Merge changes Id931d441,I83faf974

* changes:
  Zygote: Improve logging and error handling during connections.
  Zygote: Fix race condition on package preloads.

core/java/android/os/ZygoteProcess.java

@@ -463,7 +463,7 @@ public class ZygoteProcess {
      * Instructs the zygote to pre-load the classes and native libraries at the given paths
      * for the specified abi. Not all zygotes support this function.
      */
-    public void preloadPackageForAbi(String packagePath, String libsPath, String cacheKey,
+    public boolean preloadPackageForAbi(String packagePath, String libsPath, String cacheKey,
                                         String abi) throws ZygoteStartFailedEx, IOException {
         synchronized(mLock) {
             ZygoteState state = openZygoteSocketIfNeeded(abi);
@@ -483,6 +483,8 @@ public class ZygoteProcess {
             state.writer.newLine();
 
             state.writer.flush();
+
+            return (state.inputStream.readInt() == 0);
         }
     }
 

core/java/com/android/internal/os/RuntimeInit.java

@@ -31,6 +31,7 @@ import android.util.Slog;
 import com.android.internal.logging.AndroidConfig;
 import com.android.server.NetworkManagementSocketTagger;
 import dalvik.system.VMRuntime;
+import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.util.TimeZone;
@@ -228,8 +229,8 @@ public class RuntimeInit {
      * @param argv Argument vector for main()
      * @param classLoader the classLoader to load {@className} with
      */
-    private static void invokeStaticMain(String className, String[] argv, ClassLoader classLoader)
+    private static Runnable findStaticMain(String className, String[] argv,
-            throws Zygote.MethodAndArgsCaller {
+            ClassLoader classLoader) {
         Class<?> cl;
 
         try {
@@ -263,7 +264,7 @@ public class RuntimeInit {
          * clears up all the stack frames that were required in setting
          * up the process.
          */
-        throw new Zygote.MethodAndArgsCaller(m, argv);
+        return new MethodAndArgsCaller(m, argv);
     }
 
     public static final void main(String[] argv) {
@@ -286,8 +287,8 @@ public class RuntimeInit {
         if (DEBUG) Slog.d(TAG, "Leaving RuntimeInit!");
     }
 
-    protected static void applicationInit(int targetSdkVersion, String[] argv, ClassLoader classLoader)
+    protected static Runnable applicationInit(int targetSdkVersion, String[] argv,
-            throws Zygote.MethodAndArgsCaller {
+            ClassLoader classLoader) {
         // If the application calls System.exit(), terminate the process
         // immediately without running any shutdown hooks.  It is not possible to
         // shutdown an Android application gracefully.  Among other things, the
@@ -300,20 +301,13 @@ public class RuntimeInit {
         VMRuntime.getRuntime().setTargetHeapUtilization(0.75f);
         VMRuntime.getRuntime().setTargetSdkVersion(targetSdkVersion);
 
-        final Arguments args;
+        final Arguments args = new Arguments(argv);
-        try {
-            args = new Arguments(argv);
-        } catch (IllegalArgumentException ex) {
-            Slog.e(TAG, ex.getMessage());
-            // let the process exit
-            return;
-        }
 
         // The end of of the RuntimeInit event (see #zygoteInit).
         Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
 
         // Remaining arguments are passed to the start class's static main
-        invokeStaticMain(args.startClass, args.startArgs, classLoader);
+        return findStaticMain(args.startClass, args.startArgs, classLoader);
     }
 
     /**
@@ -422,4 +416,37 @@ public class RuntimeInit {
             System.arraycopy(args, curArg, startArgs, 0, startArgs.length);
         }
     }
+
+    /**
+     * Helper class which holds a method and arguments and can call them. This is used as part of
+     * a trampoline to get rid of the initial process setup stack frames.
+     */
+    static class MethodAndArgsCaller implements Runnable {
+        /** method to call */
+        private final Method mMethod;
+
+        /** argument array */
+        private final String[] mArgs;
+
+        public MethodAndArgsCaller(Method method, String[] args) {
+            mMethod = method;
+            mArgs = args;
+        }
+
+        public void run() {
+            try {
+                mMethod.invoke(null, new Object[] { mArgs });
+            } catch (IllegalAccessException ex) {
+                throw new RuntimeException(ex);
+            } catch (InvocationTargetException ex) {
+                Throwable cause = ex.getCause();
+                if (cause instanceof RuntimeException) {
+                    throw (RuntimeException) cause;
+                } else if (cause instanceof Error) {
+                    throw (Error) cause;
+                }
+                throw new RuntimeException(ex);
+            }
+        }
+    }
 }

