1 /* 2 * Copyright (C) 2006 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 static android.system.OsConstants.AF_UNIX; 20 import static android.system.OsConstants.O_APPEND; 21 import static android.system.OsConstants.O_CREAT; 22 import static android.system.OsConstants.O_RDONLY; 23 import static android.system.OsConstants.O_RDWR; 24 import static android.system.OsConstants.O_TRUNC; 25 import static android.system.OsConstants.O_WRONLY; 26 import static android.system.OsConstants.SEEK_SET; 27 import static android.system.OsConstants.SOCK_SEQPACKET; 28 import static android.system.OsConstants.SOCK_STREAM; 29 import static android.system.OsConstants.S_IROTH; 30 import static android.system.OsConstants.S_IRWXG; 31 import static android.system.OsConstants.S_IRWXU; 32 import static android.system.OsConstants.S_ISLNK; 33 import static android.system.OsConstants.S_ISREG; 34 import static android.system.OsConstants.S_IWOTH; 35 36 import android.content.BroadcastReceiver; 37 import android.content.ContentProvider; 38 import android.os.MessageQueue.OnFileDescriptorEventListener; 39 import android.system.ErrnoException; 40 import android.system.Os; 41 import android.system.OsConstants; 42 import android.system.StructStat; 43 import android.util.Log; 44 45 import dalvik.system.CloseGuard; 46 47 import libcore.io.IoUtils; 48 import libcore.io.Memory; 49 50 import java.io.Closeable; 51 import java.io.File; 52 import java.io.FileDescriptor; 53 import java.io.FileInputStream; 54 import java.io.FileNotFoundException; 55 import java.io.FileOutputStream; 56 import java.io.IOException; 57 import java.io.InterruptedIOException; 58 import java.net.DatagramSocket; 59 import java.net.Socket; 60 import java.nio.ByteOrder; 61 62 /** 63 * The FileDescriptor returned by {@link Parcel#readFileDescriptor}, allowing 64 * you to close it when done with it. 65 */ 66 public class ParcelFileDescriptor implements Parcelable, Closeable { 67 private static final String TAG = "ParcelFileDescriptor"; 68 69 private final FileDescriptor mFd; 70 71 /** 72 * Optional socket used to communicate close events, status at close, and 73 * detect remote process crashes. 74 */ 75 private FileDescriptor mCommFd; 76 77 /** 78 * Wrapped {@link ParcelFileDescriptor}, if any. Used to avoid 79 * double-closing {@link #mFd}. 80 */ 81 private final ParcelFileDescriptor mWrapped; 82 83 /** 84 * Maximum {@link #mStatusBuf} size; longer status messages will be 85 * truncated. 86 */ 87 private static final int MAX_STATUS = 1024; 88 89 /** 90 * Temporary buffer used by {@link #readCommStatus(FileDescriptor, byte[])}, 91 * allocated on-demand. 92 */ 93 private byte[] mStatusBuf; 94 95 /** 96 * Status read by {@link #checkError()}, or null if not read yet. 97 */ 98 private Status mStatus; 99 100 private volatile boolean mClosed; 101 102 private final CloseGuard mGuard = CloseGuard.get(); 103 104 /** 105 * For use with {@link #open}: if {@link #MODE_CREATE} has been supplied and 106 * this file doesn't already exist, then create the file with permissions 107 * such that any application can read it. 108 * 109 * @deprecated Creating world-readable files is very dangerous, and likely 110 * to cause security holes in applications. It is strongly 111 * discouraged; instead, applications should use more formal 112 * mechanism for interactions such as {@link ContentProvider}, 113 * {@link BroadcastReceiver}, and {@link android.app.Service}. 114 * There are no guarantees that this access mode will remain on 115 * a file, such as when it goes through a backup and restore. 116 */ 117 @Deprecated 118 public static final int MODE_WORLD_READABLE = 0x00000001; 119 120 /** 121 * For use with {@link #open}: if {@link #MODE_CREATE} has been supplied and 122 * this file doesn't already exist, then create the file with permissions 123 * such that any application can write it. 124 * 125 * @deprecated Creating world-writable files is very dangerous, and likely 126 * to cause security holes in applications. It is strongly 127 * discouraged; instead, applications should use more formal 128 * mechanism for interactions such as {@link ContentProvider}, 129 * {@link BroadcastReceiver}, and {@link android.app.Service}. 130 * There are no guarantees that this access mode will remain on 131 * a file, such as when it goes through a backup and restore. 132 */ 133 @Deprecated 134 public static final int MODE_WORLD_WRITEABLE = 0x00000002; 135 136 /** 137 * For use with {@link #open}: open the file with read-only access. 138 */ 139 public static final int MODE_READ_ONLY = 0x10000000; 140 141 /** 142 * For use with {@link #open}: open the file with write-only access. 