/*
* Copyright (C) 2015 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 android.os;
import android.annotation.UnsupportedAppUsage;
import android.util.Slog;
import com.android.internal.util.FastPrintWriter;
import java.io.BufferedInputStream;
import java.io.FileDescriptor;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
/**
* Helper for implementing {@link Binder#onShellCommand Binder.onShellCommand}.
* @hide
*/
public abstract class ShellCommand {
static final String TAG = "ShellCommand";
static final boolean DEBUG = false;
private Binder mTarget;
private FileDescriptor mIn;
private FileDescriptor mOut;
private FileDescriptor mErr;
private String[] mArgs;
private ShellCallback mShellCallback;
private ResultReceiver mResultReceiver;
private String mCmd;
private int mArgPos;
private String mCurArgData;
private FileInputStream mFileIn;
private FileOutputStream mFileOut;
private FileOutputStream mFileErr;
private FastPrintWriter mOutPrintWriter;
private FastPrintWriter mErrPrintWriter;
private InputStream mInputStream;
public void init(Binder target, FileDescriptor in, FileDescriptor out, FileDescriptor err,
String[] args, ShellCallback callback, int firstArgPos) {
mTarget = target;
mIn = in;
mOut = out;
mErr = err;
mArgs = args;
mShellCallback = callback;
mResultReceiver = null;
mCmd = null;
mArgPos = firstArgPos;
mCurArgData = null;
mFileIn = null;
mFileOut = null;
mFileErr = null;
mOutPrintWriter = null;
mErrPrintWriter = null;
mInputStream = null;
}
public int exec(Binder target, FileDescriptor in, FileDescriptor out, FileDescriptor err,
String[] args, ShellCallback callback, ResultReceiver resultReceiver) {
String cmd;
int start;
if (args != null && args.length > 0) {
cmd = args[0];
start = 1;
} else {
cmd = null;
start = 0;
}
init(target, in, out, err, args, callback, start);
mCmd = cmd;
mResultReceiver = resultReceiver;
if (DEBUG) {
RuntimeException here = new RuntimeException("here");
here.fillInStackTrace();
Slog.d(TAG, "Starting command " + mCmd + " on " + mTarget, here);
Slog.d(TAG, "Calling uid=" + Binder.getCallingUid()
+ " pid=" + Binder.getCallingPid() + " ShellCallback=" + getShellCallback());
}
int res = -1;
try {
res = onCommand(mCmd);
if (DEBUG) Slog.d(TAG, "Executed command " + mCmd + " on " + mTarget);
} catch (SecurityException e) {
PrintWriter eout = getErrPrintWriter();
eout.println("Security exception: " + e.getMessage());
eout.println();
e.printStackTrace(eout);
} catch (Throwable e) {
// Unlike usual calls, in this case if an exception gets thrown
// back to us we want to print it back in to the dump data, since
// that is where the caller expects all interesting information to
// go.
PrintWriter eout = getErrPrintWriter();
eout.println();
eout.println("Exception occurred while executing:");
e.printStackTrace(eout);
} finally {
if (DEBUG) Slog.d(TAG, "Flushing output streams on " + mTarget);
if (mOutPrintWriter != null) {
mOutPrintWriter.flush();
}
if (mErrPrintWriter != null) {
mErrPrintWriter.flush();
}
if (DEBUG) Slog.d(TAG, "Sending command result on " + mTarget);
if (mResultReceiver != null) {
mResultReceiver.send(res, null);
}
}
if (DEBUG) Slog.d(TAG, "Finished command " + mCmd + " on " + mTarget);
return res;
}
/**
* Adopt the ResultReceiver that was given to this shell command from it, taking
* it over. Primarily used to dispatch to another shell command. Once called,
* this shell command will no longer return its own result when done.
*/
public ResultReceiver adoptResultReceiver() {
ResultReceiver rr = mResultReceiver;
mResultReceiver = null;
return rr;
}
/**
* Return the raw FileDescriptor for the output stream.
*/
public FileDescriptor getOutFileDescriptor() {
return mOut;
}
/**
* Return direct raw access (not buffered) to the command's output data stream.
*/
public OutputStream getRawOutputStream() {
if (mFileOut == null) {
mFileOut = new FileOutputStream(mOut);
}
return mFileOut;
}
/**
* Return a PrintWriter for formatting output to {@link #getRawOutputStream()}.
*/
public PrintWriter getOutPrintWriter() {
if (mOutPrintWriter == null) {
mOutPrintWriter = new FastPrintWriter(getRawOutputStream());
}
return mOutPrintWriter;
}
/**
* Return the raw FileDescriptor for the error stream.
*/
public FileDescriptor getErrFileDescriptor() {
return mErr;
}
/**
* Return direct raw access (not buffered) to the command's error output data stream.
*/
public OutputStream getRawErrorStream() {
if (mFileErr == null) {
mFileErr = new FileOutputStream(mErr);
}
return mFileErr;
}
/**
* Return a PrintWriter for formatting output to {@link #getRawErrorStream()}.
*/
public PrintWriter getErrPrintWriter() {
if (mErr == null) {
return getOutPrintWriter();
}
if (mErrPrintWriter == null) {
mErrPrintWriter = new FastPrintWriter(getRawErrorStream());
}
return mErrPrintWriter;
}
/**
* Return the raw FileDescriptor for the input stream.
