gcc/libjava/java/util/zip/ZipInputStream.java

/* Copyright (C) 1999, 2000  Free Software Foundation

   This file is part of libgcj.

This software is copyrighted work licensed under the terms of the
Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
details.  */

package java.util.zip;
import java.io.*;

/**
 * @author Per Bothner
 * @date May 1999.
 */

/*
 * Written using on-line Java Platform 1.2 API Specification, as well
 * as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998).
 * Status:  Quite incomplete, but can read uncompressed .zip archives.
 */

// JDK1.2 has "protected ZipEntry createZipEntry(String)" but is very
// vague about what the method does.  FIXME.
// We do not calculate the CRC and compare it with the specified value;
// we probably should.  FIXME.
   

public class ZipInputStream extends InflaterInputStream implements ZipConstants
{
  public ZipInputStream (InputStream in)
  {
    super (in, new Inflater (true));
  }

  public ZipEntry getNextEntry () throws IOException
  {
    if (current != null)
      closeEntry();
    if (in.read() != 'P'
	|| in.read() != 'K')
      return null;
    int code = in.read();
    while (code == '\001')
      {
	code = in.read();
	if (code != '\002')
	  return null;
	in.skip(16);
	int size = read4();
	in.skip(4);
	int fname_length = readu2();
	int extra_length = readu2();
	int fcomment_length = readu2();
	// `12' is the number of bytes between the comment length
	// field and the end of the fixed part of the header:
	// 2 bytes for `disk number start'
	// 2 bytes for `internal file attributes'
	// 4 bytes for `external file attributes'
	// 4 bytes for `relative offset of local header'
	in.skip(12 + fname_length + extra_length + fcomment_length);
	if (in.read() != 'P' || in.read() != 'K')
	  return null;
	code = in.read();
      }
    if (code == '\005')
      {
	if (in.read() != '\006')
	  return null;
	in.skip(16);
	int comment_size = readu2();
	in.skip(comment_size);
	if (in.read() != 'P' || in.read() != 'K')
	  return null;
	code = in.read();
      }
    if (code != '\003'
	|| in.read() != '\004')
      return null;
    int ex_version = readu2();
    current_flags = readu2();
    int method = readu2();
    int modtime = readu2();
    int moddate = readu2();
    int crc = read4();
    int compressedSize = read4();
    int uncompressedSize = read4();
    int filenameLength = readu2();
    int extraLength = readu2();
    byte[] bname = new byte[filenameLength];
    readFully(bname);
    ZipEntry entry = createZipEntry(new String(bname, "8859_1"));
    if (extraLength > 0)
      {
	byte[] bextra = new byte[extraLength];
	readFully(bextra);
	entry.extra = bextra;
      }
    entry.compressedSize = compressedSize;
    entry.size = uncompressedSize;
    entry.crc = (long) crc & 0xffffffffL;
    entry.method = method;
    entry.time = ZipEntry.timeFromDOS(moddate, modtime);
    current = entry;
    avail = uncompressedSize;
    compressed_bytes = compressedSize;
    return entry;
  }

  // We override fill to let us control how much data gets read from
  // the underlying input stream.  This lets us avoid having to push
  // back data.
  protected void fill () throws IOException
  {
    int count = buf.length;
    if (count > compressed_bytes)
      count = compressed_bytes;
    len = in.read(buf, 0, count);
    if (len != -1)
      {
	compressed_bytes -= len;
	inf.setInput(buf, 0, len);
      }
  }

  protected ZipEntry createZipEntry (String name)
  {
    return new ZipEntry (name);
  }
  
  public int read (byte[] b, int off, int len)  throws IOException
  {
    if (len > avail)
      len = avail;
    int count;
    if (current.method == Deflater.DEFLATED)
      count = super.read(b, off, len);
    else
      count = in.read(b, off, len);
    if (count == -1 || avail == 0)
      {
	inf.reset();
	count = -1;
      }
    else
      avail -= count;
    return count;
  }

  public long skip (long n)  throws IOException
  {
    if (n > avail)
      n = avail;
    long count;
    if (current.method == Deflater.DEFLATED)
      count = super.skip(n);
    else
      count = in.skip(n);
    avail = avail - (int) count;
    return count;
  }

  public int available() {
    if (closed)
      return 0;
    else
      return 1;
  }

  private void readFully (byte[] b)  throws IOException
  {
    int off = 0;
    int len = b.length;
    while (len > 0)
      {
	int count = in.read(b, off, len);
	if (count <= 0)
	  throw new EOFException(".zip archive ended prematurely");
	off += count;
	len -= count;
      }
  }

  private int readu2 ()  throws IOException
  {
    int byte0 = in.read();
    int byte1 = in.read();
    if (byte0 < 0 || byte1 < 0)
      throw new EOFException(".zip archive ended prematurely");
    return ((byte1 & 0xFF) << 8) | (byte0 & 0xFF);
  }

  private int read4 () throws IOException
  {
    int byte0 = in.read();
    int byte1 = in.read();
    int byte2 = in.read();
    int byte3 = in.read();
    if (byte3 < 0)
      throw new EOFException(".zip archive ended prematurely");
    return ((byte3 & 0xFF) << 24) + ((byte2 & 0xFF) << 16)
      + ((byte1 & 0xFF) << 8) + (byte0 & 0xFF);
  }

  public void closeEntry ()  throws IOException
  {
    if (current != null)
      {
	if (avail > 0)
	  skip (avail);
	if ((current_flags & 8) != 0)
	  {
	    int sig = read4();
	    if (sig != 0x04034b50)
	      throw new ZipException("bad/missing magic number at end of .zip entry");
	    int crc = read4();
	    int compressedSize = read4();
	    int uncompressedSize = read4();
	    if (current.compressedSize != compressedSize
		|| current.size != uncompressedSize
		|| current.crc != crc)
	      throw new ZipException("bad data descriptor at end of .zip entry");
	  }
	current = null;
	avail = 0;
      }
  }

  public void close ()  throws IOException
  {
    current = null;
    closed = true;
    super.close();
  }

  private ZipEntry current;
  private int current_flags;
  // Number of uncompressed bytes to be read.
  private int avail;
  // Number of bytes we can read from underlying stream.
  private int compressed_bytes;
  // Is this ZipInputStream closed? Set by the close() method.
  private boolean closed = false;
}