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 17 package com.android.internal.os; 18 19 import android.content.pm.ActivityInfo; 20 import android.content.res.Resources; 21 import android.content.res.TypedArray; 22 import android.graphics.drawable.Drawable; 23 import android.net.LocalServerSocket; 24 import android.os.Debug; 25 import android.os.SystemClock; 26 import android.os.SystemProperties; 27 import android.util.Config; 28 import android.util.EventLog; 29 import android.util.Log; 30 31 import dalvik.system.VMRuntime; 32 import dalvik.system.Zygote; 33 import dalvik.system.SamplingProfiler; 34 35 import java.io.BufferedReader; 36 import java.io.FileDescriptor; 37 import java.io.IOException; 38 import java.io.InputStream; 39 import java.io.InputStreamReader; 40 import java.lang.reflect.InvocationTargetException; 41 import java.lang.reflect.Method; 42 import java.lang.reflect.Modifier; 43 import 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 */ 57 public 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 public static final String USAGE_STRING = 70 " <\"true\"|\"false\" for startSystemServer>"; 71 72 private static LocalServerSocket sServerSocket; 73 74 /** 75 * Used to pre-load resources. We hold a global reference on it so it 76 * never gets destroyed. 77 */ 78 private static Resources mResources; 79 80 /** 81 * The number of times that the main Zygote loop 82 * should run before calling gc() again. 83 */ 84 static final int GC_LOOP_COUNT = 10; 85 86 /** 87 * If true, zygote forks for each peer. If false, a select loop is used 88 * inside a single process. The latter is preferred. 89 */ 90 private static final boolean ZYGOTE_FORK_MODE = false; 91 92 /** 93 * The name of a resource file that contains classes to preload. 94 */ 95 private static final String PRELOADED_CLASSES = "preloaded-classes"; 96 97 /** Controls whether we should preload resources during zygote init. */ 98 private static final boolean PRELOAD_RESOURCES = true; 99 100 /** 101 * List of methods we "warm up" in the register map cache. These were 102 * chosen because they appeared on the stack in GCs in multiple 103 * applications. 104 * 105 * This is in a VM-ready format, to minimize string processing. If a 106 * class is not already loaded, or a method is not found, the entry 107 * will be skipped. 108 * 109 * This doesn't really merit a separately-generated input file at this 110 * time. The list is fairly short, and the consequences of failure 111 * are minor. 112 */ 113 private static final String[] REGISTER_MAP_METHODS = { 114 // (currently not doing any) 115 //"Landroid/app/Activity;.setContentView:(I)V", 116 }; 117 118 119 /** 120 * Invokes a static "main(argv[]) method on class "className". 121 * Converts various failing exceptions into RuntimeExceptions, with 122 * the assumption that they will then cause the VM instance to exit. 123 * 124 * @param loader class loader to use 125 * @param className Fully-qualified class name 126 * @param argv Argument vector for main() 127 */ 128 static void invokeStaticMain(ClassLoader loader, 129 String className, String[] argv) 130 throws ZygoteInit.MethodAndArgsCaller { 131 Class<?> cl; 132 133 try { 134 cl = loader.loadClass(className); 135 } catch (ClassNotFoundException ex) { 136 throw new RuntimeException( 137 "Missing class when invoking static main " + className, 138 ex); 139 } 140 141 Method m; 142 try { 143 m = cl.getMethod("main", new Class[] { String[].class }); 144 } catch (NoSuchMethodException ex) { 145 throw new RuntimeException( 146 "Missing static main on " + className, ex); 147 } catch (SecurityException ex) { 148 throw new RuntimeException( 149 "Problem getting static main on " + className, ex); 150 } 151 152 int modifiers = m.getModifiers(); 153 if (! (Modifier.isStatic(modifiers) && Modifier.isPublic(modifiers))) { 154 throw new RuntimeException( 155 "Main method is not public and static on " + className); 156 } 157 158 /* 159 * This throw gets caught in ZygoteInit.main(), which responds 160 * by invoking the exception's run() method. This arrangement 161 * clears up all the stack frames that were required in setting 162 * up the process. 