143 */ 144 public static final int MODE_WRITE_ONLY = 0x20000000; 145 146 /** 147 * For use with {@link #open}: open the file with read and write access. 148 */ 149 public static final int MODE_READ_WRITE = 0x30000000; 150 151 /** 152 * For use with {@link #open}: create the file if it doesn't already exist. 153 */ 154 public static final int MODE_CREATE = 0x08000000; 155 156 /** 157 * For use with {@link #open}: erase contents of file when opening. 158 */ 159 public static final int MODE_TRUNCATE = 0x04000000; 160 161 /** 162 * For use with {@link #open}: append to end of file while writing. 163 */ 164 public static final int MODE_APPEND = 0x02000000; 165 166 /** 167 * Create a new ParcelFileDescriptor wrapped around another descriptor. By 168 * default all method calls are delegated to the wrapped descriptor. 169 */ ParcelFileDescriptor(ParcelFileDescriptor wrapped)170 public ParcelFileDescriptor(ParcelFileDescriptor wrapped) { 171 // We keep a strong reference to the wrapped PFD, and rely on its 172 // finalizer to trigger CloseGuard. All calls are delegated to wrapper. 173 mWrapped = wrapped; 174 mFd = null; 175 mCommFd = null; 176 mClosed = true; 177 } 178 179 /** {@hide} */ ParcelFileDescriptor(FileDescriptor fd)180 public ParcelFileDescriptor(FileDescriptor fd) { 181 this(fd, null); 182 } 183 184 /** {@hide} */ ParcelFileDescriptor(FileDescriptor fd, FileDescriptor commChannel)185 public ParcelFileDescriptor(FileDescriptor fd, FileDescriptor commChannel) { 186 if (fd == null) { 187 throw new NullPointerException("FileDescriptor must not be null"); 188 } 189 mWrapped = null; 190 mFd = fd; 191 mCommFd = commChannel; 192 mGuard.open("close"); 193 } 194 195 /** 196 * Create a new ParcelFileDescriptor accessing a given file. 197 * 198 * @param file The file to be opened. 199 * @param mode The desired access mode, must be one of 200 * {@link #MODE_READ_ONLY}, {@link #MODE_WRITE_ONLY}, or 201 * {@link #MODE_READ_WRITE}; may also be any combination of 202 * {@link #MODE_CREATE}, {@link #MODE_TRUNCATE}, 203 * {@link #MODE_WORLD_READABLE}, and 204 * {@link #MODE_WORLD_WRITEABLE}. 205 * @return a new ParcelFileDescriptor pointing to the given file. 206 * @throws FileNotFoundException if the given file does not exist or can not 207 * be opened with the requested mode. 208 * @see #parseMode(String) 209 */ open(File file, int mode)210 public static ParcelFileDescriptor open(File file, int mode) throws FileNotFoundException { 211 final FileDescriptor fd = openInternal(file, mode); 212 if (fd == null) return null; 213 214 return new ParcelFileDescriptor(fd); 215 } 216 217 /** 218 * Create a new ParcelFileDescriptor accessing a given file. 219 * 220 * @param file The file to be opened. 221 * @param mode The desired access mode, must be one of 222 * {@link #MODE_READ_ONLY}, {@link #MODE_WRITE_ONLY}, or 223 * {@link #MODE_READ_WRITE}; may also be any combination of 224 * {@link #MODE_CREATE}, {@link #MODE_TRUNCATE}, 225 * {@link #MODE_WORLD_READABLE}, and 226 * {@link #MODE_WORLD_WRITEABLE}. 227 * @param handler to call listener from; must not be null. 228 * @param listener to be invoked when the returned descriptor has been 229 * closed; must not be null. 230 * @return a new ParcelFileDescriptor pointing to the given file. 231 * @throws FileNotFoundException if the given file does not exist or can not 232 * be opened with the requested mode. 233 * @see #parseMode(String) 234 */ open(File file, int mode, Handler handler, final OnCloseListener listener)235 public static ParcelFileDescriptor open(File file, int mode, Handler handler, 236 final OnCloseListener listener) throws IOException { 237 if (handler == null) { 238 throw new IllegalArgumentException("Handler must not be null"); 239 } 240 if (listener == null) { 241 throw new IllegalArgumentException("Listener must not be null"); 242 } 243 244 final FileDescriptor fd = openInternal(file, mode); 245 if (fd == null) return null; 246 247 return fromFd(fd, handler, listener); 248 } 249 250 /** {@hide} */ fromFd( FileDescriptor fd, Handler handler, final OnCloseListener listener)251 public static ParcelFileDescriptor fromFd( 252 FileDescriptor fd, Handler handler, final OnCloseListener listener) throws IOException { 253 if (handler == null) { 254 throw new IllegalArgumentException("Handler must not be null"); 255 } 256 if (listener == null) { 257 throw new IllegalArgumentException("Listener must not be null"); 258 } 259 260 final FileDescriptor[] comm = createCommSocketPair(); 261 final ParcelFileDescriptor pfd = new ParcelFileDescriptor(fd, comm[0]); 262 final MessageQueue queue = handler.getLooper().getQueue(); 263 queue.addOnFileDescriptorEventListener(comm[1], 264 OnFileDescriptorEventListener.EVENT_INPUT, new