1 /*
2 * Copyright (c) 1995, 2008, 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.io;
27
28 import java.util.concurrent.atomic.AtomicInteger;
29
30 /**
31 * Instances of the file descriptor class serve as an opaque handle
32 * to the underlying machine-specific structure representing an open
33 * file, an open socket, or another source or sink of bytes. The
34 * main practical use for a file descriptor is to create a
35 * <code>FileInputStream</code> or <code>FileOutputStream</code> to
36 * contain it.
37 * <p>
38 * Applications should not create their own file descriptors.
39 *
40 * @author Pavani Diwanji
41 * @see java.io.FileInputStream
42 * @see java.io.FileOutputStream
43 * @since JDK1.0
44 */
45 public final class FileDescriptor {
46
47 private int fd;
48
49 /**
50 * A counter for tracking the FIS/FOS/RAF instances that
51 * use this FileDescriptor. The FIS/FOS.finalize() will not release
52 * the FileDescriptor if it is still under user by a stream.
53 */
54 private AtomicInteger useCount;
55
56 /**
57 * Constructs an (invalid) FileDescriptor
58 * object.
59 */
60 public /**/ FileDescriptor() {
61 fd = -1;
62 useCount = new AtomicInteger();
63 }
64
65 private /* */ FileDescriptor(int fd) {
66 this.fd = fd;
67 useCount = new AtomicInteger();
68 }
69
70 /**
71 * A handle to the standard input stream. Usually, this file
72 * descriptor is not used directly, but rather via the input stream
73 * known as <code>System.in</code>.
74 *
75 * @see java.lang.System#in
76 */
77 public static final FileDescriptor in = new FileDescriptor(0);
78
79 /**
80 * A handle to the standard output stream. Usually, this file
81 * descriptor is not used directly, but rather via the output stream
82 * known as <code>System.out</code>.
83 * @see java.lang.System#out
84 */
85 public static final FileDescriptor out = new FileDescriptor(1);
86
87 /**
147 new sun.misc.JavaIOFileDescriptorAccess() {
148 public void set(FileDescriptor obj, int fd) {
149 obj.fd = fd;
150 }
151
152 public int get(FileDescriptor obj) {
153 return obj.fd;
154 }
155
156 public void setHandle(FileDescriptor obj, long handle) {
157 throw new UnsupportedOperationException();
158 }
159
160 public long getHandle(FileDescriptor obj) {
161 throw new UnsupportedOperationException();
162 }
163 }
164 );
165 }
166
167 // package private methods used by FIS, FOS and RAF
168
169 int incrementAndGetUseCount() {
170 return useCount.incrementAndGet();
171 }
172
173 int decrementAndGetUseCount() {
174 return useCount.decrementAndGet();
175 }
176 }
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1 /*
2 * Copyright (c) 1995, 2011, 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.io;
27
28 import java.util.ArrayList;
29 import java.util.List;
30
31 /**
32 * Instances of the file descriptor class serve as an opaque handle
33 * to the underlying machine-specific structure representing an open
34 * file, an open socket, or another source or sink of bytes. The
35 * main practical use for a file descriptor is to create a
36 * <code>FileInputStream</code> or <code>FileOutputStream</code> to
37 * contain it.
38 * <p>
39 * Applications should not create their own file descriptors.
40 *
41 * @author Pavani Diwanji
42 * @see java.io.FileInputStream
43 * @see java.io.FileOutputStream
44 * @since JDK1.0
45 */
46 public final class FileDescriptor {
47
48 private int fd;
49
50 private Closeable parent;
51 private List<Closeable> otherParents;
52 private boolean closed;
53
54 /**
55 * Constructs an (invalid) FileDescriptor
56 * object.
57 */
58 public /**/ FileDescriptor() {
59 fd = -1;
60 }
61
62 private /* */ FileDescriptor(int fd) {
63 this.fd = fd;
64 }
65
66 /**
67 * A handle to the standard input stream. Usually, this file
68 * descriptor is not used directly, but rather via the input stream
69 * known as <code>System.in</code>.
70 *
71 * @see java.lang.System#in
72 */
73 public static final FileDescriptor in = new FileDescriptor(0);
74
75 /**
76 * A handle to the standard output stream. Usually, this file
77 * descriptor is not used directly, but rather via the output stream
78 * known as <code>System.out</code>.
79 * @see java.lang.System#out
80 */
81 public static final FileDescriptor out = new FileDescriptor(1);
82
83 /**
143 new sun.misc.JavaIOFileDescriptorAccess() {
144 public void set(FileDescriptor obj, int fd) {
145 obj.fd = fd;
146 }
147
148 public int get(FileDescriptor obj) {
149 return obj.fd;
150 }
151
152 public void setHandle(FileDescriptor obj, long handle) {
153 throw new UnsupportedOperationException();
154 }
155
156 public long getHandle(FileDescriptor obj) {
157 throw new UnsupportedOperationException();
158 }
159 }
160 );
161 }
162
163 /*
164 * Package private methods to track referents.
165 * If multiple streams point to the same FileDescriptor, we cycle
166 * through the list of all referents and call close()
167 */
168
169 /**
170 * Attach a Closeable to this FD for tracking.
171 * parent reference is added to otherParents when
172 * needed to make closeAll simpler.
173 */
174 synchronized void attach(Closeable c) {
175 if (parent == null) {
176 // first caller gets to do this
177 parent = c;
178 } else if (otherParents == null) {
179 otherParents = new ArrayList<>();
180 otherParents.add(parent);
181 otherParents.add(c);
182 } else {
183 otherParents.add(c);
184 }
185 }
186
187 /**
188 * Cycle through all Closeables sharing this FD and call
189 * close() on each one.
190 *
191 * The caller closeable gets to call close0().
192 */
193 @SuppressWarnings("try")
194 synchronized void closeAll(Closeable releaser) throws IOException {
195 if (!closed) {
196 closed = true;
197 IOException ioe = null;
198 try (Closeable c = releaser) {
199 if (otherParents != null) {
200 for (Closeable referent : otherParents) {
201 try {
202 referent.close();
203 } catch(IOException x) {
204 if (ioe == null) {
205 ioe = x;
206 } else {
207 ioe.addSuppressed(x);
208 }
209 }
210 }
211 }
212 } catch(IOException ex) {
213 /*
214 * If releaser close() throws IOException
215 * add other exceptions as suppressed.
216 */
217 if (ioe != null)
218 ex.addSuppressed(ioe);
219 ioe = ex;
220 } finally {
221 if (ioe != null)
222 throw ioe;
223 }
224 }
225 }
226 }
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