1 /* 2 * Copyright (C) 2014 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.internal.os; 18 19 20 import android.os.Trace; 21 import dalvik.system.ZygoteHooks; 22 import android.system.ErrnoException; 23 import android.system.Os; 24 25 import java.lang.reflect.InvocationTargetException; 26 import java.lang.reflect.Method; 27 28 /** @hide */ 29 public final class Zygote { 30 /* 31 * Bit values for "debugFlags" argument. The definitions are duplicated 32 * in the native code. 33 */ 34 35 /** enable debugging over JDWP */ 36 public static final int DEBUG_ENABLE_JDWP = 1; 37 /** enable JNI checks */ 38 public static final int DEBUG_ENABLE_CHECKJNI = 1 << 1; 39 /** enable Java programming language "assert" statements */ 40 public static final int DEBUG_ENABLE_ASSERT = 1 << 2; 41 /** disable the AOT compiler and JIT */ 42 public static final int DEBUG_ENABLE_SAFEMODE = 1 << 3; 43 /** Enable logging of third-party JNI activity. */ 44 public static final int DEBUG_ENABLE_JNI_LOGGING = 1 << 4; 45 /** Force generation of native debugging information. */ 46 public static final int DEBUG_GENERATE_DEBUG_INFO = 1 << 5; 47 /** Always use JIT-ed code. */ 48 public static final int DEBUG_ALWAYS_JIT = 1 << 6; 49 /** Make the code native debuggable by turning off some optimizations. */ 50 public static final int DEBUG_NATIVE_DEBUGGABLE = 1 << 7; 51 /** Make the code Java debuggable by turning off some optimizations. */ 52 public static final int DEBUG_JAVA_DEBUGGABLE = 1 << 8; 53 54 /** No external storage should be mounted. */ 55 public static final int MOUNT_EXTERNAL_NONE = 0; 56 /** Default external storage should be mounted. */ 57 public static final int MOUNT_EXTERNAL_DEFAULT = 1; 58 /** Read-only external storage should be mounted. */ 59 public static final int MOUNT_EXTERNAL_READ = 2; 60 /** Read-write external storage should be mounted. */ 61 public static final int MOUNT_EXTERNAL_WRITE = 3; 62 63 private static final ZygoteHooks VM_HOOKS = new ZygoteHooks(); 64 65 private Zygote() {} 66 67 /** 68 * Forks a new VM instance. The current VM must have been started 69 * with the -Xzygote flag. <b>NOTE: new instance keeps all 70 * root capabilities. The new process is expected to call capset()</b>. 71 * 72 * @param uid the UNIX uid that the new process should setuid() to after 73 * fork()ing and and before spawning any threads. 74 * @param gid the UNIX gid that the new process should setgid() to after 75 * fork()ing and and before spawning any threads. 76 * @param gids null-ok; a list of UNIX gids that the new process should 77 * setgroups() to after fork and before spawning any threads. 78 * @param debugFlags bit flags that enable debugging features. 79 * @param rlimits null-ok an array of rlimit tuples, with the second 80 * dimension having a length of 3 and representing 81 * (resource, rlim_cur, rlim_max). These are set via the posix 82 * setrlimit(2) call. 83 * @param seInfo null-ok a string specifying SELinux information for 84 * the new process. 85 * @param niceName null-ok a string specifying the process name. 86 * @param fdsToClose an array of ints, holding one or more POSIX 87 * file descriptor numbers that are to be closed by the child 88 * (and replaced by /dev/null) after forking. An integer value 89 * of -1 in any entry in the array means "ignore this one". 90 * @param fdsToIgnore null-ok an array of ints, either null or holding 91 * one or more POSIX file descriptor numbers that are to be ignored 92 * in the file descriptor table check. 93 * @param instructionSet null-ok the instruction set to use. 94 * @param appDataDir null-ok the data directory of the app. 95 * 96 * @return 0 if this is the child, pid of the child 97 * if this is the parent, or -1 on error. 98 */ 99 public static int forkAndSpecialize(int uid, int gid, int[] gids, int debugFlags, 100 int[][] rlimits, int mountExternal, String seInfo, String niceName, int[] fdsToClose, 101 int[] fdsToIgnore, String instructionSet, String appDataDir) { 102 VM_HOOKS.preFork(); 103 // Resets nice priority for zygote process. 104 resetNicePriority(); 105 int pid = nativeForkAndSpecialize( 106 uid, gid, gids, debugFlags, rlimits, mountExternal, seInfo, niceName, fdsToClose, 107 fdsToIgnore, instructionSet, appDataDir); 108 // Enable tracing as soon as possible for the child process. 