core/java/com/android/internal/os/WebViewZygoteInit.java

@@ -26,6 +26,7 @@ import android.util.Log;
 import android.webkit.WebViewFactory;
 import android.webkit.WebViewFactoryProvider;
 
+import java.io.DataOutputStream;
 import java.io.File;
 import java.io.IOException;
 import java.lang.reflect.InvocationTargetException;
@@ -68,8 +69,7 @@ class WebViewZygoteInit {
         }
 
         @Override
-        protected boolean handlePreloadPackage(String packagePath, String libsPath,
+        protected void handlePreloadPackage(String packagePath, String libsPath, String cacheKey) {
-                                               String cacheKey) {
             Log.i(TAG, "Beginning package preload");
             // Ask ApplicationLoaders to create and cache a classloader for the WebView APK so that
             // our children will reuse the same classloader instead of creating their own.
@@ -87,19 +87,28 @@ class WebViewZygoteInit {
             // Once we have the classloader, look up the WebViewFactoryProvider implementation and
             // call preloadInZygote() on it to give it the opportunity to preload the native library
             // and perform any other initialisation work that should be shared among the children.
+            boolean preloadSucceeded = false;
             try {
                 Class<WebViewFactoryProvider> providerClass =
                         WebViewFactory.getWebViewProviderClass(loader);
                 Object result = providerClass.getMethod("preloadInZygote").invoke(null);
-                if (!((Boolean)result).booleanValue()) {
+                preloadSucceeded = ((Boolean) result).booleanValue();
+                if (!preloadSucceeded) {
                     Log.e(TAG, "preloadInZygote returned false");
                 }
             } catch (ClassNotFoundException | NoSuchMethodException | SecurityException |
                      IllegalAccessException | InvocationTargetException e) {
                 Log.e(TAG, "Exception while preloading package", e);
             }
+
+            try {
+                DataOutputStream socketOut = getSocketOutputStream();
+                socketOut.writeInt(preloadSucceeded ? 1 : 0);
+            } catch (IOException ioe) {
+                throw new IllegalStateException("Error writing to command socket", ioe);
+            }
+
             Log.i(TAG, "Package preload done");
-            return false;
         }
     }
 
@@ -113,16 +122,23 @@ class WebViewZygoteInit {
             throw new RuntimeException("Failed to setpgid(0,0)", ex);
         }
 
+        final Runnable caller;
         try {
             sServer.registerServerSocket("webview_zygote");
-            sServer.runSelectLoop(TextUtils.join(",", Build.SUPPORTED_ABIS));
+            // The select loop returns early in the child process after a fork and
-            sServer.closeServerSocket();
+            // loops forever in the zygote.
-        } catch (Zygote.MethodAndArgsCaller caller) {
+            caller = sServer.runSelectLoop(TextUtils.join(",", Build.SUPPORTED_ABIS));
-            caller.run();
         } catch (RuntimeException e) {
             Log.e(TAG, "Fatal exception:", e);
+            throw e;
+        } finally {
+            sServer.closeServerSocket();
         }
 
-        System.exit(0);
+        // We're in the child process and have exited the select loop. Proceed to execute the
+        // command.
+        if (caller != null) {
+            caller.run();
+        }
     }
 }

