Makoto Onuki | 4c7073b | 2019-11-04 10:37:15 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2019 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 android.os; |
| 18 | |
| 19 | import android.util.Log; |
| 20 | |
| 21 | import java.io.BufferedInputStream; |
| 22 | import java.io.FileDescriptor; |
| 23 | import java.io.FileInputStream; |
| 24 | import java.io.FileOutputStream; |
| 25 | import java.io.InputStream; |
| 26 | import java.io.OutputStream; |
| 27 | import java.io.PrintWriter; |
| 28 | |
| 29 | /** |
| 30 | * Helper for implementing {@link Binder#onShellCommand Binder.onShellCommand}. This is meant to |
| 31 | * be copied into mainline modules, so this class must not use any hidden APIs. |
| 32 | * |
| 33 | * @hide |
| 34 | */ |
| 35 | public abstract class BasicShellCommandHandler { |
| 36 | static final String TAG = "ShellCommand"; |
| 37 | static final boolean DEBUG = false; |
| 38 | |
| 39 | private Binder mTarget; |
| 40 | private FileDescriptor mIn; |
| 41 | private FileDescriptor mOut; |
| 42 | private FileDescriptor mErr; |
| 43 | private String[] mArgs; |
| 44 | |
| 45 | private String mCmd; |
| 46 | private int mArgPos; |
| 47 | private String mCurArgData; |
| 48 | |
| 49 | private FileInputStream mFileIn; |
| 50 | private FileOutputStream mFileOut; |
| 51 | private FileOutputStream mFileErr; |
| 52 | |
| 53 | private PrintWriter mOutPrintWriter; |
| 54 | private PrintWriter mErrPrintWriter; |
| 55 | private InputStream mInputStream; |
| 56 | |
| 57 | public void init(Binder target, FileDescriptor in, FileDescriptor out, FileDescriptor err, |
| 58 | String[] args, int firstArgPos) { |
| 59 | mTarget = target; |
| 60 | mIn = in; |
| 61 | mOut = out; |
| 62 | mErr = err; |
| 63 | mArgs = args; |
| 64 | mCmd = null; |
| 65 | mArgPos = firstArgPos; |
| 66 | mCurArgData = null; |
| 67 | mFileIn = null; |
| 68 | mFileOut = null; |
| 69 | mFileErr = null; |
| 70 | mOutPrintWriter = null; |
| 71 | mErrPrintWriter = null; |
| 72 | mInputStream = null; |
| 73 | } |
| 74 | |
| 75 | public int exec(Binder target, FileDescriptor in, FileDescriptor out, FileDescriptor err, |
| 76 | String[] args) { |
| 77 | String cmd; |
| 78 | int start; |
| 79 | if (args != null && args.length > 0) { |
| 80 | cmd = args[0]; |
| 81 | start = 1; |
| 82 | } else { |
| 83 | cmd = null; |
| 84 | start = 0; |
| 85 | } |
| 86 | init(target, in, out, err, args, start); |
| 87 | mCmd = cmd; |
| 88 | |
| 89 | if (DEBUG) { |
| 90 | RuntimeException here = new RuntimeException("here"); |
| 91 | here.fillInStackTrace(); |
| 92 | Log.d(TAG, "Starting command " + mCmd + " on " + mTarget, here); |
| 93 | Log.d(TAG, "Calling uid=" + Binder.getCallingUid() |
| 94 | + " pid=" + Binder.getCallingPid()); |
| 95 | } |
| 96 | int res = -1; |
| 97 | try { |
| 98 | res = onCommand(mCmd); |
| 99 | if (DEBUG) Log.d(TAG, "Executed command " + mCmd + " on " + mTarget); |
| 100 | } catch (Throwable e) { |
| 101 | // Unlike usual calls, in this case if an exception gets thrown |
| 102 | // back to us we want to print it back in to the dump data, since |
| 103 | // that is where the caller expects all interesting information to |
| 104 | // go. |
| 105 | PrintWriter eout = getErrPrintWriter(); |
| 106 | eout.println(); |
| 107 | eout.println("Exception occurred while executing: " + e.getMessage()); |
| 108 | e.printStackTrace(eout); |
| 109 | } finally { |
| 110 | if (DEBUG) Log.d(TAG, "Flushing output streams on " + mTarget); |
| 111 | if (mOutPrintWriter != null) { |
| 112 | mOutPrintWriter.flush(); |
| 113 | } |
| 114 | if (mErrPrintWriter != null) { |
