ZygoteInit.java revision 599c918d9794b51992de85b42befa0c71d9ec07f
1/* 2 * Copyright (C) 2007 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 17package com.android.internal.os; 18 19import android.content.pm.ActivityInfo; 20import android.content.res.Resources; 21import android.content.res.TypedArray; 22import android.content.res.ColorStateList; 23import android.graphics.drawable.Drawable; 24import android.net.LocalServerSocket; 25import android.os.Debug; 26import android.os.SystemClock; 27import android.os.SystemProperties; 28import android.util.Config; 29import android.util.EventLog; 30import android.util.Log; 31 32import dalvik.system.VMRuntime; 33import dalvik.system.Zygote; 34 35import java.io.BufferedReader; 36import java.io.FileDescriptor; 37import java.io.IOException; 38import java.io.InputStream; 39import java.io.InputStreamReader; 40import java.lang.reflect.InvocationTargetException; 41import java.lang.reflect.Method; 42import java.lang.reflect.Modifier; 43import java.util.ArrayList; 44 45/** 46 * Startup class for the zygote process. 47 * 48 * Pre-initializes some classes, and then waits for commands on a UNIX domain 49 * socket. Based on these commands, forks of child processes that inherit 50 * the initial state of the VM. 51 * 52 * Please see {@link ZygoteConnection.Arguments} for documentation on the 53 * client protocol. 54 * 55 * @hide 56 */ 57public class ZygoteInit { 58 59 private static final String TAG = "Zygote"; 60 61 private static final String ANDROID_SOCKET_ENV = "ANDROID_SOCKET_zygote"; 62 63 private static final int LOG_BOOT_PROGRESS_PRELOAD_START = 3020; 64 private static final int LOG_BOOT_PROGRESS_PRELOAD_END = 3030; 65 66 /** when preloading, GC after allocating this many bytes */ 67 private static final int PRELOAD_GC_THRESHOLD = 50000; 68 69 private static LocalServerSocket sServerSocket; 70 71 /** 72 * Used to pre-load resources. We hold a global reference on it so it 73 * never gets destroyed. 74 */ 75 private static Resources mResources; 76 77 /** 78 * The number of times that the main Zygote loop 79 * should run before calling gc() again. 80 */ 81 static final int GC_LOOP_COUNT = 10; 82 83 /** 84 * If true, zygote forks for each peer. If false, a select loop is used 85 * inside a single process. The latter is preferred. 86 */ 87 private static final boolean ZYGOTE_FORK_MODE = false; 88 89 /** 90 * The name of a resource file that contains classes to preload. 91 */ 92 private static final String PRELOADED_CLASSES = "preloaded-classes"; 93 94 /** Controls whether we should preload resources during zygote init. */ 95 private static final boolean PRELOAD_RESOURCES = true; 96 97 /** 98 * List of methods we "warm up" in the register map cache. These were 99 * chosen because they appeared on the stack in GCs in multiple 100 * applications. 101 * 102 * This is in a VM-ready format, to minimize string processing. If a 103 * class is not already loaded, or a method is not found, the entry 104 * will be skipped. 105 * 106 * This doesn't really merit a separately-generated input file at this 107 * time. The list is fairly short, and the consequences of failure 108 * are minor. 109 */ 110 private static final String[] REGISTER_MAP_METHODS = { 111 // (currently not doing any) 112 //"Landroid/app/Activity;.setContentView:(I)V", 113 }; 114 115 116 /** 117 * Invokes a static "main(argv[]) method on class "className". 