1 /* 2 * Copyright (c) 1994, 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 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 JDK1.0 47 */ 48 public 49 class FileInputStream extends InputStream 50 { 51 /* File Descriptor - handle to the open file */ 52 private final FileDescriptor fd; 53 54 private FileChannel channel = null; 55 56 private final Object closeLock = new Object(); 57 private volatile boolean closed = false; 58 59 private static final ThreadLocal<Boolean> runningFinalize = 60 new ThreadLocal<>(); 61 62 private static boolean isRunningFinalize() { 63 Boolean val; 64 if ((val = runningFinalize.get()) != null) 65 return val.booleanValue(); 66 return false; 67 } 68 69 /** 70 * Creates a <code>FileInputStream</code> by 71 * opening a connection to an actual file, 72 * the file named by the path name <code>name</code> 73 * in the file system. A new <code>FileDescriptor</code> 74 * object is created to represent this file 75 * connection. 76 * <p> 77 * First, if there is a security 78 * manager, its <code>checkRead</code> method 79 * is called with the <code>name</code> argument 80 * as its argument. 81 * <p> 82 * If the named file does not exist, is a directory rather than a regular 83 * file, or for some other reason cannot be opened for reading then a 84 * <code>FileNotFoundException</code> is thrown. 85 * 86 * @param name the system-dependent file name. 87 * @exception FileNotFoundException if the file does not exist, 88 * is a directory rather than a regular file, 89 * or for some other reason cannot be opened for 90 * reading. 91 * @exception SecurityException if a security manager exists and its 92 * <code>checkRead</code> method denies read access 93 * to the file. 94 * @see java.lang.SecurityManager#checkRead(java.lang.String) 95 */ 96 public FileInputStream(String name) throws FileNotFoundException { 97 this(name != null ? new File(name) : null); 98 } 99 100 /** 101 * Creates a <code>FileInputStream</code> by 102 * opening a connection to an actual file, 103 * the file named by the <code>File</code> 104 * object <code>file</code> in the file system. 105 * A new <code>FileDescriptor</code> object 106 * is created to represent this file connection. 107 * <p> 108 * First, if there is a security manager, 109 * its <code>checkRead</code> method is called 110 * with the path represented by the <code>file</code> 111 * argument as its argument. 112 * <p> 113 * If the named file does not exist, is a directory rather than a regular 114 * file, or for some other reason cannot be opened for reading then a 115 * <code>FileNotFoundException</code> is thrown. 116 * 117 * @param file the file to be opened for reading. 118 * @exception FileNotFoundException if the file does not exist, 119 * is a directory rather than a regular file, 120 * or for some other reason cannot be opened for 121 * reading. 122 * @exception SecurityException if a security manager exists and its 123 * <code>checkRead</code> method denies read access to the file. 124 * @see java.io.File#getPath() 125 * @see java.lang.SecurityManager#checkRead(java.lang.String) 126 */ 127 public FileInputStream(File file) throws FileNotFoundException { 128 String name = (file != null ? file.getPath() : null); 129 SecurityManager security = System.getSecurityManager(); 130 if (security != null) { 131 security.checkRead(name); 132 } 133 if (name == null) { 134 throw new NullPointerException(); 135 } 136 fd = new FileDescriptor(); 137 fd.incrementAndGetUseCount(); 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; 174 175 /* 176 * FileDescriptor is being shared by streams. 177 * Ensure that it's GC'ed only when all the streams/channels are done 178 * using it. 179 */ 180 fd.incrementAndGetUseCount(); 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 native int read() throws IOException; 198 199 /** 200 * Reads a subarray as a sequence of bytes. 201 * @param b the data to be written 202 * @param off the start offset in the data 203 * @param len the number of bytes that are written 204 * @exception IOException If an I/O error has occurred. 205 */ 206 private native int readBytes(byte b[], int off, int len) throws IOException; 207 208 /** 209 * Reads up to <code>b.length</code> bytes of data from this input 210 * stream into an array of bytes. This method blocks until some input 211 * is available. 212 * 213 * @param b the buffer into which the data is read. 214 * @return the total number of bytes read into the buffer, or 215 * <code>-1</code> if there is no more data because the end of 216 * the file has been reached. 217 * @exception IOException if an I/O error occurs. 218 */ 219 public int read(byte b[]) throws IOException { 220 return readBytes(b, 0, b.length); 221 } 222 223 /** 224 * Reads up to <code>len</code> bytes of data from this input stream 225 * into an array of bytes. If <code>len</code> is not zero, the method 226 * blocks until some input is available; otherwise, no 227 * bytes are read and <code>0</code> is returned. 228 * 229 * @param b the buffer into which the data is read. 230 * @param off the start offset in the destination array <code>b</code> 231 * @param len the maximum number of bytes read. 232 * @return the total number of bytes read into the buffer, or 233 * <code>-1</code> if there is no more data because the end of 234 * the file has been reached. 235 * @exception NullPointerException If <code>b</code> is <code>null</code>. 236 * @exception IndexOutOfBoundsException If <code>off</code> is negative, 237 * <code>len</code> is negative, or <code>len</code> is greater than 238 * <code>b.length - off</code> 239 * @exception IOException if an I/O error occurs. 