| /* FileInputStream.java -- An input stream that reads from disk files. |
| Copyright (C) 1998, 2002, 2003, 2004, 2005 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package java.io; |
| |
| import gnu.java.nio.channels.FileChannelImpl; |
| |
| import java.nio.channels.FileChannel; |
| |
| /* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3 |
| * "The Java Language Specification", ISBN 0-201-63451-1 |
| * plus online API docs for JDK 1.2 beta from http://www.javasoft.com. |
| * Status: Believed complete and correct. |
| */ |
| |
| /** |
| * This class is a stream that reads its bytes from a file. |
| * |
| * @author Aaron M. Renn (arenn@urbanophile.com) |
| * @author Warren Levy (warrenl@cygnus.com) |
| */ |
| public class FileInputStream extends InputStream |
| { |
| /** |
| * This is the native file handle for the file this stream is reading from |
| */ |
| private FileDescriptor fd; |
| |
| private FileChannelImpl ch; |
| |
| /** |
| * This method initializes a <code>FileInputStream</code> to read from the |
| * specified named file. A security check is first made to determine |
| * whether or not access to this file is allowed. This is done by |
| * calling the <code>checkRead()</code> method of the |
| * <code>SecurityManager</code> |
| * (if one exists) with the name of this file. An exception is thrown |
| * if reading is not allowed. If the file does not exist, an exception |
| * is also thrown. |
| * |
| * @param name The name of the file this stream should read from |
| * |
| * @exception SecurityException If read access to the file is not allowed |
| * @exception FileNotFoundException If the file does not exist |
| * or if it is a directory |
| */ |
| public FileInputStream(String name) throws FileNotFoundException |
| { |
| this(new File(name)); |
| } |
| |
| /** |
| * This method initializes a <code>FileInputStream</code> to read from the |
| * specified <code>File</code> object. A security check is first |
| * made to determine |
| * whether or not access to this file is allowed. This is done by |
| * calling the <code>checkRead()</code> method of the |
| * <code>SecurityManager</code> |
| * (if one exists) with the name of this file. An exception is thrown |
| * if reading is not allowed. If the file does not exist, an exception |
| * is also thrown. |
| * |
| * @param file The <code>File</code> object this stream should read from |
| * |
| * @exception SecurityException If read access to the file is not allowed |
| * @exception FileNotFoundException If the file does not exist |
| * or if it is a directory. |
| */ |
| public FileInputStream(File file) throws FileNotFoundException |
| { |
| SecurityManager s = System.getSecurityManager(); |
| if (s != null) |
| s.checkRead(file.getPath()); |
| |
| ch = FileChannelImpl.create(file, FileChannelImpl.READ); |
| } |
| |
| /** |
| * This method initializes a <code>FileInputStream</code> to read from the |
| * specified <code>FileDescriptor</code> object. A security |
| * check is first made to |
| * determine whether or not access to this file is allowed. This is done by |
| * calling the <code>checkRead()</code> method of the |
| * <code>SecurityManager</code> |
| * (if one exists) with the specified <code>FileDescriptor</code> |
| * An exception is |
| * thrown if reading is not allowed. |
| * |
| * @param fdObj The <code>FileDescriptor</code> object this stream |
| * should read from |
| * |
| * @exception SecurityException If read access to the file is not allowed |
| */ |
| public FileInputStream(FileDescriptor fdObj) |
| { |
| SecurityManager s = System.getSecurityManager(); |
| if (s != null) |
| s.checkRead(fdObj); |
| |
| fd = fdObj; |
| ch = (FileChannelImpl) fdObj.channel; |
| } |
| |
| FileInputStream(FileChannelImpl ch) |
| { |
| this.ch = ch; |
| } |
| |
| /** |
| * This method returns the number of bytes that can be read from this |
| * stream before a read can block. A return of 0 indicates that blocking |
| * might (or might not) occur on the very next read attempt. |
| * <p> |
| * This method returns the number of unread bytes remaining in the file if |
| * the descriptor being read from is an actual file. If this method is |
| * reading from a ''special'' file such a the standard input, this method |
| * will return the appropriate value for the stream being read. |
| * <p> |
| * Be aware that reads on plain files that do not reside locally might |
| * possibly block even if this method says they should not. For example, |
| * a remote server might crash, preventing an NFS mounted file from being |
| * read. |
| * |