core/java/com/android/internal/os/WrapperInit.java

@@ -25,7 +25,6 @@ import android.system.StructCapUserData;
 import android.system.StructCapUserHeader;
 import android.util.BootTimingsTraceLog;
 import android.util.Slog;
-import com.android.internal.os.Zygote.MethodAndArgsCaller;
 import dalvik.system.VMRuntime;
 import java.io.DataOutputStream;
 import java.io.FileDescriptor;
@@ -61,7 +60,6 @@ public class WrapperInit {
      * @param args The command-line arguments.
      */
     public static void main(String[] args) {
-        try {
         // Parse our mandatory arguments.
         int fdNum = Integer.parseInt(args[0], 10);
         int targetSdkVersion = Integer.parseInt(args[1], 10);
@@ -88,10 +86,9 @@ public class WrapperInit {
         // Launch the application.
         String[] runtimeArgs = new String[args.length - 2];
         System.arraycopy(args, 2, runtimeArgs, 0, runtimeArgs.length);
-            WrapperInit.wrapperInit(targetSdkVersion, runtimeArgs);
+        Runnable r = wrapperInit(targetSdkVersion, runtimeArgs);
-        } catch (Zygote.MethodAndArgsCaller caller) {
+
-            caller.run();
+        r.run();
-        }
     }
 
     /**
@@ -142,8 +139,7 @@ public class WrapperInit {
      * @param targetSdkVersion target SDK version
      * @param argv arg strings
      */
-    private static void wrapperInit(int targetSdkVersion, String[] argv)
+    private static Runnable wrapperInit(int targetSdkVersion, String[] argv) {
-            throws Zygote.MethodAndArgsCaller {
         if (RuntimeInit.DEBUG) {
             Slog.d(RuntimeInit.TAG, "RuntimeInit: Starting application from wrapper");
         }
@@ -165,7 +161,7 @@ public class WrapperInit {
 
         // Perform the same initialization that would happen after the Zygote forks.
         Zygote.nativePreApplicationInit();
-        RuntimeInit.applicationInit(targetSdkVersion, argv, classLoader);
+        return RuntimeInit.applicationInit(targetSdkVersion, argv, classLoader);
     }
 
     /**

core/java/com/android/internal/os/Zygote.java

@@ -221,39 +221,4 @@ public final class Zygote {
             command.append(" '").append(arg.replace("'", "'\\''")).append("'");
         }
     }
-
-    /**
-     * Helper exception class which holds a method and arguments and
-     * can call them. This is used as part of a trampoline to get rid of
-     * the initial process setup stack frames.
-     */
-    public static class MethodAndArgsCaller extends Exception
-            implements Runnable {
-        /** method to call */
-        private final Method mMethod;
-
-        /** argument array */
-        private final String[] mArgs;
-
-        public MethodAndArgsCaller(Method method, String[] args) {
-            mMethod = method;
-            mArgs = args;
-        }
-
-        public void run() {
-            try {
-                mMethod.invoke(null, new Object[] { mArgs });
-            } catch (IllegalAccessException ex) {
-                throw new RuntimeException(ex);
-            } catch (InvocationTargetException ex) {
-                Throwable cause = ex.getCause();
-                if (cause instanceof RuntimeException) {
-                    throw (RuntimeException) cause;
-                } else if (cause instanceof Error) {
-                    throw (Error) cause;
-                }
-                throw new RuntimeException(ex);
-            }
-        }
-    }
 }

core/java/com/android/internal/os/ZygoteConnection.java

@@ -30,7 +30,6 @@ import android.net.Credentials;
 import android.net.LocalSocket;
 import android.os.FactoryTest;
 import android.os.Process;
-import android.os.SELinux;
 import android.os.SystemProperties;
 import android.os.Trace;
 import android.system.ErrnoException;
@@ -42,14 +41,13 @@ import java.io.BufferedReader;
 import java.io.ByteArrayInputStream;
 import java.io.DataInputStream;
 import java.io.DataOutputStream;
+import java.io.EOFException;
 import java.io.FileDescriptor;
-import java.io.FileOutputStream;
+import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStreamReader;
-import java.io.PrintStream;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
-import java.util.Arrays;
 import libcore.io.IoUtils;
 
 /**
@@ -73,6 +71,7 @@ class ZygoteConnection {
     private final BufferedReader mSocketReader;
     private final Credentials peer;
     private final String abiList;
+    private boolean isEof;
 
     /**
      * Constructs instance from connected socket.
@@ -99,6 +98,8 @@ class ZygoteConnection {
             Log.e(TAG, "Cannot read peer credentials", ex);
             throw ex;
         }
+
+        isEof = false;
     }
 