240 */ 241 public int read(byte b[], int off, int len) throws IOException { 242 return readBytes(b, off, len); 243 } 244 245 /** 246 * Skips over and discards <code>n</code> bytes of data from the 247 * input stream. 248 * 249 * <p>The <code>skip</code> method may, for a variety of 250 * reasons, end up skipping over some smaller number of bytes, 251 * possibly <code>0</code>. If <code>n</code> is negative, an 252 * <code>IOException</code> is thrown, even though the <code>skip</code> 253 * method of the {@link InputStream} superclass does nothing in this case. 254 * The actual number of bytes skipped is returned. 255 * 256 * <p>This method may skip more bytes than are remaining in the backing 257 * file. This produces no exception and the number of bytes skipped 258 * may include some number of bytes that were beyond the EOF of the 259 * backing file. Attempting to read from the stream after skipping past 260 * the end will result in -1 indicating the end of the file. 261 * 262 * @param n the number of bytes to be skipped. 263 * @return the actual number of bytes skipped. 264 * @exception IOException if n is negative, if the stream does not 265 * support seek, or if an I/O error occurs. 266 */ 267 public native long skip(long n) throws IOException; 268 269 /** 270 * Returns an estimate of the number of remaining bytes that can be read (or 271 * skipped over) from this input stream without blocking by the next 272 * invocation of a method for this input stream. The next invocation might be 273 * the same thread or another thread. A single read or skip of this 274 * many bytes will not block, but may read or skip fewer bytes. 275 * 276 * <p> In some cases, a non-blocking read (or skip) may appear to be 277 * blocked when it is merely slow, for example when reading large 278 * files over slow networks. 279 * 280 * @return an estimate of the number of remaining bytes that can be read 281 * (or skipped over) from this input stream without blocking. 282 * @exception IOException if this file input stream has been closed by calling 283 * {@code close} or an I/O error occurs. 284 */ 285 public native int available() throws IOException; 286 287 /** 288 * Closes this file input stream and releases any system resources 289 * associated with the stream. 290 * 291 * <p> If this stream has an associated channel then the channel is closed 292 * as well. 293 * 294 * @exception IOException if an I/O error occurs. 295 * 296 * @revised 1.4 297 * @spec JSR-51 298 */ 299 public void close() throws IOException { 300 synchronized (closeLock) { 301 if (closed) { 302 return; 303 } 304 closed = true; 305 } 306 if (channel != null) { 307 /* 308 * Decrement the FD use count associated with the channel 309 * The use count is incremented whenever a new channel 310 * is obtained from this stream. 311 */ 312 fd.decrementAndGetUseCount(); 313 channel.close(); 314 } 315 316 /* 317 * Decrement the FD use count associated with this stream 318 */ 319 int useCount = fd.decrementAndGetUseCount(); 320 321 /* 322 * If FileDescriptor is still in use by another stream, the finalizer 323 * will not close it. 324 */ 325 if ((useCount <= 0) || !isRunningFinalize()) { 326 close0(); 327 } 328 } 329 330 /** 331 * Returns the <code>FileDescriptor</code> 332 * object that represents the connection to 333 * the actual file in the file system being 334 * used by this <code>FileInputStream</code>. 335 * 336 * @return the file descriptor object associated with this stream. 337 * @exception IOException if an I/O error occurs. 338 * @see java.io.FileDescriptor 339 */ 340 public final FileDescriptor getFD() throws IOException { 341 if (fd != null) return fd; 342 throw new IOException(); 343 } 344 345 /** 346 * Returns the unique {@link java.nio.channels.FileChannel FileChannel} 347 * object associated with this file input stream. 348 * 349 * <p> The initial {@link java.nio.channels.FileChannel#position() 350 * </code>position<code>} of the returned channel will be equal to the 351 * number of bytes read from the file so far. Reading bytes from this 352 * stream will increment the channel's position. Changing the channel's 353 * position, either explicitly or by reading, will change this stream's 354 * file position. 355 * 356 * @return the file channel associated with this file input stream 357 * 358 * @since 1.4 359 * @spec JSR-51 360 */ 361 public FileChannel getChannel() { 362 synchronized (this) { 363 if (channel == null) { 364 channel = FileChannelImpl.open(fd, true, false, this); 365 366 /* 367 * Increment fd's use count. Invoking the channel's close() 368 * method will result in decrementing the use count set for 369 * the channel. 370 */ 371 fd.incrementAndGetUseCount(); 372 } 373 return channel; 374 } 375 } 376 377 private static native void initIDs(); 378 379 private native void close0() throws IOException; 380 381 static { 382 initIDs(); 383 } 384 385 /** 386 * Ensures that the <code>close</code> method of this file input stream is 387 * called when there are no more references to it. 388 * 389 * @exception IOException if an I/O error occurs. 390 * @see java.io.FileInputStream#close() 391 */ 392 protected void finalize() throws IOException { 393 if ((fd != null) && (fd != FileDescriptor.in)) { 394 395 /* 396 * Finalizer should not release the FileDescriptor if another 397 * stream is still using it. If the user directly invokes 398 * close() then the FileDescriptor is also released. 399 */ 400 runningFinalize.set(Boolean.TRUE); 401 try { 402 close(); 403 } finally { 404 runningFinalize.set(Boolean.FALSE); 405 } 406 } 407 } 408 }