163 */ 164 throw new ZygoteInit.MethodAndArgsCaller(m, argv); 165 } 166 167 /** 168 * Registers a server socket for zygote command connections 169 * 170 * @throws RuntimeException when open fails 171 */ 172 private static void registerZygoteSocket() { 173 if (sServerSocket == null) { 174 int fileDesc; 175 try { 176 String env = System.getenv(ANDROID_SOCKET_ENV); 177 fileDesc = Integer.parseInt(env); 178 } catch (RuntimeException ex) { 179 throw new RuntimeException( 180 ANDROID_SOCKET_ENV + " unset or invalid", ex); 181 } 182 183 try { 184 sServerSocket = new LocalServerSocket( 185 createFileDescriptor(fileDesc)); 186 } catch (IOException ex) { 187 throw new RuntimeException( 188 "Error binding to local socket '" + fileDesc + "'", ex); 189 } 190 } 191 } 192 193 /** 194 * Waits for and accepts a single command connection. Throws 195 * RuntimeException on failure. 196 */ 197 private static ZygoteConnection acceptCommandPeer() { 198 try { 199 return new ZygoteConnection(sServerSocket.accept()); 200 } catch (IOException ex) { 201 throw new RuntimeException( 202 "IOException during accept()", ex); 203 } 204 } 205 206 /** 207 * Close and clean up zygote sockets. Called on shutdown and on the 208 * child's exit path. 209 */ 210 static void closeServerSocket() { 211 try { 212 if (sServerSocket != null) { 213 sServerSocket.close(); 214 } 215 } catch (IOException ex) { 216 Log.e(TAG, "Zygote: error closing sockets", ex); 217 } 218 219 sServerSocket = null; 220 } 221 222 private static final int UNPRIVILEGED_UID = 9999; 223 private static final int UNPRIVILEGED_GID = 9999; 224 225 private static final int ROOT_UID = 0; 226 private static final int ROOT_GID = 0; 227 228 /** 229 * Sets effective user ID. 230 */ 231 private static void setEffectiveUser(int uid) { 232 int errno = setreuid(ROOT_UID, uid); 233 if (errno != 0) { 234 Log.e(TAG, "setreuid() failed. errno: " + errno); 235 } 236 } 237 238 /** 239 * Sets effective group ID. 240 */ 241 private static void setEffectiveGroup(int gid) { 242 int errno = setregid(ROOT_GID, gid); 243 if (errno != 0) { 244 Log.e(TAG, "setregid() failed. errno: " + errno); 245 } 246 } 247 248 /** 249 * Performs Zygote process initialization. Loads and initializes 250 * commonly used classes. 251 * 252 * Most classes only cause a few hundred bytes to be allocated, but 253 * a few will allocate a dozen Kbytes (in one case, 500+K). 254 */ 255 private static void preloadClasses() { 256 final VMRuntime runtime = VMRuntime.getRuntime(); 257 258 InputStream is = ZygoteInit.class.getClassLoader().getResourceAsStream( 259 PRELOADED_CLASSES); 260 if (is == null) { 261 Log.e(TAG, "Couldn't find " + PRELOADED_CLASSES + "."); 262 } else { 263 Log.i(TAG, "Preloading classes..."); 264 long startTime = SystemClock.uptimeMillis(); 265 266 // Drop root perms while running static initializers. 267 setEffectiveGroup(UNPRIVILEGED_GID); 268 setEffectiveUser(UNPRIVILEGED_UID); 269 270 // Alter the target heap utilization. With explicit GCs this 271 // is not likely to have any effect. 272 float defaultUtilization = runtime.getTargetHeapUtilization(); 273 runtime.setTargetHeapUtilization(0.8f); 274 275 // Start with a clean slate. 276 runtime.gcSoftReferences(); 277 runtime.runFinalizationSync(); 278 Debug.startAllocCounting(); 279 280 try { 281 BufferedReader br 282 = new BufferedReader(new InputStreamReader(is), 256); 283 284 int count = 0; 285 String line; 286 while ((line = br.readLine()) != null) { 287 // Skip comments and blank lines. 