ZygoteInit.java revision 6c3baf12e0a6417177793a2e7e95d22721203813
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 static libcore.io.OsConstants.S_IRWXG; 20import static libcore.io.OsConstants.S_IRWXO; 21 22import android.content.res.Resources; 23import android.content.res.TypedArray; 24import android.net.LocalServerSocket; 25import android.opengl.EGL14; 26import android.os.Debug; 27import android.os.Process; 28import android.os.SystemClock; 29import android.os.SystemProperties; 30import android.os.Trace; 31import android.util.EventLog; 32import android.util.Log; 33 34import dalvik.system.VMRuntime; 35import dalvik.system.Zygote; 36 37import libcore.io.IoUtils; 38import libcore.io.Libcore; 39import libcore.io.OsConstants; 40 41import java.io.BufferedReader; 42import java.io.FileDescriptor; 43import java.io.IOException; 44import java.io.InputStream; 45import java.io.InputStreamReader; 46import java.lang.reflect.InvocationTargetException; 47import java.lang.reflect.Method; 48import java.lang.reflect.Modifier; 49import java.util.ArrayList; 50 51/** 52 * Startup class for the zygote process. 53 * 54 * Pre-initializes some classes, and then waits for commands on a UNIX domain 55 * socket. Based on these commands, forks off child processes that inherit 56 * the initial state of the VM. 57 * 58 * Please see {@link ZygoteConnection.Arguments} for documentation on the 59 * client protocol. 60 * 61 * @hide 62 */ 63public class ZygoteInit { 64 private static final String TAG = "Zygote"; 65 66 private static final String PROPERTY_DISABLE_OPENGL_PRELOADING = "ro.zygote.disable_gl_preload"; 67 68 private static final String ANDROID_SOCKET_ENV = "ANDROID_SOCKET_zygote"; 69 70 private static final int LOG_BOOT_PROGRESS_PRELOAD_START = 3020; 71 private static final int LOG_BOOT_PROGRESS_PRELOAD_END = 3030; 72 73 /** when preloading, GC after allocating this many bytes */ 74 private static final int PRELOAD_GC_THRESHOLD = 50000; 75 76 public static final String USAGE_STRING = 77 " <\"start-system-server\"|\"\" for startSystemServer>"; 78 79 private static LocalServerSocket sServerSocket; 80 81 /** 82 * Used to pre-load resources. We hold a global reference on it so it 83 * never gets destroyed. 84 */ 85 private static Resources mResources; 86 87 /** 88 * The number of times that the main Zygote loop 89 * should run before calling gc() again. 90 */ 91 static final int GC_LOOP_COUNT = 10; 92 93 /** 94 * The name of a resource file that contains classes to preload. 95 */ 96 private static final String PRELOADED_CLASSES = "preloaded-classes"; 97 98 /** Controls whether we should preload resources during zygote init. */ 99 private static final boolean PRELOAD_RESOURCES = true; 100 101 /** 102 * Invokes a static "main(argv[]) method on class "className". 103 * Converts various failing exceptions into RuntimeExceptions, with 104 * the assumption that they will then cause the VM instance to exit. 105 * 106 * @param loader class loader to use 107 * @param className Fully-qualified class name 108 * @param argv Argument vector for main() 109 */ 110 static void invokeStaticMain(ClassLoader loader, 111 String className, String[] argv) 112 throws ZygoteInit.MethodAndArgsCaller { 113 Class<?> cl; 114 115 try { 116 cl = loader.loadClass(className); 117 } catch (ClassNotFoundException ex) { 118 throw new RuntimeException( 119 "Missing class when invoking static main " + className, 120 ex); 121 } 122 123 Method m; 124 try { 125 m = cl.getMethod("main", new Class[] { String[].class }); 126 } catch (NoSuchMethodException ex) { 127 throw new RuntimeException( 128 "Missing static main on " + className, ex); 129 } catch (SecurityException ex) { 130 throw new RuntimeException( 131 "Problem getting static main on " + className, ex); 132 } 133 134 int modifiers = m.getModifiers(); 135 if (! (Modifier.isStatic(modifiers) && Modifier.isPublic(modifiers))) { 136 throw new RuntimeException( 137 "Main method is not public and static on " + className); 138 } 139 140 /* 141 * This throw gets caught in ZygoteInit.main(), which responds 142 * by invoking the exception's run() method. This arrangement 143 * clears up all the stack frames that were required in setting 144 * up the process. 