1 /* 2 * Copyright (c) 1994, 2013, 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 java.nio.channels.FileChannel; 29 import sun.nio.ch.FileChannelImpl; 30 31 32 /** 33 * A <code>FileInputStream</code> obtains input bytes 34 * from a file in a file system. What files 35 * are available depends on the host environment. 36 * 37 * <p><code>FileInputStream</code> is meant for reading streams of raw bytes 38 * such as image data. For reading streams of characters, consider using 39 * <code>FileReader</code>. 40 * 41 * @author Arthur van Hoff 42 * @see java.io.File 43 * @see java.io.FileDescriptor 44 * @see java.io.FileOutputStream 45 * @see java.nio.file.Files#newInputStream 46 * @since 1.0 47 */ 48 public 49 class FileInputStream extends InputStream 50 { 51 /* File Descriptor - handle to the open file */ 52 private final FileDescriptor fd; 53 54 /** 55 * The path of the referenced file 56 * (null if the stream is created with a file descriptor) 57 */ 58 private final String path; 59 60 private FileChannel channel = null; 61 62 private final Object closeLock = new Object(); 63 private volatile boolean closed = false; 64 65 /** 66 * Creates a <code>FileInputStream</code> by 67 * opening a connection to an actual file, 68 * the file named by the path name <code>name</code> 69 * in the file system. A new <code>FileDescriptor</code> 70 * object is created to represent this file 71 * connection. 72 * <p> 73 * First, if there is a security 74 * manager, its <code>checkRead</code> method 75 * is called with the <code>name</code> argument 76 * as its argument. 77 * <p> 78 * If the named file does not exist, is a directory rather than a regular 79 * file, or for some other reason cannot be opened for reading then a 80 * <code>FileNotFoundException</code> is thrown. 81 * 82 * @param name the system-dependent file name. 83 * @exception FileNotFoundException if the file does not exist, 84 * is a directory rather than a regular file, 85 * or for some other reason cannot be opened for 86 * reading. 87 * @exception SecurityException if a security manager exists and its 88 * <code>checkRead</code> method denies read access 89 * to the file. 90 * @see java.lang.SecurityManager#checkRead(java.lang.String) 91 */ 92 public FileInputStream(String name) throws FileNotFoundException { 93 this(name != null ? new File(name) : null); 94 } 95 96 /** 97 * Creates a <code>FileInputStream</code> by 98 * opening a connection to an actual file, 99 * the file named by the <code>File</code> 100 * object <code>file</code> in the file system. 101 * A new <code>FileDescriptor</code> object 102 * is created to represent this file connection. 103 * <p> 104 * First, if there is a security manager, 105 * its <code>checkRead</code> method is called 106 * with the path represented by the <code>file</code> 107 * argument as its argument. 108 * <p> 109 * If the named file does not exist, is a directory rather than a regular 110 * file, or for some other reason cannot be opened for reading then a 111 * <code>FileNotFoundException</code> is thrown. 112 * 113 * @param file the file to be opened for reading. 114 * @exception FileNotFoundException if the file does not exist, 115 * is a directory rather than a regular file, 116 * or for some other reason cannot be opened for 117 * reading. 118 * @exception SecurityException if a security manager exists and its 119 * <code>checkRead</code> method denies read access to the file. 120 * @see java.io.File#getPath() 121 * @see java.lang.SecurityManager#checkRead(java.lang.String) 122 */ 123 public FileInputStream(File file) throws FileNotFoundException { 124 String name = (file != null ? file.getPath() : null); 125 SecurityManager security = System.getSecurityManager(); 126 if (security != null) { 127 security.checkRead(name); 128 } 129 if (name == null) { 130 throw new NullPointerException(); 131 } 132 if (file.isInvalid()) { 133 throw new FileNotFoundException("Invalid file path"); 134 } 135 fd = new FileDescriptor(); 136 fd.attach(this); 137 path = name; 138 open(name); 139 } 140 141 /** 142 * Creates a <code>FileInputStream</code> by using the file descriptor 143 * <code>fdObj</code>, which represents an existing connection to an 144 * actual file in the file system. 