GZIPInputStream.java [plain text]
package java.util.zip;
import java.io.InputStream;
import java.io.IOException;
public class GZIPInputStream extends InflaterInputStream
{
public static final int GZIP_MAGIC = 0x8b1f;
public void close () throws IOException
{
super.close();
}
public GZIPInputStream (InputStream istream) throws IOException
{
this (istream, 512);
}
private final int eof_read () throws IOException
{
int r = in.read();
if (r == -1)
throw new ZipException ("gzip header corrupted");
return r & 0xff;
}
public GZIPInputStream (InputStream istream, int readsize)
throws IOException
{
super (istream, new Inflater (true), readsize);
int magic = eof_read () | (eof_read () << 8);
if (magic != GZIP_MAGIC)
throw new ZipException ("gzip header corrupted");
int method = eof_read ();
int flags = eof_read ();
if (method != Z_DEFLATED || (flags & RESERVED) != 0)
throw new ZipException ("gzip header corrupted");
for (int i = 0; i < 6; ++i)
eof_read ();
if ((flags & EXTRA_FIELD) != 0)
{
int len = eof_read () | (eof_read () << 8);
while (len-- != 0)
eof_read ();
}
if ((flags & ORIG_NAME) != 0)
{
while (true)
{
int c = eof_read ();
if (c == 0)
break;
}
}
if ((flags & COMMENT) != 0)
{
while (true)
{
int c = eof_read ();
if (c == 0)
break;
}
}
if ((flags & HEAD_CRC) != 0)
{
eof_read ();
eof_read ();
}
crc = new CRC32 ();
}
public int read (byte[] buf, int off, int len) throws IOException
{
if (eos)
return -1;
int r = super.read(buf, off, len);
if (r == -1)
{
eos = true;
byte[] tmp = new byte[8];
int avail = inf.getRemaining ();
System.arraycopy (this.buf, this.len - avail, tmp, 0, avail);
for (int i = avail; i < 8; ++i)
{
tmp[i] = (byte) eof_read ();
}
int header_crc = read4 (tmp, 0);
if (crc.getValue() != header_crc)
throw new ZipException ("corrupted gzip file - crc mismatch");
int isize = read4 (tmp, 4);
if (inf.getTotalOut() != isize)
throw new ZipException ("corrupted gzip file - size mismatch");
return -1;
}
crc.update(buf, off, r);
return r;
}
private final int read4 (byte[] buf, int offset) throws IOException
{
return (((buf[offset + 3] & 0xFF) << 24) + ((buf[offset + 2] & 0xFF) << 16)
+ ((buf[offset + 1] & 0xFF) << 8) + (buf[offset] & 0xFF));
}
protected CRC32 crc;
protected boolean eos;
static final int Z_DEFLATED = 8;
static final int HEAD_CRC = 0x02;
static final int EXTRA_FIELD = 0x04;
static final int ORIG_NAME = 0x08;
static final int COMMENT = 0x10;
static final int RESERVED = 0xe0;
}