1 /*
2 * junixsocket
3 *
4 * Copyright 2009-2024 Christian Kohlschütter
5 *
6 * Licensed under the Apache License, Version 2.0 (the "License");
7 * you may not use this file except in compliance with the License.
8 * You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18 package org.newsclub.net.unix.rmi;
19
20 import java.io.FileDescriptor;
21 import java.io.FileOutputStream;
22 import java.io.IOException;
23 import java.io.ObjectInput;
24
25 /**
26 * A specialized subclass of {@link RemoteFileDescriptorBase}, specifically for
27 * {@link FileOutputStream}s.
28 *
29 * @author Christian Kohlschütter
30 */
31 public final class RemoteFileOutput extends RemoteFileDescriptorBase<FileOutputStream> {
32 private static final long serialVersionUID = 1L;
33
34 /**
35 * Creates an uninitialized instance; used for externalization.
36 *
37 * @see #readExternal(ObjectInput)
38 */
39 public RemoteFileOutput() {
40 super();
41 }
42
43 /**
44 * Creates a new {@link RemoteFileOutput} instance, encapsulating a {@link FileOutputStream} so
45 * that it can be shared with other processes via RMI.
46 *
47 * @param socketFactory The socket factory.
48 * @param fout The {@link FileOutputStream}.
49 * @throws IOException if the operation fails.
50 */
51 public RemoteFileOutput(AFUNIXRMISocketFactory socketFactory, FileOutputStream fout)
52 throws IOException {
53 super(socketFactory, fout, fout.getFD(), RemoteFileDescriptorBase.MAGIC_VALUE_MASK
54 | RemoteFileDescriptorBase.BIT_WRITABLE);
55 }
56
57 /**
58 * Returns a FileOutputStream for the given instance. This either is the actual instance provided
59 * by the constructor or a new instance created from the file descriptor.
60 *
61 * @return The FileOutputStream.
62 * @throws IOException if the operation fails.
63 */
64 public FileOutputStream asFileOutputStream() throws IOException {
65 if ((getMagicValue() & RemoteFileDescriptorBase.BIT_WRITABLE) == 0) {
66 throw new IOException("FileDescriptor is not writable");
67 }
68
69 return resource.accumulateAndGet(null, (prev, x) -> {
70 if (prev != null) {
71 return prev;
72 }
73 FileDescriptor fd = getFileDescriptor();
74 if (!fd.valid()) {
75 throw new IllegalStateException("Invalid file descriptor");
76 }
77 return new FileOutputStream(fd) {
78 @Override
79 public synchronized void close() throws IOException {
80 RemoteFileOutput.this.close();
81 super.close();
82 }
83 };
84 });
85 }
86 }