     /**
@@ -111,21 +112,14 @@ class ZygoteConnection {
     }
 
     /**
-     * Reads one start command from the command socket. If successful,
+     * Reads one start command from the command socket. If successful, a child is forked and a
-     * a child is forked and a {@link Zygote.MethodAndArgsCaller}
+     * {@code Runnable} that calls the childs main method (or equivalent) is returned in the child
-     * exception is thrown in that child while in the parent process,
+     * process. {@code null} is always returned in the parent process (the zygote).
-     * the method returns normally. On failure, the child is not
-     * spawned and messages are printed to the log and stderr. Returns
-     * a boolean status value indicating whether an end-of-file on the command
-     * socket has been encountered.
      *
-     * @return false if command socket should continue to be read from, or
+     * If the client closes the socket, an {@code EOF} condition is set, which callers can test
-     * true if an end-of-file has been encountered.
+     * for by calling {@code ZygoteConnection.isClosedByPeer}.
-     * @throws Zygote.MethodAndArgsCaller trampoline to invoke main()
-     * method in child process
      */
-    boolean runOnce(ZygoteServer zygoteServer) throws Zygote.MethodAndArgsCaller {
+    Runnable processOneCommand(ZygoteServer zygoteServer) {
-
         String args[];
         Arguments parsedArgs = null;
         FileDescriptor[] descriptors;
@@ -134,43 +128,36 @@ class ZygoteConnection {
             args = readArgumentList();
             descriptors = mSocket.getAncillaryFileDescriptors();
         } catch (IOException ex) {
-            Log.w(TAG, "IOException on command socket " + ex.getMessage());
+            throw new IllegalStateException("IOException on command socket", ex);
-            closeSocket();
-            return true;
         }
 
+        // readArgumentList returns null only when it has reached EOF with no available
+        // data to read. This will only happen when the remote socket has disconnected.
         if (args == null) {
-            // EOF reached.
+            isEof = true;
-            closeSocket();
+            return null;
-            return true;
-        }
-
-        /** the stderr of the most recent request, if avail */
-        PrintStream newStderr = null;
-
-        if (descriptors != null && descriptors.length >= 3) {
-            newStderr = new PrintStream(
-                    new FileOutputStream(descriptors[2]));
         }
 
         int pid = -1;
         FileDescriptor childPipeFd = null;
         FileDescriptor serverPipeFd = null;
 
-        try {
         parsedArgs = new Arguments(args);
 
         if (parsedArgs.abiListQuery) {
-                return handleAbiListQuery();
+            handleAbiListQuery();
+            return null;
         }
 
         if (parsedArgs.preloadDefault) {
-                return handlePreload();
+            handlePreload();
+            return null;
         }
 
         if (parsedArgs.preloadPackage != null) {
-                return handlePreloadPackage(parsedArgs.preloadPackage,
+            handlePreloadPackage(parsedArgs.preloadPackage, parsedArgs.preloadPackageLibs,
-                        parsedArgs.preloadPackageLibs, parsedArgs.preloadPackageCacheKey);
+                    parsedArgs.preloadPackageCacheKey);
+            return null;
         }
 
         if (parsedArgs.permittedCapabilities != 0 || parsedArgs.effectiveCapabilities != 0) {
@@ -194,11 +181,15 @@ class ZygoteConnection {
         int[] fdsToIgnore = null;
 
         if (parsedArgs.invokeWith != null) {
+            try {
                 FileDescriptor[] pipeFds = Os.pipe2(O_CLOEXEC);
                 childPipeFd = pipeFds[1];
                 serverPipeFd = pipeFds[0];
                 Os.fcntlInt(childPipeFd, F_SETFD, 0);
                 fdsToIgnore = new int[]{childPipeFd.getInt$(), serverPipeFd.getInt$()};
+            } catch (ErrnoException errnoEx) {
+                throw new IllegalStateException("Unable to set up pipe for invoke-with", errnoEx);
+            }
         }
 