145 * <p> 146 * If there is a security manager, its <code>checkRead</code> method is 147 * called with the file descriptor <code>fdObj</code> as its argument to 148 * see if it's ok to read the file descriptor. If read access is denied 149 * to the file descriptor a <code>SecurityException</code> is thrown. 150 * <p> 151 * If <code>fdObj</code> is null then a <code>NullPointerException</code> 152 * is thrown. 153 * <p> 154 * This constructor does not throw an exception if <code>fdObj</code> 155 * is {@link java.io.FileDescriptor#valid() invalid}. 156 * However, if the methods are invoked on the resulting stream to attempt 157 * I/O on the stream, an <code>IOException</code> is thrown. 158 * 159 * @param fdObj the file descriptor to be opened for reading. 160 * @throws SecurityException if a security manager exists and its 161 * <code>checkRead</code> method denies read access to the 162 * file descriptor. 163 * @see SecurityManager#checkRead(java.io.FileDescriptor) 164 */ 165 public FileInputStream(FileDescriptor fdObj) { 166 SecurityManager security = System.getSecurityManager(); 167 if (fdObj == null) { 168 throw new NullPointerException(); 169 } 170 if (security != null) { 171 security.checkRead(fdObj); 172 } 173 fd = fdObj; 174 path = null; 175 176 /* 177 * FileDescriptor is being shared by streams. 178 * Register this stream with FileDescriptor tracker. 179 */ 180 fd.attach(this); 181 } 182 183 /** 184 * Opens the specified file for reading. 185 * @param name the name of the file 186 */ 187 private native void open(String name) throws FileNotFoundException; 188 189 /** 190 * Reads a byte of data from this input stream. This method blocks 191 * if no input is yet available. 192 * 193 * @return the next byte of data, or <code>-1</code> if the end of the 194 * file is reached. 195 * @exception IOException if an I/O error occurs. 196 */ 197 public int read() throws IOException { 198 return read0(); 199 } 200 201 private native int read0() throws IOException; 202 203 /** 204 * Reads a subarray as a sequence of bytes. 205 * @param b the data to be written 206 * @param off the start offset in the data 207 * @param len the number of bytes that are written 208 * @exception IOException If an I/O error has occurred. 209 */ 210 private native int readBytes(byte b[], int off, int len) throws IOException; 211 212 /** 213 * Reads up to <code>b.length</code> bytes of data from this input 214 * stream into an array of bytes. This method blocks until some input 215 * is available. 216 * 217 * @param b the buffer into which the data is read. 218 * @return the total number of bytes read into the buffer, or 219 * <code>-1</code> if there is no more data because the end of 220 * the file has been reached. 221 * @exception IOException if an I/O error occurs. 222 */ 223 public int read(byte b[]) throws IOException { 224 return readBytes(b, 0, b.length); 225 } 226 227 /** 228 * Reads up to <code>len</code> bytes of data from this input stream 229 * into an array of bytes. If <code>len</code> is not zero, the method 230 * blocks until some input is available; otherwise, no 231 * bytes are read and <code>0</code> is returned. 232 * 233 * @param b the buffer into which the data is read. 234 * @param off the start offset in the destination array <code>b</code> 235 * @param len the maximum number of bytes read. 236 * @return the total number of bytes read into the buffer, or 237 * <code>-1</code> if there is no more data because the end of 238 * the file has been reached. 239 * @exception NullPointerException If <code>b</code> is <code>null</code>. 240 * @exception IndexOutOfBoundsException If <code>off</code> is negative, 241 * <code>len</code> is negative, or <code>len</code> is greater than 242 * <code>b.length - off</code> 243 * @exception IOException if an I/O error occurs. 244 */ 245 public int read(byte b[], int off, int len) throws IOException { 246 return readBytes(b, off, len); 247 } 248 249 /** 250 * Skips over and discards <code>n</code> bytes of data from the 251 * input stream. 252 * 253 * <p>The <code>skip</code> method may, for a variety of 254 * reasons, end up skipping over some smaller number of bytes, 255 * possibly <code>0</code>. If <code>n</code> is negative, the method 256 * will try to skip backwards. In case the backing file does not support 257 * backward skip at its current position, an <code>IOException</code> is 258 * thrown. The actual number of bytes skipped is returned. If it skips 259 * forwards, it returns a positive value. If it skips backwards, it 260 * returns a negative value. 