145 */ 146 throw new ZygoteInit.MethodAndArgsCaller(m, argv); 147 } 148 149 /** 150 * Registers a server socket for zygote command connections 151 * 152 * @throws RuntimeException when open fails 153 */ 154 private static void registerZygoteSocket() { 155 if (sServerSocket == null) { 156 int fileDesc; 157 try { 158 String env = System.getenv(ANDROID_SOCKET_ENV); 159 fileDesc = Integer.parseInt(env); 160 } catch (RuntimeException ex) { 161 throw new RuntimeException( 162 ANDROID_SOCKET_ENV + " unset or invalid", ex); 163 } 164 165 try { 166 sServerSocket = new LocalServerSocket( 167 createFileDescriptor(fileDesc)); 168 } catch (IOException ex) { 169 throw new RuntimeException( 170 "Error binding to local socket '" + fileDesc + "'", ex); 171 } 172 } 173 } 174 175 /** 176 * Waits for and accepts a single command connection. Throws 177 * RuntimeException on failure. 178 */ 179 private static ZygoteConnection acceptCommandPeer() { 180 try { 181 return new ZygoteConnection(sServerSocket.accept()); 182 } catch (IOException ex) { 183 throw new RuntimeException( 184 "IOException during accept()", ex); 185 } 186 } 187 188 /** 189 * Close and clean up zygote sockets. Called on shutdown and on the 190 * child's exit path. 191 */ 192 static void closeServerSocket() { 193 try { 194 if (sServerSocket != null) { 195 sServerSocket.close(); 196 } 197 } catch (IOException ex) { 198 Log.e(TAG, "Zygote: error closing sockets", ex); 199 } 200 201 sServerSocket = null; 202 } 203 204 private static final int UNPRIVILEGED_UID = 9999; 205 private static final int UNPRIVILEGED_GID = 9999; 206 207 private static final int ROOT_UID = 0; 208 private static final int ROOT_GID = 0; 209 210 /** 211 * Sets effective user ID. 212 */ 213 private static void setEffectiveUser(int uid) { 214 int errno = setreuid(ROOT_UID, uid); 215 if (errno != 0) { 216 Log.e(TAG, "setreuid() failed. errno: " + errno); 217 } 218 } 219 220 /** 221 * Sets effective group ID. 222 */ 223 private static void setEffectiveGroup(int gid) { 224 int errno = setregid(ROOT_GID, gid); 225 if (errno != 0) { 226 Log.e(TAG, "setregid() failed. errno: " + errno); 227 } 228 } 229 230 static void preload() { 231 preloadClasses(); 232 preloadResources(); 233 preloadOpenGL(); 234 } 235 236 private static void preloadOpenGL() { 237 if (!SystemProperties.getBoolean(PROPERTY_DISABLE_OPENGL_PRELOADING, false)) { 238 EGL14.eglGetDisplay(EGL14.EGL_DEFAULT_DISPLAY); 239 } 240 } 241 242 /** 243 * Performs Zygote process initialization. Loads and initializes 244 * commonly used classes. 245 * 246 * Most classes only cause a few hundred bytes to be allocated, but 247 * a few will allocate a dozen Kbytes (in one case, 500+K). 248 */ 249 private static void preloadClasses() { 250 final VMRuntime runtime = VMRuntime.getRuntime(); 251 252 InputStream is = ClassLoader.getSystemClassLoader().getResourceAsStream( 253 PRELOADED_CLASSES); 254 if (is == null) { 255 Log.e(TAG, "Couldn't find " + PRELOADED_CLASSES + "."); 256 } else { 257 Log.i(TAG, "Preloading classes..."); 258 long startTime = SystemClock.uptimeMillis(); 259 260 // Drop root perms while running static initializers. 261 setEffectiveGroup(UNPRIVILEGED_GID); 262 setEffectiveUser(UNPRIVILEGED_UID); 263 264 // Alter the target heap utilization. With explicit GCs this 265 // is not likely to have any effect. 