1 /* 2 * Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.lang; 27 28 import java.io.BufferedInputStream; 29 import java.io.BufferedOutputStream; 30 import java.io.ByteArrayInputStream; 31 import java.io.FileDescriptor; 32 import java.io.FileInputStream; 33 import java.io.FileOutputStream; 34 import java.io.IOException; 35 import java.io.InputStream; 36 import java.io.OutputStream; 37 import java.util.Arrays; 38 import java.util.concurrent.Executors; 39 import java.util.concurrent.Executor; 40 import java.util.concurrent.ThreadFactory; 41 import java.util.concurrent.TimeUnit; 42 import java.security.AccessController; 43 import static java.security.AccessController.doPrivileged; 44 import java.security.PrivilegedAction; 45 import java.security.PrivilegedActionException; 46 import java.security.PrivilegedExceptionAction; 47 48 /** 49 * java.lang.Process subclass in the UNIX environment. 50 * 51 * @author Mario Wolczko and Ross Knippel. 52 * @author Konstantin Kladko (ported to Bsd) 53 * @author Martin Buchholz 54 */ 55 final class UNIXProcess extends Process { 56 private static final sun.misc.JavaIOFileDescriptorAccess fdAccess 57 = sun.misc.SharedSecrets.getJavaIOFileDescriptorAccess(); 58 59 private final int pid; 60 private int exitcode; 61 private boolean hasExited; 62 63 private /* final */ OutputStream stdin; 64 private /* final */ InputStream stdout; 65 private /* final */ InputStream stderr; 66 67 private static enum LaunchMechanism { 68 FORK(1), 69 POSIX_SPAWN(2); 70 71 private int value; 72 LaunchMechanism(int x) {value = x;} 73 }; 74 75 /* On BSD, the default is to spawn */ 76 private static final LaunchMechanism launchMechanism; 77 private static byte[] helperpath; 78 79 private static byte[] toCString(String s) { 80 if (s == null) 81 return null; 82 byte[] bytes = s.getBytes(); 83 byte[] result = new byte[bytes.length + 1]; 84 System.arraycopy(bytes, 0, 85 result, 0, 86 bytes.length); 87 result[result.length-1] = (byte)0; 88 return result; 89 } 90 91 static { 92 launchMechanism = AccessController.doPrivileged( 93 new PrivilegedAction<LaunchMechanism>() 94 { 95 public LaunchMechanism run() { 96 String javahome = System.getProperty("java.home"); 97 98 helperpath = toCString(javahome + "/lib/jspawnhelper"); 99 String s = System.getProperty( 100 "jdk.lang.Process.launchMechanism", "posix_spawn"); 101 102 try { 103 return LaunchMechanism.valueOf(s.toUpperCase()); 104 } catch (IllegalArgumentException e) { 105 throw new Error(s + " is not a supported " + 106 "process launch mechanism on this platform."); 107 } 108 } 109 }); 110 } 111 112 /* this is for the reaping thread */ 113 private native int waitForProcessExit(int pid); 114 115 /** 116 * Create a process. Depending on the mode flag, this is done by 117 * one of the following mechanisms. 118 * - fork(2) and exec(2) 119 * - posix_spawn(2) 120 * 121 * @param fds an array of three file descriptors. 122 * Indexes 0, 1, and 2 correspond to standard input, 123 * standard output and standard error, respectively. On 124 * input, a value of -1 means to create a pipe to connect 125 * child and parent processes. On output, a value which 126 * is not -1 is the parent pipe fd corresponding to the 127 * pipe which has been created. An element of this array 128 * is -1 on input if and only if it is <em>not</em> -1 on 129 * output. 130 * @return the pid of the subprocess 131 */ 132 private native int forkAndExec(int mode, byte[] helperpath, 133 byte[] prog, 134 byte[] argBlock, int argc, 135 byte[] envBlock, int envc, 136 byte[] dir, 137 int[] fds, 138 boolean redirectErrorStream) 139 throws IOException; 140 141 /** 142 * The thread factory used to create "process reaper" daemon threads. 