         /**
@@ -233,31 +224,24 @@ class ZygoteConnection {
                 parsedArgs.runtimeFlags, rlimits, parsedArgs.mountExternal, parsedArgs.seInfo,
                 parsedArgs.niceName, fdsToClose, fdsToIgnore, parsedArgs.instructionSet,
                 parsedArgs.appDataDir);
-        } catch (ErrnoException ex) {
-            logAndPrintError(newStderr, "Exception creating pipe", ex);
-        } catch (IllegalArgumentException ex) {
-            logAndPrintError(newStderr, "Invalid zygote arguments", ex);
-        } catch (ZygoteSecurityException ex) {
-            logAndPrintError(newStderr,
-                    "Zygote security policy prevents request: ", ex);
-        }
 
         try {
             if (pid == 0) {
                 // in child
+                zygoteServer.setForkChild();
+
                 zygoteServer.closeServerSocket();
                 IoUtils.closeQuietly(serverPipeFd);
                 serverPipeFd = null;
-                handleChildProc(parsedArgs, descriptors, childPipeFd, newStderr);
 
-                // should never get here, the child is expected to either
+                return handleChildProc(parsedArgs, descriptors, childPipeFd);
-                // throw Zygote.MethodAndArgsCaller or exec().
-                return true;
             } else {
-                // in parent...pid of < 0 means failure
+                // In the parent. A pid < 0 indicates a failure and will be handled in
+                // handleParentProc.
                 IoUtils.closeQuietly(childPipeFd);
                 childPipeFd = null;
-                return handleParentProc(pid, descriptors, serverPipeFd, parsedArgs);
+                handleParentProc(pid, descriptors, serverPipeFd);
+                return null;
             }
         } finally {
             IoUtils.closeQuietly(childPipeFd);
@@ -265,15 +249,13 @@ class ZygoteConnection {
         }
     }
 
-    private boolean handleAbiListQuery() {
+    private void handleAbiListQuery() {
         try {
             final byte[] abiListBytes = abiList.getBytes(StandardCharsets.US_ASCII);
             mSocketOutStream.writeInt(abiListBytes.length);
             mSocketOutStream.write(abiListBytes);
-            return false;
         } catch (IOException ioe) {
-            Log.e(TAG, "Error writing to command socket", ioe);
+            throw new IllegalStateException("Error writing to command socket", ioe);
-            return true;
         }
     }
 
@@ -283,7 +265,7 @@ class ZygoteConnection {
      * if no preload was initiated. The latter implies that the zygote is not configured to load
      * resources lazy or that the zygote has already handled a previous request to handlePreload.
      */
-    private boolean handlePreload() {
+    private void handlePreload() {
         try {
             if (isPreloadComplete()) {
                 mSocketOutStream.writeInt(1);
@@ -291,11 +273,8 @@ class ZygoteConnection {
                 preload();
                 mSocketOutStream.writeInt(0);
             }
-
-            return false;
         } catch (IOException ioe) {
-            Log.e(TAG, "Error writing to command socket", ioe);
+            throw new IllegalStateException("Error writing to command socket", ioe);
-            return true;
         }
     }
 
@@ -307,7 +286,11 @@ class ZygoteConnection {
         return ZygoteInit.isPreloadComplete();
     }
 
-    protected boolean handlePreloadPackage(String packagePath, String libsPath, String cacheKey) {
+    protected DataOutputStream getSocketOutputStream() {
+        return mSocketOutStream;
+    }
+
+    protected void handlePreloadPackage(String packagePath, String libsPath, String cacheKey) {
         throw new RuntimeException("Zyogte does not support package preloading");
     }
 