*/
public FileDescriptor getInFileDescriptor() {
return mIn;
}
/**
* Return direct raw access (not buffered) to the command's input data stream.
*/
public InputStream getRawInputStream() {
if (mFileIn == null) {
mFileIn = new FileInputStream(mIn);
}
return mFileIn;
}
/**
* Return buffered access to the command's {@link #getRawInputStream()}.
*/
public InputStream getBufferedInputStream() {
if (mInputStream == null) {
mInputStream = new BufferedInputStream(getRawInputStream());
}
return mInputStream;
}
/**
* Helper for just system services to ask the shell to open an output file.
* @hide
*/
public ParcelFileDescriptor openFileForSystem(String path, String mode) {
if (DEBUG) Slog.d(TAG, "openFileForSystem: " + path + " mode=" + mode);
try {
ParcelFileDescriptor pfd = getShellCallback().openFile(path,
"u:r:system_server:s0", mode);
if (pfd != null) {
if (DEBUG) Slog.d(TAG, "Got file: " + pfd);
return pfd;
}
} catch (RuntimeException e) {
if (DEBUG) Slog.d(TAG, "Failure opening file: " + e.getMessage());
getErrPrintWriter().println("Failure opening file: " + e.getMessage());
}
if (DEBUG) Slog.d(TAG, "Error: Unable to open file: " + path);
getErrPrintWriter().println("Error: Unable to open file: " + path);
String suggestedPath = "/data/local/tmp/";
if (path == null || !path.startsWith(suggestedPath)) {
getErrPrintWriter().println("Consider using a file under " + suggestedPath);
}
return null;
}
/**
* Return the next option on the command line -- that is an argument that
* starts with '-'. If the next argument is not an option, null is returned.
*/
public String getNextOption() {
if (mCurArgData != null) {
String prev = mArgs[mArgPos - 1];
throw new IllegalArgumentException("No argument expected after \"" + prev + "\"");
}
if (mArgPos >= mArgs.length) {
return null;
}
String arg = mArgs[mArgPos];
if (!arg.startsWith("-")) {
return null;
}
mArgPos++;
if (arg.equals("--")) {
return null;
}
if (arg.length() > 1 && arg.charAt(1) != '-') {
if (arg.length() > 2) {
mCurArgData = arg.substring(2);
return arg.substring(0, 2);
} else {
mCurArgData = null;
return arg;
}
}
mCurArgData = null;
return arg;
}
/**
* Return the next argument on the command line, whatever it is; if there are
* no arguments left, return null.
*/
public String getNextArg() {
if (mCurArgData != null) {
String arg = mCurArgData;
mCurArgData = null;
return arg;
} else if (mArgPos < mArgs.length) {
return mArgs[mArgPos++];
} else {
return null;
}
}
@UnsupportedAppUsage
public String peekNextArg() {
if (mCurArgData != null) {
return mCurArgData;
} else if (mArgPos < mArgs.length) {
return mArgs[mArgPos];
} else {
return null;
}
}
/**
* Return the next argument on the command line, whatever it is; if there are
* no arguments left, throws an IllegalArgumentException to report this to the user.
*/
public String getNextArgRequired() {
String arg = getNextArg();
if (arg == null) {
String prev = mArgs[mArgPos - 1];
throw new IllegalArgumentException("Argument expected after \"" + prev + "\"");
}
return arg;
}
/**
* Return the {@link ShellCallback} for communicating back with the calling shell.
*/
public ShellCallback getShellCallback() {
return mShellCallback;
}
public int handleDefaultCommands(String cmd) {
if ("dump".equals(cmd)) {
String[] newArgs = new String[mArgs.length-1];
System.arraycopy(mArgs, 1, newArgs, 0, mArgs.length-1);
mTarget.doDump(mOut, getOutPrintWriter(), newArgs);
return 0;
} else if (cmd == null || "help".equals(cmd) || "-h".equals(cmd)) {
onHelp();
} else {
getOutPrintWriter().println("Unknown command: " + cmd);
}
return -1;
}
/**
* Implement parsing and execution of a command. If it isn't a command you understand,
* call {@link #handleDefaultCommands(String)} and return its result as a last resort.
* Use {@link #getNextOption()}, {@link #getNextArg()}, and {@link #getNextArgRequired()}
* to process additional command line arguments. Command output can be written to
* {@link #getOutPrintWriter()} and errors to {@link #getErrPrintWriter()}.
*
* <p class="caution">Note that no permission checking has been done before entering this function,
* so you need to be sure to do your own security verification for any commands you
* are executing. The easiest way to do this is to have the ShellCommand contain
* only a reference to your service's aidl interface, and do all of your command
* implementations on top of that -- that way you can rely entirely on your executing security
* code behind that interface.</p>
*
* @param cmd The first command line argument representing the name of the command to execute.
* @return Return the command result; generally 0 or positive indicates success and
* negative values indicate error.
*/
public abstract int onCommand(String cmd);
/**
* Implement this to print help text about your command to {@link #getOutPrintWriter()}.
*/
public abstract void onHelp();
}