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A library jar that provides APIs for Applications written for the Google Android Platform.
/*
* Copyright (C) 2007 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 android.system.OsConstants.S_IRWXG;
import static android.system.OsConstants.S_IRWXO;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.net.LocalServerSocket;
import android.opengl.EGL14;
import android.os.Build;
import android.os.Debug;
import android.os.Process;
import android.os.SystemClock;
import android.os.SystemProperties;
import android.os.Trace;
import android.system.ErrnoException;
import android.system.Os;
import android.system.OsConstants;
import android.util.EventLog;
import android.util.Log;
import android.util.Slog;
import android.webkit.WebViewFactory;
import dalvik.system.DexFile;
import dalvik.system.PathClassLoader;
import dalvik.system.VMRuntime;
import libcore.io.IoUtils;
import java.io.BufferedReader;
import java.io.FileDescriptor;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
/**
* Startup class for the zygote process.
*
* Pre-initializes some classes, and then waits for commands on a UNIX domain
* socket. Based on these commands, forks off child processes that inherit
* the initial state of the VM.
*
* Please see {@link ZygoteConnection.Arguments} for documentation on the
* client protocol.
*
* @hide
*/
public class ZygoteInit {
private static final String TAG = "Zygote";
private static final String PROPERTY_DISABLE_OPENGL_PRELOADING = "ro.zygote.disable_gl_preload";
private static final String ANDROID_SOCKET_PREFIX = "ANDROID_SOCKET_";
private static final int LOG_BOOT_PROGRESS_PRELOAD_START = 3020;
private static final int LOG_BOOT_PROGRESS_PRELOAD_END = 3030;
/** when preloading, GC after allocating this many bytes */
private static final int PRELOAD_GC_THRESHOLD = 50000;
private static final String ABI_LIST_ARG = "--abi-list=";
private static final String SOCKET_NAME_ARG = "--socket-name=";
private static LocalServerSocket sServerSocket;
/**
* Used to pre-load resources. We hold a global reference on it so it
* never gets destroyed.
*/
private static Resources mResources;
/**
* The number of times that the main Zygote loop
* should run before calling gc() again.
*/
static final int GC_LOOP_COUNT = 10;
/**
* The name of a resource file that contains classes to preload.
*/
private static final String PRELOADED_CLASSES = "preloaded-classes";
/** Controls whether we should preload resources during zygote init. */
private static final boolean PRELOAD_RESOURCES = true;
/**
* Invokes a static "main(argv[]) method on class "className".
* Converts various failing exceptions into RuntimeExceptions, with
* the assumption that they will then cause the VM instance to exit.
*
* @param loader class loader to use
* @param className Fully-qualified class name
* @param argv Argument vector for main()
*/
static void invokeStaticMain(ClassLoader loader,
String className, String[] argv)
throws ZygoteInit.MethodAndArgsCaller {
Class cl;
try {
cl = loader.loadClass(className);
} catch (ClassNotFoundException ex) {
throw new RuntimeException(
"Missing class when invoking static main " + className,
ex);
}
Method m;
try {
m = cl.getMethod("main", new Class[] { String[].class });
} catch (NoSuchMethodException ex) {
throw new RuntimeException(
"Missing static main on " + className, ex);
} catch (SecurityException ex) {
throw new RuntimeException(
"Problem getting static main on " + className, ex);
}
int modifiers = m.getModifiers();
if (! (Modifier.isStatic(modifiers) && Modifier.isPublic(modifiers))) {
throw new RuntimeException(
"Main method is not public and static on " + className);
}
/*
* This throw gets caught in ZygoteInit.main(), which responds
* by invoking the exception's run() method. This arrangement
* clears up all the stack frames that were required in setting
* up the process.
*/
throw new ZygoteInit.MethodAndArgsCaller(m, argv);
}
/**
* Registers a server socket for zygote command connections
*
* @throws RuntimeException when open fails
*/
private static void registerZygoteSocket(String socketName) {
if (sServerSocket == null) {
int fileDesc;
final String fullSocketName = ANDROID_SOCKET_PREFIX + socketName;
try {
String env = System.getenv(fullSocketName);
fileDesc = Integer.parseInt(env);
} catch (RuntimeException ex) {
throw new RuntimeException(fullSocketName + " unset or invalid", ex);
}
try {
sServerSocket = new LocalServerSocket(
createFileDescriptor(fileDesc));
} catch (IOException ex) {
throw new RuntimeException(
"Error binding to local socket '" + fileDesc + "'", ex);
}
}
}
/**
* Waits for and accepts a single command connection. Throws
* RuntimeException on failure.