OnFileDescriptorEventListener() { 265 @Override 266 public int onFileDescriptorEvents(FileDescriptor fd, int events) { 267 Status status = null; 268 if ((events & OnFileDescriptorEventListener.EVENT_INPUT) != 0) { 269 final byte[] buf = new byte[MAX_STATUS]; 270 status = readCommStatus(fd, buf); 271 } else if ((events & OnFileDescriptorEventListener.EVENT_ERROR) != 0) { 272 status = new Status(Status.DEAD); 273 } 274 if (status != null) { 275 queue.removeOnFileDescriptorEventListener(fd); 276 IoUtils.closeQuietly(fd); 277 listener.onClose(status.asIOException()); 278 return 0; 279 } 280 return EVENT_INPUT; 281 } 282 }); 283 284 return pfd; 285 } 286 openInternal(File file, int mode)287 private static FileDescriptor openInternal(File file, int mode) throws FileNotFoundException { 288 if ((mode & MODE_READ_WRITE) == 0) { 289 throw new IllegalArgumentException( 290 "Must specify MODE_READ_ONLY, MODE_WRITE_ONLY, or MODE_READ_WRITE"); 291 } 292 293 int flags = 0; 294 switch (mode & MODE_READ_WRITE) { 295 case 0: 296 case MODE_READ_ONLY: flags = O_RDONLY; break; 297 case MODE_WRITE_ONLY: flags = O_WRONLY; break; 298 case MODE_READ_WRITE: flags = O_RDWR; break; 299 } 300 301 if ((mode & MODE_CREATE) != 0) flags |= O_CREAT; 302 if ((mode & MODE_TRUNCATE) != 0) flags |= O_TRUNC; 303 if ((mode & MODE_APPEND) != 0) flags |= O_APPEND; 304 305 int realMode = S_IRWXU | S_IRWXG; 306 if ((mode & MODE_WORLD_READABLE) != 0) realMode |= S_IROTH; 307 if ((mode & MODE_WORLD_WRITEABLE) != 0) realMode |= S_IWOTH; 308 309 final String path = file.getPath(); 310 try { 311 return Os.open(path, flags, realMode); 312 } catch (ErrnoException e) { 313 throw new FileNotFoundException(e.getMessage()); 314 } 315 } 316 317 /** 318 * Create a new ParcelFileDescriptor that is a dup of an existing 319 * FileDescriptor. This obeys standard POSIX semantics, where the 320 * new file descriptor shared state such as file position with the 321 * original file descriptor. 322 */ dup(FileDescriptor orig)323 public static ParcelFileDescriptor dup(FileDescriptor orig) throws IOException { 324 try { 325 final FileDescriptor fd = Os.dup(orig); 326 return new ParcelFileDescriptor(fd); 327 } catch (ErrnoException e) { 328 throw e.rethrowAsIOException(); 329 } 330 } 331 332 /** 333 * Create a new ParcelFileDescriptor that is a dup of the existing 334 * FileDescriptor. This obeys standard POSIX semantics, where the 335 * new file descriptor shared state such as file position with the 336 * original file descriptor. 337 */ dup()338 public ParcelFileDescriptor dup() throws IOException { 339 if (mWrapped != null) { 340 return mWrapped.dup(); 341 } else { 342 return dup(getFileDescriptor()); 343 } 344 } 345 346 /** 347 * Create a new ParcelFileDescriptor from a raw native fd. The new 348 * ParcelFileDescriptor holds a dup of the original fd passed in here, 349 * so you must still close that fd as well as the new ParcelFileDescriptor. 350 * 351 * @param fd The native fd that the ParcelFileDescriptor should dup. 352 * 353 * @return Returns a new ParcelFileDescriptor holding a FileDescriptor 354 * for a dup of the given fd. 355 */ fromFd(int fd)356 public static ParcelFileDescriptor fromFd(int fd) throws IOException { 357 final FileDescriptor original = new FileDescriptor(); 358 original.setInt$(fd); 359 360 try { 361 final FileDescriptor dup = Os.dup(original); 362 return new ParcelFileDescriptor(dup); 363 } catch (ErrnoException e) { 364 throw e.rethrowAsIOException(); 365 } 366 } 367 368 /** 369 * Take ownership of a raw native fd in to a new ParcelFileDescriptor. 370 * The returned ParcelFileDescriptor now owns the given fd, and will be 371 * responsible for closing it. You must not close the fd yourself. 372 * 373 * @param fd The native fd that the ParcelFileDescriptor should adopt. 374 * 375 * @return Returns a new ParcelFileDescriptor holding a FileDescriptor 376 * for the given fd. 377 */ adoptFd(int fd)378 public static ParcelFileDescriptor adoptFd(int fd) { 379 final FileDescriptor fdesc = new FileDescriptor(); 380 fdesc.setInt$(fd); 381 382 return new ParcelFileDescriptor(fdesc); 383 } 384 385 /** 386 * Create a new ParcelFileDescriptor from the specified Socket. The new 387 * ParcelFileDescriptor holds a dup of the original FileDescriptor in 388 * the Socket, so you must still close the Socket as well as the new 389 * ParcelFileDescriptor. 390 * 391 * @param socket The Socket whose FileDescriptor is used to create 392 * a new ParcelFileDescriptor. 393 * 394 * @return A new ParcelFileDescriptor with the FileDescriptor of the 395 * specified Socket. 