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.*;
29 import java.util.concurrent.TimeUnit;
30 import java.security.AccessController;
31 import java.security.PrivilegedAction;
32
33 /* java.lang.Process subclass in the UNIX environment.
34 *
35 * @author Mario Wolczko and Ross Knippel.
36 */
37
38 final class UNIXProcess extends Process {
39 private static final sun.misc.JavaIOFileDescriptorAccess fdAccess
40 = sun.misc.SharedSecrets.getJavaIOFileDescriptorAccess();
41
42 private final int pid;
43 private int exitcode;
44 private boolean hasExited;
45
46 private OutputStream stdin_stream;
47 private InputStream stdout_stream;
48 private DeferredCloseInputStream stdout_inner_stream;
49 private InputStream stderr_stream;
50
51 private static String javahome;
52 private static String arch;
53 private static String helperpath;
54
55 enum LaunchMechanism {
56 fork(1),
57 posix_spawn(2);
58
59 private int value;
60 LaunchMechanism(int x) {value = x;}
61 };
62
63 /* On Solaris, the default is to spawn */
64 private static LaunchMechanism launchMechanism;
65
66 static {
67 AccessController.doPrivileged(new PrivilegedAction<Void>() {
68 public Void run() {
69 String javahome = System.getProperty("java.home");
70 String osArch = System.getProperty("os.arch");
71 if (osArch.equals("x86")) {
72 osArch = "i386";
73 } else if (osArch.equals("x86_64")) {
74 osArch = "amd64";
75 }
76
77 helperpath = javahome + "/lib/" + osArch + "/jspawnhelper";
78 String s = System.getProperty(
79 "jdk.lang.Process.launchMechanism", "posix_spawn");
80
81 try {
82 launchMechanism = LaunchMechanism.valueOf(s);
83 } catch (IllegalArgumentException e) {
84 throw new Error(s + " is not a supported " +
85 "process launch mechanism on this platform.");
86 }
87 return null;
88 }
89 });
90 }
91
92 /* this is for the reaping thread */
93 private native int waitForProcessExit(int pid);
94
95 /**
96 * Create a process. Depending on the mode flag, this is done by
97 * one of the following mechanisms.
98 * - fork(2) and exec(2)
99 * - vfork(2) and exec(2)
100 * - posix_spawn(2)
101 *
102 * @param std_fds array of file descriptors. Indexes 0, 1, and
103 * 2 correspond to standard input, standard output and
104 * standard error, respectively. On input, a value of -1
105 * means to create a pipe to connect child and parent
106 * processes. On output, a value which is not -1 is the
107 * parent pipe fd corresponding to the pipe which has
108 * been created. An element of this array is -1 on input
109 * if and only if it is <em>not</em> -1 on output.
110 * @return the pid of the subprocess
111 */
112 private native int forkAndExec(int mode, byte[] prog,
113 byte[] argBlock, int argc,
114 byte[] envBlock, int envc,
115 byte[] dir,
116 int[] std_fds,
117 boolean redirectErrorStream)
118 throws IOException;
119
120 UNIXProcess(final byte[] prog,
121 final byte[] argBlock, int argc,
122 final byte[] envBlock, int envc,
123 final byte[] dir,
124 final int[] std_fds,
125 final boolean redirectErrorStream)
126 throws IOException {
127 pid = forkAndExec(launchMechanism.value,
128 prog,
129 argBlock, argc,
130 envBlock, envc,
131 dir,
132 std_fds,
133 redirectErrorStream);
134
135 java.security.AccessController.doPrivileged(
136 new java.security.PrivilegedAction<Void>() { public Void run() {
137 if (std_fds[0] == -1)
138 stdin_stream = ProcessBuilder.NullOutputStream.INSTANCE;
139 else {
140 FileDescriptor stdin_fd = new FileDescriptor();
141 fdAccess.set(stdin_fd, std_fds[0]);
142 stdin_stream = new BufferedOutputStream(
143 new FileOutputStream(stdin_fd));
144 }
145
146 if (std_fds[1] == -1)
147 stdout_stream = ProcessBuilder.NullInputStream.INSTANCE;
148 else {
149 FileDescriptor stdout_fd = new FileDescriptor();
150 fdAccess.set(stdout_fd, std_fds[1]);
151 stdout_inner_stream = new DeferredCloseInputStream(stdout_fd);
152 stdout_stream = new BufferedInputStream(stdout_inner_stream);
153 }
154
155 if (std_fds[2] == -1)
156 stderr_stream = ProcessBuilder.NullInputStream.INSTANCE;
157 else {
158 FileDescriptor stderr_fd = new FileDescriptor();
159 fdAccess.set(stderr_fd, std_fds[2]);
160 stderr_stream = new DeferredCloseInputStream(stderr_fd);
161 }
162
163 return null; }});
164
165 /*
166 * For each subprocess forked a corresponding reaper thread
167 * is started. That thread is the only thread which waits
168 * for the subprocess to terminate and it doesn't hold any
169 * locks while doing so. This design allows waitFor() and
170 * exitStatus() to be safely executed in parallel (and they
171 * need no native code).