118 * Converts various failing exceptions into RuntimeExceptions, with 119 * the assumption that they will then cause the VM instance to exit. 120 * 121 * @param loader class loader to use 122 * @param className Fully-qualified class name 123 * @param argv Argument vector for main() 124 */ 125 static void invokeStaticMain(ClassLoader loader, 126 String className, String[] argv) 127 throws ZygoteInit.MethodAndArgsCaller { 128 Class<?> cl; 129 130 try { 131 cl = loader.loadClass(className); 132 } catch (ClassNotFoundException ex) { 133 throw new RuntimeException( 134 "Missing class when invoking static main " + className, 135 ex); 136 } 137 138 Method m; 139 try { 140 m = cl.getMethod("main", new Class[] { String[].class }); 141 } catch (NoSuchMethodException ex) { 142 throw new RuntimeException( 143 "Missing static main on " + className, ex); 144 } catch (SecurityException ex) { 145 throw new RuntimeException( 146 "Problem getting static main on " + className, ex); 147 } 148 149 int modifiers = m.getModifiers(); 150 if (! (Modifier.isStatic(modifiers) && Modifier.isPublic(modifiers))) { 151 throw new RuntimeException( 152 "Main method is not public and static on " + className); 153 } 154 155 /* 156 * This throw gets caught in ZygoteInit.main(), which responds 157 * by invoking the exception's run() method. This arrangement 158 * clears up all the stack frames that were required in setting 159 * up the process. 160 */ 161 throw new ZygoteInit.MethodAndArgsCaller(m, argv); 162 } 163 164 /** 165 * Registers a server socket for zygote command connections 166 * 167 * @throws RuntimeException when open fails 168 */ 169 private static void registerZygoteSocket() { 170 if (sServerSocket == null) { 171 int fileDesc; 172 try { 173 String env = System.getenv(ANDROID_SOCKET_ENV); 174 fileDesc = Integer.parseInt(env); 175 } catch (RuntimeException ex) { 176 throw new RuntimeException( 177 ANDROID_SOCKET_ENV + " unset or invalid", ex); 178 } 179 180 try { 181 sServerSocket = new LocalServerSocket( 182 createFileDescriptor(fileDesc)); 183 } catch (IOException ex) { 184 throw new RuntimeException( 185 "Error binding to local socket '" + fileDesc + "'", ex); 186 } 187 } 188 } 189 190 /** 191 * Waits for and accepts a single command connection. Throws 192 * RuntimeException on failure. 193 */ 194 private static ZygoteConnection acceptCommandPeer() { 195 try { 196 return new ZygoteConnection(sServerSocket.accept()); 197 } catch (IOException ex) { 198 throw new RuntimeException( 199 "IOException during accept()", ex); 200 } 201 } 202 203 /** 204 * Close and clean up zygote sockets. Called on shutdown and on the 205 * child's exit path. 206 */ 207 static void closeServerSocket() { 208 try { 209 if (sServerSocket != null) { 210 sServerSocket.close(); 211 } 212 } catch (IOException ex) { 213 Log.e(TAG, "Zygote: error closing sockets", ex); 214 } 215 216 sServerSocket = null; 217 } 218 219 private static final int UNPRIVILEGED_UID = 9999; 220 private static final int UNPRIVILEGED_GID = 9999; 221 222 private static final int ROOT_UID = 0; 223 private static final int ROOT_GID = 0; 224 225 /** 226 * Sets effective user ID. 227 */ 228 private static void setEffectiveUser(int uid) { 229 int errno = setreuid(ROOT_UID, uid); 230 if (errno != 0) { 231 Log.e(TAG, "setreuid() failed. errno: " + errno); 232 } 233 } 234 235 /** 236 * Sets effective group ID. 237 */ 238 private static void setEffectiveGroup(int gid) { 239 int errno = setregid(ROOT_GID, gid); 240 if (errno != 0) { 241 Log.e(TAG, "setregid() failed. errno: " + errno); 242 } 243 } 244 245 /** 246 * Performs Zygote process initialization. Loads and initializes 247 * commonly used classes. 