396 */ fromSocket(Socket socket)397 public static ParcelFileDescriptor fromSocket(Socket socket) { 398 FileDescriptor fd = socket.getFileDescriptor$(); 399 return fd != null ? new ParcelFileDescriptor(fd) : null; 400 } 401 402 /** 403 * Create a new ParcelFileDescriptor from the specified DatagramSocket. 404 * 405 * @param datagramSocket The DatagramSocket whose FileDescriptor is used 406 * to create a new ParcelFileDescriptor. 407 * 408 * @return A new ParcelFileDescriptor with the FileDescriptor of the 409 * specified DatagramSocket. 410 */ fromDatagramSocket(DatagramSocket datagramSocket)411 public static ParcelFileDescriptor fromDatagramSocket(DatagramSocket datagramSocket) { 412 FileDescriptor fd = datagramSocket.getFileDescriptor$(); 413 return fd != null ? new ParcelFileDescriptor(fd) : null; 414 } 415 416 /** 417 * Create two ParcelFileDescriptors structured as a data pipe. The first 418 * ParcelFileDescriptor in the returned array is the read side; the second 419 * is the write side. 420 */ createPipe()421 public static ParcelFileDescriptor[] createPipe() throws IOException { 422 try { 423 final FileDescriptor[] fds = Os.pipe(); 424 return new ParcelFileDescriptor[] { 425 new ParcelFileDescriptor(fds[0]), 426 new ParcelFileDescriptor(fds[1]) }; 427 } catch (ErrnoException e) { 428 throw e.rethrowAsIOException(); 429 } 430 } 431 432 /** 433 * Create two ParcelFileDescriptors structured as a data pipe. The first 434 * ParcelFileDescriptor in the returned array is the read side; the second 435 * is the write side. 436 * <p> 437 * The write end has the ability to deliver an error message through 438 * {@link #closeWithError(String)} which can be handled by the read end 439 * calling {@link #checkError()}, usually after detecting an EOF. 440 * This can also be used to detect remote crashes. 441 */ createReliablePipe()442 public static ParcelFileDescriptor[] createReliablePipe() throws IOException { 443 try { 444 final FileDescriptor[] comm = createCommSocketPair(); 445 final FileDescriptor[] fds = Os.pipe(); 446 return new ParcelFileDescriptor[] { 447 new ParcelFileDescriptor(fds[0], comm[0]), 448 new ParcelFileDescriptor(fds[1], comm[1]) }; 449 } catch (ErrnoException e) { 450 throw e.rethrowAsIOException(); 451 } 452 } 453 454 /** 455 * Create two ParcelFileDescriptors structured as a pair of sockets 456 * connected to each other. The two sockets are indistinguishable. 457 */ createSocketPair()458 public static ParcelFileDescriptor[] createSocketPair() throws IOException { 459 return createSocketPair(SOCK_STREAM); 460 } 461 462 /** 463 * @hide 464 */ createSocketPair(int type)465 public static ParcelFileDescriptor[] createSocketPair(int type) throws IOException { 466 try { 467 final FileDescriptor fd0 = new FileDescriptor(); 468 final FileDescriptor fd1 = new FileDescriptor(); 469 Os.socketpair(AF_UNIX, type, 0, fd0, fd1); 470 return new ParcelFileDescriptor[] { 471 new ParcelFileDescriptor(fd0), 472 new ParcelFileDescriptor(fd1) }; 473 } catch (ErrnoException e) { 474 throw e.rethrowAsIOException(); 475 } 476 } 477 478 /** 479 * Create two ParcelFileDescriptors structured as a pair of sockets 480 * connected to each other. The two sockets are indistinguishable. 481 * <p> 482 * Both ends have the ability to deliver an error message through 483 * {@link #closeWithError(String)} which can be detected by the other end 484 * calling {@link #checkError()}, usually after detecting an EOF. 485 * This can also be used to detect remote crashes. 486 */ createReliableSocketPair()487 public static ParcelFileDescriptor[] createReliableSocketPair() throws IOException { 488 return createReliableSocketPair(SOCK_STREAM); 489 } 490 491 /** 492 * @hide 493 */ createReliableSocketPair(int type)494 public static ParcelFileDescriptor[] createReliableSocketPair(int type) throws IOException { 495 try { 496 final FileDescriptor[] comm = createCommSocketPair(); 497 final FileDescriptor fd0 = new FileDescriptor(); 498 final FileDescriptor fd1 = new FileDescriptor(); 499 Os.socketpair(AF_UNIX, type, 0, fd0, fd1); 500 return new ParcelFileDescriptor[] { 501 new ParcelFileDescriptor(fd0, comm[0]), 502 new ParcelFileDescriptor(fd1, comm[1]) }; 503 } catch (ErrnoException e) { 504 throw e.rethrowAsIOException(); 505 } 506 } 507 createCommSocketPair()508 private static FileDescriptor[] createCommSocketPair() throws IOException { 509 try { 510 // Use SOCK_SEQPACKET so that we have a guarantee that the status 511 // is written and read atomically as one unit and is not split 512 // across multiple IO operations. 