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 }