288 line = line.trim(); 289 if (line.startsWith("#") || line.equals("")) { 290 continue; 291 } 292 293 try { 294 if (Config.LOGV) { 295 Log.v(TAG, "Preloading " + line + "..."); 296 } 297 Class.forName(line); 298 if (Debug.getGlobalAllocSize() > PRELOAD_GC_THRESHOLD) { 299 if (Config.LOGV) { 300 Log.v(TAG, 301 " GC at " + Debug.getGlobalAllocSize()); 302 } 303 runtime.gcSoftReferences(); 304 runtime.runFinalizationSync(); 305 Debug.resetGlobalAllocSize(); 306 } 307 count++; 308 } catch (ClassNotFoundException e) { 309 Log.w(TAG, "Class not found for preloading: " + line); 310 } catch (Throwable t) { 311 Log.e(TAG, "Error preloading " + line + ".", t); 312 if (t instanceof Error) { 313 throw (Error) t; 314 } 315 if (t instanceof RuntimeException) { 316 throw (RuntimeException) t; 317 } 318 throw new RuntimeException(t); 319 } 320 } 321 322 Log.i(TAG, "...preloaded " + count + " classes in " 323 + (SystemClock.uptimeMillis()-startTime) + "ms."); 324 } catch (IOException e) { 325 Log.e(TAG, "Error reading " + PRELOADED_CLASSES + ".", e); 326 } finally { 327 // Restore default. 328 runtime.setTargetHeapUtilization(defaultUtilization); 329 330 Debug.stopAllocCounting(); 331 332 // Bring back root. We'll need it later. 333 setEffectiveUser(ROOT_UID); 334 setEffectiveGroup(ROOT_GID); 335 } 336 } 337 } 338 339 /** 340 * Pre-caches register maps for methods that are commonly used. 341 */ 342 private static void cacheRegisterMaps() { 343 String failed = null; 344 int failure; 345 long startTime = System.nanoTime(); 346 347 failure = 0; 348 349 for (int i = 0; i < REGISTER_MAP_METHODS.length; i++) { 350 String str = REGISTER_MAP_METHODS[i]; 351 352 if (!Debug.cacheRegisterMap(str)) { 353 if (failed == null) 354 failed = str; 355 failure++; 356 } 357 } 358 359 long delta = System.nanoTime() - startTime; 360 361 if (failure == REGISTER_MAP_METHODS.length) { 362 if (REGISTER_MAP_METHODS.length > 0) { 363 Log.i(TAG, 364 "Register map caching failed (precise GC not enabled?)"); 365 } 366 return; 367 } 368 369 Log.i(TAG, "Register map cache: found " + 370 (REGISTER_MAP_METHODS.length - failure) + " of " + 371 REGISTER_MAP_METHODS.length + " methods in " + 372 (delta / 1000000L) + "ms"); 373 if (failure > 0) { 374 Log.i(TAG, " First failure: " + failed); 375 } 376 } 377 378 /** 379 * Load in commonly used resources, so they can be shared across 380 * processes. 381 * 382 * These tend to be a few Kbytes, but are frequently in the 20-40K 383 * range, and occasionally even larger. 384 */ 385 private static void preloadResources() { 386 final VMRuntime runtime = VMRuntime.getRuntime(); 387 388 Debug.startAllocCounting(); 389 try { 390 runtime.gcSoftReferences(); 391 runtime.runFinalizationSync(); 392 mResources = Resources.getSystem(); 393 mResources.startPreloading(); 394 if (PRELOAD_RESOURCES) { 395 Log.i(TAG, "Preloading resources..."); 396 397 long startTime = SystemClock.uptimeMillis(); 398 TypedArray ar = mResources.obtainTypedArray( 399 com.android.internal.R.array.preloaded_drawables); 400 int N = preloadDrawables(runtime, ar); 401 Log.i(TAG, "...preloaded " + N + " resources in " 402 + (SystemClock.uptimeMillis()-startTime) + "ms."); 403 404 startTime = SystemClock.uptimeMillis(); 405 ar = mResources.obtainTypedArray( 406 com.android.internal.R.array.preloaded_color_state_lists); 407 N = preloadColorStateLists(runtime, ar); 408 Log.i(TAG, "...preloaded " + N + " resources in " 409 + (SystemClock.uptimeMillis()-startTime) + "ms."); 410 } 411 mResources.finishPreloading(); 412 } catch (RuntimeException e) { 413 Log.w(TAG, "Failure preloading resources", e); 414 } finally { 415 Debug.stopAllocCounting(); 416 } 417 } 418 419 private static int preloadColorStateLists(VMRuntime runtime, TypedArray ar) { 420 int N = ar.length(); 421 for (int i=0; i<N; i++) { 422 if (Debug.getGlobalAllocSize() > PRELOAD_GC_THRESHOLD) { 423 if (Config.LOGV) { 424 Log.v(TAG, " GC at " + Debug.getGlobalAllocSize()); 425 } 426 runtime.gcSoftReferences(); 427 runtime.runFinalizationSync(); 428 Debug.resetGlobalAllocSize(); 429 } 430 int id = ar.getResourceId(i, 0); 431 if (Config.LOGV) { 432 Log.v(TAG, "Preloading resource #" + Integer.toHexString(id)); 433 } 434 if (id != 0) { 435 mResources.getColorStateList(id); 436 } 437 } 