/*
* 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 android.os.Trace;
import dalvik.system.ZygoteHooks;
import android.system.ErrnoException;
import android.system.Os;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
/** @hide */
public final class Zygote {
/*
* Bit values for "debugFlags" 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;
/** No external storage should be mounted. */
public static final int MOUNT_EXTERNAL_NONE = 0;
/** Default external storage should be mounted. */
public static final int MOUNT_EXTERNAL_DEFAULT = 1;
/** Read-only external storage should be mounted. */
public static final int MOUNT_EXTERNAL_READ = 2;
/** Read-write external storage should be mounted. */
public static final int MOUNT_EXTERNAL_WRITE = 3;
private static final ZygoteHooks VM_HOOKS = new ZygoteHooks();
private Zygote() {}
/**
* 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 debugFlags bit flags that enable debugging 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 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 debugFlags,
int[][] rlimits, int mountExternal, String seInfo, String niceName, int[] fdsToClose,
int[] fdsToIgnore, String instructionSet, String appDataDir) {
VM_HOOKS.preFork();
// Resets nice priority for zygote process.
resetNicePriority();
int pid = nativeForkAndSpecialize(
uid, gid, gids, debugFlags, rlimits, mountExternal, seInfo, niceName, fdsToClose,
fdsToIgnore, instructionSet, appDataDir);
// Enable tracing as soon as possible for the child process.
if (pid == 0) {
Trace.setTracingEnabled(true);
// Note that this event ends at the end of handleChildProc,
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "PostFork");
}
VM_HOOKS.postForkCommon();
return pid;
}
native private static int nativeForkAndSpecialize(int uid, int gid, int[] gids,int debugFlags,
int[][] rlimits, int mountExternal, String seInfo, String niceName, int[] fdsToClose,
int[] fdsToIgnore, String instructionSet, String appDataDir);
/**
* 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 debugFlags bit flags that enable debugging 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 debugFlags,
int[][] rlimits, long permittedCapabilities, long effectiveCapabilities) {
VM_HOOKS.preFork();
// Resets nice priority for zygote process.
resetNicePriority();
int pid = nativeForkSystemServer(
uid, gid, gids, debugFlags, rlimits, permittedCapabilities, effectiveCapabilities);
// Enable tracing as soon as we enter the system_server.
if (pid == 0) {
Trace.setTracingEnabled(true);
}
VM_HOOKS.postForkCommon();
return pid;
}
native private static int nativeForkSystemServer(int uid, int gid, int[] gids, int debugFlags,
int[][] rlimits, long permittedCapabilities, long effectiveCapabilities);
/**
* Lets children of the zygote inherit open file descriptors to this path.
*/
native protected static void nativeAllowFileAcrossFork(String path);
/**
* Zygote unmount storage space on initializing.
* This method is called once.
*/
native protected static void nativeUnmountStorageOnInit();
private static void callPostForkChildHooks(int debugFlags, boolean isSystemServer,
String instructionSet) {
VM_HOOKS.postForkChild(debugFlags, isSystemServer, 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("'");
}
}
/**
* 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);
}
}
}
}