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.Closeable;
21 import java.io.FileInputStream;
22 import java.io.IOException;
23 import java.io.ObjectInput;
24
25 /**
26 * A specialized subclass of {@link RemoteFileDescriptorBase}, specifically for
27 * {@link FileInputStream}s.
28 *
29 * @author Christian Kohlschütter
30 */
31 public final class RemoteFileInput extends RemoteFileDescriptorBase<FileInputStream> implements
32 Closeable {
33 private static final long serialVersionUID = 1L;
34
35 /**
36 * Creates an uninitialized instance; used for externalization.
37 *
38 * @see #readExternal(ObjectInput)
39 */
40 public RemoteFileInput() {
41 super();
42 }
43
44 /**
45 * Creates a new {@link RemoteFileInput} instance, encapsulating a {@link FileInputStream} so that
46 * it can be shared with other processes via RMI.
47 *
48 * @param socketFactory The socket factory.
49 * @param fin The {@link FileInputStream}.
50 * @throws IOException if the operation fails.
51 */
52 public RemoteFileInput(AFUNIXRMISocketFactory socketFactory, FileInputStream fin)
53 throws IOException {
54 super(socketFactory, fin, fin.getFD(), RemoteFileDescriptorBase.MAGIC_VALUE_MASK
55 | RemoteFileDescriptorBase.BIT_READABLE);
56 }
57
58 /**
59 * Returns a FileInputStream for the given instance. This either is the actual instance provided
60 * by the constructor or a new instance created from the file descriptor.
61 *
62 * @return The FileInputStream.
63 * @throws IOException if the operation fails.
64 */
65 public FileInputStream asFileInputStream() throws IOException {
66 if ((getMagicValue() & RemoteFileDescriptorBase.BIT_READABLE) == 0) {
67 throw new IOException("FileDescriptor is not readable");
68 }
69
70 return resource.accumulateAndGet(null, (prev, x) -> {
71 if (prev != null) {
72 return prev;
73 }
74 return new FileInputStream(getFileDescriptor()) {
75 @Override
76 public void close() throws IOException {
77 super.close();
78
79 synchronized (RemoteFileInput.this) {
80 RemoteFileInput.this.close();
81 }
82 }
83 };
84 });
85 }
86 }