core/java/com/android/internal/os/Zygote.java - platform/frameworks/base - Gitiles

 /*
  * Copyright (C) 2014 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package com.android.internal.os;

 import static com.android.internal.os.ZygoteConnectionConstants.MAX_ZYGOTE_ARGC;

 import android.net.Credentials;
 import android.os.FactoryTest;
 import android.os.IVold;
 import android.os.Process;
 import android.os.SystemProperties;
 import android.os.Trace;
 import android.system.ErrnoException;
 import android.system.Os;
 import android.util.Log;

 import dalvik.system.ZygoteHooks;

 import java.io.BufferedReader;
 import java.io.IOException;

 /** @hide */
 public final class Zygote {
     /*
     * Bit values for "runtimeFlags" argument.  The definitions are duplicated
     * in the native code.
     */

     /** enable debugging over JDWP */
     public static final int DEBUG_ENABLE_JDWP   = 1;
     /** enable JNI checks */
     public static final int DEBUG_ENABLE_CHECKJNI   = 1 << 1;
     /** enable Java programming language "assert" statements */
     public static final int DEBUG_ENABLE_ASSERT     = 1 << 2;
     /** disable the AOT compiler and JIT */
     public static final int DEBUG_ENABLE_SAFEMODE   = 1 << 3;
     /** Enable logging of third-party JNI activity. */
     public static final int DEBUG_ENABLE_JNI_LOGGING = 1 << 4;
     /** Force generation of native debugging information. */
     public static final int DEBUG_GENERATE_DEBUG_INFO = 1 << 5;
     /** Always use JIT-ed code. */
     public static final int DEBUG_ALWAYS_JIT = 1 << 6;
     /** Make the code native debuggable by turning off some optimizations. */
     public static final int DEBUG_NATIVE_DEBUGGABLE = 1 << 7;
     /** Make the code Java debuggable by turning off some optimizations. */
     public static final int DEBUG_JAVA_DEBUGGABLE = 1 << 8;

     /** Turn off the verifier. */
     public static final int DISABLE_VERIFIER = 1 << 9;
     /** Only use oat files located in /system. Otherwise use dex/jar/apk . */
     public static final int ONLY_USE_SYSTEM_OAT_FILES = 1 << 10;
     /** Force generation of native debugging information for backtraces. */
     public static final int DEBUG_GENERATE_MINI_DEBUG_INFO = 1 << 11;
     /**
      * Hidden API access restrictions. This is a mask for bits representing the API enforcement
      * policy, defined by {@code @ApplicationInfo.HiddenApiEnforcementPolicy}.
      */
     public static final int API_ENFORCEMENT_POLICY_MASK = (1 << 12) | (1 << 13);
     /**
      * Bit shift for use with {@link #API_ENFORCEMENT_POLICY_MASK}.
      *
      * (flags & API_ENFORCEMENT_POLICY_MASK) >> API_ENFORCEMENT_POLICY_SHIFT gives
      * @ApplicationInfo.ApiEnforcementPolicy values.
      */
     public static final int API_ENFORCEMENT_POLICY_SHIFT =
             Integer.numberOfTrailingZeros(API_ENFORCEMENT_POLICY_MASK);
     /**
      * Enable system server ART profiling.
      */
     public static final int PROFILE_SYSTEM_SERVER = 1 << 14;

     /** No external storage should be mounted. */
     public static final int MOUNT_EXTERNAL_NONE = IVold.REMOUNT_MODE_NONE;
     /** Default external storage should be mounted. */
     public static final int MOUNT_EXTERNAL_DEFAULT = IVold.REMOUNT_MODE_DEFAULT;
     /** Read-only external storage should be mounted. */
     public static final int MOUNT_EXTERNAL_READ = IVold.REMOUNT_MODE_READ;
     /** Read-write external storage should be mounted. */
     public static final int MOUNT_EXTERNAL_WRITE = IVold.REMOUNT_MODE_WRITE;

     private static final ZygoteHooks VM_HOOKS = new ZygoteHooks();

     /**
      * An extraArg passed when a zygote process is forking a child-zygote, specifying a name
      * in the abstract socket namespace. This socket name is what the new child zygote
      * should listen for connections on.
      */
     public static final String CHILD_ZYGOTE_SOCKET_NAME_ARG = "--zygote-socket=";