248 * 249 * Most classes only cause a few hundred bytes to be allocated, but 250 * a few will allocate a dozen Kbytes (in one case, 500+K). 251 */ 252 private static void preloadClasses() { 253 final VMRuntime runtime = VMRuntime.getRuntime(); 254 255 InputStream is = ZygoteInit.class.getClassLoader().getResourceAsStream( 256 PRELOADED_CLASSES); 257 if (is == null) { 258 Log.e(TAG, "Couldn't find " + PRELOADED_CLASSES + "."); 259 } else { 260 Log.i(TAG, "Preloading classes..."); 261 long startTime = SystemClock.uptimeMillis(); 262 263 // Drop root perms while running static initializers. 264 setEffectiveGroup(UNPRIVILEGED_GID); 265 setEffectiveUser(UNPRIVILEGED_UID); 266 267 // Alter the target heap utilization. With explicit GCs this 268 // is not likely to have any effect. 269 float defaultUtilization = runtime.getTargetHeapUtilization(); 270 runtime.setTargetHeapUtilization(0.8f); 271 272 // Start with a clean slate. 273 runtime.gcSoftReferences(); 274 runtime.runFinalizationSync(); 275 Debug.startAllocCounting(); 276 277 try { 278 BufferedReader br 279 = new BufferedReader(new InputStreamReader(is), 256); 280 281 int count = 0; 282 String line; 283 String missingClasses = null; 284 while ((line = br.readLine()) != null) { 285 // Skip comments and blank lines. 286 line = line.trim(); 287 if (line.startsWith("#") || line.equals("")) { 288 continue; 289 } 290 291 try { 292 if (Config.LOGV) { 293 Log.v(TAG, "Preloading " + line + "..."); 294 } 295 Class.forName(line); 296 if (Debug.getGlobalAllocSize() > PRELOAD_GC_THRESHOLD) { 297 if (Config.LOGV) { 298 Log.v(TAG, 299 " GC at " + Debug.getGlobalAllocSize()); 300 } 301 runtime.gcSoftReferences(); 302 runtime.runFinalizationSync(); 303 Debug.resetGlobalAllocSize(); 304 } 305 count++; 306 } catch (ClassNotFoundException e) { 307 Log.e(TAG, "Class not found for preloading: " + line); 308 if (missingClasses == null) { 309 missingClasses = line; 310 } else { 311 missingClasses += " " + line; 312 } 313 } 314 } 315 316 if (missingClasses != null && 317 "1".equals(SystemProperties.get("persist.service.adb.enable"))) { 318 throw new IllegalStateException( 319 "Missing class(es) for preloading, update preloaded-classes [" 320 + missingClasses + "]"); 321 } 322 323 Log.i(TAG, "...preloaded " + count + " classes in " 324 + (SystemClock.uptimeMillis()-startTime) + "ms."); 325 } catch (IOException e) { 326 Log.e(TAG, "Error reading " + PRELOADED_CLASSES + ".", e); 327 } finally { 328 // Restore default. 329 runtime.setTargetHeapUtilization(defaultUtilization); 330 331 Debug.stopAllocCounting(); 332 333 // Bring back root. We'll need it later. 334 setEffectiveUser(ROOT_UID); 335 setEffectiveGroup(ROOT_GID); 336 } 337 } 338 } 339 340 /** 341 * Pre-caches register maps for methods that are commonly used. 342 */ 343 private static void cacheRegisterMaps() { 344 String failed = null; 345 int failure; 346 long startTime = System.nanoTime(); 347 348 failure = 0; 349 350 for (int i = 0; i < REGISTER_MAP_METHODS.length; i++) { 351 String str = REGISTER_MAP_METHODS[i]; 352 353 if (!Debug.cacheRegisterMap(str)) { 354 if (failed == null) 355 failed = str; 356 failure++; 357 } 358 } 359 360 long delta = System.nanoTime() - startTime; 361 362 if (failure == REGISTER_MAP_METHODS.length) { 363 if (REGISTER_MAP_METHODS.length > 0) { 364 Log.i(TAG, 365 "Register map caching failed (precise GC not enabled?)"); 366 } 367 return; 368 } 369 370 Log.i(TAG, "Register map cache: found " + 371 (REGISTER_MAP_METHODS.length - failure) + " of " + 372 REGISTER_MAP_METHODS.length + " methods in " + 373 (delta / 1000000L) + "ms"); 374 if (failure > 0) { 375 Log.i(TAG, " First failure: " + failed); 376 } 377 } 378 379 /** 380 * Load in commonly used resources, so they can be shared across 381 * processes. 