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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
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 *
 * 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).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
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package sun.security.ssl;

import java.io.*;
import java.nio.*;

A simple InputStream which uses ByteBuffers as it's backing store.

The only IOException should come if the InputStream has been closed.
All other IOException should not occur because all the data is local.
Data reads on an exhausted ByteBuffer returns a -1.
Author:
 Brad Wetmore/**
 * A simple InputStream which uses ByteBuffers as it's backing store.
 * <P>
 * The only IOException should come if the InputStream has been closed.
 * All other IOException should not occur because all the data is local.
 * Data reads on an exhausted ByteBuffer returns a -1.
 *
 * @author  Brad Wetmore
 */
class ByteBufferInputStream extends InputStream {

    ByteBuffer bb;

    ByteBufferInputStream(ByteBuffer bb) {
        this.bb = bb;
    }

    
Returns a byte from the ByteBuffer.
Increments position().
/**
     * Returns a byte from the ByteBuffer.
     *
     * Increments position().
     */
    @Override
    public int read() throws IOException {

        if (bb == null) {
            throw new IOException("read on a closed InputStream");
        }

        if (bb.remaining() == 0) {
            return -1;
        }

        return (bb.get() & 0xFF);   // need to be in the range 0 to 255
    }

    
Returns a byte array from the ByteBuffer.
Increments position().
/**
     * Returns a byte array from the ByteBuffer.
     *
     * Increments position().
     */
    @Override
    public int read(byte[] b) throws IOException {

        if (bb == null) {
            throw new IOException("read on a closed InputStream");
        }

        return read(b, 0, b.length);
    }

    
Returns a byte array from the ByteBuffer.
Increments position().
/**
     * Returns a byte array from the ByteBuffer.
     *
     * Increments position().
     */
    @Override
    public int read(byte[] b, int off, int len) throws IOException {

        if (bb == null) {
            throw new IOException("read on a closed InputStream");
        }

        if (b == null) {
            throw new NullPointerException();
        } else if (off < 0 || len < 0 || len > b.length - off) {
            throw new IndexOutOfBoundsException();
        } else if (len == 0) {
            return 0;
        }

        int length = Math.min(bb.remaining(), len);
        if (length == 0) {
            return -1;
        }

        bb.get(b, off, length);
        return length;
    }

    
Skips over and discards n bytes of data from this input
stream.
/**
     * Skips over and discards <code>n</code> bytes of data from this input
     * stream.
     */
    @Override
    public long skip(long n) throws IOException {

        if (bb == null) {
            throw new IOException("skip on a closed InputStream");
        }

        if (n <= 0) {
            return 0;
        }

        /*
         * ByteBuffers have at most an int, so lose the upper bits.
         * The contract allows this.
         */
        int nInt = (int) n;
        int skip = Math.min(bb.remaining(), nInt);

        bb.position(bb.position() + skip);

        return nInt;
    }

    
Returns the number of bytes that can be read (or skipped over)
from this input stream without blocking by the next caller of a
method for this input stream.
/**
     * Returns the number of bytes that can be read (or skipped over)
     * from this input stream without blocking by the next caller of a
     * method for this input stream.
     */
    @Override
    public int available() throws IOException {

        if (bb == null) {
            throw new IOException("available on a closed InputStream");
        }

        return bb.remaining();
    }

    
Closes this input stream and releases any system resources associated
with the stream.
Throws:
IOException –  if an I/O error occurs./**
     * Closes this input stream and releases any system resources associated
     * with the stream.
     *
     * @exception  IOException  if an I/O error occurs.
     */
    @Override
    public void close() throws IOException {
        bb = null;
    }

    
Marks the current position in this input stream.
/**
     * Marks the current position in this input stream.
     */
    @Override
    public synchronized void mark(int readlimit) {}

    
Repositions this stream to the position at the time the
mark method was last called on this input stream.
/**
     * Repositions this stream to the position at the time the
     * <code>mark</code> method was last called on this input stream.
     */
    @Override
    public synchronized void reset() throws IOException {
        throw new IOException("mark/reset not supported");
    }

    
Tests if this input stream supports the mark and
reset methods.
/**
     * Tests if this input stream supports the <code>mark</code> and
     * <code>reset</code> methods.
     */
    @Override
    public boolean markSupported() {
        return false;
    }
}