261 * 262 * <p>This method may skip more bytes than what are remaining in the 263 * backing file. This produces no exception and the number of bytes skipped 264 * may include some number of bytes that were beyond the EOF of the 265 * backing file. Attempting to read from the stream after skipping past 266 * the end will result in -1 indicating the end of the file. 267 * 268 * @param n the number of bytes to be skipped. 269 * @return the actual number of bytes skipped. 270 * @exception IOException if n is negative, if the stream does not 271 * support seek, or if an I/O error occurs. 272 */ 273 public native long skip(long n) throws IOException; 274 275 /** 276 * Returns an estimate of the number of remaining bytes that can be read (or 277 * skipped over) from this input stream without blocking by the next 278 * invocation of a method for this input stream. Returns 0 when the file 279 * position is beyond EOF. The next invocation might be the same thread 280 * or another thread. A single read or skip of this many bytes will not 281 * block, but may read or skip fewer bytes. 282 * 283 * <p> In some cases, a non-blocking read (or skip) may appear to be 284 * blocked when it is merely slow, for example when reading large 285 * files over slow networks. 286 * 287 * @return an estimate of the number of remaining bytes that can be read 288 * (or skipped over) from this input stream without blocking. 289 * @exception IOException if this file input stream has been closed by calling 290 * {@code close} or an I/O error occurs. 291 */ 292 public native int available() throws IOException; 293 294 /** 295 * Closes this file input stream and releases any system resources 296 * associated with the stream. 297 * 298 * <p> If this stream has an associated channel then the channel is closed 299 * as well. 300 * 301 * @exception IOException if an I/O error occurs. 302 * 303 * @revised 1.4 304 * @spec JSR-51 305 */ 306 public void close() throws IOException { 307 synchronized (closeLock) { 308 if (closed) { 309 return; 310 } 311 closed = true; 312 } 313 if (channel != null) { 314 channel.close(); 315 } 316 317 fd.closeAll(new Closeable() { 318 public void close() throws IOException { 319 close0(); 320 } 321 }); 322 } 323 324 /** 325 * Returns the <code>FileDescriptor</code> 326 * object that represents the connection to 327 * the actual file in the file system being 328 * used by this <code>FileInputStream</code>. 329 * 330 * @return the file descriptor object associated with this stream. 331 * @exception IOException if an I/O error occurs. 332 * @see java.io.FileDescriptor 333 */ 334 public final FileDescriptor getFD() throws IOException { 335 if (fd != null) { 336 return fd; 337 } 338 throw new IOException(); 339 } 340 341 /** 342 * Returns the unique {@link java.nio.channels.FileChannel FileChannel} 343 * object associated with this file input stream. 344 * 345 * <p> The initial {@link java.nio.channels.FileChannel#position() 346 * position} of the returned channel will be equal to the 347 * number of bytes read from the file so far. Reading bytes from this 348 * stream will increment the channel's position. Changing the channel's 349 * position, either explicitly or by reading, will change this stream's 350 * file position. 351 * 352 * @return the file channel associated with this file input stream 353 * 354 * @since 1.4 355 * @spec JSR-51 356 */ 357 public FileChannel getChannel() { 358 synchronized (this) { 359 if (channel == null) { 360 channel = FileChannelImpl.open(fd, path, true, false, this); 361 } 362 return channel; 363 } 364 } 365 366 private static native void initIDs(); 367 368 private native void close0() throws IOException; 369 370 static { 371 initIDs(); 372 } 373 374 /** 375 * Ensures that the <code>close</code> method of this file input stream is 376 * called when there are no more references to it. 377 * 378 * @exception IOException if an I/O error occurs. 379 * @see java.io.FileInputStream#close() 380 */ 381 protected void finalize() throws IOException { 382 if ((fd != null) && (fd != FileDescriptor.in)) { 383 /* if fd is shared, the references in FileDescriptor 384 * will ensure that finalizer is only called when 385 * safe to do so. All references using the fd have 386 * become unreachable. We can call close() 387 */ 388 close(); 389 } 390 } 391 }