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