*/
private static ZygoteConnection acceptCommandPeer(String abiList) {
try {
return new ZygoteConnection(sServerSocket.accept(), abiList);
} catch (IOException ex) {
throw new RuntimeException(
"IOException during accept()", ex);
}
}
/**
* Close and clean up zygote sockets. Called on shutdown and on the
* child's exit path.
*/
static void closeServerSocket() {
try {
if (sServerSocket != null) {
FileDescriptor fd = sServerSocket.getFileDescriptor();
sServerSocket.close();
if (fd != null) {
Os.close(fd);
}
}
} catch (IOException ex) {
Log.e(TAG, "Zygote: error closing sockets", ex);
} catch (ErrnoException ex) {
Log.e(TAG, "Zygote: error closing descriptor", ex);
}
sServerSocket = null;
}
/**
* Return the server socket's underlying file descriptor, so that
* ZygoteConnection can pass it to the native code for proper
* closure after a child process is forked off.
*/
static FileDescriptor getServerSocketFileDescriptor() {
return sServerSocket.getFileDescriptor();
}
private static final int UNPRIVILEGED_UID = 9999;
private static final int UNPRIVILEGED_GID = 9999;
private static final int ROOT_UID = 0;
private static final int ROOT_GID = 0;
/**
* Sets effective user ID.
*/
private static void setEffectiveUser(int uid) {
int errno = setreuid(ROOT_UID, uid);
if (errno != 0) {
Log.e(TAG, "setreuid() failed. errno: " + errno);
}
}
/**
* Sets effective group ID.
*/
private static void setEffectiveGroup(int gid) {
int errno = setregid(ROOT_GID, gid);
if (errno != 0) {
Log.e(TAG, "setregid() failed. errno: " + errno);
}
}
static void preload() {
Log.d(TAG, "begin preload");
preloadClasses();
preloadResources();
preloadOpenGL();
preloadSharedLibraries();
// Ask the WebViewFactory to do any initialization that must run in the zygote process,
// for memory sharing purposes.
WebViewFactory.prepareWebViewInZygote();
Log.d(TAG, "end preload");
}
private static void preloadSharedLibraries() {
Log.i(TAG, "Preloading shared libraries...");
System.loadLibrary("android");
System.loadLibrary("compiler_rt");
System.loadLibrary("jnigraphics");
}
private static void preloadOpenGL() {
if (!SystemProperties.getBoolean(PROPERTY_DISABLE_OPENGL_PRELOADING, false)) {
EGL14.eglGetDisplay(EGL14.EGL_DEFAULT_DISPLAY);
}
}
/**
* Performs Zygote process initialization. Loads and initializes
* commonly used classes.
*
* Most classes only cause a few hundred bytes to be allocated, but
* a few will allocate a dozen Kbytes (in one case, 500+K).
*/
private static void preloadClasses() {
final VMRuntime runtime = VMRuntime.getRuntime();
InputStream is = ClassLoader.getSystemClassLoader().getResourceAsStream(
PRELOADED_CLASSES);
if (is == null) {
Log.e(TAG, "Couldn't find " + PRELOADED_CLASSES + ".");
} else {
Log.i(TAG, "Preloading classes...");
long startTime = SystemClock.uptimeMillis();
// Drop root perms while running static initializers.
setEffectiveGroup(UNPRIVILEGED_GID);
setEffectiveUser(UNPRIVILEGED_UID);
// Alter the target heap utilization. With explicit GCs this
// is not likely to have any effect.
float defaultUtilization = runtime.getTargetHeapUtilization();
runtime.setTargetHeapUtilization(0.8f);
// Start with a clean slate.
