1 /* 2 * Copyright (c) 1995, 2012, 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 Linux) 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 /* this is for the reaping thread */ 68 private native int waitForProcessExit(int pid); 69 70 /** 71 * Create a process using fork(2) and exec(2). 72 * 73 * @param fds an array of three file descriptors. 74 * Indexes 0, 1, and 2 correspond to standard input, 75 * standard output and standard error, respectively. On 76 * input, a value of -1 means to create a pipe to connect 77 * child and parent processes. On output, a value which 78 * is not -1 is the parent pipe fd corresponding to the 79 * pipe which has been created. An element of this array 80 * is -1 on input if and only if it is <em>not</em> -1 on 81 * output. 82 * @return the pid of the subprocess 83 */ 84 private native int forkAndExec(byte[] prog, 85 byte[] argBlock, int argc, 86 byte[] envBlock, int envc, 87 byte[] dir, 88 int[] fds, 89 boolean redirectErrorStream) 90 throws IOException; 91 92 /** 93 * The thread factory used to create "process reaper" daemon threads. 94 */ 95 private static class ProcessReaperThreadFactory implements ThreadFactory { 96 private final static ThreadGroup group = getRootThreadGroup(); 97 98 private static ThreadGroup getRootThreadGroup() { 99 return doPrivileged(new PrivilegedAction<ThreadGroup> () { 100 public ThreadGroup run() { 101 ThreadGroup root = Thread.currentThread().getThreadGroup(); 102 while (root.getParent() != null) 103 root = root.getParent(); 104 return root; 105 }}); 106 } 107 108 public Thread newThread(Runnable grimReaper) { 109 // Our thread stack requirement is quite modest. 110 Thread t = new Thread(group, grimReaper, "process reaper", 32768); 111 t.setDaemon(true); 112 // A small attempt (probably futile) to avoid priority inversion 113 t.setPriority(Thread.MAX_PRIORITY); 114 return t; 115 } 116 } 117 118 /** 119 * The thread pool of "process reaper" daemon threads. 120 */ 121 private static final Executor processReaperExecutor = 122 doPrivileged(new PrivilegedAction<Executor>() { 123 public Executor run() { 124 return Executors.newCachedThreadPool 125 (new ProcessReaperThreadFactory()); 126 }}); 127 128 UNIXProcess(final byte[] prog, 129 final byte[] argBlock, final int argc, 130 final byte[] envBlock, final int envc, 131 final byte[] dir, 132 final int[] fds, 133 final boolean redirectErrorStream) 134 throws IOException { 135 136 pid = forkAndExec(prog, 137 argBlock, argc, 138 envBlock, envc, 139 dir, 140 fds, 141 redirectErrorStream); 142 143 try { 144 doPrivileged(new PrivilegedExceptionAction<Void>() { 145 public Void run() throws IOException { 146 initStreams(fds); 147 return null; 148 }}); 149 } catch (PrivilegedActionException ex) { 150 throw (IOException) ex.getException(); 151 } 152 } 153 154 static FileDescriptor newFileDescriptor(int fd) { 155 FileDescriptor fileDescriptor = new FileDescriptor(); 156 fdAccess.set(fileDescriptor, fd); 157 return fileDescriptor; 158 } 159 160 void initStreams(int[] fds) throws IOException { 161 stdin = (fds[0] == -1) ? 162 ProcessBuilder.NullOutputStream.INSTANCE : 163 new ProcessPipeOutputStream(fds[0]); 164 165 stdout = (fds[1] == -1) ? 166 ProcessBuilder.NullInputStream.INSTANCE : 167 new ProcessPipeInputStream(fds[1]); 168 169 stderr = (fds[2] == -1) ? 170 ProcessBuilder.NullInputStream.INSTANCE : 171 new ProcessPipeInputStream(fds[2]); 172 173 processReaperExecutor.execute(new Runnable() { 174 public void run() { 175 int exitcode = waitForProcessExit(pid); 176 UNIXProcess.this.processExited(exitcode); 177 }}); 178 } 179 180 void processExited(int exitcode) { 181 synchronized (this) { 182 this.exitcode = exitcode; 183 hasExited = true; 184 notifyAll(); 185 } 186 187 if (stdout instanceof ProcessPipeInputStream) 188 ((ProcessPipeInputStream) stdout).processExited(); 189 190 if (stderr instanceof ProcessPipeInputStream) 191 ((ProcessPipeInputStream) stderr).processExited(); 192 193 if (stdin instanceof ProcessPipeOutputStream) 194 ((ProcessPipeOutputStream) stdin).processExited(); 195 } 196 197 public OutputStream getOutputStream() { 198 return stdin; 199 } 200 201 public InputStream getInputStream() { 202 return stdout; 203 } 204 205 public InputStream getErrorStream() { 206 return stderr; 207 } 208 209 public synchronized int waitFor() throws InterruptedException { 210 while (!hasExited) { 211 wait(); 212 } 213 return exitcode; 214 } 215 216 @Override 217 public synchronized boolean waitFor(long timeout, TimeUnit unit) 218 throws InterruptedException 219 { 220 if (hasExited) return true; 221 if (timeout <= 0) return false; 222 223 long timeoutAsNanos = unit.toNanos(timeout); 224 long startTime = System.nanoTime(); 225 long rem = timeoutAsNanos; 226 227 while (!hasExited && (rem > 0)) { 228 wait(Math.max(TimeUnit.NANOSECONDS.toMillis(rem), 1)); 229 rem = timeoutAsNanos - (System.nanoTime() - startTime); 230 } 231 return hasExited; 232 } 233 234 public synchronized int exitValue() { 235 if (!hasExited) { 236 throw new IllegalThreadStateException("process hasn't exited"); 237 } 238 return exitcode; 239 } 240 241 private static native void destroyProcess(int pid, boolean force); 242 private void destroy(boolean force) { 243 // There is a risk that pid will be recycled, causing us to 244 // kill the wrong process! So we only terminate processes 245 // that appear to still be running. Even with this check, 246 // there is an unavoidable race condition here, but the window 247 // is very small, and OSes try hard to not recycle pids too 248 // soon, so this is quite safe. 249 synchronized (this) { 250 if (!hasExited) 251 destroyProcess(pid, force); 252 } 253 try { stdin.close(); } catch (IOException ignored) {} 254 try { stdout.close(); } catch (IOException ignored) {} 255 try { stderr.close(); } catch (IOException ignored) {} 256 } 257 258 public void destroy() { 259 destroy(false); 260 } 261 262 @Override 263 public Process destroyForcibly() { 264 destroy(true); 265 return this; 266 } 267 268 @Override 269 public synchronized boolean isAlive() { 270 return !hasExited; 271 } 272 273 /* This routine initializes JNI field offsets for the class */ 274 private static native void initIDs(); 275 276 static { 277 initIDs(); 278 } 279 280 /** 281 * A buffered input stream for a subprocess pipe file descriptor 282 * that allows the underlying file descriptor to be reclaimed when 283 * the process exits, via the processExited hook. 284 * 285 * This is tricky because we do not want the user-level InputStream to be 286 * closed until the user invokes close(), and we need to continue to be 287 * able to read any buffered data lingering in the OS pipe buffer. 288 */ 289 static class ProcessPipeInputStream extends BufferedInputStream { 290 ProcessPipeInputStream(int fd) { 291 super(new FileInputStream(newFileDescriptor(fd))); 292 } 293 294 private static byte[] drainInputStream(InputStream in) 295 throws IOException { 296 if (in == null) return null; 297 int n = 0; 298 int j; 299 byte[] a = null; 300 while ((j = in.available()) > 0) { 301 a = (a == null) ? new byte[j] : Arrays.copyOf(a, n + j); 302 n += in.read(a, n, j); 303 } 304 return (a == null || n == a.length) ? a : Arrays.copyOf(a, n); 305 } 306 307 /** Called by the process reaper thread when the process exits. */ 308 synchronized void processExited() { 309 // Most BufferedInputStream methods are synchronized, but close() 310 // is not, and so we have to handle concurrent racing close(). 311 try { 312 InputStream in = this.in; 313 if (in != null) { 314 byte[] stragglers = drainInputStream(in); 315 in.close(); 316 this.in = (stragglers == null) ? 317 ProcessBuilder.NullInputStream.INSTANCE : 318 new ByteArrayInputStream(stragglers); 319 if (buf == null) // asynchronous close()? 320 this.in = null; 321 } 322 } catch (IOException ignored) { 323 // probably an asynchronous close(). 324 } 325 } 326 } 327 328 /** 329 * A buffered output stream for a subprocess pipe file descriptor 330 * that allows the underlying file descriptor to be reclaimed when 331 * the process exits, via the processExited hook. 332 */ 333 static class ProcessPipeOutputStream extends BufferedOutputStream { 334 ProcessPipeOutputStream(int fd) { 335 super(new FileOutputStream(newFileDescriptor(fd))); 336 } 337 338 /** Called by the process reaper thread when the process exits. */ 339 synchronized void processExited() { 340 OutputStream out = this.out; 341 if (out != null) { 342 try { 343 out.close(); 344 } catch (IOException ignored) { 345 // We know of no reason to get an IOException, but if 346 // we do, there's nothing else to do but carry on. 347 } 348 this.out = ProcessBuilder.NullOutputStream.INSTANCE; 349 } 350 } 351 } 352 }