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JDBC Driver for the Firebird RDBMS
/*
* Firebird Open Source J2ee connector - jdbc driver
*
* Distributable under LGPL license.
* You may obtain a copy of the License at http://www.gnu.org/copyleft/lgpl.html
*
* This program 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
* LGPL License for more details.
*
* This file was created by members of the firebird development team.
* All individual contributions remain the Copyright (C) of those
* individuals. Contributors to this file are either listed here or
* can be obtained from a CVS history command.
*
* All rights reserved.
*/
/*
* The Original Code is the Firebird Java GDS implementation.
*
* The Initial Developer of the Original Code is Alejandro Alberola.
* Portions created by Alejandro Alberola are Copyright (C) 2001
* Boix i Oltra, S.L. All Rights Reserved.
*
*/
package org.firebirdsql.gds.impl.wire;
import org.firebirdsql.encodings.Encoding;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import java.io.BufferedInputStream;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
/**
* XdrInputStream is an input stream for reading in data that
* is in the XDR format. An XdrInputStream instance is wrapped
* around an underlying java.io.InputStream.
*
* This class is not thread-safe.
*
*
* @author Alejandro Alberola
* @author David Jencks
* @author Mark Rotteveel
* @version 1.0
*/
public final class XdrInputStream {
private InputStream in = null;
private static final int DEFAULT_BUFFER_SIZE = 16384;
/**
* Create a new instance of XdrInputStream.
*
* @param in The underlying InputStream to read from
*/
public XdrInputStream(InputStream in) {
this.in = new BufferedInputStream(in, DEFAULT_BUFFER_SIZE);
}
/**
* Skips the padding after a buffer of the specified length. The number of bytes to skip is calculated as
* (4 - length) & 3.
*
* @param length
* Length of the previously read buffer
* @return Actual number of bytes skipped
* @throws IOException
* IOException if an error occurs while reading from the
* underlying input stream
* @see XdrOutputStream#writePadding(int, int)
*/
public int skipPadding(int length) throws IOException {
int bytesToSkip = (4 - length) & 3;
int actual = skipFully(bytesToSkip);
assert actual == bytesToSkip
: String.format("Unexpected number of bytes skipped: %d, expected: %d", actual, bytesToSkip);
return actual;
}
/**
* Skips the specified number of bytes.
*
* @param numbytes
* Number of bytes to skip.
* @return Actual number of bytes skipped (usually {@code n}, unless the underlying input stream is closed).
* @throws IOException
* IOException if an error occurs while reading from the underlying input stream
*/
public int skipFully(int numbytes) throws IOException {
// This is the skip from SocketInputStream, which will read all bytes unless the stream is closed.
// We can't rely on InputStream.skip(int), because for example CipherInputStream will not skip beyond
// its current buffer.
if (numbytes <= 0) {
return 0;
}
int n = numbytes;
int buflen = Math.min(1024, n);
byte[] data = new byte[buflen];
while (n > 0) {
int r = in.read(data, 0, Math.min(buflen, n));
if (r < 0) {
break;
}
n -= r;
}
return numbytes - n;
}
/**
* Read in a byte buffer.
*
* @return The buffer that was read
* @throws IOException if an error occurs while reading from the
* underlying input stream
*/
public byte[] readBuffer() throws IOException {
int len = readInt();
byte[] buffer = new byte[len];
readFully(buffer, 0, len);
skipPadding(len);
return buffer;
}
/**
* Read in a raw array of bytes.
*
* @param len The number of bytes to read
* @return The byte buffer that was read
* @throws IOException if an error occurs while reading from the
* underlying input stream
*/
public byte[] readRawBuffer(int len) throws IOException {
byte[] buffer = new byte[len];
readFully(buffer, 0, len);
return buffer;
}
/**
* Read in a String.
*
* @return The String that was read
* @throws IOException if an error occurs while reading from the
* underlying input stream
*/
public String readString(Encoding encoding) throws IOException {
byte[] buffer = readBuffer();
return encoding.decodeFromCharset(buffer);
}
private final byte readBuffer[] = new byte[8];
/**
* Read in a long.
*
* @return The long that was read
* @throws IOException if an error occurs while reading from the
* underlying input stream
*/
public long readLong() throws IOException {
readFully(readBuffer, 0, 8);
return (((long) readBuffer[0] << 56) +
((long) (readBuffer[1] & 0xFF) << 48) +
((long) (readBuffer[2] & 0xFF) << 40) +
((long) (readBuffer[3] & 0xFF) << 32) +
((long) (readBuffer[4] & 0xFF) << 24) +
((readBuffer[5] & 0xFF) << 16) +
((readBuffer[6] & 0xFF) << 8) +
((readBuffer[7] & 0xFF)));
}
/**
* Read in an int.
*
* @return The int that was read
* @throws IOException if an error occurs while reading from the
* underlying input stream
*/
public int readInt() throws IOException {
int ch1 = in.read();
int ch2 = in.read();
int ch3 = in.read();
int ch4 = in.read();
if ((ch1 | ch2 | ch3 | ch4) < 0)
throw new EOFException();
return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4));
}
/**
* Read in a short.
*
* @return The short that was read
* @throws IOException if an error occurs while reading from the
* underlying input stream
*/
public int readShort() throws IOException {
int ch1 = in.read();
int ch2 = in.read();
if ((ch1 | ch2) < 0)
throw new EOFException();
return (ch1 << 8) + (ch2);
}
/**
* Read a given amount of data from the underlying input stream. The data
* that is read is stored in b, starting from offset
* off.
*
* @param b The byte buffer to hold the data that is read
* @param off The offset at which to start storing data in b
* @param len The number of bytes to be read
* @throws IOException if an error occurs while reading from the
* underlying input stream
*/
public void readFully(byte b[], int off, int len) throws IOException {
if (len < 0)
throw new IndexOutOfBoundsException();
int n = 0;
while (n < len) {
int count = in.read(b, off + n, len - n);
if (count < 0)
throw new EOFException();
n += count;
}
}
/**
* Close this input stream and the underlying input stream.
*
* @throws IOException if an error occurs while closing the underlying
* input stream
*/
public void close() throws IOException {
in.close();
}
public void setCipher(Cipher cipher) throws IOException {
if (in instanceof CipherInputStream) {
throw new IOException("Input stream already encrypted");
}
in = new CipherInputStream(in, cipher);
}
}
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