     /** a prototype instance for a future List.toArray() */
     protected static final int[][] INT_ARRAY_2D = new int[0][0];

     private Zygote() {}

     /** Called for some security initialization before any fork. */
     static native void nativeSecurityInit();

     /**
      * Forks a new VM instance.  The current VM must have been started
      * with the -Xzygote flag. <b>NOTE: new instance keeps all
      * root capabilities. The new process is expected to call capset()</b>.
      *
      * @param uid the UNIX uid that the new process should setuid() to after
      * fork()ing and and before spawning any threads.
      * @param gid the UNIX gid that the new process should setgid() to after
      * fork()ing and and before spawning any threads.
      * @param gids null-ok; a list of UNIX gids that the new process should
      * setgroups() to after fork and before spawning any threads.
      * @param runtimeFlags bit flags that enable ART features.
      * @param rlimits null-ok an array of rlimit tuples, with the second
      * dimension having a length of 3 and representing
      * (resource, rlim_cur, rlim_max). These are set via the posix
      * setrlimit(2) call.
      * @param seInfo null-ok a string specifying SELinux information for
      * the new process.
      * @param niceName null-ok a string specifying the process name.
      * @param fdsToClose an array of ints, holding one or more POSIX
      * file descriptor numbers that are to be closed by the child
      * (and replaced by /dev/null) after forking.  An integer value
      * of -1 in any entry in the array means "ignore this one".
      * @param fdsToIgnore null-ok an array of ints, either null or holding
      * one or more POSIX file descriptor numbers that are to be ignored
      * in the file descriptor table check.
      * @param startChildZygote if true, the new child process will itself be a
      * new zygote process.
      * @param instructionSet null-ok the instruction set to use.
      * @param appDataDir null-ok the data directory of the app.
      *
      * @return 0 if this is the child, pid of the child
      * if this is the parent, or -1 on error.
      */
     public static int forkAndSpecialize(int uid, int gid, int[] gids, int runtimeFlags,
             int[][] rlimits, int mountExternal, String seInfo, String niceName, int[] fdsToClose,
             int[] fdsToIgnore, boolean startChildZygote, String instructionSet, String appDataDir) {
         VM_HOOKS.preFork();
         // Resets nice priority for zygote process.
         resetNicePriority();
         int pid = nativeForkAndSpecialize(
                 uid, gid, gids, runtimeFlags, rlimits, mountExternal, seInfo, niceName, fdsToClose,
                 fdsToIgnore, startChildZygote, instructionSet, appDataDir);
         // Enable tracing as soon as possible for the child process.
         if (pid == 0) {
             Trace.setTracingEnabled(true, runtimeFlags);

             // Note that this event ends at the end of handleChildProc,
             Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "PostFork");
         }
         VM_HOOKS.postForkCommon();
         return pid;
     }

     private static native int nativeForkAndSpecialize(int uid, int gid, int[] gids,
             int runtimeFlags, int[][] rlimits, int mountExternal, String seInfo, String niceName,
             int[] fdsToClose, int[] fdsToIgnore, boolean startChildZygote, String instructionSet,
             String appDataDir);

     private static native void nativeSpecializeBlastula(int uid, int gid, int[] gids,
             int runtimeFlags, int[][] rlimits, int mountExternal, String seInfo, String niceName,
             boolean startChildZygote, String instructionSet, String appDataDir);

     /**
      * Called to do any initialization before starting an application.
      */
     static native void nativePreApplicationInit();

