1 /* 2 * Copyright (c) 2018, 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 jdk.internal.access.JavaIOFileDescriptorAccess; 29 import jdk.internal.access.SharedSecrets; 30 import jdk.internal.ref.CleanerFactory; 31 import jdk.internal.ref.PhantomCleanable; 32 33 import java.lang.ref.Cleaner; 34 35 /** 36 * Cleanable for a FileDescriptor when it becomes phantom reachable. 37 * For regular fds on Unix and regular handles on Windows 38 * register a cleanup if fd != -1 or handle != -1. 39 * <p> 40 * Subclassed from {@code PhantomCleanable} so that {@code clear} can be 41 * called to disable the cleanup when the handle is closed by any means other 42 * than calling {@link FileDescriptor#close}. 43 * Otherwise, it might incorrectly close the handle after it has been reused. 44 */ 45 final class FileCleanable extends PhantomCleanable<FileDescriptor> { 46 47 // Access to FileDescriptor private fields; 48 // avoids making fd and handle package private 49 private static final JavaIOFileDescriptorAccess fdAccess = 50 SharedSecrets.getJavaIOFileDescriptorAccess(); 51 52 /* 53 * Raw close of the file fd and/or handle. 54 * Used only for last chance cleanup. 55 */ 56 private static native void cleanupClose0(int fd, long handle) throws IOException; 57 58 // The raw fd to close 59 private final int fd; 60 61 // The handle to close 62 private final long handle; 63 64 /** 65 * Register a Cleanable with the FileDescriptor 66 * if the FileDescriptor is non-null and valid. 67 * @implNote 68 * A exception (OutOfMemoryException) will leave the FileDescriptor 69 * having allocated resources and leak the fd/handle. 70 * 71 * @param fdo the FileDescriptor; may be null 72 */ 73 static void register(FileDescriptor fdo) { 74 if (fdo != null && fdo.valid()) { 75 int fd = fdAccess.get(fdo); 76 long handle = fdAccess.getHandle(fdo); 77 fdo.registerCleanup(new FileCleanable(fdo, CleanerFactory.cleaner(), fd, handle)); 78 } 79 } 80 81 /** 82 * Unregister a Cleanable from the FileDescriptor. 83 * @param fdo the FileDescriptor; may be null 84 */ 85 static void unregister(FileDescriptor fdo) { 86 if (fdo != null) { 87 fdo.unregisterCleanup(); 88 } 89 } 90 91 /** 92 * Constructor for a phantom cleanable reference. 93 * 94 * @param obj the object to monitor 95 * @param cleaner the cleaner 96 * @param fd file descriptor to close 97 * @param handle handle to close 98 */ 99 private FileCleanable(FileDescriptor obj, Cleaner cleaner, int fd, long handle) { 100 super(obj, cleaner); 101 this.fd = fd; 102 this.handle = handle; 103 } 104 105 /** 106 * Close the native handle or fd. 107 */ 108 @Override 109 protected void performCleanup() { 110 try { 111 cleanupClose0(fd, handle); 112 } catch (IOException ioe) { 113 throw new UncheckedIOException("close", ioe); 114 } 115 } 116 }