/*
 
* Copyright (c) 1994, 2013, 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
 
*/

public
class
FileInputStream extends InputStream
{
    
/* File Descriptor - handle to the open file */
    
private final FileDescriptor fd;

    
/**
     
* The path of the referenced file
     
* (null if the stream is created with a file descriptor)
     
*/

    
private final String path;

    
private FileChannel channel = null;

    
private final Object closeLock = new Object();
    
private volatile boolean closed = 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
  
FileNotFoundExceptionif 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
  
FileNotFoundExceptionif 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();
        
}
        
if (file.isInvalid()) {
            
throw new FileNotFoundException("Invalid file path");
        
}
        
fd = new FileDescriptor();
        
fd.attach(this);
        
path = name;
        
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.
     
* @throwsSecurityException
      
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;
        
path = null;

        
/*
         
* FileDescriptor is being shared by streams.
         
* Register this stream with FileDescriptor tracker.
         
*/

        
fd.attach(this);
    
}

    
/**
     
* Opens the specified file for reading.
     
* @param name the name of the file
     
*/
    
private native void open0(String name) throws FileNotFoundException;

    
// wrap native call to allow instrumentation
    
/**
     
* Opens the specified file for reading.
     
* @param name the name of the file
     
*/
    
private void open(String name) throws FileNotFoundException {
        
open0(name);
    
}

    
/**
     
* Reads a byte of data from this input stream. This method blocks
     
* if no input is yet available.
     
*
     
* @returnthe next byte of data, or <code>-1</code> if the end of the
     
*
             
file is reached.
     
* @exception
  
IOExceptionif an I/O error occurs.
     
*/

    
public int read() throws IOException {
        
return read0();
    
}

    
private native int read0() 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.
     
* @returnthe 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
  
IOExceptionif 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
      
bthe 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.
     
* @returnthe 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
  
IOExceptionif 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, the method
     
* will try to skip backwards. In case the backing file does not support
     
* backward skip at its current position, an <code>IOException</code> is
     
* thrown. The actual number of bytes skipped is returned. If it skips
     
* forwards, it returns a positive value. If it skips backwards, it
     
* returns a negative value.
     
*
     
* <p>This method may skip more bytes than what 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.
     
* @returnthe actual number of bytes skipped.
     
* @exception
  
IOExceptionif n is negative, if the stream does not
     
*
             
support seek, or if an I/O error occurs.
     
*/

    
public long skip(long n) throws IOException {
        
return skip0(n);
    
}

    
private native long skip0(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. Returns 0 when the file
     
* position is beyond EOF. 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.
     
*
     
* @returnan estimate of the number of remaining bytes that can be read
     
*
             
(or skipped over) from this input stream without blocking.
     
* @exception
  
IOExceptionif this file input stream has been closed by calling
     
*
             
{@code close} or an I/O error occurs.
     
*/

    
public int available() throws IOException {
        
return available0();
    
}

    
private native int available0() 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
  
IOExceptionif 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) {
           
channel.close();
        
}

        
fd.closeAll(new Closeable() {
            
public void close() throws IOException {
               
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>.
     
*
     
* @returnthe file descriptor object associated with this stream.
     
* @exception
  
IOExceptionif 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()
     
* position} 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, path, true, false, this);
            
}
            
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
  
IOExceptionif an I/O error occurs.
     
* @see
        
java.io.FileInputStream#close()
     
*/

    
protected void finalize() throws IOException {
        
if ((fd != null) &&
  
(fd != FileDescriptor.in)) {
            
/* if fd is shared, the references in FileDescriptor
             
* will ensure that finalizer is only called when
             
* safe to do so. All references using the fd have
             
* become unreachable. We can call close()
             
*/

            
close();
        
}
    
}
}