438 return N; 439 } 440 441 442 private static int preloadDrawables(VMRuntime runtime, TypedArray ar) { 443 int N = ar.length(); 444 for (int i=0; i<N; i++) { 445 if (Debug.getGlobalAllocSize() > PRELOAD_GC_THRESHOLD) { 446 if (Config.LOGV) { 447 Log.v(TAG, " GC at " + Debug.getGlobalAllocSize()); 448 } 449 runtime.gcSoftReferences(); 450 runtime.runFinalizationSync(); 451 Debug.resetGlobalAllocSize(); 452 } 453 int id = ar.getResourceId(i, 0); 454 if (Config.LOGV) { 455 Log.v(TAG, "Preloading resource #" + Integer.toHexString(id)); 456 } 457 if (id != 0) { 458 Drawable dr = mResources.getDrawable(id); 459 if ((dr.getChangingConfigurations()&~ActivityInfo.CONFIG_FONT_SCALE) != 0) { 460 Log.w(TAG, "Preloaded drawable resource #0x" 461 + Integer.toHexString(id) 462 + " (" + ar.getString(i) + ") that varies with configuration!!"); 463 } 464 } 465 } 466 return N; 467 } 468 469 /** 470 * Runs several special GCs to try to clean up a few generations of 471 * softly- and final-reachable objects, along with any other garbage. 472 * This is only useful just before a fork(). 473 */ 474 /*package*/ static void gc() { 475 final VMRuntime runtime = VMRuntime.getRuntime(); 476 477 /* runFinalizationSync() lets finalizers be called in Zygote, 478 * which doesn't have a HeapWorker thread. 479 */ 480 runtime.gcSoftReferences(); 481 runtime.runFinalizationSync(); 482 runtime.gcSoftReferences(); 483 runtime.runFinalizationSync(); 484 runtime.gcSoftReferences(); 485 runtime.runFinalizationSync(); 486 } 487 488 /** 489 * Finish remaining work for the newly forked system server process. 490 */ 491 private static void handleSystemServerProcess( 492 ZygoteConnection.Arguments parsedArgs) 493 throws ZygoteInit.MethodAndArgsCaller { 494 495 closeServerSocket(); 496 497 /* 498 * Pass the remaining arguments to SystemServer. 499 * "--nice-name=system_server com.android.server.SystemServer" 500 */ 501 RuntimeInit.zygoteInit(parsedArgs.remainingArgs); 502 /* should never reach here */ 503 } 504 505 /** 506 * Prepare the arguments and fork for the system server process. 507 */ 508 private static boolean startSystemServer() 509 throws MethodAndArgsCaller, RuntimeException { 510 /* Hardcoded command line to start the system server */ 511 String args[] = { 512 "--setuid=1000", 513 "--setgid=1000", 514 "--setgroups=1001,1002,1003,1004,1005,1006,1007,1008,1009,1010,3001,3002,3003", 515 "--capabilities=130104352,130104352", 516 "--runtime-init", 517 "--nice-name=system_server", 518 "com.android.server.SystemServer", 519 }; 520 ZygoteConnection.Arguments parsedArgs = null; 521 522 int pid; 523 524 try { 525 parsedArgs = new ZygoteConnection.Arguments(args); 526 527 /* 528 * Enable debugging of the system process if *either* the command line flags 529 * indicate it should be debuggable or the ro.debuggable system property 530 * is set to "1" 531 */ 532 int debugFlags = parsedArgs.debugFlags; 533 if ("1".equals(SystemProperties.get("ro.debuggable"))) 534 debugFlags |= Zygote.DEBUG_ENABLE_DEBUGGER; 535 536 /* Request to fork the system server process */ 537 pid = Zygote.forkSystemServer( 538 parsedArgs.uid, parsedArgs.gid, 539 parsedArgs.gids, debugFlags, null, 540 parsedArgs.permittedCapabilities, 541 parsedArgs.effectiveCapabilities); 542 } catch (IllegalArgumentException ex) { 543 throw new RuntimeException(ex); 544 } 545 546 /* For child process */ 547 if (pid == 0) { 548 handleSystemServerProcess(parsedArgs); 549 } 550 551 return true; 552 } 553 554 public static void main(String argv[]) { 555 try { 556 VMRuntime.getRuntime().setMinimumHeapSize(5 * 1024 * 1024); 557 558 // Start profiling the zygote initialization. 559 SamplingProfilerIntegration.start(); 560 561 registerZygoteSocket(); 562 EventLog.writeEvent(LOG_BOOT_PROGRESS_PRELOAD_START, 563 SystemClock.uptimeMillis()); 564 preloadClasses(); 565 //cacheRegisterMaps(); 566 preloadResources(); 567 EventLog.writeEvent(LOG_BOOT_PROGRESS_PRELOAD_END, 568 SystemClock.uptimeMillis()); 569 570 // Finish profiling the zygote initialization. 