143 */ 144 private static class ProcessReaperThreadFactory implements ThreadFactory { 145 private final static ThreadGroup group = getRootThreadGroup(); 146 147 private static ThreadGroup getRootThreadGroup() { 148 return doPrivileged(new PrivilegedAction<ThreadGroup> () { 149 public ThreadGroup run() { 150 ThreadGroup root = Thread.currentThread().getThreadGroup(); 151 while (root.getParent() != null) 152 root = root.getParent(); 153 return root; 154 }}); 155 } 156 157 public Thread newThread(Runnable grimReaper) { 158 // Our thread stack requirement is quite modest. 159 Thread t = new Thread(group, grimReaper, "process reaper", 32768); 160 t.setDaemon(true); 161 // A small attempt (probably futile) to avoid priority inversion 162 t.setPriority(Thread.MAX_PRIORITY); 163 return t; 164 } 165 } 166 167 /** 168 * The thread pool of "process reaper" daemon threads. 169 */ 170 private static final Executor processReaperExecutor = 171 doPrivileged(new PrivilegedAction<Executor>() { 172 public Executor run() { 173 return Executors.newCachedThreadPool 174 (new ProcessReaperThreadFactory()); 175 }}); 176 177 UNIXProcess(final byte[] prog, 178 final byte[] argBlock, final int argc, 179 final byte[] envBlock, final int envc, 180 final byte[] dir, 181 final int[] fds, 182 final boolean redirectErrorStream) 183 throws IOException { 184 185 pid = forkAndExec(launchMechanism.value, 186 helperpath, 187 prog, 188 argBlock, argc, 189 envBlock, envc, 190 dir, 191 fds, 192 redirectErrorStream); 193 194 try { 195 doPrivileged(new PrivilegedExceptionAction<Void>() { 196 public Void run() throws IOException { 197 initStreams(fds); 198 return null; 199 }}); 200 } catch (PrivilegedActionException ex) { 201 throw (IOException) ex.getException(); 202 } 203 } 204 205 static FileDescriptor newFileDescriptor(int fd) { 206 FileDescriptor fileDescriptor = new FileDescriptor(); 207 fdAccess.set(fileDescriptor, fd); 208 return fileDescriptor; 209 } 210 211 void initStreams(int[] fds) throws IOException { 212 stdin = (fds[0] == -1) ? 213 ProcessBuilder.NullOutputStream.INSTANCE : 214 new ProcessPipeOutputStream(fds[0]); 215 216 stdout = (fds[1] == -1) ? 217 ProcessBuilder.NullInputStream.INSTANCE : 218 new ProcessPipeInputStream(fds[1]); 219 220 stderr = (fds[2] == -1) ? 221 ProcessBuilder.NullInputStream.INSTANCE : 222 new ProcessPipeInputStream(fds[2]); 223 224 processReaperExecutor.execute(new Runnable() { 225 public void run() { 226 int exitcode = waitForProcessExit(pid); 227 UNIXProcess.this.processExited(exitcode); 228 }}); 229 } 230 231 void processExited(int exitcode) { 232 synchronized (this) { 233 this.exitcode = exitcode; 234 hasExited = true; 235 notifyAll(); 236 } 237 238 if (stdout instanceof ProcessPipeInputStream) 239 ((ProcessPipeInputStream) stdout).processExited(); 240 241 if (stderr instanceof ProcessPipeInputStream) 242 ((ProcessPipeInputStream) stderr).processExited(); 243 244 if (stdin instanceof ProcessPipeOutputStream) 245 ((ProcessPipeOutputStream) stdin).processExited(); 246 } 247 248 public OutputStream getOutputStream() { 249 return stdin; 250 } 251 252 public InputStream getInputStream() { 253 return stdout; 254 } 255 256 public InputStream getErrorStream() { 257 return stderr; 258 } 259 260 public synchronized int waitFor() throws InterruptedException { 261 while (!hasExited) { 262 wait(); 263 } 264 return exitcode; 265 } 266 267 @Override 268 public synchronized boolean waitFor(long timeout, TimeUnit unit) 269 throws InterruptedException 270 { 271 if (hasExited) return true; 272 if (timeout <= 0) return false; 273 274 long timeoutAsNanos = unit.toNanos(timeout); 275 long startTime = System.nanoTime(); 276 long rem = timeoutAsNanos; 277 278 while (!hasExited && (rem > 0)) { 279 wait(Math.max(TimeUnit.NANOSECONDS.toMillis(rem), 1)); 280 rem = timeoutAsNanos - (System.nanoTime() - startTime); 281 } 282 return hasExited; 283 } 284 285 public