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 import sun.misc.IoTrace;
31 import sun.misc.IoTraceContext;
32
33
34 /**
35 * A <code>FileInputStream</code> obtains input bytes
36 * from a file in a file system. What files
37 * are available depends on the host environment.
38 *
39 * <p><code>FileInputStream</code> is meant for reading streams of raw bytes
40 * such as image data. For reading streams of characters, consider using
41 * <code>FileReader</code>.
42 *
43 * @author Arthur van Hoff
44 * @see java.io.File
45 * @see java.io.FileDescriptor
46 * @see java.io.FileOutputStream
47 * @see java.nio.file.Files#newInputStream
48 * @since JDK1.0
49 */
50 public
51 class FileInputStream extends InputStream
52 {
53 /* File Descriptor - handle to the open file */
54 private final FileDescriptor fd;
55
56 /* The path of the referenced file (null if the stream is created with a file descriptor) */
57 private final String path;
58
59 private FileChannel channel = null;
60
61 private final Object closeLock = new Object();
62 private volatile boolean closed = false;
63
64 /**
65 * Creates a <code>FileInputStream</code> by
66 * opening a connection to an actual file,
67 * the file named by the path name <code>name</code>
68 * in the file system. A new <code>FileDescriptor</code>
69 * object is created to represent this file
70 * connection.
71 * <p>
72 * First, if there is a security
73 * manager, its <code>checkRead</code> method
74 * is called with the <code>name</code> argument
75 * as its argument.
76 * <p>
77 * If the named file does not exist, is a directory rather than a regular
78 * file, or for some other reason cannot be opened for reading then a
79 * <code>FileNotFoundException</code> is thrown.
80 *
81 * @param name the system-dependent file name.
82 * @exception FileNotFoundException if the file does not exist,
83 * is a directory rather than a regular file,
84 * or for some other reason cannot be opened for
85 * reading.
86 * @exception SecurityException if a security manager exists and its
87 * <code>checkRead</code> method denies read access
88 * to the file.
89 * @see java.lang.SecurityManager#checkRead(java.lang.String)
90 */
91 public FileInputStream(String name) throws FileNotFoundException {
92 this(name != null ? new File(name) : null);
93 }
94
95 /**
96 * Creates a <code>FileInputStream</code> by
97 * opening a connection to an actual file,
98 * the file named by the <code>File</code>
99 * object <code>file</code> in the file system.
100 * A new <code>FileDescriptor</code> object
101 * is created to represent this file connection.
102 * <p>
103 * First, if there is a security manager,
104 * its <code>checkRead</code> method is called
105 * with the path represented by the <code>file</code>
106 * argument as its argument.
107 * <p>
108 * If the named file does not exist, is a directory rather than a regular
109 * file, or for some other reason cannot be opened for reading then a
110 * <code>FileNotFoundException</code> is thrown.
111 *
112 * @param file the file to be opened for reading.
113 * @exception FileNotFoundException if the file does not exist,
114 * is a directory rather than a regular file,
115 * or for some other reason cannot be opened for
116 * reading.
117 * @exception SecurityException if a security manager exists and its
118 * <code>checkRead</code> method denies read access to the file.
119 * @see java.io.File#getPath()
120 * @see java.lang.SecurityManager#checkRead(java.lang.String)
121 */
122 public FileInputStream(File file) throws FileNotFoundException {
123 String name = (file != null ? file.getPath() : null);
124 SecurityManager security = System.getSecurityManager();
125 if (security != null) {
126 security.checkRead(name);
127 }
128 if (name == null) {
129 throw new NullPointerException();
130 }
131 fd = new FileDescriptor();
132 fd.attach(this);
133 this.path = name;
134 open(name);
135 }
136
137 /**
138 * Creates a <code>FileInputStream</code> by using the file descriptor
139 * <code>fdObj</code>, which represents an existing connection to an
140 * actual file in the file system.
141 * <p>
142 * If there is a security manager, its <code>checkRead</code> method is
143 * called with the file descriptor <code>fdObj</code> as its argument to
144 * see if it's ok to read the file descriptor. If read access is denied
145 * to the file descriptor a <code>SecurityException</code> is thrown.
146 * <p>
147 * If <code>fdObj</code> is null then a <code>NullPointerException</code>
148 * is thrown.