382 * 383 * These tend to be a few Kbytes, but are frequently in the 20-40K 384 * range, and occasionally even larger. 385 */ 386 private static void preloadResources() { 387 final VMRuntime runtime = VMRuntime.getRuntime(); 388 389 Debug.startAllocCounting(); 390 try { 391 runtime.gcSoftReferences(); 392 runtime.runFinalizationSync(); 393 mResources = Resources.getSystem(); 394 mResources.startPreloading(); 395 if (PRELOAD_RESOURCES) { 396 Log.i(TAG, "Preloading resources..."); 397 398 long startTime = SystemClock.uptimeMillis(); 399 TypedArray ar = mResources.obtainTypedArray( 400 com.android.internal.R.array.preloaded_drawables); 401 int N = preloadDrawables(runtime, ar); 402 Log.i(TAG, "...preloaded " + N + " resources in " 403 + (SystemClock.uptimeMillis()-startTime) + "ms."); 404 405 startTime = SystemClock.uptimeMillis(); 406 ar = mResources.obtainTypedArray( 407 com.android.internal.R.array.preloaded_color_state_lists); 408 N = preloadColorStateLists(runtime, ar); 409 Log.i(TAG, "...preloaded " + N + " resources in " 410 + (SystemClock.uptimeMillis()-startTime) + "ms."); 411 } 412 mResources.finishPreloading(); 413 } catch (RuntimeException e) { 414 Log.w(TAG, "Failure preloading resources", e); 415 } finally { 416 Debug.stopAllocCounting(); 417 } 418 } 419 420 private static int preloadColorStateLists(VMRuntime runtime, TypedArray ar) { 421 int N = ar.length(); 422 for (int i=0; i<N; i++) { 423 if (Debug.getGlobalAllocSize() > PRELOAD_GC_THRESHOLD) { 424 if (Config.LOGV) { 425 Log.v(TAG, " GC at " + Debug.getGlobalAllocSize()); 426 } 427 runtime.gcSoftReferences(); 428 runtime.runFinalizationSync(); 429 Debug.resetGlobalAllocSize(); 430 } 431 int id = ar.getResourceId(i, 0); 432 if (Config.LOGV) { 433 Log.v(TAG, "Preloading resource #" + Integer.toHexString(id)); 434 } 435 if (id != 0) { 436 mResources.getColorStateList(id); 437 } 438 } 439 return N; 440 } 441 442 443 private static int preloadDrawables(VMRuntime runtime, TypedArray ar) { 444 int N = ar.length(); 445 for (int i=0; i<N; i++) { 446 if (Debug.getGlobalAllocSize() > PRELOAD_GC_THRESHOLD) { 447 if (Config.LOGV) { 448 Log.v(TAG, " GC at " + Debug.getGlobalAllocSize()); 449 } 450 runtime.gcSoftReferences(); 451 runtime.runFinalizationSync(); 452 Debug.resetGlobalAllocSize(); 453 } 454 int id = ar.getResourceId(i, 0); 455 if (Config.LOGV) { 456 Log.v(TAG, "Preloading resource #" + Integer.toHexString(id)); 457 } 458 if (id != 0) { 459 Drawable dr = mResources.getDrawable(id); 460 if ((dr.getChangingConfigurations()&~ActivityInfo.CONFIG_FONT_SCALE) != 0) { 461 Log.w(TAG, "Preloaded drawable resource #0x" 462 + Integer.toHexString(id) 463 + " (" + ar.getString(i) + ") that varies with configuration!!"); 464 } 465 } 466 } 467 return N; 468 } 469 470 /** 471 * Runs several special GCs to try to clean up a few generations of 472 * softly- and final-reachable objects, along with any other garbage. 473 * This is only useful just before a fork(). 474 */ 475 /*package*/ static void gc() { 476 final VMRuntime runtime = VMRuntime.getRuntime(); 477 478 /* runFinalizationSync() lets finalizers be called in Zygote, 479 * which doesn't have a HeapWorker thread. 