     /**
      * Special method to start the system server process. In addition to the
      * common actions performed in forkAndSpecialize, the pid of the child
      * process is recorded such that the death of the child process will cause
      * zygote to exit.
      *
      * @param uid the UNIX uid that the new process should setuid() to after
      * fork()ing and and before spawning any threads.
      * @param gid the UNIX gid that the new process should setgid() to after
      * fork()ing and and before spawning any threads.
      * @param gids null-ok; a list of UNIX gids that the new process should
      * setgroups() to after fork and before spawning any threads.
      * @param runtimeFlags bit flags that enable ART features.
      * @param rlimits null-ok an array of rlimit tuples, with the second
      * dimension having a length of 3 and representing
      * (resource, rlim_cur, rlim_max). These are set via the posix
      * setrlimit(2) call.
      * @param permittedCapabilities argument for setcap()
      * @param effectiveCapabilities argument for setcap()
      *
      * @return 0 if this is the child, pid of the child
      * if this is the parent, or -1 on error.
      */
     public static int forkSystemServer(int uid, int gid, int[] gids, int runtimeFlags,
             int[][] rlimits, long permittedCapabilities, long effectiveCapabilities) {
         VM_HOOKS.preFork();
         // Resets nice priority for zygote process.
         resetNicePriority();
         int pid = nativeForkSystemServer(
                 uid, gid, gids, runtimeFlags, rlimits,
                 permittedCapabilities, effectiveCapabilities);
         // Enable tracing as soon as we enter the system_server.
         if (pid == 0) {
             Trace.setTracingEnabled(true, runtimeFlags);
         }
         VM_HOOKS.postForkCommon();
         return pid;
     }

     private static native int nativeForkSystemServer(int uid, int gid, int[] gids, int runtimeFlags,
             int[][] rlimits, long permittedCapabilities, long effectiveCapabilities);

     /**
      * Lets children of the zygote inherit open file descriptors to this path.
      */
     protected static native void nativeAllowFileAcrossFork(String path);

     /**
      * Zygote unmount storage space on initializing.
      * This method is called once.
      */
     protected static native void nativeUnmountStorageOnInit();

     protected static native void nativeGetSocketFDs(boolean isPrimary);

     private static native int nativeGetBlastulaPoolCount();

     private static native int nativeGetBlastulaPoolEventFD();

     private static native int nativeForkBlastula(int readPipeFD,
                                                  int writePipeFD,
                                                  int[] sessionSocketRawFDs);

     private static native int[] nativeGetBlastulaPipeFDs();

     private static native boolean nativeRemoveBlastulaTableEntry(int blastulaPID);

     /**
      * uid 1000 (Process.SYSTEM_UID) may specify any uid &gt; 1000 in normal
      * operation. It may also specify any gid and setgroups() list it chooses.
      * In factory test mode, it may specify any UID.
      *
      * @param args non-null; zygote spawner arguments
      * @param peer non-null; peer credentials
      * @throws ZygoteSecurityException
      */
     protected static void applyUidSecurityPolicy(ZygoteArguments args, Credentials peer)
             throws ZygoteSecurityException {

         if (peer.getUid() == Process.SYSTEM_UID) {
             /* In normal operation, SYSTEM_UID can only specify a restricted
              * set of UIDs. In factory test mode, SYSTEM_UID may specify any uid.
              */
             boolean uidRestricted = FactoryTest.getMode() == FactoryTest.FACTORY_TEST_OFF;

             if (uidRestricted && args.mUidSpecified && (args.mUid < Process.SYSTEM_UID)) {
                 throw new ZygoteSecurityException(
                     "System UID may not launch process with UID < "
                         + Process.SYSTEM_UID);
             }
         }

         // If not otherwise specified, uid and gid are inherited from peer
         if (!args.mUidSpecified) {
             args.mUid = peer.getUid();
             args.mUidSpecified = true;
         }
         if (!args.mGidSpecified) {
             args.mGid = peer.getGid();
             args.mGidSpecified = true;
         }
     }

     /**
      * Applies debugger system properties to the zygote arguments.
      *
      * If "ro.debuggable" is "1", all apps are debuggable. Otherwise,
      * the debugger state is specified via the "--enable-jdwp" flag
      * in the spawn request.
      *
      * @param args non-null; zygote spawner args
      */
     protected static void applyDebuggerSystemProperty(ZygoteArguments args) {
         if (RoSystemProperties.DEBUGGABLE) {
             args.mRuntimeFlags |= Zygote.DEBUG_ENABLE_JDWP;
         }
     }

