diff options
Diffstat (limited to 'src/org/apache/commons/net/io/DotTerminatedMessageReader.java')
| -rw-r--r-- | src/org/apache/commons/net/io/DotTerminatedMessageReader.java | 280 |
1 files changed, 280 insertions, 0 deletions
diff --git a/src/org/apache/commons/net/io/DotTerminatedMessageReader.java b/src/org/apache/commons/net/io/DotTerminatedMessageReader.java new file mode 100644 index 0000000..c0f344d --- /dev/null +++ b/src/org/apache/commons/net/io/DotTerminatedMessageReader.java @@ -0,0 +1,280 @@ +/*
+ * 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.PushbackReader;
+import java.io.Reader;
+
+/**
+ * DotTerminatedMessageReader is a class used to read messages from a
+ * server that are terminated by a single dot followed by a
+ * <CR><LF>
+ * sequence and with double dots appearing at the begining of lines which
+ * do not signal end of message yet start with a dot. Various Internet
+ * protocols such as NNTP and POP3 produce messages of this type.
+ * <p>
+ * This class handles stripping of the duplicate period at the beginning
+ * of lines starting with a period, converts NETASCII newlines to the
+ * local line separator format, truncates the end of message indicator,
+ * and ensures you cannot read past the end of the message.
+ * @author <a href="mailto:savarese@apache.org">Daniel F. Savarese</a>
+ * @version $Id: DotTerminatedMessageReader.java 636825 2008-03-13 18:34:52Z sebb $
+ */
+public final class DotTerminatedMessageReader extends Reader
+{
+ private static final String LS;
+ private static final char[] LS_CHARS;
+
+ static
+ {
+ LS = System.getProperty("line.separator");
+ LS_CHARS = LS.toCharArray();
+ }
+
+ private boolean atBeginning;
+ private boolean eof;
+ private int pos;
+ private char[] internalBuffer;
+ private PushbackReader internalReader;
+
+ /**
+ * Creates a DotTerminatedMessageReader that wraps an existing Reader
+ * input source.
+ * @param reader The Reader input source containing the message.
+ */
+ public DotTerminatedMessageReader(Reader reader)
+ {
+ super(reader);
+ internalBuffer = new char[LS_CHARS.length + 3];
+ pos = internalBuffer.length;
+ // Assumes input is at start of message
+ atBeginning = true;
+ eof = false;
+ internalReader = new PushbackReader(reader);
+ }
+
+ /**
+ * Reads and returns the next character in the message. 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 to decode
+ * the message properly (removing doubled dots and so on). All of
+ * this is transparent to the programmer and is only mentioned for
+ * completeness.
+ * @return The next character in the message. Returns -1 if the end of the
+ * message has been reached.
+ * @exception IOException If an error occurs while reading the underlying
+ * stream.
+ */
+ @Override
+ public int read() throws IOException
+ {
+ int ch;
+
+ synchronized (lock)
+ {
+ if (pos < internalBuffer.length)
+ {
+ return internalBuffer[pos++];
+ }
+
+ if (eof)
+ {
+ return -1;
+ }
+
+ if ((ch = internalReader.read()) == -1)
+ {
+ eof = true;
+ return -1;
+ }
+
+ if (atBeginning)
+ {
+ atBeginning = false;
+ if (ch == '.')
+ {
+ ch = internalReader.read();
+
+ if (ch != '.')
+ {
+ // read newline
+ eof = true;
+ internalReader.read();
+ return -1;
+ }
+ else
+ {
+ return '.';
+ }
+ }
+ }
+
+ if (ch == '\r')
+ {
+ ch = internalReader.read();
+
+ if (ch == '\n')
+ {
+ ch = internalReader.read();
+
+ if (ch == '.')
+ {
+ ch = internalReader.read();
+
+ if (ch != '.')
+ {
+ // read newline and indicate end of file
+ internalReader.read();
+ eof = true;
+ }
+ else
+ {
+ internalBuffer[--pos] = (char) ch;
+ }
+ }
+ else
+ {
+ internalReader.unread(ch);
+ }
+
+ pos -= LS_CHARS.length;
+ System.arraycopy(LS_CHARS, 0, internalBuffer, pos,
+ LS_CHARS.length);
+ ch = internalBuffer[pos++];
+ }
+ else
+ {
+ internalBuffer[--pos] = (char) ch;
+ return '\r';
+ }
+ }
+
+ return ch;
+ }
+ }
+
+ /**
+ * Reads the next characters from the message into an array and
+ * returns the number of characters read. Returns -1 if the end of the
+ * message has been reached.
+ * @param buffer The character array in which to store the characters.
+ * @return The number of characters 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(char[] buffer) throws IOException
+ {
+ return read(buffer, 0, buffer.length);
+ }
+
+ /**
+ * Reads the next characters from the message into an array and
+ * returns the number of characters 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.
+ * @param buffer The character array in which to store the characters.
+ * @param offset The offset into the array at which to start storing
+ * characters.
+ * @param length The number of characters to read.
+ * @return The number of characters 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(char[] buffer, int offset, int length) throws IOException
+ {
+ int ch, off;
+ synchronized (lock)
+ {
+ if (length < 1)
+ {
+ return 0;
+ }
+ if ((ch = read()) == -1)
+ {
+ return -1;
+ }
+ off = offset;
+
+ do
+ {
+ buffer[offset++] = (char) ch;
+ }
+ while (--length > 0 && (ch = read()) != -1);
+
+ return (offset - off);
+ }
+ }
+
+ /**
+ * Determines if the message is ready to be read.
+ * @return True if the message is ready to be read, false if not.
+ * @exception IOException If an error occurs while checking the underlying
+ * stream.
+ */
+ @Override
+ public boolean ready() throws IOException
+ {
+ synchronized (lock)
+ {
+ return (pos < internalBuffer.length || internalReader.ready());
+ }
+ }
+
+ /**
+ * Closes the message for reading. This doesn't actually close the
+ * underlying stream. The underlying stream may still be used for
+ * communicating with the server and therefore is not closed.
+ * <p>
+ * If the end of the message has not yet been reached, this method
+ * will read the remainder of the message until it reaches the end,
+ * so that the underlying stream may continue to be used properly
+ * for communicating with the server. If you do not fully read
+ * a message, you MUST close it, otherwise your program will likely
+ * hang or behave improperly.
+ * @exception IOException If an error occurs while reading the
+ * underlying stream.
+ */
+ @Override
+ public void close() throws IOException
+ {
+ synchronized (lock)
+ {
+ if (internalReader == null)
+ {
+ return;
+ }
+
+ if (!eof)
+ {
+ while (read() != -1)
+ {
+ ;
+ }
+ }
+ eof = true;
+ atBeginning = false;
+ pos = internalBuffer.length;
+ internalReader = null;
+ }
+ }
+}
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