571 SamplingProfilerIntegration.writeZygoteSnapshot(); 572 573 // Do an initial gc to clean up after startup 574 gc(); 575 576 // If requested, start system server directly from Zygote 577 if (argv.length != 2) { 578 throw new RuntimeException(argv[0] + USAGE_STRING); 579 } 580 581 if (argv[1].equals("true")) { 582 startSystemServer(); 583 } else if (!argv[1].equals("false")) { 584 throw new RuntimeException(argv[0] + USAGE_STRING); 585 } 586 587 Log.i(TAG, "Accepting command socket connections"); 588 589 if (ZYGOTE_FORK_MODE) { 590 runForkMode(); 591 } else { 592 runSelectLoopMode(); 593 } 594 595 closeServerSocket(); 596 } catch (MethodAndArgsCaller caller) { 597 caller.run(); 598 } catch (RuntimeException ex) { 599 Log.e(TAG, "Zygote died with exception", ex); 600 closeServerSocket(); 601 throw ex; 602 } 603 } 604 605 /** 606 * Runs the zygote in accept-and-fork mode. In this mode, each peer 607 * gets its own zygote spawner process. This code is retained for 608 * reference only. 609 * 610 * @throws MethodAndArgsCaller in a child process when a main() should 611 * be executed. 612 */ 613 private static void runForkMode() throws MethodAndArgsCaller { 614 while (true) { 615 ZygoteConnection peer = acceptCommandPeer(); 616 617 int pid; 618 619 pid = Zygote.fork(); 620 621 if (pid == 0) { 622 // The child process should handle the peer requests 623 624 // The child does not accept any more connections 625 try { 626 sServerSocket.close(); 627 } catch (IOException ex) { 628 Log.e(TAG, "Zygote Child: error closing sockets", ex); 629 } finally { 630 sServerSocket = null; 631 } 632 633 peer.run(); 634 break; 635 } else if (pid > 0) { 636 peer.closeSocket(); 637 } else { 638 throw new RuntimeException("Error invoking fork()"); 639 } 640 } 641 } 642 643 /** 644 * Runs the zygote process's select loop. Accepts new connections as 645 * they happen, and reads commands from connections one spawn-request's 646 * worth at a time. 647 * 648 * @throws MethodAndArgsCaller in a child process when a main() should 649 * be executed. 650 */ 651 private static void runSelectLoopMode() throws MethodAndArgsCaller { 652 ArrayList<FileDescriptor> fds = new ArrayList(); 653 ArrayList<ZygoteConnection> peers = new ArrayList(); 654 FileDescriptor[] fdArray = new FileDescriptor[4]; 655 656 fds.add(sServerSocket.getFileDescriptor()); 657 peers.add(null); 658 659 int loopCount = GC_LOOP_COUNT; 660 while (true) { 661 int index; 662 663 /* 664 * Call gc() before we block in select(). 665 * It's work that has to be done anyway, and it's better 666 * to avoid making every child do it. It will also 667 * madvise() any free memory as a side-effect. 668 * 669 * Don't call it every time, because walking the entire 670 * heap is a lot of overhead to free a few hundred bytes. 671 */ 672 if (loopCount <= 0) { 673 gc(); 674 loopCount = GC_LOOP_COUNT; 675 } else { 676 loopCount--; 677 } 678 679 680 try { 681 fdArray = fds.toArray(fdArray); 682 index = selectReadable(fdArray); 683 } catch (IOException ex) { 684 throw new RuntimeException("Error in select()", ex); 685 } 686 687 if (index < 0) { 688 throw new RuntimeException("Error in select()"); 689 } else if (index == 0) { 690 ZygoteConnection newPeer = acceptCommandPeer(); 691 peers.add(newPeer); 692 fds.add(newPeer.getFileDesciptor()); 693 } else { 694 boolean done; 695 done = peers.get(index).runOnce(); 696 697 if (done) { 698 peers.remove(index); 699 fds.remove(index); 700 } 701 } 702 } 703 } 704 705 /** 706 * The Linux syscall "setreuid()" 707 * @param ruid real uid 708 * @param euid effective uid 709 * @return 0 on success, non-zero errno on fail 710 */ 711 static native int setreuid(int ruid, int euid); 712 713 /** 714 * The Linux syscall "setregid()" 715 * @param rgid real gid 716 * @param egid effective gid 717 * @return 0 on success, non-zero errno on fail 718 */ 719 static native int setregid(int rgid, int egid); 720 721 /** 722 * Invokes