/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.net.io;
import java.io.IOException;
import java.io.InputStream;
import java.io.PushbackInputStream;
/***
* This class wraps an input stream, replacing all occurrences
* of <CR><LF> (carriage return followed by a linefeed),
* which is the NETASCII standard for representing a newline, with the
* local line separator representation. You would use this class to
* implement ASCII file transfers requiring conversion from NETASCII.
* <p>
* <p>
* @author Daniel F. Savarese
***/
public final class FromNetASCIIInputStream extends PushbackInputStream
{
static final boolean _noConversionRequired;
static final String _lineSeparator;
static final byte[] _lineSeparatorBytes;
static {
_lineSeparator = System.getProperty("line.separator");
_noConversionRequired = _lineSeparator.equals("\r\n");
_lineSeparatorBytes = _lineSeparator.getBytes();
}
private int __length = 0;
/***
* Returns true if the NetASCII line separator differs from the system
* line separator, false if they are the same. This method is useful
* to determine whether or not you need to instantiate a
* FromNetASCIIInputStream object.
* <p>
* @return True if the NETASCII line separator differs from the local
* system line separator, false if they are the same.
***/
public static final boolean isConversionRequired()
{
return !_noConversionRequired;
}
/***
* Creates a FromNetASCIIInputStream instance that wraps an existing
* InputStream.
***/
public FromNetASCIIInputStream(InputStream input)
{
super(input, _lineSeparatorBytes.length + 1);
}
private int __read() throws IOException
{
int ch;
ch = super.read();
if (ch == '\r')
{
ch = super.read();
if (ch == '\n')
{
unread(_lineSeparatorBytes);
ch = super.read();
// This is a kluge for read(byte[], ...) to read the right amount
--__length;
}
else
{
if (ch != -1)
unread(ch);
return '\r';
}
}
return ch;
}
/***
* Reads and returns the next byte in the stream. If the end of the
* message has been reached, returns -1. Note that a call to this method
* may result in multiple reads from the underlying input stream in order
* to convert NETASCII line separators to the local line separator format.
* This is transparent to the programmer and is only mentioned for
* completeness.
* <p>
* @return The next character in the stream. Returns -1 if the end of the
* stream has been reached.
* @exception IOException If an error occurs while reading the underlying
* stream.
***/
@Override
public int read() throws IOException
{
if (_noConversionRequired)
return super.read();
return __read();
}
/***
* Reads the next number of bytes from the stream into an array and
* returns the number of bytes read. Returns -1 if the end of the
* stream has been reached.
* <p>
* @param buffer The byte array in which to store the data.
* @return The number of bytes read. Returns -1 if the
* end of the message has been reached.
* @exception IOException If an error occurs in reading the underlying
* stream.
***/
@Override
public int read(byte buffer[]) throws IOException
{
return read(buffer, 0, buffer.length);
}
/***
* Reads the next number of bytes from the stream into an array and returns
* the number of bytes read. Returns -1 if the end of the
* message has been reached. The characters are stored in the array
* starting from the given offset and up to the length specified.
* <p>
* @param buffer The byte array in which to store the data.
* @param offset The offset into the array at which to start storing data.
* @param length The number of bytes to read.
* @return The number of bytes read. Returns -1 if the
* end of the stream has been reached.
* @exception IOException If an error occurs while reading the underlying
* stream.
***/
@Override
public int read(byte buffer[], int offset, int length) throws IOException
{
int ch, off;
if (length < 1)
return 0;
ch = available();
__length = (length > ch ? ch : length);
// If nothing is available, block to read only one character
if (__length < 1)
__length = 1;
if (_noConversionRequired)
return super.read(buffer, offset, __length);
if ((ch = __read()) == -1)
return -1;
off = offset;
do
{
buffer[offset++] = (byte)ch;
}
while (--__length > 0 && (ch = __read()) != -1);
return (offset - off);
}
// PushbackInputStream in JDK 1.1.3 returns the wrong thing
/***
* Returns the number of bytes that can be read without blocking EXCEPT
* when newline conversions have to be made somewhere within the
* available block of bytes. In other words, you really should not
* rely on the value returned by this method if you are trying to avoid
* blocking.
***/
@Override
public int available() throws IOException
{
return (buf.length - pos) + in.available();
}
}