libjava/java/util/zip/InflaterInputStream.java

/* InflaterInputStream.java - Input stream filter for decompressing
   Copyright (C) 1999, 2000 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., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

As a special exception, if you link this library with other files to
produce an executable, this library does not by itself cause the
resulting executable to be covered by the GNU General Public License.
This exception does not however invalidate any other reasons why the
executable file might be covered by the GNU General Public License. */

package java.util.zip;

import java.io.FilterInputStream;
import java.io.InputStream;
import java.io.IOException;

/**
 * @author Tom Tromey
 * @date May 17, 1999
 */

/* Written using on-line Java Platform 1.2 API Specification
 * and JCL book.
 * Believed complete and correct.
 */

public class InflaterInputStream extends FilterInputStream
{
  protected void fill () throws IOException
  {
    len = in.read(buf, 0, buf.length);
    if (len != -1)
      inf.setInput(buf, 0, len);
  }

  public InflaterInputStream (InputStream in)
  {
    this (in, new Inflater (), 512);
  }

  public InflaterInputStream (InputStream in, Inflater infl)
  {
    this (in, infl, 512);
  }

  public InflaterInputStream (InputStream in, Inflater infl, int bufsize)
  {
    super (in);
    this.inf = infl;
    this.buf = new byte[bufsize];
  }

  public int read () throws IOException
  {
    byte[] buf = new byte[1];
    int r = read (buf, 0, 1);
    if (r != -1)
      r = buf[0] & 0xff;
    return r;
  }

  public int read (byte[] buf, int off, int len) throws IOException
  {
    if (inf == null)
      throw new IOException ("stream closed");
    if (inf.finished())
      return -1;
    if (inf.needsInput())
      fill ();
    int count;
    try
      {
	count = inf.inflate(buf, off, len);	
	if (count == 0)
	  {
	    if (this.len == -1)
	      return -1; // Couldn't get any more data to feed to the Inflater
	    if (inf.needsDictionary())
	      throw new ZipException ("Inflater needs Dictionary");
	  }	      
      }
    catch (DataFormatException dfe)
      {
	throw new ZipException (dfe.getMessage());
      }
    return count;
  }

  public void close () throws IOException
  {
    inf = null;
    super.close ();
  }

  public int available () throws IOException
  {
    // According to the JDK 1.2 docs, this should only ever return 0
    // or 1 and should not be relied upon by Java programs.
    if (inf == null)
      throw new IOException ("stream closed");
    return inf.finished () ? 0 : 1;
  }

  public long skip (long n) throws IOException
  {
    if (inf == null)
      throw new IOException ("stream closed");

    if (n == 0)
      return 0;

    int min = (int) Math.min(n, 1024);
    byte[] buf = new byte[min];

    long s = 0;
    while (n > 0)
      {
	int r = read (buf, 0, min);
	if (r == -1)
	  break;
	n -= r;
	s += r;
	min = (int) Math.min(n, 1024);
      }

    return s;
  }

  // Buffer for delivering uncompressed data to inflater.
  protected byte[] buf;

  // Inflater used to decompress data.
  protected Inflater inf;

  // Number of read bytes in buf.
  protected int len;
}