266 float defaultUtilization = runtime.getTargetHeapUtilization(); 267 runtime.setTargetHeapUtilization(0.8f); 268 269 // Start with a clean slate. 270 System.gc(); 271 runtime.runFinalizationSync(); 272 Debug.startAllocCounting(); 273 274 try { 275 BufferedReader br 276 = new BufferedReader(new InputStreamReader(is), 256); 277 278 int count = 0; 279 String line; 280 while ((line = br.readLine()) != null) { 281 // Skip comments and blank lines. 282 line = line.trim(); 283 if (line.startsWith("#") || line.equals("")) { 284 continue; 285 } 286 287 try { 288 if (false) { 289 Log.v(TAG, "Preloading " + line + "..."); 290 } 291 Class.forName(line); 292 if (Debug.getGlobalAllocSize() > PRELOAD_GC_THRESHOLD) { 293 if (false) { 294 Log.v(TAG, 295 " GC at " + Debug.getGlobalAllocSize()); 296 } 297 System.gc(); 298 runtime.runFinalizationSync(); 299 Debug.resetGlobalAllocSize(); 300 } 301 count++; 302 } catch (ClassNotFoundException e) { 303 Log.w(TAG, "Class not found for preloading: " + line); 304 } catch (Throwable t) { 305 Log.e(TAG, "Error preloading " + line + ".", t); 306 if (t instanceof Error) { 307 throw (Error) t; 308 } 309 if (t instanceof RuntimeException) { 310 throw (RuntimeException) t; 311 } 312 throw new RuntimeException(t); 313 } 314 } 315 316 Log.i(TAG, "...preloaded " + count + " classes in " 317 + (SystemClock.uptimeMillis()-startTime) + "ms."); 318 } catch (IOException e) { 319 Log.e(TAG, "Error reading " + PRELOADED_CLASSES + ".", e); 320 } finally { 321 IoUtils.closeQuietly(is); 322 // Restore default. 323 runtime.setTargetHeapUtilization(defaultUtilization); 324 325 // Fill in dex caches with classes, fields, and methods brought in by preloading. 326 runtime.preloadDexCaches(); 327 328 Debug.stopAllocCounting(); 329 330 // Bring back root. We'll need it later. 331 setEffectiveUser(ROOT_UID); 332 setEffectiveGroup(ROOT_GID); 333 } 334 } 335 } 336 337 /** 338 * Load in commonly used resources, so they can be shared across 339 * processes. 340 * 341 * These tend to be a few Kbytes, but are frequently in the 20-40K 342 * range, and occasionally even larger. 343 */ 344 private static void preloadResources() { 345 final VMRuntime runtime = VMRuntime.getRuntime(); 346 347 Debug.startAllocCounting(); 348 try { 349 System.gc(); 350 runtime.runFinalizationSync(); 351 mResources = Resources.getSystem(); 352 mResources.startPreloading(); 353 if (PRELOAD_RESOURCES) { 354 Log.i(TAG, "Preloading resources..."); 355 356 long startTime = SystemClock.uptimeMillis(); 357 TypedArray ar = mResources.obtainTypedArray( 358 com.android.internal.R.array.preloaded_drawables); 359 int N = preloadDrawables(runtime, ar); 360 ar.recycle(); 361 Log.i(TAG, "...preloaded " + N + " resources in " 362 + (SystemClock.uptimeMillis()-startTime) + "ms."); 363 364 startTime = SystemClock.uptimeMillis(); 365 ar = mResources.obtainTypedArray( 366 com.android.internal.R.array.preloaded_color_state_lists); 367 N = preloadColorStateLists(runtime, ar); 368 ar.recycle(); 369 Log.i(TAG, "...preloaded " + N + " resources in " 370 + (SystemClock.uptimeMillis()-startTime) + "ms."); 371 } 372 mResources.finishPreloading(); 373 } catch (RuntimeException e) { 374 Log.w(TAG, "Failure preloading resources", e); 375 } finally { 376 Debug.stopAllocCounting(); 377 } 378 } 379 380 private static int preloadColorStateLists(VMRuntime runtime, TypedArray ar) { 381 int N = ar.length(); 382 for (int i=0; i<N; i++) { 383 if (Debug.getGlobalAllocSize() > PRELOAD_GC_THRESHOLD) { 384 if (false) { 385 Log.v(TAG, " GC at " + Debug.getGlobalAllocSize()); 386 } 387 System.gc(); 388 runtime.runFinalizationSync(); 389 Debug.resetGlobalAllocSize(); 390 } 391 int id = ar.getResourceId(i, 0); 392 if (false) { 393 Log.v(TAG, "Preloading resource #" + Integer.toHexString(id)); 394 } 395 if (id != 0) { 396 if (mResources.getColorStateList(id) == null) { 