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.*;
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 enum LaunchMechanism {
52 FORK(1),
53 POSIX_SPAWN(2);
54
55 private int value;
56 LaunchMechanism(int x) {value = x;}
57 };
58
59 /* On Solaris, the default is to spawn */
60 private static final LaunchMechanism launchMechanism;
61 private static byte[] helperpath;
62
63 private static byte[] toCString(String s) {
64 if (s == null)
65 return null;
66 byte[] bytes = s.getBytes();
67 byte[] result = new byte[bytes.length + 1];
68 System.arraycopy(bytes, 0,
69 result, 0,
70 bytes.length);
71 result[result.length-1] = (byte)0;
72 return result;
73 }
74
75 static {
76 launchMechanism = AccessController.doPrivileged(
77 new PrivilegedAction<LaunchMechanism>()
78 {
79 public LaunchMechanism run() {
80 String javahome = System.getProperty("java.home");
81 String osArch = System.getProperty("os.arch");
82 if (osArch.equals("x86")) {
83 osArch = "i386";
84 } else if (osArch.equals("x86_64")) {
85 osArch = "amd64";
86 }
87
88 helperpath = toCString(javahome + "/lib/" + osArch + "/jspawnhelper");
89 String s = System.getProperty(
90 "jdk.lang.Process.launchMechanism", "posix_spawn");
91
92 try {
93 return LaunchMechanism.valueOf(s.toUpperCase());
94 } catch (IllegalArgumentException e) {
95 throw new Error(s + " is not a supported " +
96 "process launch mechanism on this platform.");
97 }
98 }
99 });
100 }
101
102 /* this is for the reaping thread */
103 private native int waitForProcessExit(int pid);
104
105 /**
106 * Create a process. Depending on the mode flag, this is done by
107 * one of the following mechanisms.
108 * - fork(2) and exec(2)
109 * - posix_spawn(2)
110 *
111 * @param std_fds array of file descriptors. Indexes 0, 1, and
112 * 2 correspond to standard input, standard output and
113 * standard error, respectively. On input, a value of -1
114 * means to create a pipe to connect child and parent
115 * processes. On output, a value which is not -1 is the
116 * parent pipe fd corresponding to the pipe which has
117 * been created. An element of this array is -1 on input
118 * if and only if it is <em>not</em> -1 on output.
119 * @return the pid of the subprocess
120 */
121 private native int forkAndExec(int mode, byte[] helperpath,
122 byte[] prog,
123 byte[] argBlock, int argc,
124 byte[] envBlock, int envc,
125 byte[] dir,
126 int[] std_fds,
127 boolean redirectErrorStream)
128 throws IOException;
129
130 UNIXProcess(final byte[] prog,
131 final byte[] argBlock, int argc,
132 final byte[] envBlock, int envc,
133 final byte[] dir,
134 final int[] std_fds,
135 final boolean redirectErrorStream)
136 throws IOException {
137 pid = forkAndExec(launchMechanism.value,
138 helperpath,
139 prog,
140 argBlock, argc,
141 envBlock, envc,
142 dir,
143 std_fds,
144 redirectErrorStream);
145
146 java.security.AccessController.doPrivileged(
147 new java.security.PrivilegedAction<Void>() { public Void run() {
148 if (std_fds[0] == -1)
149 stdin_stream = ProcessBuilder.NullOutputStream.INSTANCE;
150 else {
151 FileDescriptor stdin_fd = new FileDescriptor();
152 fdAccess.set(stdin_fd, std_fds[0]);
153 stdin_stream = new BufferedOutputStream(
154 new FileOutputStream(stdin_fd));
155 }
156
157 if (std_fds[1] == -1)
158 stdout_stream = ProcessBuilder.NullInputStream.INSTANCE;
159 else {
160 FileDescriptor stdout_fd = new FileDescriptor();
161 fdAccess.set(stdout_fd, std_fds[1]);
162 stdout_inner_stream = new DeferredCloseInputStream(stdout_fd);
163 stdout_stream = new BufferedInputStream(stdout_inner_stream);
164 }
165
166 if (std_fds[2] == -1)
167 stderr_stream = ProcessBuilder.NullInputStream.INSTANCE;
168 else {
169 FileDescriptor stderr_fd = new FileDescriptor();
170 fdAccess.set(stderr_fd, std_fds[2]);
171 stderr_stream = new DeferredCloseInputStream(stderr_fd);
172 }
173
174 return null; }});
175
176 /*
177 * For each subprocess forked a corresponding reaper thread
178 * is started. That thread is the only thread which waits
179 * for the subprocess to terminate and it doesn't hold any
180 * locks while doing so. This design allows waitFor() and
181 * exitStatus() to be safely executed in parallel (and they
182 * need no native code).