149 * <p>
150 * This constructor does not throw an exception if <code>fdObj</code>
151 * is {@link java.io.FileDescriptor#valid() invalid}.
152 * However, if the methods are invoked on the resulting stream to attempt
153 * I/O on the stream, an <code>IOException</code> is thrown.
154 *
155 * @param fdObj the file descriptor to be opened for reading.
156 * @throws SecurityException if a security manager exists and its
157 * <code>checkRead</code> method denies read access to the
158 * file descriptor.
159 * @see SecurityManager#checkRead(java.io.FileDescriptor)
160 */
161 public FileInputStream(FileDescriptor fdObj) {
162 SecurityManager security = System.getSecurityManager();
163 if (fdObj == null) {
164 throw new NullPointerException();
165 }
166 if (security != null) {
167 security.checkRead(fdObj);
168 }
169 fd = fdObj;
170 path = null;
171
172 /*
173 * FileDescriptor is being shared by streams.
174 * Register this stream with FileDescriptor tracker.
175 */
176 fd.attach(this);
177 }
178
179 /**
180 * Opens the specified file for reading.
181 * @param name the name of the file
182 */
183 private native void open(String name) throws FileNotFoundException;
184
185 /**
186 * Reads a byte of data from this input stream. This method blocks
187 * if no input is yet available.
188 *
189 * @return the next byte of data, or <code>-1</code> if the end of the
190 * file is reached.
191 * @exception IOException if an I/O error occurs.
192 */
193 public int read() throws IOException {
194 IoTraceContext traceContext = IoTrace.fileReadBegin(path);
195 int b = 0;
196 try {
197 b = read0();
198 } finally {
199 IoTrace.fileReadEnd(traceContext, b == -1 ? 0 : 1);
200 }
201 return b;
202 }
203
204 private native int read0() throws IOException;
205
206 /**
207 * Reads a subarray as a sequence of bytes.
208 * @param b the data to be written
209 * @param off the start offset in the data
210 * @param len the number of bytes that are written
211 * @exception IOException If an I/O error has occurred.
212 */
213 private native int readBytes(byte b[], int off, int len) throws IOException;
214
215 /**
216 * Reads up to <code>b.length</code> bytes of data from this input
217 * stream into an array of bytes. This method blocks until some input
218 * is available.
219 *
220 * @param b the buffer into which the data is read.
221 * @return the total number of bytes read into the buffer, or
222 * <code>-1</code> if there is no more data because the end of
223 * the file has been reached.
224 * @exception IOException if an I/O error occurs.
225 */
226 public int read(byte b[]) throws IOException {
227 IoTraceContext traceContext = IoTrace.fileReadBegin(path);
228 int bytesRead = 0;
229 try {
230 bytesRead = readBytes(b, 0, b.length);
231 } finally {
232 IoTrace.fileReadEnd(traceContext, bytesRead);
233 }
234 return bytesRead;
235 }
236
237 /**
238 * Reads up to <code>len</code> bytes of data from this input stream
239 * into an array of bytes. If <code>len</code> is not zero, the method
240 * blocks until some input is available; otherwise, no
241 * bytes are read and <code>0</code> is returned.
242 *
243 * @param b the buffer into which the data is read.
244 * @param off the start offset in the destination array <code>b</code>
245 * @param len the maximum number of bytes read.
246 * @return the total number of bytes read into the buffer, or
247 * <code>-1</code> if there is no more data because the end of
248 * the file has been reached.
249 * @exception NullPointerException If <code>b</code> is <code>null</code>.
250 * @exception IndexOutOfBoundsException If <code>off</code> is negative,
251 * <code>len</code> is negative, or <code>len</code> is greater than
252 * <code>b.length - off</code>
253 * @exception IOException if an I/O error occurs.
254 */
255 public int read(byte b[], int off, int len) throws IOException {
256 IoTraceContext traceContext = IoTrace.fileReadBegin(path);
257 int bytesRead = 0;
258 try {
259 bytesRead = readBytes(b, off, len);
260 } finally {
261 IoTrace.fileReadEnd(traceContext, bytesRead);
262 }
263 return bytesRead;
264 }
265
266 /**
267 * Skips over and discards <code>n</code> bytes of data from the
268 * input stream.