@@ -323,6 +306,10 @@ class ZygoteConnection {
         }
     }
 
+    boolean isClosedByPeer() {
+        return isEof;
+    }
+
     /**
      * Handles argument parsing for args related to the zygote spawner.
      *
@@ -753,15 +740,9 @@ class ZygoteConnection {
      * @param parsedArgs non-null; zygote args
      * @param descriptors null-ok; new file descriptors for stdio if available.
      * @param pipeFd null-ok; pipe for communication back to Zygote.
-     * @param newStderr null-ok; stream to use for stderr until stdio
-     * is reopened.
-     *
-     * @throws Zygote.MethodAndArgsCaller on success to
-     * trampoline to code that invokes static main.
      */
-    private void handleChildProc(Arguments parsedArgs,
+    private Runnable handleChildProc(Arguments parsedArgs, FileDescriptor[] descriptors,
-            FileDescriptor[] descriptors, FileDescriptor pipeFd, PrintStream newStderr)
+            FileDescriptor pipeFd) {
-            throws Zygote.MethodAndArgsCaller {
         /**
          * By the time we get here, the native code has closed the two actual Zygote
          * socket connections, and substituted /dev/null in their place.  The LocalSocket
@@ -778,7 +759,6 @@ class ZygoteConnection {
                 for (FileDescriptor fd: descriptors) {
                     IoUtils.closeQuietly(fd);
                 }
-                newStderr = System.err;
             } catch (ErrnoException ex) {
                 Log.e(TAG, "Error reopening stdio", ex);
             }
@@ -795,9 +775,12 @@ class ZygoteConnection {
                     parsedArgs.niceName, parsedArgs.targetSdkVersion,
                     VMRuntime.getCurrentInstructionSet(),
                     pipeFd, parsedArgs.remainingArgs);
+
+            // Should not get here.
+            throw new IllegalStateException("WrapperInit.execApplication unexpectedly returned");
         } else {
-            ZygoteInit.zygoteInit(parsedArgs.targetSdkVersion,
+            return ZygoteInit.zygoteInit(parsedArgs.targetSdkVersion, parsedArgs.remainingArgs,
-                    parsedArgs.remainingArgs, null /* classLoader */);
+                    null /* classLoader */);
         }
     }
 
@@ -809,13 +792,8 @@ class ZygoteConnection {
      * @param descriptors null-ok; file descriptors for child's new stdio if
      * specified.
      * @param pipeFd null-ok; pipe for communication with child.
-     * @param parsedArgs non-null; zygote args
-     * @return true for "exit command loop" and false for "continue command
-     * loop"
      */
-    private boolean handleParentProc(int pid,
+    private void handleParentProc(int pid, FileDescriptor[] descriptors, FileDescriptor pipeFd) {
-            FileDescriptor[] descriptors, FileDescriptor pipeFd, Arguments parsedArgs) {
-
         if (pid > 0) {
             setChildPgid(pid);
         }
@@ -907,11 +885,8 @@ class ZygoteConnection {
             mSocketOutStream.writeInt(pid);
             mSocketOutStream.writeBoolean(usingWrapper);
         } catch (IOException ex) {
-            Log.e(TAG, "Error writing to command socket", ex);
+            throw new IllegalStateException("Error writing to command socket", ex);
-            return true;
         }
-
-        return false;
     }
 
     private void setChildPgid(int pid) {
@@ -927,20 +902,4 @@ class ZygoteConnection {
                 + "normal if peer is not in our session");
         }
     }
-
-    /**
-     * Logs an error message and prints it to the specified stream, if
-     * provided
-     *
-     * @param newStderr null-ok; a standard error stream
-     * @param message non-null; error message
-     * @param ex null-ok an exception
-     */
-    private static void logAndPrintError (PrintStream newStderr,
-            String message, Throwable ex) {
-        Log.e(TAG, message, ex);
-        if (newStderr != null) {
-            newStderr.println(message + (ex == null ? "" : ex));
-        }
-    }
 }

core/java/com/android/internal/os/ZygoteInit.java

@@ -24,7 +24,6 @@ import android.content.res.TypedArray;
 import android.icu.impl.CacheValue;
 import android.icu.text.DecimalFormatSymbols;
 import android.icu.util.ULocale;
-import android.net.LocalServerSocket;
 import android.opengl.EGL14;
 import android.os.Build;
 import android.os.IInstalld;
@@ -447,10 +446,7 @@ public class ZygoteInit {
     /**
      * Finish remaining work for the newly forked system server process.
      */
-    private static void handleSystemServerProcess(
+    private static Runnable handleSystemServerProcess(ZygoteConnection.Arguments parsedArgs) {
-            ZygoteConnection.Arguments parsedArgs)
-            throws Zygote.MethodAndArgsCaller {
-
         // set umask to 0077 so new files and directories will default to owner-only permissions.
         Os.umask(S_IRWXG | S_IRWXO);
 