397 throw new IllegalArgumentException( 398 "Unable to find preloaded color resource #0x" 399 + Integer.toHexString(id) 400 + " (" + ar.getString(i) + ")"); 401 } 402 } 403 } 404 return N; 405 } 406 407 408 private static int preloadDrawables(VMRuntime runtime, TypedArray ar) { 409 int N = ar.length(); 410 for (int i=0; i<N; i++) { 411 if (Debug.getGlobalAllocSize() > PRELOAD_GC_THRESHOLD) { 412 if (false) { 413 Log.v(TAG, " GC at " + Debug.getGlobalAllocSize()); 414 } 415 System.gc(); 416 runtime.runFinalizationSync(); 417 Debug.resetGlobalAllocSize(); 418 } 419 int id = ar.getResourceId(i, 0); 420 if (false) { 421 Log.v(TAG, "Preloading resource #" + Integer.toHexString(id)); 422 } 423 if (id != 0) { 424 if (mResources.getDrawable(id) == null) { 425 throw new IllegalArgumentException( 426 "Unable to find preloaded drawable resource #0x" 427 + Integer.toHexString(id) 428 + " (" + ar.getString(i) + ")"); 429 } 430 } 431 } 432 return N; 433 } 434 435 /** 436 * Runs several special GCs to try to clean up a few generations of 437 * softly- and final-reachable objects, along with any other garbage. 438 * This is only useful just before a fork(). 439 */ 440 /*package*/ static void gc() { 441 final VMRuntime runtime = VMRuntime.getRuntime(); 442 443 /* runFinalizationSync() lets finalizers be called in Zygote, 444 * which doesn't have a HeapWorker thread. 445 */ 446 System.gc(); 447 runtime.runFinalizationSync(); 448 System.gc(); 449 runtime.runFinalizationSync(); 450 System.gc(); 451 runtime.runFinalizationSync(); 452 } 453 454 /** 455 * Finish remaining work for the newly forked system server process. 456 */ 457 private static void handleSystemServerProcess( 458 ZygoteConnection.Arguments parsedArgs) 459 throws ZygoteInit.MethodAndArgsCaller { 460 461 closeServerSocket(); 462 463 // set umask to 0077 so new files and directories will default to owner-only permissions. 464 Libcore.os.umask(S_IRWXG | S_IRWXO); 465 466 if (parsedArgs.niceName != null) { 467 Process.setArgV0(parsedArgs.niceName); 468 } 469 470 if (parsedArgs.invokeWith != null) { 471 WrapperInit.execApplication(parsedArgs.invokeWith, 472 parsedArgs.niceName, parsedArgs.targetSdkVersion, 473 null, parsedArgs.remainingArgs); 474 } else { 475 /* 476 * Pass the remaining arguments to SystemServer. 477 */ 478 RuntimeInit.zygoteInit(parsedArgs.targetSdkVersion, parsedArgs.remainingArgs); 479 } 480 481 /* should never reach here */ 482 } 483 484 /** 485 * Prepare the arguments and fork for the system server process. 486 */ 487 private static boolean startSystemServer() 488 throws MethodAndArgsCaller, RuntimeException { 489 long capabilities = posixCapabilitiesAsBits( 490 OsConstants.CAP_KILL, 491 OsConstants.CAP_NET_ADMIN, 492 OsConstants.CAP_NET_BIND_SERVICE, 493 OsConstants.CAP_NET_BROADCAST, 494 OsConstants.CAP_NET_RAW, 495 OsConstants.CAP_SYS_MODULE, 496 OsConstants.CAP_SYS_NICE, 497 OsConstants.CAP_SYS_RESOURCE, 498 OsConstants.CAP_SYS_TIME, 499 OsConstants.CAP_SYS_TTY_CONFIG 500 ); 501 /* Hardcoded command line to start the system server */ 502 String args[] = { 503 "--setuid=1000", 504 "--setgid=1000", 505 "--setgroups=1001,1002,1003,1004,1005,1006,1007,1008,1009,1010,1018,1032,3001,3002,3003,3006,3007", 506 "--capabilities=" + capabilities + "," + capabilities, 507 "--runtime-init", 508 "--nice-name=system_server", 509 "com.android.server.SystemServer", 510 }; 511 ZygoteConnection.Arguments parsedArgs = null; 512 513 int pid; 514 515 try { 516 parsedArgs = new ZygoteConnection.Arguments(args); 517 ZygoteConnection.applyDebuggerSystemProperty(parsedArgs); 518 ZygoteConnection.applyInvokeWithSystemProperty(parsedArgs); 519 520 /* Request to fork the system server process */ 521 pid = Zygote.forkSystemServer( 522 parsedArgs.uid, parsedArgs.gid, 523 parsedArgs.gids, 524 parsedArgs.debugFlags, 525 null, 526 parsedArgs.permittedCapabilities, 527 parsedArgs.effectiveCapabilities); 528 } catch (IllegalArgumentException ex) { 529 throw new RuntimeException(ex); 530 } 531 532 /* For child process */ 533 if (pid == 0) { 534 handleSystemServerProcess(parsedArgs); 535 } 536 537 return true; 538 } 539 540 /** 541 * Gets the bit array representation of the provided list of POSIX capabilities. 