| * @return The number of bytes that can be read before blocking could occur |
| * |
| * @exception IOException If an error occurs |
| */ |
| public int available() throws IOException |
| { |
| return ch.available(); |
| } |
| |
| /** |
| * This method closes the stream. Any futher attempts to read from the |
| * stream will likely generate an IOException since the underlying file |
| * will be closed. |
| * |
| * @exception IOException If an error occurs. |
| */ |
| public void close() throws IOException |
| { |
| ch.close(); |
| } |
| |
| protected void finalize() throws IOException |
| { |
| // We don't actually need this, but we include it because it is |
| // mentioned in the JCL. |
| } |
| |
| /** |
| * This method returns a <code>FileDescriptor</code> object representing the |
| * underlying native file handle of the file this stream is reading |
| * from |
| * |
| * @return A <code>FileDescriptor</code> for this stream |
| * |
| * @exception IOException If an error occurs |
| */ |
| public final FileDescriptor getFD() throws IOException |
| { |
| synchronized (this) |
| { |
| if (fd == null) |
| fd = new FileDescriptor (ch); |
| return fd; |
| } |
| } |
| |
| /** |
| * This method reads an unsigned byte from the input stream and returns it |
| * as an int in the range of 0-255. This method also will return -1 if |
| * the end of the stream has been reached. |
| * <p> |
| * This method will block until the byte can be read. |
| * |
| * @return The byte read or -1 if end of stream |
| * |
| * @exception IOException If an error occurs |
| */ |
| public int read() throws IOException |
| { |
| return ch.read(); |
| } |
| |
| /** |
| * This method reads bytes from a stream and stores them into a caller |
| * supplied buffer. This method attempts to completely fill the buffer, |
| * but can return before doing so. The actual number of bytes read is |
| * returned as an int. A -1 is returned to indicate the end of the stream. |
| * <p> |
| * This method will block until some data can be read. |
| * <p> |
| * This method operates by calling an overloaded read method like so: |
| * <code>read(buf, 0, buf.length)</code> |
| * |
| * @param buf The buffer into which the bytes read will be stored. |
| * |
| * @return The number of bytes read or -1 if end of stream. |
| * |
| * @exception IOException If an error occurs. |
| */ |
| public int read(byte[] buf) throws IOException |
| { |
| return read(buf, 0, buf.length); |
| } |
| |
| /** |
| * This method read bytes from a stream and stores them into a caller |
| * supplied buffer. It starts storing the data at index |
| * <code>offset</code> into |
| * the buffer and attempts to read <code>len</code> bytes. This method can |
| * return before reading the number of bytes requested. The actual number |
| * of bytes read is returned as an int. A -1 is returned to indicate the |
| * end of the stream. |
| * <p> |
| * This method will block until some data can be read. |
| * |
| * @param buf The array into which the bytes read should be stored |
| * @param offset The offset into the array to start storing bytes |
| * @param len The requested number of bytes to read |
| * |
| * @return The actual number of bytes read, or -1 if end of stream. |
| * |
| * @exception IOException If an error occurs. |
| */ |
| public int read(byte[] buf, int offset, int len) throws IOException |
| { |
| if (offset < 0 |
| || len < 0 |
| || offset + len > buf.length) |
| throw new ArrayIndexOutOfBoundsException(); |
| |
| return ch.read(buf, offset, len); |
| } |
| |
| /** |
| * This method skips the specified number of bytes in the stream. It |
| * returns the actual number of bytes skipped, which may be less than the |
| * requested amount. |
| * <p> |
| * @param numBytes The requested number of bytes to skip |
| * |
| * @return The actual number of bytes skipped. |
| * |
| * @exception IOException If an error occurs |
| */ |
| public synchronized long skip (long numBytes) throws IOException |
| { |
| if (numBytes < 0) |
| throw new IllegalArgumentException ("Can't skip negative bytes: " + |
| numBytes); |
| |
| if (numBytes == 0) |
| return 0; |
| |
| long oldPos = ch.position (); |
| ch.position(oldPos + numBytes); |
| return ch.position() - oldPos; |
| } |
| |
| /** |
| * This method creates a java.nio.channels.FileChannel. |
| * Nio does not allow one to create a file channel directly. |
| * A file channel must be created by first creating an instance of |
| * Input/Output/RandomAccessFile and invoking the getChannel() method on it. |
| */ |
| public synchronized FileChannel getChannel () |
| { |
| return ch; |
| } |
| |
| } // class FileInputStream |
| |