@@ -496,6 +492,8 @@ public class ZygoteInit {
             WrapperInit.execApplication(parsedArgs.invokeWith,
                     parsedArgs.niceName, parsedArgs.targetSdkVersion,
                     VMRuntime.getCurrentInstructionSet(), null, args);
+
+            throw new IllegalStateException("Unexpected return from WrapperInit.execApplication");
         } else {
             ClassLoader cl = null;
             if (systemServerClasspath != null) {
@@ -507,7 +505,7 @@ public class ZygoteInit {
             /*
              * Pass the remaining arguments to SystemServer.
              */
-            ZygoteInit.zygoteInit(parsedArgs.targetSdkVersion, parsedArgs.remainingArgs, cl);
+            return ZygoteInit.zygoteInit(parsedArgs.targetSdkVersion, parsedArgs.remainingArgs, cl);
         }
 
         /* should never reach here */
@@ -589,10 +587,13 @@ public class ZygoteInit {
     }
 
     /**
-     * Prepare the arguments and fork for the system server process.
+     * Prepare the arguments and forks for the system server process.
+     *
+     * Returns an {@code Runnable} that provides an entrypoint into system_server code in the
+     * child process, and {@code null} in the parent.
      */
-    private static boolean startSystemServer(String abiList, String socketName, ZygoteServer zygoteServer)
+    private static Runnable forkSystemServer(String abiList, String socketName,
-            throws Zygote.MethodAndArgsCaller, RuntimeException {
+            ZygoteServer zygoteServer) {
         long capabilities = posixCapabilitiesAsBits(
             OsConstants.CAP_IPC_LOCK,
             OsConstants.CAP_KILL,
@@ -657,10 +658,10 @@ public class ZygoteInit {
             }
 
             zygoteServer.closeServerSocket();
-            handleSystemServerProcess(parsedArgs);
+            return handleSystemServerProcess(parsedArgs);
         }
 
-        return true;
+        return null;
     }
 
     /**
@@ -691,6 +692,7 @@ public class ZygoteInit {
             throw new RuntimeException("Failed to setpgid(0,0)", ex);
         }
 
+        final Runnable caller;
         try {
             // Report Zygote start time to tron unless it is a runtime restart
             if (!"1".equals(SystemProperties.get("sys.boot_completed"))) {
@@ -760,19 +762,32 @@ public class ZygoteInit {
             ZygoteHooks.stopZygoteNoThreadCreation();
 
             if (startSystemServer) {
-                startSystemServer(abiList, socketName, zygoteServer);
+                Runnable r = forkSystemServer(abiList, socketName, zygoteServer);
+
+                // {@code r == null} in the parent (zygote) process, and {@code r != null} in the
+                // child (system_server) process.
+                if (r != null) {
+                    r.run();
+                    return;
+                }
             }
 
             Log.i(TAG, "Accepting command socket connections");
-            zygoteServer.runSelectLoop(abiList);
 
-            zygoteServer.closeServerSocket();
+            // The select loop returns early in the child process after a fork and
-        } catch (Zygote.MethodAndArgsCaller caller) {
+            // loops forever in the zygote.
-            caller.run();
+            caller = zygoteServer.runSelectLoop(abiList);
         } catch (Throwable ex) {
             Log.e(TAG, "System zygote died with exception", ex);
-            zygoteServer.closeServerSocket();
             throw ex;
+        } finally {
+            zygoteServer.closeServerSocket();
+        }
+
+        // We're in the child process and have exited the select loop. Proceed to execute the
+        // command.
+        if (caller != null) {
+            caller.run();
         }
     }
 
@@ -830,8 +845,7 @@ public class ZygoteInit {
      * @param targetSdkVersion target SDK version
      * @param argv arg strings
      */
-    public static final void zygoteInit(int targetSdkVersion, String[] argv,
+    public static final Runnable zygoteInit(int targetSdkVersion, String[] argv, ClassLoader classLoader) {
-            ClassLoader classLoader) throws Zygote.MethodAndArgsCaller {
         if (RuntimeInit.DEBUG) {
             Slog.d(RuntimeInit.TAG, "RuntimeInit: Starting application from zygote");
         }
@@ -841,7 +855,7 @@ public class ZygoteInit {
 