System.gc();
runtime.runFinalizationSync();
Debug.startAllocCounting();
try {
BufferedReader br
= new BufferedReader(new InputStreamReader(is), 256);
int count = 0;
String line;
while ((line = br.readLine()) != null) {
// Skip comments and blank lines.
line = line.trim();
if (line.startsWith("#") || line.equals("")) {
continue;
}
try {
if (false) {
Log.v(TAG, "Preloading " + line + "...");
}
Class.forName(line);
if (Debug.getGlobalAllocSize() > PRELOAD_GC_THRESHOLD) {
if (false) {
Log.v(TAG,
" GC at " + Debug.getGlobalAllocSize());
}
System.gc();
runtime.runFinalizationSync();
Debug.resetGlobalAllocSize();
}
count++;
} catch (ClassNotFoundException e) {
Log.w(TAG, "Class not found for preloading: " + line);
} catch (UnsatisfiedLinkError e) {
Log.w(TAG, "Problem preloading " + line + ": " + e);
} catch (Throwable t) {
Log.e(TAG, "Error preloading " + line + ".", t);
if (t instanceof Error) {
throw (Error) t;
}
if (t instanceof RuntimeException) {
throw (RuntimeException) t;
}
throw new RuntimeException(t);
}
}
Log.i(TAG, "...preloaded " + count + " classes in "
+ (SystemClock.uptimeMillis()-startTime) + "ms.");
} catch (IOException e) {
Log.e(TAG, "Error reading " + PRELOADED_CLASSES + ".", e);
} finally {
IoUtils.closeQuietly(is);
// Restore default.
runtime.setTargetHeapUtilization(defaultUtilization);
// Fill in dex caches with classes, fields, and methods brought in by preloading.
runtime.preloadDexCaches();
Debug.stopAllocCounting();
// Bring back root. We'll need it later.
setEffectiveUser(ROOT_UID);
setEffectiveGroup(ROOT_GID);
}
}
}
/**
* Load in commonly used resources, so they can be shared across
* processes.
*
* These tend to be a few Kbytes, but are frequently in the 20-40K
* range, and occasionally even larger.
*/
private static void preloadResources() {
final VMRuntime runtime = VMRuntime.getRuntime();
Debug.startAllocCounting();
try {
System.gc();
runtime.runFinalizationSync();
mResources = Resources.getSystem();
mResources.startPreloading();
if (PRELOAD_RESOURCES) {
Log.i(TAG, "Preloading resources...");
long startTime = SystemClock.uptimeMillis();
TypedArray ar = mResources.obtainTypedArray(
com.android.internal.R.array.preloaded_drawables);
int N = preloadDrawables(runtime, ar);
ar.recycle();
Log.i(TAG, "...preloaded " + N + " resources in "
+ (SystemClock.uptimeMillis()-startTime) + "ms.");
startTime = SystemClock.uptimeMillis();
ar = mResources.obtainTypedArray(
com.android.internal.R.array.preloaded_color_state_lists);
N = preloadColorStateLists(runtime, ar);
ar.recycle();
Log.i(TAG, "...preloaded " + N + " resources in "
+ (SystemClock.uptimeMillis()-startTime) + "ms.");
}
mResources.finishPreloading();
} catch (RuntimeException e) {
Log.w(TAG, "Failure preloading resources", e);
} finally {
Debug.stopAllocCounting();
}
}
private static int preloadColorStateLists(VMRuntime runtime, TypedArray ar) {
int N = ar.length();
for (int i=0; i PRELOAD_GC_THRESHOLD) {
if (false) {
Log.v(TAG, " GC at " + Debug.getGlobalAllocSize());
}
System.gc();
runtime.runFinalizationSync();
Debug.resetGlobalAllocSize();
}
int id = ar.getResourceId(i, 0);
if (false) {
Log.v(TAG, "Preloading resource #" + Integer.toHexString(id));
}
if (id != 0) {
if (mResources.getColorStateList(id) == null) {
throw new IllegalArgumentException(
"Unable to find preloaded color resource #0x"
+ Integer.toHexString(id)
+ " (" + ar.getString(i) + ")");
}
}
}
return N;
}
private static int preloadDrawables(VMRuntime runtime, TypedArray ar) {
int N = ar.length();
for (int i=0; i PRELOAD_GC_THRESHOLD) {
if (false) {
Log.v(TAG, " GC at " + Debug.getGlobalAllocSize());
}
System.gc();
runtime.runFinalizationSync();
Debug.resetGlobalAllocSize();
}
int id = ar.getResourceId(i, 0);
if (false) {
Log.v(TAG, "Preloading resource #" + Integer.toHexString(id));
}
if (id != 0) {
if (mResources.getDrawable(id, null) == null) {
throw new IllegalArgumentException(
"Unable to find preloaded drawable resource #0x"
+ Integer.toHexString(id)
+ " (" + ar.getString(i) + ")");
}
}
}
return N;
}
/**
* Runs several special GCs to try to clean up a few generations of
* softly- and final-reachable objects, along with any other garbage.
