2 * Copyright (C) 2014 The Android Open Source Project
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
17 package com.android.internal.os;
20 import android.os.Trace;
21 import dalvik.system.ZygoteHooks;
22 import android.system.ErrnoException;
23 import android.system.Os;
26 public final class Zygote {
28 * Bit values for "debugFlags" argument. The definitions are duplicated
32 /** enable debugging over JDWP */
33 public static final int DEBUG_ENABLE_DEBUGGER = 1;
34 /** enable JNI checks */
35 public static final int DEBUG_ENABLE_CHECKJNI = 1 << 1;
36 /** enable Java programming language "assert" statements */
37 public static final int DEBUG_ENABLE_ASSERT = 1 << 2;
38 /** disable the AOT compiler and JIT */
39 public static final int DEBUG_ENABLE_SAFEMODE = 1 << 3;
40 /** Enable logging of third-party JNI activity. */
41 public static final int DEBUG_ENABLE_JNI_LOGGING = 1 << 4;
42 /** enable the JIT compiler */
43 public static final int DEBUG_ENABLE_JIT = 1 << 5;
44 /** Force generation of native debugging information. */
45 public static final int DEBUG_GENERATE_DEBUG_INFO = 1 << 6;
47 /** No external storage should be mounted. */
48 public static final int MOUNT_EXTERNAL_NONE = 0;
49 /** Default external storage should be mounted. */
50 public static final int MOUNT_EXTERNAL_DEFAULT = 1;
51 /** Read-only external storage should be mounted. */
52 public static final int MOUNT_EXTERNAL_READ = 2;
53 /** Read-write external storage should be mounted. */
54 public static final int MOUNT_EXTERNAL_WRITE = 3;
56 private static final ZygoteHooks VM_HOOKS = new ZygoteHooks();
61 * Forks a new VM instance. The current VM must have been started
62 * with the -Xzygote flag. <b>NOTE: new instance keeps all
63 * root capabilities. The new process is expected to call capset()</b>.
65 * @param uid the UNIX uid that the new process should setuid() to after
66 * fork()ing and and before spawning any threads.
67 * @param gid the UNIX gid that the new process should setgid() to after
68 * fork()ing and and before spawning any threads.
69 * @param gids null-ok; a list of UNIX gids that the new process should
70 * setgroups() to after fork and before spawning any threads.
71 * @param debugFlags bit flags that enable debugging features.
72 * @param rlimits null-ok an array of rlimit tuples, with the second
73 * dimension having a length of 3 and representing
74 * (resource, rlim_cur, rlim_max). These are set via the posix
76 * @param seInfo null-ok a string specifying SELinux information for
78 * @param niceName null-ok a string specifying the process name.
79 * @param fdsToClose an array of ints, holding one or more POSIX
80 * file descriptor numbers that are to be closed by the child
81 * (and replaced by /dev/null) after forking. An integer value
82 * of -1 in any entry in the array means "ignore this one".
83 * @param instructionSet null-ok the instruction set to use.
84 * @param appDataDir null-ok the data directory of the app.
86 * @return 0 if this is the child, pid of the child
87 * if this is the parent, or -1 on error.
89 public static int forkAndSpecialize(int uid, int gid, int[] gids, int debugFlags,
90 int[][] rlimits, int mountExternal, String seInfo, String niceName, int[] fdsToClose,
91 String instructionSet, String appDataDir) {
93 int pid = nativeForkAndSpecialize(
94 uid, gid, gids, debugFlags, rlimits, mountExternal, seInfo, niceName, fdsToClose,
95 instructionSet, appDataDir);
96 // Enable tracing as soon as possible for the child process.
98 Trace.setTracingEnabled(true);
100 // Note that this event ends at the end of handleChildProc,
101 Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "PostFork");
103 VM_HOOKS.postForkCommon();
107 native private static int nativeForkAndSpecialize(int uid, int gid, int[] gids,int debugFlags,
108 int[][] rlimits, int mountExternal, String seInfo, String niceName, int[] fdsToClose,
109 String instructionSet, String appDataDir);
112 * Special method to start the system server process. In addition to the
113 * common actions performed in forkAndSpecialize, the pid of the child
114 * process is recorded such that the death of the child process will cause
117 * @param uid the UNIX uid that the new process should setuid() to after
118 * fork()ing and and before spawning any threads.
119 * @param gid the UNIX gid that the new process should setgid() to after
120 * fork()ing and and before spawning any threads.
121 * @param gids null-ok; a list of UNIX gids that the new process should
122 * setgroups() to after fork and before spawning any threads.
123 * @param debugFlags bit flags that enable debugging features.
124 * @param rlimits null-ok an array of rlimit tuples, with the second
125 * dimension having a length of 3 and representing
126 * (resource, rlim_cur, rlim_max). These are set via the posix
128 * @param permittedCapabilities argument for setcap()
129 * @param effectiveCapabilities argument for setcap()
131 * @return 0 if this is the child, pid of the child
132 * if this is the parent, or -1 on error.
134 public static int forkSystemServer(int uid, int gid, int[] gids, int debugFlags,
135 int[][] rlimits, long permittedCapabilities, long effectiveCapabilities) {
137 int pid = nativeForkSystemServer(
138 uid, gid, gids, debugFlags, rlimits, permittedCapabilities, effectiveCapabilities);
139 // Enable tracing as soon as we enter the system_server.
141 Trace.setTracingEnabled(true);
143 VM_HOOKS.postForkCommon();
147 native private static int nativeForkSystemServer(int uid, int gid, int[] gids, int debugFlags,
148 int[][] rlimits, long permittedCapabilities, long effectiveCapabilities);
151 * Zygote unmount storage space on initializing.
152 * This method is called once.
154 native protected static void nativeUnmountStorageOnInit();
156 private static void callPostForkChildHooks(int debugFlags, String instructionSet) {
157 VM_HOOKS.postForkChild(debugFlags, instructionSet);
162 * Executes "/system/bin/sh -c <command>" using the exec() system call.
163 * This method throws a runtime exception if exec() failed, otherwise, this
164 * method never returns.
166 * @param command The shell command to execute.
168 public static void execShell(String command) {
169 String[] args = { "/system/bin/sh", "-c", command };
171 Os.execv(args[0], args);
172 } catch (ErrnoException e) {
173 throw new RuntimeException(e);
178 * Appends quotes shell arguments to the specified string builder.
179 * The arguments are quoted using single-quotes, escaped if necessary,
180 * prefixed with a space, and appended to the command.
182 * @param command A string builder for the shell command being constructed.
183 * @param args An array of argument strings to be quoted and appended to the command.
184 * @see #execShell(String)
186 public static void appendQuotedShellArgs(StringBuilder command, String[] args) {
187 for (String arg : args) {
188 command.append(" '").append(arg.replace("'", "'\\''")).append("'");