172 */
173
174 java.security.AccessController.doPrivileged(
175 new java.security.PrivilegedAction<Void>() { public Void run() {
176 Thread t = new Thread("process reaper") {
177 public void run() {
178 int res = waitForProcessExit(pid);
179 synchronized (UNIXProcess.this) {
180 hasExited = true;
181 exitcode = res;
182 UNIXProcess.this.notifyAll();
183 }
184 }
185 };
186 t.setDaemon(true);
187 t.start();
188 return null; }});
189 }
190
191 public OutputStream getOutputStream() {
192 return stdin_stream;
193 }
194
195 public InputStream getInputStream() {
196 return stdout_stream;
197 }
198
199 public InputStream getErrorStream() {
200 return stderr_stream;
201 }
202
203 public synchronized int waitFor() throws InterruptedException {
204 while (!hasExited) {
205 wait();
206 }
207 return exitcode;
208 }
209
210 @Override
211 public synchronized boolean waitFor(long timeout, TimeUnit unit)
212 throws InterruptedException
213 {
214 if (hasExited) return true;
215 if (timeout <= 0) return false;
216
217 long timeoutAsNanos = unit.toNanos(timeout);
218 long startTime = System.nanoTime();
219 long rem = timeoutAsNanos;
220
221 while (!hasExited && (rem > 0)) {
222 wait(Math.max(TimeUnit.NANOSECONDS.toMillis(rem), 1));
223 rem = timeoutAsNanos - (System.nanoTime() - startTime);
224 }
225 return hasExited;
226 }
227
228 public synchronized int exitValue() {
229 if (!hasExited) {
230 throw new IllegalThreadStateException("process hasn't exited");
231 }
232 return exitcode;
233 }
234
235 private static native void destroyProcess(int pid, boolean force);
236 private synchronized void destroy(boolean force) {
237 // There is a risk that pid will be recycled, causing us to
238 // kill the wrong process! So we only terminate processes
239 // that appear to still be running. Even with this check,
240 // there is an unavoidable race condition here, but the window
241 // is very small, and OSes try hard to not recycle pids too
242 // soon, so this is quite safe.
243 if (!hasExited)
244 destroyProcess(pid, force);
245 try {
246 stdin_stream.close();
247 if (stdout_inner_stream != null)
248 stdout_inner_stream.closeDeferred(stdout_stream);
249 if (stderr_stream instanceof DeferredCloseInputStream)
250 ((DeferredCloseInputStream) stderr_stream)
251 .closeDeferred(stderr_stream);
252 } catch (IOException e) {
253 // ignore
254 }
255 }
256
257 public void destroy() {
258 destroy(false);
259 }
260
261 @Override
262 public Process destroyForcibly() {
263 destroy(true);
264 return this;
265 }
266
267 @Override
268 public synchronized boolean isAlive() {
269 return !hasExited;
270 }
271
272 // A FileInputStream that supports the deferment of the actual close
273 // operation until the last pending I/O operation on the stream has
274 // finished. This is required on Solaris because we must close the stdin
275 // and stdout streams in the destroy method in order to reclaim the
276 // underlying file descriptors. Doing so, however, causes any thread
277 // currently blocked in a read on one of those streams to receive an
278 // IOException("Bad file number"), which is incompatible with historical
279 // behavior. By deferring the close we allow any pending reads to see -1
280 // (EOF) as they did before.
281 //
282 private static class DeferredCloseInputStream
283 extends FileInputStream
284 {
285
286 private DeferredCloseInputStream(FileDescriptor fd) {
287 super(fd);
288 }
289
290 private Object lock = new Object(); // For the following fields
291 private boolean closePending = false;
292 private int useCount = 0;
293 private InputStream streamToClose;
294
295 private void raise() {
296 synchronized (lock) {
297 useCount++;
298 }
299 }
300
301 private void lower() throws IOException {
302 synchronized (lock) {
303 useCount--;
304 if (useCount == 0 && closePending) {
305 streamToClose.close();
306 }
307 }
308 }
309
310 // stc is the actual stream to be closed; it might be this object, or
311 // it might be an upstream object for which this object is downstream.
312 //
313 private void closeDeferred(InputStream stc) throws IOException {
314 synchronized (lock) {
315 if (useCount == 0) {
316 stc.close();
317 } else {
318 closePending = true;
319 streamToClose = stc;
320 }
321 }
322 }
323
324 public void close() throws IOException {
325 synchronized (lock) {
326 useCount = 0;
327 closePending = false;
328 }
329 super.close();
330 }
331
332 public int read() throws IOException {
333 raise();
334 try {
335 return super.read();
336 } finally {
337 lower();
338 }
339 }
340
341 public int read(byte[] b) throws IOException {
342 raise();
343 try {
344 return super.read(b);
345 } finally {
346 lower();
347 }
348 }
349
350 public int read(byte[] b, int off, int len) throws IOException {
351 raise();
352 try {
353 return super.read(b, off, len);
354 } finally {
355 lower();
356 }
357 }
358
359 public long skip(long n) throws IOException {
360 raise();
361 try {
362 return super.skip(n);
363 } finally {
364 lower();
365 }
366 }
367
368 public int available() throws IOException {
369 raise();
370 try {
371 return super.available();
372 } finally {
373 lower();
374 }
375 }
376
377 }
378
379 private static native void init();
380
381 static {
382 init();
383 }
384 }