| /* |
| * Copyright (C) 2006 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 dalvik.system; |
| |
| import java.io.File; |
| |
| /** |
| * Provides access to the Dalvik "zygote" feature, which allows a VM instance to |
| * be partially initialized and then fork()'d from the partially initialized |
| * state. |
| * |
| * @hide |
| */ |
| public 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_DEBUGGER = 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 JIT compiler */ |
| 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; |
| |
| /** |
| * When set by the system server, all subsequent apps will be launched in |
| * VM safe mode. |
| */ |
| public static boolean systemInSafeMode = false; |
| |
| private Zygote() {} |
| |
| private static void preFork() { |
| Daemons.stop(); |
| waitUntilAllThreadsStopped(); |
| } |
| |
| /** |
| * We must not fork until we're single-threaded again. Wait until /proc shows we're |
| * down to just one thread. |
| */ |
| private static void waitUntilAllThreadsStopped() { |
| File tasks = new File("/proc/self/task"); |
| while (tasks.list().length > 1) { |
| try { |
| // Experimentally, booting and playing about with a stingray, I never saw us |
| // go round this loop more than once with a 10ms sleep. |
| Thread.sleep(10); |
| } catch (InterruptedException ignored) { |
| } |
| } |
| } |
| |
| private static void postFork() { |
| Daemons.start(); |
| } |
| |
| /** |
| * Forks a new Zygote instance, but does not leave the zygote mode. |
| * The current VM must have been started with the -Xzygote flag. The |
| * new child is expected to eventually call forkAndSpecialize() |
| * |
| * @return 0 if this is the child, pid of the child |
| * if this is the parent, or -1 on error |
| */ |
| public static int fork() { |
| preFork(); |
| int pid = nativeFork(); |
| postFork(); |
| return pid; |
| } |
| |
| native public static int nativeFork(); |
| |
| /** |
| * 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. |
| * |
| * @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) { |
| preFork(); |
| int pid = nativeForkAndSpecialize(uid, gid, gids, debugFlags, rlimits); |
| postFork(); |
| return pid; |
| } |
| |
| native public static int nativeForkAndSpecialize(int uid, int gid, |
| int[] gids, int debugFlags, int[][] rlimits); |
| |
| /** |
| * Forks a new VM instance. |
| * @deprecated use {@link Zygote#forkAndSpecialize(int, int, int[], int, int[][])} |
| */ |
| @Deprecated |
| public static int forkAndSpecialize(int uid, int gid, int[] gids, |
| boolean enableDebugger, int[][] rlimits) { |
| int debugFlags = enableDebugger ? DEBUG_ENABLE_DEBUGGER : 0; |
| return forkAndSpecialize(uid, gid, gids, debugFlags, rlimits); |
| } |
| |
| /** |
| * 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) { |
| preFork(); |
| int pid = nativeForkSystemServer(uid, gid, gids, debugFlags, rlimits, |
| permittedCapabilities, |
| effectiveCapabilities); |
| postFork(); |
| return pid; |
| } |
| |
| /** |
| * Special method to start the system server process. |
| * @deprecated use {@link Zygote#forkSystemServer(int, int, int[], int, int[][])} |
| */ |
| @Deprecated |
| public static int forkSystemServer(int uid, int gid, int[] gids, |
| boolean enableDebugger, int[][] rlimits) { |
| int debugFlags = enableDebugger ? DEBUG_ENABLE_DEBUGGER : 0; |
| return forkAndSpecialize(uid, gid, gids, debugFlags, rlimits); |
| } |
| |
| native public static int nativeForkSystemServer(int uid, int gid, |
| int[] gids, int debugFlags, int[][] rlimits, |
| long permittedCapabilities, long effectiveCapabilities); |
| |
| /** |
| * Executes "/system/bin/sh -c <command>" using the exec() system call. |
| * This method never returns. |
| * |
| * @param command The shell command to execute. |
| */ |
| public static void execShell(String command) { |
| nativeExecShell(command); |
| } |
| |
| /** |
| * 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("'"); |
| } |
| } |
| |
| native private static void nativeExecShell(String command); |
| } |