ZipInputStream.java

//

package net.sf.zipme;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;

/** 
 * This is a FilterInputStream that reads the files in an zip archive
 * one after another.  It has a special method to get the zip entry of
 * the next file.  The zip entry contains information about the file name
 * size, compressed size, CRC, etc.
 * It includes support for STORED and DEFLATED entries.
 * @author Jochen Hoenicke
 */
public class ZipInputStream extends InflaterInputStream implements ZipConstants {
  private ZipEntry entry=null;
  private int csize;
  private int size;
  private int method;
  private int flags;
  private int avail;
  private boolean entryAtEOF;
  /** 
 * Creates a new Zip input stream, reading a zip archive.
 */
  public ZipInputStream(  InputStream in){
    super(in,new Inflater(true));
  }
  private void fillBuf() throws IOException {
    avail=len=in.read(buf,0,buf.length);
  }
  private int readBuf(  byte[] out,  int offset,  int length) throws IOException {
    if (avail <= 0) {
      fillBuf();
      if (avail <= 0)       return -1;
    }
    if (length > avail)     length=avail;
    System.arraycopy(buf,len - avail,out,offset,length);
    avail-=length;
    return length;
  }
  private void readFully(  byte[] out) throws IOException {
    int off=0;
    int len=out.length;
    while (len > 0) {
      int count=readBuf(out,off,len);
      if (count == -1)       throw new EOFException();
      off+=count;
      len-=count;
    }
  }
  private int readLeByte() throws IOException {
    if (avail <= 0) {
      fillBuf();
      if (avail <= 0)       throw new ZipException("EOF in header");
    }
    return buf[len - avail--] & 0xff;
  }
  /** 
 * Read an unsigned short in little endian byte order.
 */
  private int readLeShort() throws IOException {
    return readLeByte() | (readLeByte() << 8);
  }
  /** 
 * Read an int in little endian byte order.
 */
  private int readLeInt() throws IOException {
    return readLeShort() | (readLeShort() << 16);
  }
  /** 
 * Open the next entry from the zip archive, and return its description.
 * If the previous entry wasn't closed, this method will close it.
 */
  public ZipEntry getNextEntry() throws IOException {
    if (entry != null)     closeEntry();
    int header=readLeInt();
    if (header == CENSIG) {
      close();
      return null;
    }
    if (header != LOCSIG)     throw new ZipException("Wrong Local header signature: " + Integer.toHexString(header));
    readLeShort();
    flags=readLeShort();
    method=readLeShort();
    int dostime=readLeInt();
    int crc=readLeInt();
    csize=readLeInt();
    size=readLeInt();
    int nameLen=readLeShort();
    int extraLen=readLeShort();
    if (method == ZipOutputStream.STORED && csize != size)     throw new ZipException("Stored, but compressed != uncompressed");
    byte[] buffer=new byte[nameLen];
    readFully(buffer);
    String name;
    try {
      name=new String(buffer,"UTF-8");
    }
 catch (    UnsupportedEncodingException uee) {
      throw new Error(uee.toString());
    }
    entry=createZipEntry(name);
    entryAtEOF=false;
    entry.setMethod(method);
    if ((flags & 8) == 0) {
      entry.setCrc(crc & 0xffffffffL);
      entry.setSize(size & 0xffffffffL);
      entry.setCompressedSize(csize & 0xffffffffL);
    }
    entry.setDOSTime(dostime);
    if (extraLen > 0) {
      byte[] extra=new byte[extraLen];
      readFully(extra);
      entry.setExtra(extra);
    }
    if (method == ZipOutputStream.DEFLATED && avail > 0) {
      System.arraycopy(buf,len - avail,buf,0,avail);
      len=avail;
      avail=0;
      inf.setInput(buf,0,len);
    }
    return entry;
  }
  private void readDataDescr() throws IOException {
    if (readLeInt() != EXTSIG)     throw new ZipException("Data descriptor signature not found");
    entry.setCrc(readLeInt() & 0xffffffffL);
    csize=readLeInt();
    size=readLeInt();
    entry.setSize(size & 0xffffffffL);
    entry.setCompressedSize(csize & 0xffffffffL);
  }
  /** 
 * Closes the current zip entry and moves to the next one.
 */
  public void closeEntry() throws IOException {
    if (entry == null)     return;
    if (method == ZipOutputStream.DEFLATED) {
      if ((flags & 8) != 0) {
        byte[] tmp=new byte[2048];
        while (read(tmp) > 0)         ;
        return;
      }
      csize-=inf.getTotalIn();
      avail=inf.getRemaining();
    }
    if (avail > csize && csize >= 0)     avail-=csize;
 else {
      csize-=avail;
      avail=0;
      while (csize != 0) {
        long skipped=in.skip(csize & 0xffffffffL);
        if (skipped <= 0)         throw new ZipException("zip archive ends early.");
        csize-=skipped;
      }
    }
    size=0;
    this.hook36();
    if (method == ZipOutputStream.DEFLATED)     inf.reset();
    entry=null;
    entryAtEOF=true;
  }
  public int available() throws IOException {
    return entryAtEOF ? 0 : 1;
  }
  /** 
 * Reads a byte from the current zip entry.
 * @return the byte or -1 on EOF.
 * @exception IOException if a i/o error occured.
 * @exception ZipException if the deflated stream is corrupted.
 */
  public int read() throws IOException {
    byte[] b=new byte[1];
    if (read(b,0,1) <= 0)     return -1;
    return b[0] & 0xff;
  }
  /** 
 * Reads a block of bytes from the current zip entry.
 * @return the number of bytes read (may be smaller, even before
 * EOF), or -1 on EOF.
 * @exception IOException if a i/o error occured.
 * @exception ZipException if the deflated stream is corrupted.
 */
  public int read(  byte[] b,  int off,  int len) throws IOException {
    if (len == 0)     return 0;
    this.hook38();
    if (entry == null)     return -1;
    boolean finished=false;
switch (method) {
case ZipOutputStream.DEFLATED:
      len=super.read(b,off,len);
    if (len < 0) {
      if (!inf.finished())       throw new ZipException("Inflater not finished!?");
      avail=inf.getRemaining();
      if ((flags & 8) != 0)       readDataDescr();
      if (inf.getTotalIn() != csize || inf.getTotalOut() != size)       throw new ZipException("size mismatch: " + csize + ";"+ size+ " <-> "+ inf.getTotalIn()+ ";"+ inf.getTotalOut());
      inf.reset();
      finished=true;
    }
  break;
case ZipOutputStream.STORED:
if (len > csize && csize >= 0) len=csize;
len=readBuf(b,off,len);
if (len > 0) {
csize-=len;
size-=len;
}
if (csize == 0) finished=true;
 else if (len < 0) throw new ZipException("EOF in stored block");
break;
}
this.hook37(b,off,len);
if (finished) {
this.hook39();
entry=null;
entryAtEOF=true;
}
return len;
}
/** 
 * Closes the zip file.
 * @exception IOException if a i/o error occured.
 */
public void close() throws IOException {
super.close();
this.hook40();
entry=null;
entryAtEOF=true;
}
/** 
 * Creates a new zip entry for the given name.  This is equivalent
 * to new ZipEntry(name).
 * @param name the name of the zip entry.
 */
protected ZipEntry createZipEntry(String name){
return new ZipEntry(name);
}
protected void hook36() throws IOException {
}
protected void hook37(byte[] b,int off,int len) throws IOException {
}
protected void hook38() throws IOException {
}
protected void hook39() throws IOException {
}
protected void hook40() throws IOException {
}
}