542 */ 543 private static long posixCapabilitiesAsBits(int... capabilities) { 544 long result = 0; 545 for (int capability : capabilities) { 546 if ((capability < 0) || (capability > OsConstants.CAP_LAST_CAP)) { 547 throw new IllegalArgumentException(String.valueOf(capability)); 548 } 549 result |= (1L << capability); 550 } 551 return result; 552 } 553 554 public static void main(String argv[]) { 555 try { 556 // Start profiling the zygote initialization. 557 SamplingProfilerIntegration.start(); 558 559 registerZygoteSocket(); 560 EventLog.writeEvent(LOG_BOOT_PROGRESS_PRELOAD_START, 561 SystemClock.uptimeMillis()); 562 preload(); 563 EventLog.writeEvent(LOG_BOOT_PROGRESS_PRELOAD_END, 564 SystemClock.uptimeMillis()); 565 566 // Finish profiling the zygote initialization. 567 SamplingProfilerIntegration.writeZygoteSnapshot(); 568 569 // Do an initial gc to clean up after startup 570 gc(); 571 572 // Disable tracing so that forked processes do not inherit stale tracing tags from 573 // Zygote. 574 Trace.setTracingEnabled(false); 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("start-system-server")) { 582 startSystemServer(); 583 } else if (!argv[1].equals("")) { 584 throw new RuntimeException(argv[0] + USAGE_STRING); 585 } 586 587 Log.i(TAG, "Accepting command socket connections"); 588 589 runSelectLoop(); 590 591 closeServerSocket(); 592 } catch (MethodAndArgsCaller caller) { 593 caller.run(); 594 } catch (RuntimeException ex) { 595 Log.e(TAG, "Zygote died with exception", ex); 596 closeServerSocket(); 597 throw ex; 598 } 599 } 600 601 /** 602 * Runs the zygote process's select loop. Accepts new connections as 603 * they happen, and reads commands from connections one spawn-request's 604 * worth at a time. 605 * 606 * @throws MethodAndArgsCaller in a child process when a main() should 607 * be executed. 608 */ 609 private static void runSelectLoop() throws MethodAndArgsCaller { 610 ArrayList<FileDescriptor> fds = new ArrayList<FileDescriptor>(); 611 ArrayList<ZygoteConnection> peers = new ArrayList<ZygoteConnection>(); 612 FileDescriptor[] fdArray = new FileDescriptor[4]; 613 614 fds.add(sServerSocket.getFileDescriptor()); 615 peers.add(null); 616 617 int loopCount = GC_LOOP_COUNT; 618 while (true) { 619 int index; 620 621 /* 622 * Call gc() before we block in select(). 623 * It's work that has to be done anyway, and it's better 624 * to avoid making every child do it. It will also 625 * madvise() any free memory as a side-effect. 626 * 627 * Don't call it every time, because walking the entire 628 * heap is a lot of overhead to free a few hundred bytes. 629 */ 630 if (loopCount <= 0) { 631 gc(); 632 loopCount = GC_LOOP_COUNT; 633 } else { 634 loopCount--; 635 } 636 637 638 try { 639 fdArray = fds.toArray(fdArray); 640 index = selectReadable(fdArray); 641 } catch (IOException ex) { 642 throw new RuntimeException("Error in select()", ex); 643 } 644 645 if (index < 0) { 646 throw new RuntimeException("Error in select()"); 647 } else if (index == 0) { 648 ZygoteConnection newPeer = acceptCommandPeer(); 649 peers.add(newPeer); 650 fds.add(newPeer.getFileDesciptor()); 651 } else { 652 boolean done; 653 done = peers.get(index).runOnce(); 654 655 if (done) { 656 peers.remove(index); 657 fds.remove(index); 658 } 659 } 660 } 661 } 662 663 /** 664 * The Linux syscall "setreuid()" 665 * @param ruid real uid 