppIsolatedUidRangeAllocator;
+
+        // Create initial range
+        ApplicationInfo appInfo = new ApplicationInfo();
+        appInfo.processName = "com.android.test.app";
+        appInfo.uid = 10000;
+        final IsolatedUidRange range = allocator.getOrCreateIsolatedUidRangeLocked(appInfo);
+        validateAppZygoteIsolatedUidRange(range);
+        verifyIsolatedUidAllocator(range);
+
+        // Create a second range
+        ApplicationInfo appInfo2 = new ApplicationInfo();
+        appInfo2.processName = "com.android.test.app2";
+        appInfo2.uid = 10001;
+        IsolatedUidRange range2 = allocator.getOrCreateIsolatedUidRangeLocked(appInfo2);
+        validateAppZygoteIsolatedUidRange(range2);
+        verifyIsolatedUidAllocator(range2);
+
+        // Verify ranges don't overlap
+        verifyUidRangesNoOverlap(range, range2);
+
+        // Free range, reallocate and verify
+        allocator.freeUidRangeLocked(appInfo2);
+        range2 = allocator.getOrCreateIsolatedUidRangeLocked(appInfo2);
+        validateAppZygoteIsolatedUidRange(range2);
+        verifyUidRangesNoOverlap(range, range2);
+        verifyIsolatedUidAllocator(range2);
+
+        // Free both, then try to allocate the maximum number of UID ranges
+        allocator.freeUidRangeLocked(appInfo);
+        allocator.freeUidRangeLocked(appInfo2);
+
+        int maxNumUidRanges = (Process.LAST_APP_ZYGOTE_ISOLATED_UID
+                - Process.FIRST_APP_ZYGOTE_ISOLATED_UID + 1) / Process.NUM_UIDS_PER_APP_ZYGOTE;
+        for (int i = 0; i < maxNumUidRanges; i++) {
+            appInfo = new ApplicationInfo();
+            appInfo.uid = 10000 + i;
+            appInfo.processName = "com.android.test.app" + Integer.toString(i);
+            IsolatedUidRange uidRange = allocator.getOrCreateIsolatedUidRangeLocked(appInfo);
+            validateAppZygoteIsolatedUidRange(uidRange);
+            verifyIsolatedUidAllocator(uidRange);
+        }
+
+        // Try to allocate another one and make sure it fails
+        appInfo = new ApplicationInfo();
+        appInfo.uid = 9000;
+        appInfo.processName = "com.android.test.app.failed";
+        IsolatedUidRange failedRange = allocator.getOrCreateIsolatedUidRangeLocked(appInfo);
+
+        assertNull(failedRange);
+    }
+
+    public void verifyIsolatedUid(ProcessList.IsolatedUidRange range, int uid) {
+        assertTrue(uid >= range.mFirstUid && uid <= range.mLastUid);
+    }
+
+    public void verifyIsolatedUidAllocator(ProcessList.IsolatedUidRange range) {
+        int uid = range.allocateIsolatedUidLocked(0);
+        verifyIsolatedUid(range, uid);
+
+        int uid2 = range.allocateIsolatedUidLocked(0);
+        verifyIsolatedUid(range, uid2);
+        assertTrue(uid2 != uid);
+
+        // Free both
+        range.freeIsolatedUidLocked(uid);
+        range.freeIsolatedUidLocked(uid2);
+
+        // Allocate the entire range
+        for (int i = 0; i < (range.mLastUid - range.mFirstUid + 1); ++i) {
+            uid = range.allocateIsolatedUidLocked(0);
+            verifyIsolatedUid(range, uid);
+        }
+
+        // Ensure the next one fails
+        uid = range.allocateIsolatedUidLocked(0);
+        assertEquals(uid, -1);
+    }
+
+    @Test
+    public void testGlobalIsolatedUidAllocator() {
+        final IsolatedUidRange globalUidRange = mAms.mProcessList.mGlobalIsolatedUids;
+        assertEquals(globalUidRange.mFirstUid, Process.FIRST_ISOLATED_UID);
+        assertEquals(globalUidRange.mLastUid, Process.LAST_ISOLATED_UID);
+        verifyIsolatedUidAllocator(globalUidRange);
+    }
+
     @Test
     public void testBlockStateForUid() {
         final UidRecord uidRec = new UidRecord(TEST_UID, null /* atmInternal */);