109 if (pid == 0) { 110 Trace.setTracingEnabled(true, debugFlags); 111 112 // Note that this event ends at the end of handleChildProc, 113 Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "PostFork"); 114 } 115 VM_HOOKS.postForkCommon(); 116 return pid; 117 } 118 119 native private static int nativeForkAndSpecialize(int uid, int gid, int[] gids,int debugFlags, 120 int[][] rlimits, int mountExternal, String seInfo, String niceName, int[] fdsToClose, 121 int[] fdsToIgnore, String instructionSet, String appDataDir); 122 123 /** 124 * Called to do any initialization before starting an application. 125 */ 126 native static void nativePreApplicationInit(); 127 128 /** 129 * Special method to start the system server process. In addition to the 130 * common actions performed in forkAndSpecialize, the pid of the child 131 * process is recorded such that the death of the child process will cause 132 * zygote to exit. 133 * 134 * @param uid the UNIX uid that the new process should setuid() to after 135 * fork()ing and and before spawning any threads. 136 * @param gid the UNIX gid that the new process should setgid() to after 137 * fork()ing and and before spawning any threads. 138 * @param gids null-ok; a list of UNIX gids that the new process should 139 * setgroups() to after fork and before spawning any threads. 140 * @param debugFlags bit flags that enable debugging features. 141 * @param rlimits null-ok an array of rlimit tuples, with the second 142 * dimension having a length of 3 and representing 143 * (resource, rlim_cur, rlim_max). These are set via the posix 144 * setrlimit(2) call. 145 * @param permittedCapabilities argument for setcap() 146 * @param effectiveCapabilities argument for setcap() 147 * 148 * @return 0 if this is the child, pid of the child 149 * if this is the parent, or -1 on error. 150 */ 151 public static int forkSystemServer(int uid, int gid, int[] gids, int debugFlags, 152 int[][] rlimits, long permittedCapabilities, long effectiveCapabilities) { 153 VM_HOOKS.preFork(); 154 // Resets nice priority for zygote process. 155 resetNicePriority(); 156 int pid = nativeForkSystemServer( 157 uid, gid, gids, debugFlags, rlimits, permittedCapabilities, effectiveCapabilities); 158 // Enable tracing as soon as we enter the system_server. 159 if (pid == 0) { 160 Trace.setTracingEnabled(true, debugFlags); 161 } 162 VM_HOOKS.postForkCommon(); 163 return pid; 164 } 165 166 native private static int nativeForkSystemServer(int uid, int gid, int[] gids, int debugFlags, 167 int[][] rlimits, long permittedCapabilities, long effectiveCapabilities); 168 169 /** 170 * Lets children of the zygote inherit open file descriptors to this path. 171 */ 172 native protected static void nativeAllowFileAcrossFork(String path); 173 174 /** 175 * Zygote unmount storage space on initializing. 176 * This method is called once. 177 */ 178 native protected static void nativeUnmountStorageOnInit(); 179 180 private static void callPostForkChildHooks(int debugFlags, boolean isSystemServer, 181 String instructionSet) { 182 VM_HOOKS.postForkChild(debugFlags, isSystemServer, instructionSet); 183 } 184 185 /** 186 * Resets the calling thread priority to the default value (Thread.NORM_PRIORITY 187 * or nice value 0). This updates both the priority value in java.lang.Thread and 188 * the nice value (setpriority). 189 */ 190 static void resetNicePriority() { 191 Thread.currentThread().setPriority(Thread.NORM_PRIORITY); 192 } 193 194 /** 195 * Executes "/system/bin/sh -c <command>" using the exec() system call. 196 * This method throws a runtime exception if exec() failed, otherwise, this 197 * method never returns. 198 * 199 * @param command The shell command to execute. 200 */ 201 public static void execShell(String command) { 202 String[] args = { "/system/bin/sh", "-c", command }; 203 try { 204 Os.execv(args[0], args); 205 } catch (ErrnoException e) { 206 throw new RuntimeException(e); 207 } 208 } 209 210 /** 211 * Appends quotes shell arguments to the specified string builder. 212 * The arguments are quoted using single-quotes, escaped if necessary, 213 * prefixed with a space, and appended to the command. 214 * 215 * @param command A string builder for the shell command being constructed. 216 * @param args An array of argument strings to be quoted and appended to the command. 217 * @see #execShell(String) 218 */ 219 public static void appendQuotedShellArgs(StringBuilder command, String[] args) { 220 for (String arg : args) { 221 command.append(" '").append(arg.replace("'", "'\\''")).append("'"); 222 } 223 } 224 } 225
