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 // Android-added: Track fd owner to guard against accidental closure. http://b/110100358 58 // The owner on the libc side is an pointer-sized value that can be set to an arbitrary 59 // value (with 0 meaning 'unowned'). libcore chooses to use System.identityHashCode. 60 private long ownerId = NO_OWNER; 61 62 // Android-added: value of ownerId indicating that a FileDescriptor is unowned. 63 /** @hide */ 64 public static final long NO_OWNER = 0L; 65 66 /** 67 * Constructs an (invalid) FileDescriptor 68 * object. 69 */ FileDescriptor()70 public /**/ FileDescriptor() { 71 descriptor = -1; 72 } 73 FileDescriptor(int descriptor)74 private /* */ FileDescriptor(int descriptor) { 75 this.descriptor = descriptor; 76 } 77 78 /** 79 * A handle to the standard input stream. Usually, this file 80 * descriptor is not used directly, but rather via the input stream 81 * known as <code>System.in</code>. 82 * 83 * @see java.lang.System#in 84 */ 85 // Android-changed: Duplicates of FDs needed for RuntimeInit#redirectLogStreams 86 public static final FileDescriptor in = dupFd(0); 87 88 /** 89 * A handle to the standard output stream. Usually, this file 90 * descriptor is not used directly, but rather via the output stream 91 * known as <code>System.out</code>. 92 * @see java.lang.System#out 93 */ 94 // Android-changed: Duplicates of FDs needed for RuntimeInit#redirectLogStreams 95 public static final FileDescriptor out = dupFd(1); 96 97 /** 98 * A handle to the standard error stream. Usually, this file 99 * descriptor is not used directly, but rather via the output stream 100 * known as <code>System.err</code>. 101 * 102 * @see java.lang.System#err 103 */ 104 // Android-changed: Duplicates of FDs needed for RuntimeInit#redirectLogStreams 105 public static final FileDescriptor err = dupFd(2); 106 107 /** 108 * Tests if this file descriptor object is valid. 109 * 110 * @return <code>true</code> if the file descriptor object represents a 111 * valid, open file, socket, or other active I/O connection; 112 * <code>false</code> otherwise. 113 */ valid()114 public boolean valid() { 115 return descriptor != -1; 116 } 117 118 /** 119 * Force all system buffers to synchronize with the underlying 120 * device. This method returns after all modified data and 121 * attributes of this FileDescriptor have been written to the 122 * relevant device(s). In particular, if this FileDescriptor 123 * refers to a physical storage medium, such as a file in a file 124 * system, sync will not return until all in-memory modified copies 125 * of buffers associated with this FileDescriptor have been 126 * written to the physical medium. 127 * 128 * sync is meant to be used by code that requires physical 129 * storage (such as a file) to be in a known state For 130 * example, a class that provided a simple transaction facility 131 * might use sync to ensure that all changes to a file caused 132 * by a given transaction were recorded on a storage medium. 133 * 134 * sync only affects buffers downstream of this FileDescriptor. If 135 * any in-memory buffering is being done by the application (for 136 * example, by a BufferedOutputStream object), those buffers must 137 * be flushed into the FileDescriptor (for example, by invoking 138 * OutputStream.flush) before that data will be affected by sync. 139 * 140 * @exception SyncFailedException 141 * Thrown when the buffers cannot be flushed, 142 * or because the system cannot guarantee that all the 143 * buffers have been synchronized with physical media. 144 * @since JDK1.1 145 */ sync()146 public native void sync() throws SyncFailedException; 147 148 // Android-removed: initIDs not used to allow compile-time intialization 149 /* This routine initializes JNI field offsets for the class */ 150 //private static native void initIDs(); 151 152 // Android-added: Needed for framework to access descriptor value 153 /** 154 * Returns 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 */ getInt$()158 public final int getInt$() { 159 return descriptor; 160 } 161 162 // Android-added: Needed for framework to access descriptor value 163 /** 164 * Sets the int descriptor. It's highly unlikely you should be calling this. Please discuss 165 * your needs with a libcore maintainer before using this method. 166 * @hide internal use only 167 */ setInt$(int fd)168 public final void setInt$(int fd) { 169 this.descriptor = fd; 170 } 171 172 // BEGIN Android-added: Methods to enable ownership enforcement of Unix file descriptors. 173 /** 174 * Returns the owner ID of this FileDescriptor. It's highly unlikely you should be calling this. 175 * Please discuss your needs with a libcore maintainer before using this method. 176 * @hide internal use only 177 */ getOwnerId$()178 public long getOwnerId$() { 179 return this.ownerId; 180 } 181 182 /** 183 * Sets the owner ID of this FileDescriptor. The owner ID does not need to be unique, but it is 184 * assumed that clashes are rare. See bionic/include/android/fdsan.h for more details. 185 * 186 * It's highly unlikely you should be calling this. 187 * Please discuss your needs with a libcore maintainer before using this method. 188 * @param owner the owner ID of the Object that is responsible for closing this FileDescriptor 189 * @hide internal use only 190 */ setOwnerId$(long newOwnerId)191 public void setOwnerId$(long newOwnerId) { 192 this.ownerId = newOwnerId; 193 } 194 195 /** 196 * Returns a copy of this FileDescriptor, and sets this to an invalid state. 197 * @hide internal use only 198 */ release$()199 public FileDescriptor release$() { 200 FileDescriptor result = new FileDescriptor(); 201 result.descriptor = this.descriptor; 202 result.ownerId = this.ownerId; 203 this.descriptor = -1; 204 this.ownerId = FileDescriptor.NO_OWNER; 205 return result; 206 } 207 // END Android-added: Methods to enable ownership enforcement of Unix file descriptors. 208 209 /** 210 * @hide internal use only 211 */ 212 // Android-added: Needed for framework to test if it's a socket isSocket$()213 public boolean isSocket$() { 214 return isSocket(descriptor); 215 } 216 217 // Android-added: Needed for RuntimeInit#redirectLogStreams. dupFd(int fd)218 private static FileDescriptor dupFd(int fd) { 219 try { 220 return new FileDescriptor(Os.fcntlInt(new FileDescriptor(fd), F_DUPFD_CLOEXEC, 0)); 221 } catch (ErrnoException e) { 222 throw new RuntimeException(e); 223 } 224 } 225 isSocket(int descriptor)226 private static native boolean isSocket(int descriptor); 227 // Set up JavaIOFileDescriptorAccess in SharedSecrets 228 static { sun.misc.SharedSecrets.setJavaIOFileDescriptorAccess( new sun.misc.JavaIOFileDescriptorAccess() { public void set(FileDescriptor obj, int fd) { obj.descriptor = fd; } public int get(FileDescriptor obj) { return obj.descriptor; } public void setHandle(FileDescriptor obj, long handle) { throw new UnsupportedOperationException(); } public long getHandle(FileDescriptor obj) { throw new UnsupportedOperationException(); } } )229 sun.misc.SharedSecrets.setJavaIOFileDescriptorAccess( 230 new sun.misc.JavaIOFileDescriptorAccess() { 231 public void set(FileDescriptor obj, int fd) { 232 obj.descriptor = fd; 233 } 234 235 public int get(FileDescriptor obj) { 236 return obj.descriptor; 237 } 238 239 public void setHandle(FileDescriptor obj, long handle) { 240 throw new UnsupportedOperationException(); 241 } 242 243 public long getHandle(FileDescriptor obj) { 244 throw new UnsupportedOperationException(); 245 } 246 } 247 ); 248 } 249 // Android-removed: Removed method required for parents reference counting 250 } 251