     /**
      * Applies zygote security policy.
      * Based on the credentials of the process issuing a zygote command:
      * <ol>
      * <li> uid 0 (root) may specify --invoke-with to launch Zygote with a
      * wrapper command.
      * <li> Any other uid may not specify any invoke-with argument.
      * </ul>
      *
      * @param args non-null; zygote spawner arguments
      * @param peer non-null; peer credentials
      * @throws ZygoteSecurityException
      */
     protected static void applyInvokeWithSecurityPolicy(ZygoteArguments args, Credentials peer)
             throws ZygoteSecurityException {
         int peerUid = peer.getUid();

         if (args.mInvokeWith != null && peerUid != 0
                 && (args.mRuntimeFlags & Zygote.DEBUG_ENABLE_JDWP) == 0) {
             throw new ZygoteSecurityException("Peer is permitted to specify an"
                 + "explicit invoke-with wrapper command only for debuggable"
                 + "applications.");
         }
     }

     /**
      * Applies invoke-with system properties to the zygote arguments.
      *
      * @param args non-null; zygote args
      */
     protected static void applyInvokeWithSystemProperty(ZygoteArguments args) {
         if (args.mInvokeWith == null && args.mNiceName != null) {
             String property = "wrap." + args.mNiceName;
             args.mInvokeWith = SystemProperties.get(property);
             if (args.mInvokeWith != null && args.mInvokeWith.length() == 0) {
                 args.mInvokeWith = null;
             }
         }
     }

     /**
      * Reads an argument list from the provided socket
      * @return Argument list or null if EOF is reached
      * @throws IOException passed straight through
      */
     static String[] readArgumentList(BufferedReader socketReader) throws IOException {

         /**
          * See android.os.Process.zygoteSendArgsAndGetPid()
          * Presently the wire format to the zygote process is:
          * a) a count of arguments (argc, in essence)
          * b) a number of newline-separated argument strings equal to count
          *
          * After the zygote process reads these it will write the pid of
          * the child or -1 on failure.
          */

         int argc;

         try {
             String argc_string = socketReader.readLine();

             if (argc_string == null) {
                 // EOF reached.
                 return null;
             }
             argc = Integer.parseInt(argc_string);

         } catch (NumberFormatException ex) {
             Log.e("Zygote", "Invalid Zygote wire format: non-int at argc");
             throw new IOException("Invalid wire format");
         }

         // See bug 1092107: large argc can be used for a DOS attack
         if (argc > MAX_ZYGOTE_ARGC) {
             throw new IOException("Max arg count exceeded");
         }

         String[] args = new String[argc];
         for (int arg_index = 0; arg_index < argc; arg_index++) {
             args[arg_index] = socketReader.readLine();
             if (args[arg_index] == null) {
                 // We got an unexpected EOF.
                 throw new IOException("Truncated request");
             }
         }

         return args;
     }


     private static void callPostForkSystemServerHooks() {
         // SystemServer specific post fork hooks run before child post fork hooks.
         VM_HOOKS.postForkSystemServer();
     }

     private static void callPostForkChildHooks(int runtimeFlags, boolean isSystemServer,
             boolean isZygote, String instructionSet) {
         VM_HOOKS.postForkChild(runtimeFlags, isSystemServer, isZygote, instructionSet);
     }

     /**
      * Resets the calling thread priority to the default value (Thread.NORM_PRIORITY
      * or nice value 0). This updates both the priority value in java.lang.Thread and
      * the nice value (setpriority).
      */
     static void resetNicePriority() {
         Thread.currentThread().setPriority(Thread.NORM_PRIORITY);
     }

     /**
      * Executes "/system/bin/sh -c &lt;command&gt;" using the exec() system call.
      * This method throws a runtime exception if exec() failed, otherwise, this
      * method never returns.
      *
      * @param command The shell command to execute.
      */
     public static void execShell(String command) {
         String[] args = { "/system/bin/sh", "-c", command };
         try {
             Os.execv(args[0], args);
         } catch (ErrnoException e) {
             throw new RuntimeException(e);
         }
     }