| 115 | mErrPrintWriter.flush(); |
| 116 | } |
| 117 | if (DEBUG) Log.d(TAG, "Sending command result on " + mTarget); |
| 118 | } |
| 119 | if (DEBUG) Log.d(TAG, "Finished command " + mCmd + " on " + mTarget); |
| 120 | return res; |
| 121 | } |
| 122 | |
| 123 | /** |
| 124 | * Return the raw FileDescriptor for the output stream. |
| 125 | */ |
| 126 | public FileDescriptor getOutFileDescriptor() { |
| 127 | return mOut; |
| 128 | } |
| 129 | |
| 130 | /** |
| 131 | * Return direct raw access (not buffered) to the command's output data stream. |
| 132 | */ |
| 133 | public OutputStream getRawOutputStream() { |
| 134 | if (mFileOut == null) { |
| 135 | mFileOut = new FileOutputStream(mOut); |
| 136 | } |
| 137 | return mFileOut; |
| 138 | } |
| 139 | |
| 140 | /** |
| 141 | * Return a PrintWriter for formatting output to {@link #getRawOutputStream()}. |
| 142 | */ |
| 143 | public PrintWriter getOutPrintWriter() { |
| 144 | if (mOutPrintWriter == null) { |
| 145 | mOutPrintWriter = new PrintWriter(getRawOutputStream()); |
| 146 | } |
| 147 | return mOutPrintWriter; |
| 148 | } |
| 149 | |
| 150 | /** |
| 151 | * Return the raw FileDescriptor for the error stream. |
| 152 | */ |
| 153 | public FileDescriptor getErrFileDescriptor() { |
| 154 | return mErr; |
| 155 | } |
| 156 | |
| 157 | /** |
| 158 | * Return direct raw access (not buffered) to the command's error output data stream. |
| 159 | */ |
| 160 | public OutputStream getRawErrorStream() { |
| 161 | if (mFileErr == null) { |
| 162 | mFileErr = new FileOutputStream(mErr); |
| 163 | } |
| 164 | return mFileErr; |
| 165 | } |
| 166 | |
| 167 | /** |
| 168 | * Return a PrintWriter for formatting output to {@link #getRawErrorStream()}. |
| 169 | */ |
| 170 | public PrintWriter getErrPrintWriter() { |
| 171 | if (mErr == null) { |
| 172 | return getOutPrintWriter(); |
| 173 | } |
| 174 | if (mErrPrintWriter == null) { |
| 175 | mErrPrintWriter = new PrintWriter(getRawErrorStream()); |
| 176 | } |
| 177 | return mErrPrintWriter; |
| 178 | } |
| 179 | |
| 180 | /** |
| 181 | * Return the raw FileDescriptor for the input stream. |
| 182 | */ |
| 183 | public FileDescriptor getInFileDescriptor() { |
| 184 | return mIn; |
| 185 | } |
| 186 | |
| 187 | /** |
| 188 | * Return direct raw access (not buffered) to the command's input data stream. |
| 189 | */ |
| 190 | public InputStream getRawInputStream() { |
| 191 | if (mFileIn == null) { |
| 192 | mFileIn = new FileInputStream(mIn); |
| 193 | } |
| 194 | return mFileIn; |
| 195 | } |
| 196 | |
| 197 | /** |
| 198 | * Return buffered access to the command's {@link #getRawInputStream()}. |
| 199 | */ |
| 200 | public InputStream getBufferedInputStream() { |
| 201 | if (mInputStream == null) { |
| 202 | mInputStream = new BufferedInputStream(getRawInputStream()); |
| 203 | } |
| 204 | return mInputStream; |
| 205 | } |
| 206 | |
| 207 | /** |
| 208 | * Return the next option on the command line -- that is an argument that |
| 209 | * starts with '-'. If the next argument is not an option, null is returned. |
| 210 | */ |
| 211 | public String getNextOption() { |
| 212 | if (mCurArgData != null) { |
| 213 | String prev = mArgs[mArgPos - 1]; |
| 214 | throw new IllegalArgumentException("No argument expected after \"" + prev + "\""); |
| 215 | } |
| 216 | if (mArgPos >= mArgs.length) { |
| 217 | return null; |
| 218 | } |
| 219 | String arg = mArgs[mArgPos]; |
| 220 | if (!arg.startsWith("-")) { |
| 221 | return null; |
| 222 | } |
| 223 | mArgPos++; |
| 224 | if (arg.equals("--")) { |
| 225 | return null; |
| 226 | } |