269 *
270 * <p>The <code>skip</code> method may, for a variety of
271 * reasons, end up skipping over some smaller number of bytes,
272 * possibly <code>0</code>. If <code>n</code> is negative, an
273 * <code>IOException</code> is thrown, even though the <code>skip</code>
274 * method of the {@link InputStream} superclass does nothing in this case.
275 * The actual number of bytes skipped is returned.
276 *
277 * <p>This method may skip more bytes than are remaining in the backing
278 * file. This produces no exception and the number of bytes skipped
279 * may include some number of bytes that were beyond the EOF of the
280 * backing file. Attempting to read from the stream after skipping past
281 * the end will result in -1 indicating the end of the file.
282 *
283 * @param n the number of bytes to be skipped.
284 * @return the actual number of bytes skipped.
285 * @exception IOException if n is negative, if the stream does not
286 * support seek, or if an I/O error occurs.
287 */
288 public native long skip(long n) throws IOException;
289
290 /**
291 * Returns an estimate of the number of remaining bytes that can be read (or
292 * skipped over) from this input stream without blocking by the next
293 * invocation of a method for this input stream. The next invocation might be
294 * the same thread or another thread. A single read or skip of this
295 * many bytes will not block, but may read or skip fewer bytes.
296 *
297 * <p> In some cases, a non-blocking read (or skip) may appear to be
298 * blocked when it is merely slow, for example when reading large
299 * files over slow networks.
300 *
301 * @return an estimate of the number of remaining bytes that can be read
302 * (or skipped over) from this input stream without blocking.
303 * @exception IOException if this file input stream has been closed by calling
304 * {@code close} or an I/O error occurs.
305 */
306 public native int available() throws IOException;
307
308 /**
309 * Closes this file input stream and releases any system resources
310 * associated with the stream.
311 *
312 * <p> If this stream has an associated channel then the channel is closed
313 * as well.
314 *
315 * @exception IOException if an I/O error occurs.
316 *
317 * @revised 1.4
318 * @spec JSR-51
319 */
320 public void close() throws IOException {
321 synchronized (closeLock) {
322 if (closed) {
323 return;
324 }
325 closed = true;
326 }
327 if (channel != null) {
328 channel.close();
329 }
330
331 fd.closeAll(new Closeable() {
332 public void close() throws IOException {
333 close0();
334 }
335 });
336 }
337
338 /**
339 * Returns the <code>FileDescriptor</code>
340 * object that represents the connection to
341 * the actual file in the file system being
342 * used by this <code>FileInputStream</code>.
343 *
344 * @return the file descriptor object associated with this stream.
345 * @exception IOException if an I/O error occurs.
346 * @see java.io.FileDescriptor
347 */
348 public final FileDescriptor getFD() throws IOException {
349 if (fd != null) {
350 return fd;
351 }
352 throw new IOException();
353 }
354
355 /**
356 * Returns the unique {@link java.nio.channels.FileChannel FileChannel}
357 * object associated with this file input stream.
358 *
359 * <p> The initial {@link java.nio.channels.FileChannel#position()
360 * </code>position<code>} of the returned channel will be equal to the
361 * number of bytes read from the file so far. Reading bytes from this
362 * stream will increment the channel's position. Changing the channel's
363 * position, either explicitly or by reading, will change this stream's
364 * file position.
365 *
366 * @return the file channel associated with this file input stream
367 *
368 * @since 1.4
369 * @spec JSR-51
370 */
371 public FileChannel getChannel() {
372 synchronized (this) {
373 if (channel == null) {
374 channel = FileChannelImpl.open(fd, path, true, false, this);
375 }
376 return channel;
377 }
378 }
379
380 private static native void initIDs();
381
382 private native void close0() throws IOException;
383
384 static {
385 initIDs();
386 }
387
388 /**
389 * Ensures that the <code>close</code> method of this file input stream is
390 * called when there are no more references to it.
391 *
392 * @exception IOException if an I/O error occurs.
393 * @see java.io.FileInputStream#close()
394 */
395 protected void finalize() throws IOException {
396 if ((fd != null) && (fd != FileDescriptor.in)) {
397 /* if fd is shared, the references in FileDescriptor
398 * will ensure that finalizer is only called when
399 * safe to do so. All references using the fd have
400 * become unreachable. We can call close()
401 */
402 close();
403 }
404 }
405 }