* This is only useful just before a fork().
*/
/*package*/ static void gc() {
final VMRuntime runtime = VMRuntime.getRuntime();
/* runFinalizationSync() lets finalizers be called in Zygote,
* which doesn't have a HeapWorker thread.
*/
System.gc();
runtime.runFinalizationSync();
System.gc();
runtime.runFinalizationSync();
System.gc();
runtime.runFinalizationSync();
}
/**
* Finish remaining work for the newly forked system server process.
*/
private static void handleSystemServerProcess(
ZygoteConnection.Arguments parsedArgs)
throws ZygoteInit.MethodAndArgsCaller {
closeServerSocket();
// set umask to 0077 so new files and directories will default to owner-only permissions.
Os.umask(S_IRWXG | S_IRWXO);
if (parsedArgs.niceName != null) {
Process.setArgV0(parsedArgs.niceName);
}
final String systemServerClasspath = Os.getenv("SYSTEMSERVERCLASSPATH");
if (systemServerClasspath != null) {
performSystemServerDexOpt(systemServerClasspath);
}
if (parsedArgs.invokeWith != null) {
String[] args = parsedArgs.remainingArgs;
// If we have a non-null system server class path, we'll have to duplicate the
// existing arguments and append the classpath to it. ART will handle the classpath
// correctly when we exec a new process.
if (systemServerClasspath != null) {
String[] amendedArgs = new String[args.length + 2];
amendedArgs[0] = "-cp";
amendedArgs[1] = systemServerClasspath;
System.arraycopy(parsedArgs.remainingArgs, 0, amendedArgs, 2, parsedArgs.remainingArgs.length);
}
WrapperInit.execApplication(parsedArgs.invokeWith,
parsedArgs.niceName, parsedArgs.targetSdkVersion,
null, args);
} else {
ClassLoader cl = null;
if (systemServerClasspath != null) {
cl = new PathClassLoader(systemServerClasspath, ClassLoader.getSystemClassLoader());
Thread.currentThread().setContextClassLoader(cl);
}
/*
* Pass the remaining arguments to SystemServer.
*/
RuntimeInit.zygoteInit(parsedArgs.targetSdkVersion, parsedArgs.remainingArgs, cl);
}
/* should never reach here */
}
/**
* Performs dex-opt on the elements of {@code classPath}, if needed. We
* choose the instruction set of the current runtime.
*/
private static void performSystemServerDexOpt(String classPath) {
final String[] classPathElements = classPath.split(":");
final InstallerConnection installer = new InstallerConnection();
final String instructionSet = VMRuntime.getRuntime().vmInstructionSet();
try {
for (String classPathElement : classPathElements) {
final byte dexopt = DexFile.isDexOptNeededInternal(classPathElement, "*", instructionSet,
false /* defer */);
if (dexopt == DexFile.DEXOPT_NEEDED) {
installer.dexopt(classPathElement, Process.SYSTEM_UID, false, instructionSet);
} else if (dexopt == DexFile.PATCHOAT_NEEDED) {
installer.patchoat(classPathElement, Process.SYSTEM_UID, false, instructionSet);
}
}
} catch (IOException ioe) {
throw new RuntimeException("Error starting system_server", ioe);
} finally {
installer.disconnect();
}
}
/**
* Prepare the arguments and fork for the system server process.