     /**
      * Appends quotes shell arguments to the specified string builder.
      * The arguments are quoted using single-quotes, escaped if necessary,
      * prefixed with a space, and appended to the command.
      *
      * @param command A string builder for the shell command being constructed.
      * @param args An array of argument strings to be quoted and appended to the command.
      * @see #execShell(String)
      */
     public static void appendQuotedShellArgs(StringBuilder command, String[] args) {
         for (String arg : args) {
             command.append(" '").append(arg.replace("'", "'\\''")).append("'");
         }
     }
 }
	/*
	* Copyright (C) 2014 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package com.android.internal.os;

	import static com.android.internal.os.ZygoteConnectionConstants.MAX_ZYGOTE_ARGC;

	import android.net.Credentials;
	import android.os.FactoryTest;
	import android.os.IVold;
	import android.os.Process;
	import android.os.SystemProperties;
	import android.os.Trace;
	import android.system.ErrnoException;
	import android.system.Os;
	import android.util.Log;

	import dalvik.system.ZygoteHooks;

	import java.io.BufferedReader;
	import java.io.IOException;

	/** @hide */
	public final class Zygote {
	/*
	* Bit values for "runtimeFlags" argument. The definitions are duplicated
	* in the native code.
	*/

	/** enable debugging over JDWP */
	public static final int DEBUG_ENABLE_JDWP = 1;
	/** enable JNI checks */
	public static final int DEBUG_ENABLE_CHECKJNI = 1 << 1;
	/** enable Java programming language "assert" statements */
	public static final int DEBUG_ENABLE_ASSERT = 1 << 2;
	/** disable the AOT compiler and JIT */
	public static final int DEBUG_ENABLE_SAFEMODE = 1 << 3;
	/** Enable logging of third-party JNI activity. */
	public static final int DEBUG_ENABLE_JNI_LOGGING = 1 << 4;
	/** Force generation of native debugging information. */
	public static final int DEBUG_GENERATE_DEBUG_INFO = 1 << 5;
	/** Always use JIT-ed code. */
	public static final int DEBUG_ALWAYS_JIT = 1 << 6;
	/** Make the code native debuggable by turning off some optimizations. */
	public static final int DEBUG_NATIVE_DEBUGGABLE = 1 << 7;
	/** Make the code Java debuggable by turning off some optimizations. */
	public static final int DEBUG_JAVA_DEBUGGABLE = 1 << 8;

	/** Turn off the verifier. */
	public static final int DISABLE_VERIFIER = 1 << 9;
	/** Only use oat files located in /system. Otherwise use dex/jar/apk . */
	public static final int ONLY_USE_SYSTEM_OAT_FILES = 1 << 10;
	/** Force generation of native debugging information for backtraces. */
	public static final int DEBUG_GENERATE_MINI_DEBUG_INFO = 1 << 11;
	/**
	* Hidden API access restrictions. This is a mask for bits representing the API enforcement
	* policy, defined by {@code @ApplicationInfo.HiddenApiEnforcementPolicy}.
	*/
	public static final int API_ENFORCEMENT_POLICY_MASK = (1 << 12) \| (1 << 13);
	/**
	* Bit shift for use with {@link #API_ENFORCEMENT_POLICY_MASK}.
	*
	* (flags & API_ENFORCEMENT_POLICY_MASK) >> API_ENFORCEMENT_POLICY_SHIFT gives
	* @ApplicationInfo.ApiEnforcementPolicy values.
	*/
	public static final int API_ENFORCEMENT_POLICY_SHIFT =
	Integer.numberOfTrailingZeros(API_ENFORCEMENT_POLICY_MASK);
	/**
	* Enable system server ART profiling.
	*/
	public static final int PROFILE_SYSTEM_SERVER = 1 << 14;

	/** No external storage should be mounted. */
	public static final int MOUNT_EXTERNAL_NONE = IVold.REMOUNT_MODE_NONE;
	/** Default external storage should be mounted. */
	public static final int MOUNT_EXTERNAL_DEFAULT = IVold.REMOUNT_MODE_DEFAULT;
	/** Read-only external storage should be mounted. */
	public static final int MOUNT_EXTERNAL_READ = IVold.REMOUNT_MODE_READ;
	/** Read-write external storage should be mounted. */
	public static final int MOUNT_EXTERNAL_WRITE = IVold.REMOUNT_MODE_WRITE;

	private static final ZygoteHooks VM_HOOKS = new ZygoteHooks();

	/**
	* An extraArg passed when a zygote process is forking a child-zygote, specifying a name
	* in the abstract socket namespace. This socket name is what the new child zygote
	* should listen for connections on.
	*/
	public static final String CHILD_ZYGOTE_SOCKET_NAME_ARG = "--zygote-socket=";

