/* * Copyright (c) 1994, 2011, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.io; import java.nio.channels.FileChannel;import sun.nio.ch.FileChannelImpl;  /** * A <code>FileInputStream</code> obtains input bytes * from a file in a file system. What files * are  available depends on the host environment. * * <p><code>FileInputStream</code> is meant for reading streams of raw bytes * such as image data. For reading streams of characters, consider using * <code>FileReader</code>. * * @author  Arthur van Hoff * @see     java.io.File * @see     java.io.FileDescriptor * @see     java.io.FileOutputStream * @see     java.nio.file.Files#newInputStream * @since   JDK1.0 */publicclass FileInputStream extends InputStream{    /* File Descriptor - handle to the open file */    private final FileDescriptor fd;     private FileChannel channel = null;     private final Object closeLock = new Object();    private volatile boolean closed = false;     private static final ThreadLocal<Boolean> runningFinalize =        new ThreadLocal<>();     private static boolean isRunningFinalize() {        Boolean val;        if ((val = runningFinalize.get()) != null)            return val.booleanValue();        return false;    }     /**     * Creates a <code>FileInputStream</code> by     * opening a connection to an actual file,     * the file named by the path name <code>name</code>     * in the file system.  A new <code>FileDescriptor</code>     * object is created to represent this file     * connection.     * <p>     * First, if there is a security     * manager, its <code>checkRead</code> method     * is called with the <code>name</code> argument     * as its argument.     * <p>     * If the named file does not exist, is a directory rather than a regular     * file, or for some other reason cannot be opened for reading then a     * <code>FileNotFoundException</code> is thrown.     *     * @param      name   the system-dependent file name.     * @exception  FileNotFoundException  if the file does not exist,     *                   is a directory rather than a regular file,     *                   or for some other reason cannot be opened for     *                   reading.     * @exception  SecurityException      if a security manager exists and its     *               <code>checkRead</code> method denies read access     *               to the file.     * @see        java.lang.SecurityManager#checkRead(java.lang.String)     */    public FileInputStream(String name) throws FileNotFoundException {        this(name != null ? new File(name) : null);    }     /**     * Creates a <code>FileInputStream</code> by     * opening a connection to an actual file,     * the file named by the <code>File</code>     * object <code>file</code> in the file system.     * A new <code>FileDescriptor</code> object     * is created to represent this file connection.     * <p>     * First, if there is a security manager,     * its <code>checkRead</code> method  is called     * with the path represented by the <code>file</code>     * argument as its argument.     * <p>     * If the named file does not exist, is a directory rather than a regular     * file, or for some other reason cannot be opened for reading then a     * <code>FileNotFoundException</code> is thrown.     *     * @param      file   the file to be opened for reading.     * @exception  FileNotFoundException  if the file does not exist,     *                   is a directory rather than a regular file,     *                   or for some other reason cannot be opened for     *                   reading.     * @exception  SecurityException      if a security manager exists and its     *               <code>checkRead</code> method denies read access to the file.     * @see        java.io.File#getPath()     * @see        java.lang.SecurityManager#checkRead(java.lang.String)     */    public FileInputStream(File file) throws FileNotFoundException {        String name = (file != null ? file.getPath() : null);        SecurityManager security = System.getSecurityManager();        if (security != null) {            security.checkRead(name);        }        if (name == null) {            throw new NullPointerException();        }        fd = new FileDescriptor();        fd.incrementAndGetUseCount();        open(name);    }     /**     * Creates a <code>FileInputStream</code> by using the file descriptor     * <code>fdObj</code>, which represents an existing connection to an     * actual file in the file system.     * <p>     * If there is a security manager, its <code>checkRead</code> method is     * called with the file descriptor <code>fdObj</code> as its argument to     * see if it's ok to read the file descriptor. If read access is denied     * to the file descriptor a <code>SecurityException</code> is thrown.     * <p>     * If <code>fdObj</code> is null then a <code>NullPointerException</code>     * is thrown.     * <p>     * This constructor does not throw an exception if <code>fdObj</code>     * is {@link java.io.FileDescriptor#valid() invalid}.     * However, if the methods are invoked on the resulting stream to attempt     * I/O on the stream, an <code>IOException</code> is thrown.     *     * @param      fdObj   the file descriptor to be opened for reading.     * @throws     SecurityException      if a security manager exists and its     *                 <code>checkRead</code> method denies read access to the     *                 file descriptor.     * @see        SecurityManager#checkRead(java.io.FileDescriptor)     */    public FileInputStream(FileDescriptor fdObj) {        SecurityManager security = System.getSecurityManager();        if (fdObj == null) {            throw new NullPointerException();        }        if (security != null) {            security.checkRead(fdObj);        }        fd = fdObj;         /*         * FileDescriptor is being shared by streams.         * Ensure that it's GC'ed only when all the streams/channels are done         * using it.         */        fd.incrementAndGetUseCount();    }     /**     * Opens the specified file for reading.     * @param name the name of the file     */    private native void open(String name) throws FileNotFoundException;     /**     * Reads a byte of data from this input stream. This method blocks     * if no input is yet available.     *     * @return     the next byte of data, or <code>-1</code> if the end of the     *             file is reached.     * @exception  IOException  if an I/O error occurs.     */    public native int read() throws IOException;     /**     * Reads a subarray as a sequence of bytes.     * @param b the data to be written     * @param off the start offset in the data     * @param len the number of bytes that are written     * @exception IOException If an I/O error has occurred.     */    private native int readBytes(byte b[], int off, int len) throws IOException;     /**     * Reads up to <code>b.length</code> bytes of data from this input     * stream into an array of bytes. This method blocks until some input     * is available.     *     * @param      b   the buffer into which the data is read.     * @return     the total number of bytes read into the buffer, or     *             <code>-1</code> if there is no more data because the end of     *             the file has been reached.     * @exception  IOException  if an I/O error occurs.     */    public int read(byte b[]) throws IOException {        return readBytes(b, 0, b.length);    }     /**     * Reads up to <code>len</code> bytes of data from this input stream     * into an array of bytes. If <code>len</code> is not zero, the method     * blocks until some input is available; otherwise, no     * bytes are read and <code>0</code> is returned.     *     * @param      b     the buffer into which the data is read.     * @param      off   the start offset in the destination array <code>b</code>     * @param      len   the maximum number of bytes read.     * @return     the total number of bytes read into the buffer, or     *             <code>-1</code> if there is no more data because the end of     *             the file has been reached.     * @exception  NullPointerException If <code>b</code> is <code>null</code>.     * @exception  IndexOutOfBoundsException If <code>off</code> is negative,     * <code>len</code> is negative, or <code>len</code> is greater than     * <code>b.length - off</code>     * @exception  IOException  if an I/O error occurs.     */    public int read(byte b[], int off, int len) throws IOException {        return readBytes(b, off, len);    }     /**     * Skips over and discards <code>n</code> bytes of data from the     * input stream.     *     * <p>The <code>skip</code> method may, for a variety of     * reasons, end up skipping over some smaller number of bytes,     * possibly <code>0</code>. If <code>n</code> is negative, an     * <code>IOException</code> is thrown, even though the <code>skip</code>     * method of the {@link InputStream} superclass does nothing in this case.     * The actual number of bytes skipped is returned.     *     * <p>This method may skip more bytes than are remaining in the backing     * file. This produces no exception and the number of bytes skipped     * may include some number of bytes that were beyond the EOF of the     * backing file. Attempting to read from the stream after skipping past     * the end will result in -1 indicating the end of the file.     *     * @param      n   the number of bytes to be skipped.     * @return     the actual number of bytes skipped.     * @exception  IOException  if n is negative, if the stream does not     *             support seek, or if an I/O error occurs.     */    public native long skip(long n) throws IOException;     /**     * Returns an estimate of the number of remaining bytes that can be read (or     * skipped over) from this input stream without blocking by the next     * invocation of a method for this input stream. The next invocation might be     * the same thread or another thread.  A single read or skip of this     * many bytes will not block, but may read or skip fewer bytes.     *     * <p> In some cases, a non-blocking read (or skip) may appear to be     * blocked when it is merely slow, for example when reading large     * files over slow networks.     *     * @return     an estimate of the number of remaining bytes that can be read     *             (or skipped over) from this input stream without blocking.     * @exception  IOException  if this file input stream has been closed by calling     *             {@code close} or an I/O error occurs.     */    public native int available() throws IOException;     /**     * Closes this file input stream and releases any system resources     * associated with the stream.     *     * <p> If this stream has an associated channel then the channel is closed     * as well.     *     * @exception  IOException  if an I/O error occurs.     *     * @revised 1.4     * @spec JSR-51     */    public void close() throws IOException {        synchronized (closeLock) {            if (closed) {                return;            }            closed = true;        }        if (channel != null) {            /*             * Decrement the FD use count associated with the channel             * The use count is incremented whenever a new channel             * is obtained from this stream.             */           fd.decrementAndGetUseCount();           channel.close();        }         /*         * Decrement the FD use count associated with this stream         */        int useCount = fd.decrementAndGetUseCount();         /*         * If FileDescriptor is still in use by another stream, the finalizer         * will not close it.         */        if ((useCount <= 0) || !isRunningFinalize()) {            close0();        }    }     /**     * Returns the <code>FileDescriptor</code>     * object  that represents the connection to     * the actual file in the file system being     * used by this <code>FileInputStream</code>.     *     * @return     the file descriptor object associated with this stream.     * @exception  IOException  if an I/O error occurs.     * @see        java.io.FileDescriptor     */    public final FileDescriptor getFD() throws IOException {        if (fd != null) return fd;        throw new IOException();    }     /**     * Returns the unique {@link java.nio.channels.FileChannel FileChannel}     * object associated with this file input stream.     *     * <p> The initial {@link java.nio.channels.FileChannel#position()     * </code>position<code>} of the returned channel will be equal to the     * number of bytes read from the file so far.  Reading bytes from this     * stream will increment the channel's position.  Changing the channel's     * position, either explicitly or by reading, will change this stream's     * file position.     *     * @return  the file channel associated with this file input stream     *     * @since 1.4     * @spec JSR-51     */    public FileChannel getChannel() {        synchronized (this) {            if (channel == null) {                channel = FileChannelImpl.open(fd, true, false, this);                 /*                 * Increment fd's use count. Invoking the channel's close()                 * method will result in decrementing the use count set for                 * the channel.                 */                fd.incrementAndGetUseCount();            }            return channel;        }    }     private static native void initIDs();     private native void close0() throws IOException;     static {        initIDs();    }     /**     * Ensures that the <code>close</code> method of this file input stream is     * called when there are no more references to it.     *     * @exception  IOException  if an I/O error occurs.     * @see        java.io.FileInputStream#close()     */    protected void finalize() throws IOException {        if ((fd != null) &&  (fd != FileDescriptor.in)) {             /*             * Finalizer should not release the FileDescriptor if another             * stream is still using it. If the user directly invokes             * close() then the FileDescriptor is also released.             */            runningFinalize.set(Boolean.TRUE);            try {                close();            } finally {                runningFinalize.set(Boolean.FALSE);            }        }    }}