*/
private static boolean startSystemServer(String abiList, String socketName)
throws MethodAndArgsCaller, RuntimeException {
long capabilities = posixCapabilitiesAsBits(
OsConstants.CAP_BLOCK_SUSPEND,
OsConstants.CAP_KILL,
OsConstants.CAP_NET_ADMIN,
OsConstants.CAP_NET_BIND_SERVICE,
OsConstants.CAP_NET_BROADCAST,
OsConstants.CAP_NET_RAW,
OsConstants.CAP_SYS_MODULE,
OsConstants.CAP_SYS_NICE,
OsConstants.CAP_SYS_RESOURCE,
OsConstants.CAP_SYS_TIME,
OsConstants.CAP_SYS_TTY_CONFIG
);
/* Hardcoded command line to start the system server */
String args[] = {
"--setuid=1000",
"--setgid=1000",
"--setgroups=1001,1002,1003,1004,1005,1006,1007,1008,1009,1010,1018,1032,3001,3002,3003,3006,3007",
"--capabilities=" + capabilities + "," + capabilities,
"--runtime-init",
"--nice-name=system_server",
"com.android.server.SystemServer",
};
ZygoteConnection.Arguments parsedArgs = null;
int pid;
try {
parsedArgs = new ZygoteConnection.Arguments(args);
ZygoteConnection.applyDebuggerSystemProperty(parsedArgs);
ZygoteConnection.applyInvokeWithSystemProperty(parsedArgs);
/* Request to fork the system server process */
pid = Zygote.forkSystemServer(
parsedArgs.uid, parsedArgs.gid,
parsedArgs.gids,
parsedArgs.debugFlags,
null,
parsedArgs.permittedCapabilities,
parsedArgs.effectiveCapabilities);
} catch (IllegalArgumentException ex) {
throw new RuntimeException(ex);
}
/* For child process */
if (pid == 0) {
if (hasSecondZygote(abiList)) {
waitForSecondaryZygote(socketName);
}
handleSystemServerProcess(parsedArgs);
}
return true;
}
/**
* Gets the bit array representation of the provided list of POSIX capabilities.
*/
private static long posixCapabilitiesAsBits(int... capabilities) {
long result = 0;
for (int capability : capabilities) {
if ((capability < 0) || (capability > OsConstants.CAP_LAST_CAP)) {
throw new IllegalArgumentException(String.valueOf(capability));
}
result |= (1L << capability);
}
return result;
}
public static void main(String argv[]) {
try {
// Start profiling the zygote initialization.
SamplingProfilerIntegration.start();
boolean startSystemServer = false;
String socketName = "zygote";
String abiList = null;
for (int i = 1; i < argv.length; i++) {
if ("start-system-server".equals(argv[i])) {
startSystemServer = true;
} else if (argv[i].startsWith(ABI_LIST_ARG)) {
abiList = argv[i].substring(ABI_LIST_ARG.length());
} else if (argv[i].startsWith(SOCKET_NAME_ARG)) {
socketName = argv[i].substring(SOCKET_NAME_ARG.length());
} else {
throw new RuntimeException("Unknown command line argument: " + argv[i]);
}
}
if (abiList == null) {
throw new RuntimeException("No ABI list supplied.");
}
registerZygoteSocket(socketName);
EventLog.writeEvent(LOG_BOOT_PROGRESS_PRELOAD_START,
SystemClock.uptimeMillis());
preload();
EventLog.writeEvent(LOG_BOOT_PROGRESS_PRELOAD_END,
SystemClock.uptimeMillis());
// Finish profiling the zygote initialization.
SamplingProfilerIntegration.writeZygoteSnapshot();
// Do an initial gc to clean up after startup
gc();
// Disable tracing so that forked processes do not inherit stale tracing tags from
// Zygote.
Trace.setTracingEnabled(false);
if (startSystemServer) {
startSystemServer(abiList, socketName);
}
Log.i(TAG, "Accepting command socket connections");
runSelectLoop(abiList);
closeServerSocket();
} catch (MethodAndArgsCaller caller) {
caller.run();
} catch (RuntimeException ex) {
Log.e(TAG, "Zygote died with exception", ex);
closeServerSocket();
throw ex;
}
}
/**
* Return {@code true} if this device configuration has another zygote.
*
* We determine this by comparing the device ABI list with this zygotes
* list. If this zygote supports all ABIs this device supports, there won't
* be another zygote.
*/
private static boolean hasSecondZygote(String abiList) {
return !SystemProperties.get("ro.product.cpu.abilist").equals(abiList);
}
private static void waitForSecondaryZygote(String socketName) {
String otherZygoteName = Process.ZYGOTE_SOCKET.equals(socketName) ?
