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The Apache Log4j Implementation
/*
* 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.logging.log4j.core.pattern;
import java.util.List;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.layout.PatternLayout;
import org.apache.logging.log4j.util.EnglishEnums;
import org.apache.logging.log4j.util.PerformanceSensitive;
import org.apache.logging.log4j.util.StringBuilders;
/**
* Converter that encodes the output from a pattern using a specified format. Supported formats include HTML
* (default) and JSON.
*/
@Plugin(name = "encode", category = PatternConverter.CATEGORY)
@ConverterKeys({"enc", "encode"})
@PerformanceSensitive("allocation")
public final class EncodingPatternConverter extends LogEventPatternConverter {
private final List formatters;
private final EscapeFormat escapeFormat;
/**
* Private constructor.
*
* @param formatters the PatternFormatters to generate the text to manipulate.
* @param escapeFormat the escape format strategy to use for encoding output of formatters
*/
private EncodingPatternConverter(final List formatters,
final EscapeFormat escapeFormat) {
super("encode", "encode");
this.formatters = formatters;
this.escapeFormat = escapeFormat;
}
/**
* Creates an EncodingPatternConverter using a pattern string and an optional escape format.
*
* @param config the current Configuration
* @param options first option is the nested pattern format; second option is the escape format (optional)
* @return instance of pattern converter.
*/
public static EncodingPatternConverter newInstance(final Configuration config, final String[] options) {
if (options.length > 2 || options.length == 0) {
LOGGER.error("Incorrect number of options on escape. Expected 1 or 2, but received {}",
options.length);
return null;
}
if (options[0] == null) {
LOGGER.error("No pattern supplied on escape");
return null;
}
final EscapeFormat escapeFormat = options.length < 2 ? EscapeFormat.HTML
: EnglishEnums.valueOf(EscapeFormat.class, options[1], EscapeFormat.HTML);
final PatternParser parser = PatternLayout.createPatternParser(config);
final List formatters = parser.parse(options[0]);
return new EncodingPatternConverter(formatters, escapeFormat);
}
/**
* {@inheritDoc}
*/
@Override
public void format(final LogEvent event, final StringBuilder toAppendTo) {
final int start = toAppendTo.length();
for (int i = 0; i < formatters.size(); i++) {
formatters.get(i).format(event, toAppendTo);
}
escapeFormat.escape(toAppendTo, start);
}
private enum EscapeFormat {
HTML {
@Override
void escape(final StringBuilder toAppendTo, final int start) {
for (int i = toAppendTo.length() - 1; i >= start; i--) { // backwards: length may change
final char c = toAppendTo.charAt(i);
switch (c) {
case '\r':
toAppendTo.setCharAt(i, '\\');
toAppendTo.insert(i + 1, 'r');
break;
case '\n':
toAppendTo.setCharAt(i, '\\');
toAppendTo.insert(i + 1, 'n');
break;
case '&':
toAppendTo.setCharAt(i, '&');
toAppendTo.insert(i + 1, "amp;");
break;
case '<':
toAppendTo.setCharAt(i, '&');
toAppendTo.insert(i + 1, "lt;");
break;
case '>':
toAppendTo.setCharAt(i, '&');
toAppendTo.insert(i + 1, "gt;");
break;
case '"':
toAppendTo.setCharAt(i, '&');
toAppendTo.insert(i + 1, "quot;");
break;
case '\'':
toAppendTo.setCharAt(i, '&');
toAppendTo.insert(i + 1, "apos;");
break;
case '/':
toAppendTo.setCharAt(i, '&');
toAppendTo.insert(i + 1, "#x2F;");
break;
}
}
}
},
/**
* JSON string escaping as defined in RFC 4627.
*
* @see RFC 4627
*/
JSON {
@Override
void escape(final StringBuilder toAppendTo, final int start) {
StringBuilders.escapeJson(toAppendTo, start);
}
},
CRLF {
@Override
void escape(final StringBuilder toAppendTo, final int start) {
for (int i = toAppendTo.length() - 1; i >= start; i--) { // backwards: length may change
final char c = toAppendTo.charAt(i);
switch (c) {
case '\r':
toAppendTo.setCharAt(i, '\\');
toAppendTo.insert(i + 1, 'r');
break;
case '\n':
toAppendTo.setCharAt(i, '\\');
toAppendTo.insert(i + 1, 'n');
break;
}
}
}
},
/**
* XML string escaping as defined in XML specification.
*
* @see XML specification
*/
XML {
@Override
void escape(final StringBuilder toAppendTo, final int start) {
StringBuilders.escapeXml(toAppendTo, start);
}
};
/**
* Escapes text using a standardized format from a given starting point to the end of the string.
*
* @param toAppendTo string buffer to escape
* @param start where to start escaping from
*/
abstract void escape(final StringBuilder toAppendTo, final int start);
}
}