513 final FileDescriptor comm1 = new FileDescriptor(); 514 final FileDescriptor comm2 = new FileDescriptor(); 515 Os.socketpair(AF_UNIX, SOCK_SEQPACKET, 0, comm1, comm2); 516 IoUtils.setBlocking(comm1, false); 517 IoUtils.setBlocking(comm2, false); 518 return new FileDescriptor[] { comm1, comm2 }; 519 } catch (ErrnoException e) { 520 throw e.rethrowAsIOException(); 521 } 522 } 523 524 /** 525 * @hide Please use createPipe() or ContentProvider.openPipeHelper(). 526 * Gets a file descriptor for a read-only copy of the given data. 527 * 528 * @param data Data to copy. 529 * @param name Name for the shared memory area that may back the file descriptor. 530 * This is purely informative and may be {@code null}. 531 * @return A ParcelFileDescriptor. 532 * @throws IOException if there is an error while creating the shared memory area. 533 */ 534 @Deprecated fromData(byte[] data, String name)535 public static ParcelFileDescriptor fromData(byte[] data, String name) throws IOException { 536 if (data == null) return null; 537 MemoryFile file = new MemoryFile(name, data.length); 538 if (data.length > 0) { 539 file.writeBytes(data, 0, 0, data.length); 540 } 541 file.deactivate(); 542 FileDescriptor fd = file.getFileDescriptor(); 543 return fd != null ? new ParcelFileDescriptor(fd) : null; 544 } 545 546 /** 547 * Converts a string representing a file mode, such as "rw", into a bitmask suitable for use 548 * with {@link #open}. 549 * <p> 550 * @param mode The string representation of the file mode. Can be "r", "w", "wt", "wa", "rw" 551 * or "rwt". 552 * @return A bitmask representing the given file mode. 553 * @throws IllegalArgumentException if the given string does not match a known file mode. 554 */ parseMode(String mode)555 public static int parseMode(String mode) { 556 final int modeBits; 557 if ("r".equals(mode)) { 558 modeBits = ParcelFileDescriptor.MODE_READ_ONLY; 559 } else if ("w".equals(mode) || "wt".equals(mode)) { 560 modeBits = ParcelFileDescriptor.MODE_WRITE_ONLY 561 | ParcelFileDescriptor.MODE_CREATE 562 | ParcelFileDescriptor.MODE_TRUNCATE; 563 } else if ("wa".equals(mode)) { 564 modeBits = ParcelFileDescriptor.MODE_WRITE_ONLY 565 | ParcelFileDescriptor.MODE_CREATE 566 | ParcelFileDescriptor.MODE_APPEND; 567 } else if ("rw".equals(mode)) { 568 modeBits = ParcelFileDescriptor.MODE_READ_WRITE 569 | ParcelFileDescriptor.MODE_CREATE; 570 } else if ("rwt".equals(mode)) { 571 modeBits = ParcelFileDescriptor.MODE_READ_WRITE 572 | ParcelFileDescriptor.MODE_CREATE 573 | ParcelFileDescriptor.MODE_TRUNCATE; 574 } else { 575 throw new IllegalArgumentException("Bad mode '" + mode + "'"); 576 } 577 return modeBits; 578 } 579 580 /** 581 * Return the filesystem path of the real file on disk that is represented 582 * by the given {@link FileDescriptor}. 583 * 584 * @hide 585 */ getFile(FileDescriptor fd)586 public static File getFile(FileDescriptor fd) throws IOException { 587 try { 588 final String path = Os.readlink("/proc/self/fd/" + fd.getInt$()); 589 if (OsConstants.S_ISREG(Os.stat(path).st_mode)) { 590 return new File(path); 591 } else { 592 throw new IOException("Not a regular file: " + path); 593 } 594 } catch (ErrnoException e) { 595 throw e.rethrowAsIOException(); 596 } 597 } 598 599 /** 600 * Retrieve the actual FileDescriptor associated with this object. 601 * 602 * @return Returns the FileDescriptor associated with this object. 603 */ getFileDescriptor()604 public FileDescriptor getFileDescriptor() { 605 if (mWrapped != null) { 606 return mWrapped.getFileDescriptor(); 607 } else { 608 return mFd; 609 } 610 } 611 612 /** 613 * Return the total size of the file representing this fd, as determined by 614 * {@code stat()}. Returns -1 if the fd is not a file. 615 */ getStatSize()616 public long getStatSize() { 617 if (mWrapped != null) { 618 return mWrapped.getStatSize(); 619 } else { 620 try { 621 final StructStat st = Os.fstat(mFd); 622 if (S_ISREG(st.st_mode) || S_ISLNK(st.st_mode)) { 623 return st.st_size; 624 } else { 625 return -1; 626 } 627 } catch (ErrnoException e) { 628 Log.w(TAG, "fstat() failed: " + e); 629 return -1; 630 } 631 } 632 } 633 634 /** 635 * This is needed for implementing AssetFileDescriptor.AutoCloseOutputStream, 636 * and I really don't think we want it to be public. 637 * @hide 638 */ seekTo(long pos)639 public long seekTo(long pos) throws IOException { 640 if (mWrapped != null) { 641 return mWrapped.seekTo(pos); 642 } else { 643 try { 644 return Os.lseek(mFd, pos, SEEK_SET); 645 } catch (ErrnoException e) { 646 throw e.rethrowAsIOException(); 647 } 648 } 649 } 650 651 /** 652 * Return the native fd int for this ParcelFileDescriptor. The 653 * ParcelFileDescriptor still owns the fd, and it still must be closed 654 * through this API. 655 */ getFd()656 public int getFd() { 657 if (mWrapped != null) { 658 return mWrapped.getFd(); 659 } else { 660 if (mClosed) { 661 throw new IllegalStateException("Already closed"); 662 } 663 return mFd.getInt$(); 664 } 665 } 666 667 /** 668 * Return the native fd int for this ParcelFileDescriptor and detach it from 669 * the object here. You are now responsible for closing the fd in native 670 * code. 671 * <p> 672 * You should not detach when the original creator of the descriptor is 673 * expecting a reliable signal through {@link #close()} or 674 * {@link #closeWithError(String)}. 