Process.SECONDARY_ZYGOTE_SOCKET : Process.ZYGOTE_SOCKET;
while (true) {
try {
final Process.ZygoteState zs = Process.ZygoteState.connect(otherZygoteName);
zs.close();
break;
} catch (IOException ioe) {
Log.w(TAG, "Got error connecting to zygote, retrying. msg= " + ioe.getMessage());
}
try {
Thread.sleep(1000);
} catch (InterruptedException ie) {
}
}
}
/**
* 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 MethodAndArgsCaller in a child process when a main() should
* be executed.
*/
private static void runSelectLoop(String abiList) throws MethodAndArgsCaller {
ArrayList fds = new ArrayList();
ArrayList peers = new ArrayList();
FileDescriptor[] fdArray = new FileDescriptor[4];
fds.add(sServerSocket.getFileDescriptor());
peers.add(null);
int loopCount = GC_LOOP_COUNT;
while (true) {
int index;
/*
* Call gc() before we block in select().
* It's work that has to be done anyway, and it's better
* to avoid making every child do it. It will also
* madvise() any free memory as a side-effect.
*
* Don't call it every time, because walking the entire
* heap is a lot of overhead to free a few hundred bytes.
*/
if (loopCount <= 0) {
gc();
loopCount = GC_LOOP_COUNT;
} else {
loopCount--;
}
try {
fdArray = fds.toArray(fdArray);
index = selectReadable(fdArray);
} catch (IOException ex) {
throw new RuntimeException("Error in select()", ex);
}
if (index < 0) {
throw new RuntimeException("Error in select()");
} else if (index == 0) {
ZygoteConnection newPeer = acceptCommandPeer(abiList);
peers.add(newPeer);
fds.add(newPeer.getFileDescriptor());
} else {
boolean done;
done = peers.get(index).runOnce();
if (done) {
peers.remove(index);
fds.remove(index);
}
}
}
}
/**
* The Linux syscall "setreuid()"
* @param ruid real uid
* @param euid effective uid
* @return 0 on success, non-zero errno on fail
*/
static native int setreuid(int ruid, int euid);
/**
* The Linux syscall "setregid()"
* @param rgid real gid
* @param egid effective gid
* @return 0 on success, non-zero errno on fail
*/
static native int setregid(int rgid, int egid);
/**
* Invokes the linux syscall "setpgid"
*
* @param pid pid to change
* @param pgid new process group of pid
* @return 0 on success or non-zero errno on fail
*/
static native int setpgid(int pid, int pgid);
/**
* Invokes the linux syscall "getpgid"
*
* @param pid pid to query
* @return pgid of pid in question
* @throws IOException on error
*/
static native int getpgid(int pid) throws IOException;
/**
* Invokes the syscall dup2() to copy the specified descriptors into
* stdin, stdout, and stderr. The existing stdio descriptors will be
* closed and errors during close will be ignored. The specified
* descriptors will also remain open at their original descriptor numbers,
* so the caller may want to close the original descriptors.
*
* @param in new stdin
* @param out new stdout
* @param err new stderr
* @throws IOException
*/
static native void reopenStdio(FileDescriptor in,
FileDescriptor out, FileDescriptor err) throws IOException;
/**
* Toggles the close-on-exec flag for the specified file descriptor.
*
* @param fd non-null; file descriptor
* @param flag desired close-on-exec flag state
* @throws IOException
*/
static native void setCloseOnExec(FileDescriptor fd, boolean flag)
throws IOException;
/**
* Invokes select() on the provider array of file descriptors (selecting
* for readability only). Array elements of null are ignored.
*
* @param fds non-null; array of readable file descriptors
* @return index of descriptor that is now readable or -1 for empty array.
* @throws IOException if an error occurs
*/
static native int selectReadable(FileDescriptor[] fds) throws IOException;
/**
* Creates a file descriptor from an int fd.
*
* @param fd integer OS file descriptor
* @return non-null; FileDescriptor instance
* @throws IOException if fd is invalid
*/
static native FileDescriptor createFileDescriptor(int fd)
throws IOException;
/**
* Class not instantiable.
*/
private ZygoteInit() {
}
/**
* 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);
}
}
}
}