	/** a prototype instance for a future List.toArray() */
	protected static final int[][] INT_ARRAY_2D = new int[0][0];

	private Zygote() {}

	/** Called for some security initialization before any fork. */
	static native void nativeSecurityInit();

	/**
	* Forks a new VM instance. The current VM must have been started
	* with the -Xzygote flag. <b>NOTE: new instance keeps all
	* root capabilities. The new process is expected to call capset()</b>.
	*
	* @param uid the UNIX uid that the new process should setuid() to after
	* fork()ing and and before spawning any threads.
	* @param gid the UNIX gid that the new process should setgid() to after
	* fork()ing and and before spawning any threads.
	* @param gids null-ok; a list of UNIX gids that the new process should
	* setgroups() to after fork and before spawning any threads.
	* @param runtimeFlags bit flags that enable ART features.
	* @param rlimits null-ok an array of rlimit tuples, with the second
	* dimension having a length of 3 and representing
	* (resource, rlim_cur, rlim_max). These are set via the posix
	* setrlimit(2) call.
	* @param seInfo null-ok a string specifying SELinux information for
	* the new process.
	* @param niceName null-ok a string specifying the process name.
	* @param fdsToClose an array of ints, holding one or more POSIX
	* file descriptor numbers that are to be closed by the child
	* (and replaced by /dev/null) after forking. An integer value
	* of -1 in any entry in the array means "ignore this one".
	* @param fdsToIgnore null-ok an array of ints, either null or holding
	* one or more POSIX file descriptor numbers that are to be ignored
	* in the file descriptor table check.
	* @param startChildZygote if true, the new child process will itself be a
	* new zygote process.
	* @param instructionSet null-ok the instruction set to use.
	* @param appDataDir null-ok the data directory of the app.
	*
	* @return 0 if this is the child, pid of the child
	* if this is the parent, or -1 on error.
	*/
	public static int forkAndSpecialize(int uid, int gid, int[] gids, int runtimeFlags,
	int[][] rlimits, int mountExternal, String seInfo, String niceName, int[] fdsToClose,
	int[] fdsToIgnore, boolean startChildZygote, String instructionSet, String appDataDir) {
	VM_HOOKS.preFork();
	// Resets nice priority for zygote process.
	resetNicePriority();
	int pid = nativeForkAndSpecialize(
	uid, gid, gids, runtimeFlags, rlimits, mountExternal, seInfo, niceName, fdsToClose,
	fdsToIgnore, startChildZygote, instructionSet, appDataDir);
	// Enable tracing as soon as possible for the child process.
	if (pid == 0) {
	Trace.setTracingEnabled(true, runtimeFlags);

	// Note that this event ends at the end of handleChildProc,
	Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "PostFork");
	}
	VM_HOOKS.postForkCommon();
	return pid;
	}

	private static native int nativeForkAndSpecialize(int uid, int gid, int[] gids,
	int runtimeFlags, int[][] rlimits, int mountExternal, String seInfo, String niceName,
	int[] fdsToClose, int[] fdsToIgnore, boolean startChildZygote, String instructionSet,
	String appDataDir);

	private static native void nativeSpecializeBlastula(int uid, int gid, int[] gids,
	int runtimeFlags, int[][] rlimits, int mountExternal, String seInfo, String niceName,
	boolean startChildZygote, String instructionSet, String appDataDir);

	/**
	* Called to do any initialization before starting an application.
	*/
	static native void nativePreApplicationInit();

