1 /* 2 * Copyright (c) 1995, 2011, 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 android.system.ErrnoException; 29 import android.system.Os; 30 import static android.system.OsConstants.F_DUPFD_CLOEXEC; 31 32 import java.util.concurrent.atomic.AtomicInteger; 33 34 /** 35 * Instances of the file descriptor class serve as an opaque handle 36 * to the underlying machine-specific structure representing an open 37 * file, an open socket, or another source or sink of bytes. The 38 * main practical use for a file descriptor is to create a 39 * <code>FileInputStream</code> or <code>FileOutputStream</code> to 40 * contain it. 41 * <p> 42 * Applications should not create their own file descriptors. 43 * 44 * @author Pavani Diwanji 45 * @see java.io.FileInputStream 46 * @see java.io.FileOutputStream 47 * @since JDK1.0 48 */ 49 // Android-changed: Removed parent reference counting. Creator is responsible for closing 50 // the file descriptor. 51 public final class FileDescriptor { 52 53 // Android-changed: Renamed fd to descriptor to avoid issues with JNI/reflection 54 // fetching the descriptor value. 55 private int descriptor; 56 57 /** 58 * Constructs an (invalid) FileDescriptor 59 * object. 60 */ 61 public /**/ FileDescriptor() { 62 descriptor = -1; 63 } 64 65 private /* */ FileDescriptor(int descriptor) { 66 this.descriptor = descriptor; 67 } 68 69 /** 70 * A handle to the standard input stream. Usually, this file 71 * descriptor is not used directly, but rather via the input stream 72 * known as <code>System.in</code>. 73 * 74 * @see java.lang.System#in 75 */ 76 // Android-changed: Duplicates of FDs needed for RuntimeInit#redirectLogStreams 77 public static final FileDescriptor in = dupFd(0); 78 79 /** 80 * A handle to the standard output stream. Usually, this file 81 * descriptor is not used directly, but rather via the output stream 82 * known as <code>System.out</code>. 83 * @see java.lang.System#out 84 */ 85 // Android-changed: Duplicates of FDs needed for RuntimeInit#redirectLogStreams 86 public static final FileDescriptor out = dupFd(1); 87 88 /** 89 * A handle to the standard error stream. Usually, this file 90 * descriptor is not used directly, but rather via the output stream 91 * known as <code>System.err</code>. 92 * 93 * @see java.lang.System#err 94 */ 95 // Android-changed: Duplicates of FDs needed for RuntimeInit#redirectLogStreams 96 public static final FileDescriptor err = dupFd(2); 97 98 /** 99 * Tests if this file descriptor object is valid. 100 * 101 * @return <code>true</code> if the file descriptor object represents a 102 * valid, open file, socket, or other active I/O connection; 103 * <code>false</code> otherwise. 104 */ 105 public boolean valid() { 106 return descriptor != -1; 107 } 108 109 /** 110 * Force all system buffers to synchronize with the underlying 111 * device. This method returns after all modified data and 112 * attributes of this FileDescriptor have been written to the 113 * relevant device(s). In particular, if this FileDescriptor 114 * refers to a physical storage medium, such as a file in a file 115 * system, sync will not return until all in-memory modified copies 116 * of buffers associated with this FileDescriptor have been 117 * written to the physical medium. 118 * 119 * sync is meant to be used by code that requires physical 120 * storage (such as a file) to be in a known state For 121 * example, a class that provided a simple transaction facility 122 * might use sync to ensure that all changes to a file caused 123 * by a given transaction were recorded on a storage medium. 124 * 125 * sync only affects buffers downstream of this FileDescriptor. If 126 * any in-memory buffering is being done by the application (for 127 * example, by a BufferedOutputStream object), those buffers must 128 * be flushed into the FileDescriptor (for example, by invoking 129 * OutputStream.flush) before that data will be affected by sync. 130 * 131 * @exception SyncFailedException 132 * Thrown when the buffers cannot be flushed, 133 * or because the system cannot guarantee that all the 134 * buffers have been synchronized with physical media. 135 * @since JDK1.1 136 */ 137 public native void sync() throws SyncFailedException; 138 139 // Android-removed: initIDs not used to allow compile-time intialization 140 /* This routine initializes JNI field offsets for the class */ 141 //private static native void initIDs(); 142 143 /** 144 * Returns the int descriptor. It's highly unlikely you should be calling this. Please discuss 145 * your needs with a libcore maintainer before using this method. 146 * @hide internal use only 147 */ 148 // Android-added: Needed for framework to access descriptor value 149 public final int getInt$() { 150 return descriptor; 151 } 152 153 /** 154 * Sets the int descriptor. It's highly unlikely you should be calling this. Please discuss 155 * your needs with a libcore maintainer before using this method. 156 * @hide internal use only 157 */ 158 // Android-added: Needed for framework to access descriptor value 159 public final void setInt$(int fd) { 160 this.descriptor = fd; 161 } 162 163 /** 164 * @hide internal use only 165 */ 166 // Android-added: Needed for framework to test if it's a socket 167 public boolean isSocket$() { 168 return isSocket(descriptor); 169 } 170 171 // Android-added: Needed for RuntimeInit#redirectLogStreams. 172 private static FileDescriptor dupFd(int fd) { 173 try { 174 return new FileDescriptor(Os.fcntlInt(new FileDescriptor(fd), F_DUPFD_CLOEXEC, 0)); 175 } catch (ErrnoException e) { 176 throw new RuntimeException(e); 177 } 178 } 179 180 private static native boolean isSocket(int descriptor); 181 // Set up JavaIOFileDescriptorAccess in SharedSecrets 182 static { 183 sun.misc.SharedSecrets.setJavaIOFileDescriptorAccess( 184 new sun.misc.JavaIOFileDescriptorAccess() { 185 public void set(FileDescriptor obj, int fd) { 186 obj.descriptor = fd; 187 } 188 189 public int get(FileDescriptor obj) { 190 return obj.descriptor; 191 } 192 193 public void setHandle(FileDescriptor obj, long handle) { 194 throw new UnsupportedOperationException(); 195 } 196 197 public long getHandle(FileDescriptor obj) { 198 throw new UnsupportedOperationException(); 199 } 200 } 201 ); 202 } 203 // Android-removed: Removed method required for parents reference counting 204 } 205