| 227 | if (arg.length() > 1 && arg.charAt(1) != '-') { |
| 228 | if (arg.length() > 2) { |
| 229 | mCurArgData = arg.substring(2); |
| 230 | return arg.substring(0, 2); |
| 231 | } else { |
| 232 | mCurArgData = null; |
| 233 | return arg; |
| 234 | } |
| 235 | } |
| 236 | mCurArgData = null; |
| 237 | return arg; |
| 238 | } |
| 239 | |
| 240 | /** |
| 241 | * Return the next argument on the command line, whatever it is; if there are |
| 242 | * no arguments left, return null. |
| 243 | */ |
| 244 | public String getNextArg() { |
| 245 | if (mCurArgData != null) { |
| 246 | String arg = mCurArgData; |
| 247 | mCurArgData = null; |
| 248 | return arg; |
| 249 | } else if (mArgPos < mArgs.length) { |
| 250 | return mArgs[mArgPos++]; |
| 251 | } else { |
| 252 | return null; |
| 253 | } |
| 254 | } |
| 255 | |
| 256 | public String peekNextArg() { |
| 257 | if (mCurArgData != null) { |
| 258 | return mCurArgData; |
| 259 | } else if (mArgPos < mArgs.length) { |
| 260 | return mArgs[mArgPos]; |
| 261 | } else { |
| 262 | return null; |
| 263 | } |
| 264 | } |
| 265 | |
| 266 | /** |
| 267 | * Return the next argument on the command line, whatever it is; if there are |
| 268 | * no arguments left, throws an IllegalArgumentException to report this to the user. |
| 269 | */ |
| 270 | public String getNextArgRequired() { |
| 271 | String arg = getNextArg(); |
| 272 | if (arg == null) { |
| 273 | String prev = mArgs[mArgPos - 1]; |
| 274 | throw new IllegalArgumentException("Argument expected after \"" + prev + "\""); |
| 275 | } |
| 276 | return arg; |
| 277 | } |
| 278 | |
| 279 | public int handleDefaultCommands(String cmd) { |
| 280 | if (cmd == null || "help".equals(cmd) || "-h".equals(cmd)) { |
| 281 | onHelp(); |
| 282 | } else { |
| 283 | getOutPrintWriter().println("Unknown command: " + cmd); |
| 284 | } |
| 285 | return -1; |
| 286 | } |
| 287 | |
| 288 | public Binder getTarget() { |
| 289 | return mTarget; |
| 290 | } |
| 291 | |
| 292 | public String[] getAllArgs() { |
| 293 | return mArgs; |
| 294 | } |
| 295 | |
| 296 | /** |
| 297 | * Implement parsing and execution of a command. If it isn't a command you understand, |
| 298 | * call {@link #handleDefaultCommands(String)} and return its result as a last resort. |
| 299 | * Use {@link #getNextOption()}, {@link #getNextArg()}, and {@link #getNextArgRequired()} |
| 300 | * to process additional command line arguments. Command output can be written to |
| 301 | * {@link #getOutPrintWriter()} and errors to {@link #getErrPrintWriter()}. |
| 302 | * |
| 303 | * <p class="caution">Note that no permission checking has been done before entering this |
| 304 | * function, so you need to be sure to do your own security verification for any commands you |
| 305 | * are executing. The easiest way to do this is to have the ShellCommand contain |
| 306 | * only a reference to your service's aidl interface, and do all of your command |
| 307 | * implementations on top of that -- that way you can rely entirely on your executing security |
| 308 | * code behind that interface.</p> |
| 309 | * |
| 310 | * @param cmd The first command line argument representing the name of the command to execute. |
| 311 | * @return Return the command result; generally 0 or positive indicates success and |
| 312 | * negative values indicate error. |
| 313 | */ |
| 314 | public abstract int onCommand(String cmd); |
| 315 | |
| 316 | /** |
| 317 | * Implement this to print help text about your command to {@link #getOutPrintWriter()}. |
| 318 | */ |
| 319 | public abstract void onHelp(); |
| 320 | } |