183 */
184
185 java.security.AccessController.doPrivileged(
186 new java.security.PrivilegedAction<Void>() { public Void run() {
187 Thread t = new Thread("process reaper") {
188 public void run() {
189 int res = waitForProcessExit(pid);
190 synchronized (UNIXProcess.this) {
191 hasExited = true;
192 exitcode = res;
193 UNIXProcess.this.notifyAll();
194 }
195 }
196 };
197 t.setDaemon(true);
198 t.start();
199 return null; }});
200 }
201
202 public OutputStream getOutputStream() {
203 return stdin_stream;
204 }
205
206 public InputStream getInputStream() {
207 return stdout_stream;
208 }
209
210 public InputStream getErrorStream() {
211 return stderr_stream;
212 }
213
214 public synchronized int waitFor() throws InterruptedException {
215 while (!hasExited) {
216 wait();
217 }
218 return exitcode;
219 }
220
221 @Override
222 public synchronized boolean waitFor(long timeout, TimeUnit unit)
223 throws InterruptedException
224 {
225 if (hasExited) return true;
226 if (timeout <= 0) return false;
227
228 long timeoutAsNanos = unit.toNanos(timeout);
229 long startTime = System.nanoTime();
230 long rem = timeoutAsNanos;
231
232 while (!hasExited && (rem > 0)) {
233 wait(Math.max(TimeUnit.NANOSECONDS.toMillis(rem), 1));
234 rem = timeoutAsNanos - (System.nanoTime() - startTime);
235 }
236 return hasExited;
237 }
238
239 public synchronized int exitValue() {
240 if (!hasExited) {
241 throw new IllegalThreadStateException("process hasn't exited");
242 }
243 return exitcode;
244 }
245
246 private static native void destroyProcess(int pid, boolean force);
247 private synchronized void destroy(boolean force) {
248 // There is a risk that pid will be recycled, causing us to
249 // kill the wrong process! So we only terminate processes
250 // that appear to still be running. Even with this check,
251 // there is an unavoidable race condition here, but the window
252 // is very small, and OSes try hard to not recycle pids too
253 // soon, so this is quite safe.
254 if (!hasExited)
255 destroyProcess(pid, force);
256 try {
257 stdin_stream.close();
258 if (stdout_inner_stream != null)
259 stdout_inner_stream.closeDeferred(stdout_stream);
260 if (stderr_stream instanceof DeferredCloseInputStream)
261 ((DeferredCloseInputStream) stderr_stream)
262 .closeDeferred(stderr_stream);
263 } catch (IOException e) {
264 // ignore
265 }
266 }
267
268 public void destroy() {
269 destroy(false);
270 }
271
272 @Override
273 public Process destroyForcibly() {
274 destroy(true);
275 return this;
276 }
277
278 @Override
279 public synchronized boolean isAlive() {
280 return !hasExited;
281 }
282
283 // A FileInputStream that supports the deferment of the actual close
284 // operation until the last pending I/O operation on the stream has
285 // finished. This is required on Solaris because we must close the stdin
286 // and stdout streams in the destroy method in order to reclaim the
287 // underlying file descriptors. Doing so, however, causes any thread
288 // currently blocked in a read on one of those streams to receive an
289 // IOException("Bad file number"), which is incompatible with historical
290 // behavior. By deferring the close we allow any pending reads to see -1
291 // (EOF) as they did before.
292 //
293 private static class DeferredCloseInputStream
294 extends FileInputStream
295 {
296
297 private DeferredCloseInputStream(FileDescriptor fd) {
298 super(fd);
299 }
300
301 private Object lock = new Object(); // For the following fields
302 private boolean closePending = false;
303 private int useCount = 0;
304 private InputStream streamToClose;
305
306 private void raise() {
307 synchronized (lock) {
308 useCount++;
309 }
310 }
311
312 private void lower() throws IOException {
313 synchronized (lock) {
314 useCount--;
315 if (useCount == 0 && closePending) {
316 streamToClose.close();
317 }
318 }
319 }
320
321 // stc is the actual stream to be closed; it might be this object, or
322 // it might be an upstream object for which this object is downstream.
323 //
324 private void closeDeferred(InputStream stc) throws IOException {
325 synchronized (lock) {
326 if (useCount == 0) {
327 stc.close();
328 } else {
329 closePending = true;
330 streamToClose = stc;
331 }
332 }
333 }
334
335 public void close() throws IOException {
336 synchronized (lock) {
337 useCount = 0;
338 closePending = false;
339 }
340 super.close();
341 }
342
343 public int read() throws IOException {
344 raise();
345 try {
346 return super.read();
347 } finally {
348 lower();
349 }
350 }
351
352 public int read(byte[] b) throws IOException {
353 raise();
354 try {
355 return super.read(b);
356 } finally {
357 lower();
358 }
359 }
360
361 public int read(byte[] b, int off, int len) throws IOException {
362 raise();
363 try {
364 return super.read(b, off, len);
365 } finally {
366 lower();
367 }
368 }
369
370 public long skip(long n) throws IOException {
371 raise();
372 try {
373 return super.skip(n);
374 } finally {
375 lower();
376 }
377 }
378
379 public int available() throws IOException {
380 raise();
381 try {
382 return super.available();
383 } finally {
384 lower();
385 }
386 }
387
388 }
389
390 private static native void init();
391
392 static {
393 init();
394 }
395 }