675 * 676 * @see #canDetectErrors() 677 */ detachFd()678 public int detachFd() { 679 if (mWrapped != null) { 680 return mWrapped.detachFd(); 681 } else { 682 if (mClosed) { 683 throw new IllegalStateException("Already closed"); 684 } 685 final int fd = getFd(); 686 Parcel.clearFileDescriptor(mFd); 687 writeCommStatusAndClose(Status.DETACHED, null); 688 mClosed = true; 689 mGuard.close(); 690 releaseResources(); 691 return fd; 692 } 693 } 694 695 /** 696 * Close the ParcelFileDescriptor. This implementation closes the underlying 697 * OS resources allocated to represent this stream. 698 * 699 * @throws IOException 700 * If an error occurs attempting to close this ParcelFileDescriptor. 701 */ 702 @Override close()703 public void close() throws IOException { 704 if (mWrapped != null) { 705 try { 706 mWrapped.close(); 707 } finally { 708 releaseResources(); 709 } 710 } else { 711 closeWithStatus(Status.OK, null); 712 } 713 } 714 715 /** 716 * Close the ParcelFileDescriptor, informing any peer that an error occurred 717 * while processing. If the creator of this descriptor is not observing 718 * errors, it will close normally. 719 * 720 * @param msg describing the error; must not be null. 721 */ closeWithError(String msg)722 public void closeWithError(String msg) throws IOException { 723 if (mWrapped != null) { 724 try { 725 mWrapped.closeWithError(msg); 726 } finally { 727 releaseResources(); 728 } 729 } else { 730 if (msg == null) { 731 throw new IllegalArgumentException("Message must not be null"); 732 } 733 closeWithStatus(Status.ERROR, msg); 734 } 735 } 736 closeWithStatus(int status, String msg)737 private void closeWithStatus(int status, String msg) { 738 if (mClosed) return; 739 mClosed = true; 740 mGuard.close(); 741 // Status MUST be sent before closing actual descriptor 742 writeCommStatusAndClose(status, msg); 743 IoUtils.closeQuietly(mFd); 744 releaseResources(); 745 } 746 747 /** 748 * Called when the fd is being closed, for subclasses to release any other resources 749 * associated with it, such as acquired providers. 750 * @hide 751 */ releaseResources()752 public void releaseResources() { 753 } 754 getOrCreateStatusBuffer()755 private byte[] getOrCreateStatusBuffer() { 756 if (mStatusBuf == null) { 757 mStatusBuf = new byte[MAX_STATUS]; 758 } 759 return mStatusBuf; 760 } 761 writeCommStatusAndClose(int status, String msg)762 private void writeCommStatusAndClose(int status, String msg) { 763 if (mCommFd == null) { 764 // Not reliable, or someone already sent status 765 if (msg != null) { 766 Log.w(TAG, "Unable to inform peer: " + msg); 767 } 768 return; 769 } 770 771 if (status == Status.DETACHED) { 772 Log.w(TAG, "Peer expected signal when closed; unable to deliver after detach"); 773 } 774 775 try { 776 if (status == Status.SILENCE) return; 777 778 // Since we're about to close, read off any remote status. It's 779 // okay to remember missing here. 780 mStatus = readCommStatus(mCommFd, getOrCreateStatusBuffer()); 781 782 // Skip writing status when other end has already gone away. 783 if (mStatus != null) return; 784 785 try { 786 final byte[] buf = getOrCreateStatusBuffer(); 787 int writePtr = 0; 788 789 Memory.pokeInt(buf, writePtr, status, ByteOrder.BIG_ENDIAN); 790 writePtr += 4; 791 792 if (msg != null) { 793 final byte[] rawMsg = msg.getBytes(); 794 final int len = Math.min(rawMsg.length, buf.length - writePtr); 795 System.arraycopy(rawMsg, 0, buf, writePtr, len); 796 writePtr += len; 797 } 798 799 // Must write the entire status as a single operation. 800 Os.write(mCommFd, buf, 0, writePtr); 801 } catch (ErrnoException e) { 802 // Reporting status is best-effort 803 Log.w(TAG, "Failed to report status: " + e); 804 } catch (InterruptedIOException e) { 805 // Reporting status is best-effort 806 Log.w(TAG, "Failed to report status: " + e); 807 } 808 809 } finally { 810 IoUtils.closeQuietly(mCommFd); 811 mCommFd = null; 812 } 813 } 814 readCommStatus(FileDescriptor comm, byte[] buf)815 private static Status readCommStatus(FileDescriptor comm, byte[] buf) { 816 try { 817 // Must read the entire status as a single operation. 