synchronized int exitValue() { 286 if (!hasExited) { 287 throw new IllegalThreadStateException("process hasn't exited"); 288 } 289 return exitcode; 290 } 291 292 private static native void destroyProcess(int pid, boolean force); 293 private void destroy(boolean force) { 294 // There is a risk that pid will be recycled, causing us to 295 // kill the wrong process! So we only terminate processes 296 // that appear to still be running. Even with this check, 297 // there is an unavoidable race condition here, but the window 298 // is very small, and OSes try hard to not recycle pids too 299 // soon, so this is quite safe. 300 synchronized (this) { 301 if (!hasExited) 302 destroyProcess(pid, force); 303 } 304 try { stdin.close(); } catch (IOException ignored) {} 305 try { stdout.close(); } catch (IOException ignored) {} 306 try { stderr.close(); } catch (IOException ignored) {} 307 } 308 309 public void destroy() { 310 destroy(false); 311 } 312 313 @Override 314 public Process destroyForcibly() { 315 destroy(true); 316 return this; 317 } 318 319 @Override 320 public synchronized boolean isAlive() { 321 return !hasExited; 322 } 323 324 private static native void init(); 325 326 static { 327 init(); 328 } 329 330 /** 331 * A buffered input stream for a subprocess pipe file descriptor 332 * that allows the underlying file descriptor to be reclaimed when 333 * the process exits, via the processExited hook. 334 * 335 * This is tricky because we do not want the user-level InputStream to be 336 * closed until the user invokes close(), and we need to continue to be 337 * able to read any buffered data lingering in the OS pipe buffer. 338 */ 339 static class ProcessPipeInputStream extends BufferedInputStream { 340 private final Object closeLock = new Object(); 341 342 ProcessPipeInputStream(int fd) { 343 super(new FileInputStream(newFileDescriptor(fd))); 344 } 345 private static byte[] drainInputStream(InputStream in) 346 throws IOException { 347 int n = 0; 348 int j; 349 byte[] a = null; 350 while ((j = in.available()) > 0) { 351 a = (a == null) ? new byte[j] : Arrays.copyOf(a, n + j); 352 n += in.read(a, n, j); 353 } 354 return (a == null || n == a.length) ? a : Arrays.copyOf(a, n); 355 } 356 357 /** Called by the process reaper thread when the process exits. */ 358 synchronized void processExited() { 359 synchronized (closeLock) { 360 try { 361 InputStream in = this.in; 362 // this stream is closed if and only if: in == null 363 if (in != null) { 364 byte[] stragglers = drainInputStream(in); 365 in.close(); 366 this.in = (stragglers == null) ? 367 ProcessBuilder.NullInputStream.INSTANCE : 368 new ByteArrayInputStream(stragglers); 369 } 370 } catch (IOException ignored) {} 371 } 372 } 373 374 @Override 375 public void close() throws IOException { 376 // BufferedInputStream#close() is not synchronized unlike most other methods. 377 // Synchronizing helps avoid race with processExited(). 378 synchronized (closeLock) { 379 super.close(); 380 } 381 } 382 } 383 384 /** 385 * A buffered output stream for a subprocess pipe file descriptor 386 * that allows the underlying file descriptor to be reclaimed when 387 * the process exits, via the processExited hook. 388 */ 389 static class ProcessPipeOutputStream extends BufferedOutputStream { 390 ProcessPipeOutputStream(int fd) { 391 super(new FileOutputStream(newFileDescriptor(fd))); 392 } 393 394 /** Called by the process reaper thread when the process exits. */ 395 synchronized void processExited() { 396 OutputStream out = this.out; 397 if (out != null) { 398 try { 399 out.close(); 400 } catch (IOException ignored) { 401 // We know of no reason to get an IOException, but if 402 // we do, there's nothing else to do but carry on. 403 } 404 this.out = ProcessBuilder.NullOutputStream.INSTANCE; 405 } 406 } 407 } 408 }