1 /*
2 * Copyright (c) 2000, 2025, 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 sun.nio.ch;
27
28 import java.io.FileDescriptor;
29 import java.io.IOException;
30
31 /**
32 * Allows different platforms to call different native methods
33 * for read and write operations.
34 */
35
36 abstract class NativeDispatcher {
37
38 abstract int read(FileDescriptor fd, long address, int len)
39 throws IOException;
40
41 /**
42 * Returns {@code true} if pread/pwrite needs to be synchronized with
43 * position sensitive methods.
44 */
45 boolean needsPositionLock() {
46 return false;
47 }
48
49 int pread(FileDescriptor fd, long address, int len, long position)
50 throws IOException
51 {
52 throw new IOException("Operation Unsupported");
53 }
54
55 abstract long readv(FileDescriptor fd, long address, int len)
56 throws IOException;
57
58 abstract int write(FileDescriptor fd, long address, int len)
59 throws IOException;
60
61 int pwrite(FileDescriptor fd, long address, int len, long position)
62 throws IOException
63 {
64 throw new IOException("Operation Unsupported");
65 }
66
67 abstract long writev(FileDescriptor fd, long address, int len)
68 throws IOException;
69
70 abstract void close(FileDescriptor fd) throws IOException;
71
72 /**
73 * Prepare the given file descriptor for closing. If a virtual thread is blocked
74 * on the file descriptor then it is unparked so that it stops polling. On Unix systems,
75 * if a platform thread is blocked on the file descriptor then the file descriptor is
76 * dup'ed to a special fd and the thread signalled so that the syscall fails with EINTR.
77 */
78 final void preClose(FileDescriptor fd, Thread reader, Thread writer) throws IOException {
79 if (reader != null && reader.isVirtual()) {
80 NativeThread.signal(reader); // unparks virtual thread
81 reader = null;
82 }
83 if (writer != null && writer.isVirtual()) {
84 NativeThread.signal(writer); // unparks virtual thread
85 writer = null;
86 }
87 // dup2 and signal platform threads
88 implPreClose(fd, reader, writer);
89 }
90
91 /**
92 * This method does nothing by default. On Unix systems the file descriptor is dup'ed
93 * to a special fd and native threads signalled.
94 */
95 void implPreClose(FileDescriptor fd, Thread reader, Thread writer) throws IOException {
96 // Do nothing by default; this is only needed on Unix
97 }
98
99 /**
100 * Duplicates a file descriptor.
101 * @param fd1 the file descriptor to duplicate
102 * @param fd2 the new file descriptor, the socket or file that it is connected
103 * to will be closed by this method
104 */
105 void dup(FileDescriptor fd1, FileDescriptor fd2) throws IOException {
106 throw new UnsupportedOperationException();
107 }
108 }