818 final int n = Os.read(comm, buf, 0, buf.length); 819 if (n == 0) { 820 // EOF means they're dead 821 return new Status(Status.DEAD); 822 } else { 823 final int status = Memory.peekInt(buf, 0, ByteOrder.BIG_ENDIAN); 824 if (status == Status.ERROR) { 825 final String msg = new String(buf, 4, n - 4); 826 return new Status(status, msg); 827 } 828 return new Status(status); 829 } 830 } catch (ErrnoException e) { 831 if (e.errno == OsConstants.EAGAIN) { 832 // Remote is still alive, but no status written yet 833 return null; 834 } else { 835 Log.d(TAG, "Failed to read status; assuming dead: " + e); 836 return new Status(Status.DEAD); 837 } 838 } catch (InterruptedIOException e) { 839 Log.d(TAG, "Failed to read status; assuming dead: " + e); 840 return new Status(Status.DEAD); 841 } 842 } 843 844 /** 845 * Indicates if this ParcelFileDescriptor can communicate and detect remote 846 * errors/crashes. 847 * 848 * @see #checkError() 849 */ canDetectErrors()850 public boolean canDetectErrors() { 851 if (mWrapped != null) { 852 return mWrapped.canDetectErrors(); 853 } else { 854 return mCommFd != null; 855 } 856 } 857 858 /** 859 * Detect and throw if the other end of a pipe or socket pair encountered an 860 * error or crashed. This allows a reader to distinguish between a valid EOF 861 * and an error/crash. 862 * <p> 863 * If this ParcelFileDescriptor is unable to detect remote errors, it will 864 * return silently. 865 * 866 * @throws IOException for normal errors. 867 * @throws FileDescriptorDetachedException 868 * if the remote side called {@link #detachFd()}. Once detached, the remote 869 * side is unable to communicate any errors through 870 * {@link #closeWithError(String)}. 871 * @see #canDetectErrors() 872 */ checkError()873 public void checkError() throws IOException { 874 if (mWrapped != null) { 875 mWrapped.checkError(); 876 } else { 877 if (mStatus == null) { 878 if (mCommFd == null) { 879 Log.w(TAG, "Peer didn't provide a comm channel; unable to check for errors"); 880 return; 881 } 882 883 // Try reading status; it might be null if nothing written yet. 884 // Either way, we keep comm open to write our status later. 885 mStatus = readCommStatus(mCommFd, getOrCreateStatusBuffer()); 886 } 887 888 if (mStatus == null || mStatus.status == Status.OK) { 889 // No status yet, or everything is peachy! 890 return; 891 } else { 892 throw mStatus.asIOException(); 893 } 894 } 895 } 896 897 /** 898 * An InputStream you can create on a ParcelFileDescriptor, which will 899 * take care of calling {@link ParcelFileDescriptor#close 900 * ParcelFileDescriptor.close()} for you when the stream is closed. 901 */ 902 public static class AutoCloseInputStream extends FileInputStream { 903 private final ParcelFileDescriptor mPfd; 904 AutoCloseInputStream(ParcelFileDescriptor pfd)905 public AutoCloseInputStream(ParcelFileDescriptor pfd) { 906 super(pfd.getFileDescriptor()); 907 mPfd = pfd; 908 } 909 910 @Override close()911 public void close() throws IOException { 912 try { 913 mPfd.close(); 914 } finally { 915 super.close(); 916 } 917 } 918 919 @Override read()920 public int read() throws IOException { 921 final int result = super.read(); 922 if (result == -1 && mPfd.canDetectErrors()) { 923 // Check for errors only on EOF, to minimize overhead. 924 mPfd.checkError(); 925 } 926 return result; 927 } 928 929 @Override read(byte[] b)930 public int read(byte[] b) throws IOException { 931 final int result = super.read(b); 932 if (result == -1 && mPfd.canDetectErrors()) { 933 mPfd.checkError(); 934 } 935 return result; 936 } 937 938 @Override read(byte[] b, int off, int len)939 public int read(byte[] b, int off, int len) throws IOException { 940 final int result = super.read(b, off, len); 941 if (result == -1 && mPfd.canDetectErrors()) { 942 mPfd.checkError(); 943 } 944 return result; 945 } 946 } 947 948 /** 949 * An OutputStream you can create on a ParcelFileDescriptor, which will 950 * take care of calling {@link ParcelFileDescriptor#close 951 * ParcelFileDescriptor.close()} for you when the stream is closed. 952 */ 953 public static class AutoCloseOutputStream extends FileOutputStream { 954 private final ParcelFileDescriptor mPfd; 955 AutoCloseOutputStream(ParcelFileDescriptor pfd)956 public AutoCloseOutputStream(ParcelFileDescriptor pfd) { 957 super(pfd.getFileDescriptor()); 958 mPfd = pfd; 959 } 960 961 @Override close()962 public void close() throws IOException { 963 try { 964 mPfd.close(); 965 } finally { 966 super.close(); 967 } 968 } 969 } 970 971 @Override toString()972 public String toString() { 973 if (mWrapped != null) { 974 return mWrapped.toString(); 975 } else { 976 return "{ParcelFileDescriptor: " + mFd + "}"; 977 } 978 } 979 980 @Override finalize()981 protected void finalize() throws Throwable { 982 if (mWrapped != null) { 983 releaseResources(); 984 } 985 if (mGuard != null) { 986 mGuard.warnIfOpen(); 987 } 988 try { 989 if (!mClosed) { 990 closeWithStatus(Status.LEAKED, null); 991 } 992 } finally { 993 super.finalize(); 994 } 995 } 996 997 @Override describeContents()998 public int describeContents() { 999 if (mWrapped != null) { 1000 return mWrapped.describeContents(); 1001 } else { 1002 return Parcelable.CONTENTS_FILE_DESCRIPTOR; 1003 } 1004 } 1005 1006 /** 1007 * {@inheritDoc} 1008 * If {@link Parcelable#PARCELABLE_WRITE_RETURN_VALUE} is set in flags, 1009 * the file descriptor will be closed after a copy is written to the Parcel. 