480 */ 481 runtime.gcSoftReferences(); 482 runtime.runFinalizationSync(); 483 runtime.gcSoftReferences(); 484 runtime.runFinalizationSync(); 485 runtime.gcSoftReferences(); 486 runtime.runFinalizationSync(); 487 } 488 489 /** 490 * Finish remaining work for the newly forked system server process. 491 */ 492 private static void handleSystemServerProcess( 493 ZygoteConnection.Arguments parsedArgs) 494 throws ZygoteInit.MethodAndArgsCaller { 495 /* 496 * First, set the capabilities if necessary 497 */ 498 499 if (parsedArgs.uid != 0) { 500 try { 501 setCapabilities(parsedArgs.permittedCapabilities, 502 parsedArgs.effectiveCapabilities); 503 } catch (IOException ex) { 504 Log.e(TAG, "Error setting capabilities", ex); 505 } 506 } 507 508 closeServerSocket(); 509 510 /* 511 * Pass the remaining arguments to SystemServer. 512 * "--nice-name=system_server com.android.server.SystemServer" 513 */ 514 RuntimeInit.zygoteInit(parsedArgs.remainingArgs); 515 /* should never reach here */ 516 } 517 518 /** 519 * Prepare the arguments and fork for the system server process. 520 */ 521 private static boolean startSystemServer() 522 throws MethodAndArgsCaller, RuntimeException { 523 /* Hardcoded command line to start the system server */ 524 String args[] = { 525 "--setuid=1000", 526 "--setgid=1000", 527 "--setgroups=1001,1002,1003,1004,1005,1006,1007,1008,1009,1010,3001,3002,3003", 528 "--capabilities=121715744,121715744", 529 "--runtime-init", 530 "--nice-name=system_server", 531 "com.android.server.SystemServer", 532 }; 533 ZygoteConnection.Arguments parsedArgs = null; 534 535 int pid; 536 537 try { 538 parsedArgs = new ZygoteConnection.Arguments(args); 539 540 /* 541 * Enable debugging of the system process if *either* the command line flags 542 * indicate it should be debuggable or the ro.debuggable system property 543 * is set to "1" 544 */ 545 int debugFlags = parsedArgs.debugFlags; 546 if ("1".equals(SystemProperties.get("ro.debuggable"))) 547 debugFlags |= Zygote.DEBUG_ENABLE_DEBUGGER; 548 549 /* Request to fork the system server process */ 550 pid = Zygote.forkSystemServer( 551 parsedArgs.uid, parsedArgs.gid, 552 parsedArgs.gids, debugFlags, null); 553 } catch (IllegalArgumentException ex) { 554 throw new RuntimeException(ex); 555 } 556 557 /* For child process */ 558 if (pid == 0) { 559 handleSystemServerProcess(parsedArgs); 560 } 561 562 return true; 563 } 564 565 public static void main(String argv[]) { 566 try { 567 registerZygoteSocket(); 568 EventLog.writeEvent(LOG_BOOT_PROGRESS_PRELOAD_START, 569 SystemClock.uptimeMillis()); 570 preloadClasses(); 571 //cacheRegisterMaps(); 572 preloadResources(); 573 EventLog.writeEvent(LOG_BOOT_PROGRESS_PRELOAD_END, 574 SystemClock.uptimeMillis()); 575 576 // Do an initial gc to clean up after startup 577 gc(); 578 579 // If requested, start system server directly from Zygote 580 if (argv.length != 2) { 581 throw new RuntimeException( 582 "ZygoteInit.main expects two arguments"); 583 } 584 585 if (argv[1].equals("true")) { 586 startSystemServer(); 587 } 588 589 Log.i(TAG, "Accepting command socket connections"); 590 591 if (ZYGOTE_FORK_MODE) { 592 runForkMode(); 593 } else { 594 runSelectLoopMode(); 595 } 596 597 closeServerSocket(); 598 } catch (MethodAndArgsCaller caller) { 599 caller.run(); 600 } catch (RuntimeException ex) { 601 Log.e(TAG, "Zygote died with exception", ex); 602 closeServerSocket(); 603 throw ex; 604 } 605 } 606 607 /** 608 * Runs the zygote in accept-and-fork mode. In this mode, each peer 609 * gets its own zygote spawner process. This code is retained for 610 * reference only. 611 * 612 * @throws MethodAndArgsCaller in a child process when a main() should 613 * be executed. 