	/**
	* Special method to start the system server process. In addition to the
	* common actions performed in forkAndSpecialize, the pid of the child
	* process is recorded such that the death of the child process will cause
	* zygote to exit.
	*
	* @param uid the UNIX uid that the new process should setuid() to after
	* fork()ing and and before spawning any threads.
	* @param gid the UNIX gid that the new process should setgid() to after
	* fork()ing and and before spawning any threads.
	* @param gids null-ok; a list of UNIX gids that the new process should
	* setgroups() to after fork and before spawning any threads.
	* @param runtimeFlags bit flags that enable ART features.
	* @param rlimits null-ok an array of rlimit tuples, with the second
	* dimension having a length of 3 and representing
	* (resource, rlim_cur, rlim_max). These are set via the posix
	* setrlimit(2) call.
	* @param permittedCapabilities argument for setcap()
	* @param effectiveCapabilities argument for setcap()
	*
	* @return 0 if this is the child, pid of the child
	* if this is the parent, or -1 on error.
	*/
	public static int forkSystemServer(int uid, int gid, int[] gids, int runtimeFlags,
	int[][] rlimits, long permittedCapabilities, long effectiveCapabilities) {
	VM_HOOKS.preFork();
	// Resets nice priority for zygote process.
	resetNicePriority();
	int pid = nativeForkSystemServer(
	uid, gid, gids, runtimeFlags, rlimits,
	permittedCapabilities, effectiveCapabilities);
	// Enable tracing as soon as we enter the system_server.
	if (pid == 0) {
	Trace.setTracingEnabled(true, runtimeFlags);
	}
	VM_HOOKS.postForkCommon();
	return pid;
	}

	private static native int nativeForkSystemServer(int uid, int gid, int[] gids, int runtimeFlags,
	int[][] rlimits, long permittedCapabilities, long effectiveCapabilities);

	/**
	* Lets children of the zygote inherit open file descriptors to this path.
	*/
	protected static native void nativeAllowFileAcrossFork(String path);

	/**
	* Zygote unmount storage space on initializing.
	* This method is called once.
	*/
	protected static native void nativeUnmountStorageOnInit();

	protected static native void nativeGetSocketFDs(boolean isPrimary);

	private static native int nativeGetBlastulaPoolCount();

	private static native int nativeGetBlastulaPoolEventFD();

	private static native int nativeForkBlastula(int readPipeFD,
	int writePipeFD,
	int[] sessionSocketRawFDs);

	private static native int[] nativeGetBlastulaPipeFDs();

	private static native boolean nativeRemoveBlastulaTableEntry(int blastulaPID);

	/**
	* uid 1000 (Process.SYSTEM_UID) may specify any uid > 1000 in normal
	* operation. It may also specify any gid and setgroups() list it chooses.
	* In factory test mode, it may specify any UID.
	*
	* @param args non-null; zygote spawner arguments
	* @param peer non-null; peer credentials
	* @throws ZygoteSecurityException
	*/
	protected static void applyUidSecurityPolicy(ZygoteArguments args, Credentials peer)
	throws ZygoteSecurityException {

	if (peer.getUid() == Process.SYSTEM_UID) {
	/* In normal operation, SYSTEM_UID can only specify a restricted
	* set of UIDs. In factory test mode, SYSTEM_UID may specify any uid.
	*/
	boolean uidRestricted = FactoryTest.getMode() == FactoryTest.FACTORY_TEST_OFF;

	if (uidRestricted && args.mUidSpecified && (args.mUid < Process.SYSTEM_UID)) {
	throw new ZygoteSecurityException(
	"System UID may not launch process with UID < "
	+ Process.SYSTEM_UID);
	}
	}

	// If not otherwise specified, uid and gid are inherited from peer
	if (!args.mUidSpecified) {
	args.mUid = peer.getUid();
	args.mUidSpecified = true;
	}
	if (!args.mGidSpecified) {
	args.mGid = peer.getGid();
	args.mGidSpecified = true;
	}
	}

	/**
	* Applies debugger system properties to the zygote arguments.
	*
	* If "ro.debuggable" is "1", all apps are debuggable. Otherwise,
	* the debugger state is specified via the "--enable-jdwp" flag
	* in the spawn request.
	*
	* @param args non-null; zygote spawner args
	*/
	protected static void applyDebuggerSystemProperty(ZygoteArguments args) {
	if (RoSystemProperties.DEBUGGABLE) {
	args.mRuntimeFlags \|= Zygote.DEBUG_ENABLE_JDWP;
	}
	}