1010 */ 1011 @Override writeToParcel(Parcel out, int flags)1012 public void writeToParcel(Parcel out, int flags) { 1013 if (mWrapped != null) { 1014 try { 1015 mWrapped.writeToParcel(out, flags); 1016 } finally { 1017 releaseResources(); 1018 } 1019 } else { 1020 if (mCommFd != null) { 1021 out.writeInt(1); 1022 out.writeFileDescriptor(mFd); 1023 out.writeFileDescriptor(mCommFd); 1024 } else { 1025 out.writeInt(0); 1026 out.writeFileDescriptor(mFd); 1027 } 1028 if ((flags & PARCELABLE_WRITE_RETURN_VALUE) != 0 && !mClosed) { 1029 // Not a real close, so emit no status 1030 closeWithStatus(Status.SILENCE, null); 1031 } 1032 } 1033 } 1034 1035 public static final Parcelable.Creator<ParcelFileDescriptor> CREATOR 1036 = new Parcelable.Creator<ParcelFileDescriptor>() { 1037 @Override 1038 public ParcelFileDescriptor createFromParcel(Parcel in) { 1039 int hasCommChannel = in.readInt(); 1040 final FileDescriptor fd = in.readRawFileDescriptor(); 1041 FileDescriptor commChannel = null; 1042 if (hasCommChannel != 0) { 1043 commChannel = in.readRawFileDescriptor(); 1044 } 1045 return new ParcelFileDescriptor(fd, commChannel); 1046 } 1047 1048 @Override 1049 public ParcelFileDescriptor[] newArray(int size) { 1050 return new ParcelFileDescriptor[size]; 1051 } 1052 }; 1053 1054 /** 1055 * Callback indicating that a ParcelFileDescriptor has been closed. 1056 */ 1057 public interface OnCloseListener { 1058 /** 1059 * Event indicating the ParcelFileDescriptor to which this listener was 1060 * attached has been closed. 1061 * 1062 * @param e error state, or {@code null} if closed cleanly. 1063 * If the close event was the result of 1064 * {@link ParcelFileDescriptor#detachFd()}, this will be a 1065 * {@link FileDescriptorDetachedException}. After detach the 1066 * remote side may continue reading/writing to the underlying 1067 * {@link FileDescriptor}, but they can no longer deliver 1068 * reliable close/error events. 1069 */ onClose(IOException e)1070 public void onClose(IOException e); 1071 } 1072 1073 /** 1074 * Exception that indicates that the file descriptor was detached. 1075 */ 1076 public static class FileDescriptorDetachedException extends IOException { 1077 1078 private static final long serialVersionUID = 0xDe7ac4edFdL; 1079 FileDescriptorDetachedException()1080 public FileDescriptorDetachedException() { 1081 super("Remote side is detached"); 1082 } 1083 } 1084 1085 /** 1086 * Internal class representing a remote status read by 1087 * {@link ParcelFileDescriptor#readCommStatus(FileDescriptor, byte[])}. 1088 */ 1089 private static class Status { 1090 /** Special value indicating remote side died. */ 1091 public static final int DEAD = -2; 1092 /** Special value indicating no status should be written. */ 1093 public static final int SILENCE = -1; 1094 1095 /** Remote reported that everything went better than expected. */ 1096 public static final int OK = 0; 1097 /** Remote reported error; length and message follow. */ 1098 public static final int ERROR = 1; 1099 /** Remote reported {@link #detachFd()} and went rogue. */ 1100 public static final int DETACHED = 2; 1101 /** Remote reported their object was finalized. */ 1102 public static final int LEAKED = 3; 1103 1104 public final int status; 1105 public final String msg; 1106 Status(int status)1107 public Status(int status) { 1108 this(status, null); 1109 } 1110 Status(int status, String msg)1111 public Status(int status, String msg) { 1112 this.status = status; 1113 this.msg = msg; 1114 } 1115 asIOException()1116 public IOException asIOException() { 1117 switch (status) { 1118 case DEAD: 1119 return new IOException("Remote side is dead"); 1120 case OK: 1121 return null; 1122 case ERROR: 1123 return new IOException("Remote error: " + msg); 1124 case DETACHED: 1125 return new FileDescriptorDetachedException(); 1126 case LEAKED: 1127 return new IOException("Remote side was leaked"); 1128 default: 1129 return new IOException("Unknown status: " + status); 1130 } 1131 } 1132 1133 @Override toString()1134 public String toString() { 1135 return "{" + status + ": " + msg + "}"; 1136 } 1137 } 1138 } 1139