614 */ 615 private static void runForkMode() throws MethodAndArgsCaller { 616 while (true) { 617 ZygoteConnection peer = acceptCommandPeer(); 618 619 int pid; 620 621 pid = Zygote.fork(); 622 623 if (pid == 0) { 624 // The child process should handle the peer requests 625 626 // The child does not accept any more connections 627 try { 628 sServerSocket.close(); 629 } catch (IOException ex) { 630 Log.e(TAG, "Zygote Child: error closing sockets", ex); 631 } finally { 632 sServerSocket = null; 633 } 634 635 peer.run(); 636 break; 637 } else if (pid > 0) { 638 peer.closeSocket(); 639 } else { 640 throw new RuntimeException("Error invoking fork()"); 641 } 642 } 643 } 644 645 /** 646 * Runs the zygote process's select loop. Accepts new connections as 647 * they happen, and reads commands from connections one spawn-request's 648 * worth at a time. 649 * 650 * @throws MethodAndArgsCaller in a child process when a main() should 651 * be executed. 652 */ 653 private static void runSelectLoopMode() throws MethodAndArgsCaller { 654 ArrayList<FileDescriptor> fds = new ArrayList(); 655 ArrayList<ZygoteConnection> peers = new ArrayList(); 656 FileDescriptor[] fdArray = new FileDescriptor[4]; 657 658 fds.add(sServerSocket.getFileDescriptor()); 659 peers.add(null); 660 661 int loopCount = GC_LOOP_COUNT; 662 while (true) { 663 int index; 664 665 /* 666 * Call gc() before we block in select(). 667 * It's work that has to be done anyway, and it's better 668 * to avoid making every child do it. It will also 669 * madvise() any free memory as a side-effect. 670 * 671 * Don't call it every time, because walking the entire 672 * heap is a lot of overhead to free a few hundred bytes. 673 */ 674 if (loopCount <= 0) { 675 gc(); 676 loopCount = GC_LOOP_COUNT; 677 } else { 678 loopCount--; 679 } 680 681 682 try { 683 fdArray = fds.toArray(fdArray); 684 index = selectReadable(fdArray); 685 } catch (IOException ex) { 686 throw new RuntimeException("Error in select()", ex); 687 } 688 689 if (index < 0) { 690 throw new RuntimeException("Error in select()"); 691 } else if (index == 0) { 692 ZygoteConnection newPeer = acceptCommandPeer(); 693 peers.add(newPeer); 694 fds.add(newPeer.getFileDesciptor()); 695 } else { 696 boolean done; 697 done = peers.get(index).runOnce(); 698 699 if (done) { 700 peers.remove(index); 701 fds.remove(index); 702 } 703 } 704 } 705 } 706 707 /** 708 * The Linux syscall "setreuid()" 709 * @param ruid real uid 710 * @param euid effective uid 711 * @return 0 on success, non-zero errno on fail 712 */ 713 static native int setreuid(int ruid, int euid); 714 715 /** 716 * The Linux syscall "setregid()" 717 * @param rgid real gid 718 * @param egid effective gid 719 * @return 0 on success, non-zero errno on fail 720 */ 721 static native int setregid(int rgid, int egid); 722 723 /** 724 * Invokes the linux syscall "setpgid" 725 * 726 * @param pid pid to change 727 * @param pgid new process group of pid 728 * @return 0 on success or non-zero errno on fail 729 */ 730 static native int setpgid(int pid, int pgid); 731 732 /** 733 * Invokes the linux syscall "getpgid" 734 * 735 * @param pid pid to query 736 * @return pgid of pid in question 737 * @throws IOException on error 738 */ 739 static native int getpgid(int pid) throws IOException; 740 741 /** 742 * Invokes the syscall dup2() to copy the specified descriptors into 743 * stdin, stdout, and stderr. The existing stdio descriptors will be 744 * closed and errors during close will be ignored. The specified 745 * descriptors will also remain open at their original descriptor numbers, 746 * so the caller may want to close the original descriptors. 