666 * @param euid effective uid 667 * @return 0 on success, non-zero errno on fail 668 */ 669 static native int setreuid(int ruid, int euid); 670 671 /** 672 * The Linux syscall "setregid()" 673 * @param rgid real gid 674 * @param egid effective gid 675 * @return 0 on success, non-zero errno on fail 676 */ 677 static native int setregid(int rgid, int egid); 678 679 /** 680 * Invokes the linux syscall "setpgid" 681 * 682 * @param pid pid to change 683 * @param pgid new process group of pid 684 * @return 0 on success or non-zero errno on fail 685 */ 686 static native int setpgid(int pid, int pgid); 687 688 /** 689 * Invokes the linux syscall "getpgid" 690 * 691 * @param pid pid to query 692 * @return pgid of pid in question 693 * @throws IOException on error 694 */ 695 static native int getpgid(int pid) throws IOException; 696 697 /** 698 * Invokes the syscall dup2() to copy the specified descriptors into 699 * stdin, stdout, and stderr. The existing stdio descriptors will be 700 * closed and errors during close will be ignored. The specified 701 * descriptors will also remain open at their original descriptor numbers, 702 * so the caller may want to close the original descriptors. 703 * 704 * @param in new stdin 705 * @param out new stdout 706 * @param err new stderr 707 * @throws IOException 708 */ 709 static native void reopenStdio(FileDescriptor in, 710 FileDescriptor out, FileDescriptor err) throws IOException; 711 712 /** 713 * Toggles the close-on-exec flag for the specified file descriptor. 714 * 715 * @param fd non-null; file descriptor 716 * @param flag desired close-on-exec flag state 717 * @throws IOException 718 */ 719 static native void setCloseOnExec(FileDescriptor fd, boolean flag) 720 throws IOException; 721 722 /** 723 * Retrieves the permitted capability set from another process. 724 * 725 * @param pid >=0 process ID or 0 for this process 726 * @throws IOException on error 727 */ 728 static native long capgetPermitted(int pid) 729 throws IOException; 730 731 /** 732 * Invokes select() on the provider array of file descriptors (selecting 733 * for readability only). Array elements of null are ignored. 734 * 735 * @param fds non-null; array of readable file descriptors 736 * @return index of descriptor that is now readable or -1 for empty array. 737 * @throws IOException if an error occurs 738 */ 739 static native int selectReadable(FileDescriptor[] fds) throws IOException; 740 741 /** 742 * Creates a file descriptor from an int fd. 743 * 744 * @param fd integer OS file descriptor 745 * @return non-null; FileDescriptor instance 746 * @throws IOException if fd is invalid 747 */ 748 static native FileDescriptor createFileDescriptor(int fd) 749 throws IOException; 750 751 /** 752 * Class not instantiable. 753 */ 754 private ZygoteInit() { 755 } 756 757 /** 758 * Helper exception class which holds a method and arguments and 759 * can call them. This is used as part of a trampoline to get rid of 760 * the initial process setup stack frames. 761 */ 762 public static class MethodAndArgsCaller extends Exception 763 implements Runnable { 764 /** method to call */ 765 private final Method mMethod; 766 767 /** argument array */ 768 private final String[] mArgs; 769 770 public MethodAndArgsCaller(Method method, String[] args) { 771 mMethod = method; 772 mArgs = args; 773 } 774 775 public void run() { 776 try { 777 mMethod.invoke(null, new Object[] { mArgs }); 778 } catch (IllegalAccessException ex) { 779 throw new RuntimeException(ex); 780 } catch (InvocationTargetException ex) { 781 Throwable cause = ex.getCause(); 782 if (cause instanceof RuntimeException) { 783 throw (RuntimeException) cause; 784 } else if (cause instanceof Error) { 785 throw (Error) cause; 786 } 787 throw new RuntimeException(ex); 788 } 789 } 790 } 791} 792