the linux syscall "setpgid" 723 * 724 * @param pid pid to change 725 * @param pgid new process group of pid 726 * @return 0 on success or non-zero errno on fail 727 */ 728 static native int setpgid(int pid, int pgid); 729 730 /** 731 * Invokes the linux syscall "getpgid" 732 * 733 * @param pid pid to query 734 * @return pgid of pid in question 735 * @throws IOException on error 736 */ 737 static native int getpgid(int pid) throws IOException; 738 739 /** 740 * Invokes the syscall dup2() to copy the specified descriptors into 741 * stdin, stdout, and stderr. The existing stdio descriptors will be 742 * closed and errors during close will be ignored. The specified 743 * descriptors will also remain open at their original descriptor numbers, 744 * so the caller may want to close the original descriptors. 745 * 746 * @param in new stdin 747 * @param out new stdout 748 * @param err new stderr 749 * @throws IOException 750 */ 751 static native void reopenStdio(FileDescriptor in, 752 FileDescriptor out, FileDescriptor err) throws IOException; 753 754 /** 755 * Calls close() on a file descriptor 756 * 757 * @param fd descriptor to close 758 * @throws IOException 759 */ 760 static native void closeDescriptor(FileDescriptor fd) 761 throws IOException; 762 763 /** 764 * Toggles the close-on-exec flag for the specified file descriptor. 765 * 766 * @param fd non-null; file descriptor 767 * @param flag desired close-on-exec flag state 768 * @throws IOException 769 */ 770 static native void setCloseOnExec(FileDescriptor fd, boolean flag) 771 throws IOException; 772 773 /** 774 * Retrieves the permitted capability set from another process. 775 * 776 * @param pid >=0 process ID or 0 for this process 777 * @throws IOException on error 778 */ 779 static native long capgetPermitted(int pid) 780 throws IOException; 781 782 /** 783 * Sets the permitted and effective capability sets of this process. 784 * 785 * @param permittedCapabilities permitted set 786 * @param effectiveCapabilities effective set 787 * @throws IOException on error 788 */ 789 static native void setCapabilities( 790 long permittedCapabilities, 791 long effectiveCapabilities) throws IOException; 792 793 /** 794 * Invokes select() on the provider array of file descriptors (selecting 795 * for readability only). Array elements of null are ignored. 796 * 797 * @param fds non-null; array of readable file descriptors 798 * @return index of descriptor that is now readable or -1 for empty array. 799 * @throws IOException if an error occurs 800 */ 801 static native int selectReadable(FileDescriptor[] fds) throws IOException; 802 803 /** 804 * Creates a file descriptor from an int fd. 805 * 806 * @param fd integer OS file descriptor 807 * @return non-null; FileDescriptor instance 808 * @throws IOException if fd is invalid 809 */ 810 static native FileDescriptor createFileDescriptor(int fd) 811 throws IOException; 812 813 /** 814 * Class not instantiable. 815 */ 816 private ZygoteInit() { 817 } 818 819 /** 820 * Helper exception class which holds a method and arguments and 821 * can call them. This is used as part of a trampoline to get rid of 822 * the initial process setup stack frames. 823 */ 824 public static class MethodAndArgsCaller extends Exception 825 implements Runnable { 826 /** method to call */ 827 private final Method mMethod; 828 829 /** argument array */ 830 private final String[] mArgs; 831 832 public MethodAndArgsCaller(Method method, String[] args) { 833 mMethod = method; 834 mArgs = args; 835 } 836 837 public void run() { 838 try { 839 mMethod.invoke(null, new Object[] { mArgs }); 840 } catch (IllegalAccessException ex) { 841 throw new RuntimeException(ex); 842 } catch (InvocationTargetException ex) { 843 Throwable cause = ex.getCause(); 844 if (cause instanceof RuntimeException) { 845 throw (RuntimeException) cause; 846 } else if (cause instanceof Error) { 847 throw (Error) cause; 848 } 849 throw new RuntimeException(ex); 850 } 851 } 852 } 853 } 854