747 * 748 * @param in new stdin 749 * @param out new stdout 750 * @param err new stderr 751 * @throws IOException 752 */ 753 static native void reopenStdio(FileDescriptor in, 754 FileDescriptor out, FileDescriptor err) throws IOException; 755 756 /** 757 * Calls close() on a file descriptor 758 * 759 * @param fd descriptor to close 760 * @throws IOException 761 */ 762 static native void closeDescriptor(FileDescriptor fd) 763 throws IOException; 764 765 /** 766 * Toggles the close-on-exec flag for the specified file descriptor. 767 * 768 * @param fd non-null; file descriptor 769 * @param flag desired close-on-exec flag state 770 * @throws IOException 771 */ 772 static native void setCloseOnExec(FileDescriptor fd, boolean flag) 773 throws IOException; 774 775 /** 776 * Retrieves the permitted capability set from another process. 777 * 778 * @param pid >=0 process ID or 0 for this process 779 * @throws IOException on error 780 */ 781 static native long capgetPermitted(int pid) 782 throws IOException; 783 784 /** 785 * Sets the permitted and effective capability sets of this process. 786 * 787 * @param permittedCapabilities permitted set 788 * @param effectiveCapabilities effective set 789 * @throws IOException on error 790 */ 791 static native void setCapabilities( 792 long permittedCapabilities, 793 long effectiveCapabilities) throws IOException; 794 795 /** 796 * Invokes select() on the provider array of file descriptors (selecting 797 * for readability only). Array elements of null are ignored. 798 * 799 * @param fds non-null; array of readable file descriptors 800 * @return index of descriptor that is now readable or -1 for empty array. 801 * @throws IOException if an error occurs 802 */ 803 static native int selectReadable(FileDescriptor[] fds) throws IOException; 804 805 /** 806 * Creates a file descriptor from an int fd. 807 * 808 * @param fd integer OS file descriptor 809 * @return non-null; FileDescriptor instance 810 * @throws IOException if fd is invalid 811 */ 812 static native FileDescriptor createFileDescriptor(int fd) 813 throws IOException; 814 815 /** 816 * Class not instantiable. 817 */ 818 private ZygoteInit() { 819 } 820 821 /** 822 * Helper exception class which holds a method and arguments and 823 * can call them. This is used as part of a trampoline to get rid of 824 * the initial process setup stack frames. 825 */ 826 public static class MethodAndArgsCaller extends Exception 827 implements Runnable { 828 /** method to call */ 829 private final Method mMethod; 830 831 /** argument array */ 832 private final String[] mArgs; 833 834 public MethodAndArgsCaller(Method method, String[] args) { 835 mMethod = method; 836 mArgs = args; 837 } 838 839 public void run() { 840 try { 841 mMethod.invoke(null, new Object[] { mArgs }); 842 } catch (IllegalAccessException ex) { 843 throw new RuntimeException(ex); 844 } catch (InvocationTargetException ex) { 845 Throwable cause = ex.getCause(); 846 if (cause instanceof RuntimeException) { 847 throw (RuntimeException) cause; 848 } else if (cause instanceof Error) { 849 throw (Error) cause; 850 } 851 throw new RuntimeException(ex); 852 } 853 } 854 } 855} 856