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.misc.JavaIOFileDescriptorAccess;
29 import jdk.internal.misc.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 }
117