	/**
	* Applies zygote security policy.
	* Based on the credentials of the process issuing a zygote command:
	* <ol>
	* <li> uid 0 (root) may specify --invoke-with to launch Zygote with a
	* wrapper command.
	* <li> Any other uid may not specify any invoke-with argument.
	* </ul>
	*
	* @param args non-null; zygote spawner arguments
	* @param peer non-null; peer credentials
	* @throws ZygoteSecurityException
	*/
	protected static void applyInvokeWithSecurityPolicy(ZygoteArguments args, Credentials peer)
	throws ZygoteSecurityException {
	int peerUid = peer.getUid();

	if (args.mInvokeWith != null && peerUid != 0
	&& (args.mRuntimeFlags & Zygote.DEBUG_ENABLE_JDWP) == 0) {
	throw new ZygoteSecurityException("Peer is permitted to specify an"
	+ "explicit invoke-with wrapper command only for debuggable"
	+ "applications.");
	}
	}

	/**
	* Applies invoke-with system properties to the zygote arguments.
	*
	* @param args non-null; zygote args
	*/
	protected static void applyInvokeWithSystemProperty(ZygoteArguments args) {
	if (args.mInvokeWith == null && args.mNiceName != null) {
	String property = "wrap." + args.mNiceName;
	args.mInvokeWith = SystemProperties.get(property);
	if (args.mInvokeWith != null && args.mInvokeWith.length() == 0) {
	args.mInvokeWith = null;
	}
	}
	}

	/**
	* Reads an argument list from the provided socket
	* @return Argument list or null if EOF is reached
	* @throws IOException passed straight through
	*/
	static String[] readArgumentList(BufferedReader socketReader) throws IOException {

	/**
	* See android.os.Process.zygoteSendArgsAndGetPid()
	* Presently the wire format to the zygote process is:
	* a) a count of arguments (argc, in essence)
	* b) a number of newline-separated argument strings equal to count
	*
	* After the zygote process reads these it will write the pid of
	* the child or -1 on failure.
	*/

	int argc;

	try {
	String argc_string = socketReader.readLine();

	if (argc_string == null) {
	// EOF reached.
	return null;
	}
	argc = Integer.parseInt(argc_string);

	} catch (NumberFormatException ex) {
	Log.e("Zygote", "Invalid Zygote wire format: non-int at argc");
	throw new IOException("Invalid wire format");
	}

	// See bug 1092107: large argc can be used for a DOS attack
	if (argc > MAX_ZYGOTE_ARGC) {
	throw new IOException("Max arg count exceeded");
	}

	String[] args = new String[argc];
	for (int arg_index = 0; arg_index < argc; arg_index++) {
	args[arg_index] = socketReader.readLine();
	if (args[arg_index] == null) {
	// We got an unexpected EOF.
	throw new IOException("Truncated request");
	}
	}

	return args;
	}


	private static void callPostForkSystemServerHooks() {
	// SystemServer specific post fork hooks run before child post fork hooks.
	VM_HOOKS.postForkSystemServer();
	}

	private static void callPostForkChildHooks(int runtimeFlags, boolean isSystemServer,
	boolean isZygote, String instructionSet) {
	VM_HOOKS.postForkChild(runtimeFlags, isSystemServer, isZygote, instructionSet);
	}

	/**
	* Resets the calling thread priority to the default value (Thread.NORM_PRIORITY
	* or nice value 0). This updates both the priority value in java.lang.Thread and
	* the nice value (setpriority).
	*/
	static void resetNicePriority() {
	Thread.currentThread().setPriority(Thread.NORM_PRIORITY);
	}

	/**
	* Executes "/system/bin/sh -c <command>" using the exec() system call.
	* This method throws a runtime exception if exec() failed, otherwise, this
	* method never returns.
	*
	* @param command The shell command to execute.
	*/
	public static void execShell(String command) {
	String[] args = { "/system/bin/sh", "-c", command };
	try {
	Os.execv(args[0], args);
	} catch (ErrnoException e) {
	throw new RuntimeException(e);
	}
	}

	/**
	* Appends quotes shell arguments to the specified string builder.
	* The arguments are quoted using single-quotes, escaped if necessary,
	* prefixed with a space, and appended to the command.
	*
	* @param command A string builder for the shell command being constructed.
	* @param args An array of argument strings to be quoted and appended to the command.
	* @see #execShell(String)
	*/
	public static void appendQuotedShellArgs(StringBuilder command, String[] args) {
	for (String arg : args) {
	command.append(" '").append(arg.replace("'", "'\\''")).append("'");
	}
	}
	}