         RuntimeInit.commonInit();
         ZygoteInit.nativeZygoteInit();
-        RuntimeInit.applicationInit(targetSdkVersion, argv, classLoader);
+        return RuntimeInit.applicationInit(targetSdkVersion, argv, classLoader);
     }
 
     private static final native void nativeZygoteInit();

core/java/com/android/internal/os/ZygoteServer.java

@@ -25,6 +25,7 @@ import android.system.ErrnoException;
 import android.system.StructPollfd;
 import android.util.Log;
 
+import android.util.Slog;
 import java.io.IOException;
 import java.io.FileDescriptor;
 import java.util.ArrayList;
@@ -45,9 +46,18 @@ class ZygoteServer {
 
     private LocalServerSocket mServerSocket;
 
+    /**
+     * Set by the child process, immediately after a call to {@code Zygote.forkAndSpecialize}.
+     */
+    private boolean mIsForkChild;
+
     ZygoteServer() {
     }
 
+    void setForkChild() {
+        mIsForkChild = true;
+    }
+
     /**
      * Registers a server socket for zygote command connections
      *
@@ -129,11 +139,8 @@ class ZygoteServer {
      * Runs the zygote process's select loop. Accepts new connections as
      * they happen, and reads commands from connections one spawn-request's
      * worth at a time.
-     *
-     * @throws Zygote.MethodAndArgsCaller in a child process when a main()
-     * should be executed.
      */
-    void runSelectLoop(String abiList) throws Zygote.MethodAndArgsCaller {
+    Runnable runSelectLoop(String abiList) {
         ArrayList<FileDescriptor> fds = new ArrayList<FileDescriptor>();
         ArrayList<ZygoteConnection> peers = new ArrayList<ZygoteConnection>();
 
@@ -156,17 +163,64 @@ class ZygoteServer {
                 if ((pollFds[i].revents & POLLIN) == 0) {
                     continue;
                 }
+
                 if (i == 0) {
                     ZygoteConnection newPeer = acceptCommandPeer(abiList);
                     peers.add(newPeer);
                     fds.add(newPeer.getFileDesciptor());
                 } else {
-                    boolean done = peers.get(i).runOnce(this);
+                    try {
-                    if (done) {
+                        ZygoteConnection connection = peers.get(i);
+                        final Runnable command = connection.processOneCommand(this);
+
+                        if (mIsForkChild) {
+                            // We're in the child. We should always have a command to run at this
+                            // stage if processOneCommand hasn't called "exec".
+                            if (command == null) {
+                                throw new IllegalStateException("command == null");
+                            }
+
+                            return command;
+                        } else {
+                            // We're in the server - we should never have any commands to run.
+                            if (command != null) {
+                                throw new IllegalStateException("command != null");
+                            }
+
+                            // We don't know whether the remote side of the socket was closed or
+                            // not until we attempt to read from it from processOneCommand. This shows up as
+                            // a regular POLLIN event in our regular processing loop.
+                            if (connection.isClosedByPeer()) {
+                                connection.closeSocket();
                                 peers.remove(i);
                                 fds.remove(i);
                             }
                         }
+                    } catch (Exception e) {
+                        if (!mIsForkChild) {
+                            // We're in the server so any exception here is one that has taken place
+                            // pre-fork while processing commands or reading / writing from the
+                            // control socket. Make a loud noise about any such exceptions so that
+                            // we know exactly what failed and why.
+
+                            Slog.e(TAG, "Exception executing zygote command: ", e);
+
+                            // Make sure the socket is closed so that the other end knows immediately
+                            // that something has gone wrong and doesn't time out waiting for a
+                            // response.
+                            ZygoteConnection conn = peers.remove(i);
+                            conn.closeSocket();
+
+                            fds.remove(i);
+                        } else {
+                            // We're in the child so any exception caught here has happened post
+                            // fork and before we execute ActivityThread.main (or any other main()
+                            // method). Log the details of the exception and bring down the process.
+                            Log.e(TAG, "Caught post-fork exception in child process.", e);
+                            throw e;
+                        }
+                    }
+                }
             }
         }
     }