[LOG4J2-2758] RollingFileAppender: NPE when using a custom DirectFileRolloverStrategy without fileName

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.12.1
• Fix Version/s: 2.13.1
• Component/s: Appenders
• External issue URL: https://github.com/apache/logging-log4j2/pull/331
• Assignee: Unassigned
• Reporter: Christoph Kaser
• Created: 13/Jan/20 16:27
• Updated: 10/Feb/20 07:52
• Resolved: 09/Feb/20 03:44

Description

 

I have created a custom RolloverStrategy which implements org.apache.logging.log4j.core.appender.rolling.DirectFileRolloverStrategy (but does not extend DirectWriteRolloverStrategy).

When I try to use this strategy in a RollingFileAppender with a filePattern, but no fileName, log4j writes an exception to the console and does not work:

 

2020-01-13 17:22:49,024 StartUp-Thread ERROR An exception occurred processing Appender CustomAppender java.lang.NullPointerException
 at java.base/java.io.File.<init>(File.java:276)
 at org.apache.logging.log4j.core.appender.FileManager.createOutputStream(FileManager.java:190)
 at org.apache.logging.log4j.core.appender.OutputStreamManager.getOutputStream(OutputStreamManager.java:166)
 at org.apache.logging.log4j.core.appender.OutputStreamManager.writeToDestination(OutputStreamManager.java:261)
 at org.apache.logging.log4j.core.appender.FileManager.writeToDestination(FileManager.java:272)
 at org.apache.logging.log4j.core.appender.rolling.RollingFileManager.writeToDestination(RollingFileManager.java:244)
 at org.apache.logging.log4j.core.appender.OutputStreamManager.flushBuffer(OutputStreamManager.java:293)
 at org.apache.logging.log4j.core.appender.OutputStreamManager.flush(OutputStreamManager.java:302)
 at org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.directEncodeEvent(AbstractOutputStreamAppender.java:199)
 at org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.tryAppend(AbstractOutputStreamAppender.java:190)
 at org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.append(AbstractOutputStreamAppender.java:181)
 at org.apache.logging.log4j.core.appender.RollingFileAppender.append(RollingFileAppender.java:312)
 at org.apache.logging.log4j.core.config.AppenderControl.tryCallAppender(AppenderControl.java:156)
 at org.apache.logging.log4j.core.config.AppenderControl.callAppender0(AppenderControl.java:129)
 at org.apache.logging.log4j.core.config.AppenderControl.callAppenderPreventRecursion(AppenderControl.java:120)
 at org.apache.logging.log4j.core.config.AppenderControl.callAppender(AppenderControl.java:84)
 at org.apache.logging.log4j.core.config.LoggerConfig.callAppenders(LoggerConfig.java:543)
 at org.apache.logging.log4j.core.config.LoggerConfig.processLogEvent(LoggerConfig.java:502)
 at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:485)
 at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:460)
 at org.apache.logging.log4j.core.config.AwaitCompletionReliabilityStrategy.log(AwaitCompletionReliabilityStrategy.java:82)
 at org.apache.logging.log4j.core.Logger.log(Logger.java:161)
 at org.apache.logging.log4j.spi.AbstractLogger.tryLogMessage(AbstractLogger.java:2198)
 at org.apache.logging.log4j.spi.AbstractLogger.logMessageTrackRecursion(AbstractLogger.java:2152)
 at org.apache.logging.log4j.spi.AbstractLogger.logMessageSafely(AbstractLogger.java:2135)
 at org.apache.logging.log4j.spi.AbstractLogger.logMessage(AbstractLogger.java:2011)
 at org.apache.logging.log4j.spi.AbstractLogger.logIfEnabled(AbstractLogger.java:1983)
 at org.apache.logging.log4j.spi.AbstractLogger.info(AbstractLogger.java:1320)
 at IconParc.IpionServer.IpionServer.main(IpionServer.java:1154)

The reason for this behaviour is that the RollingFileAppender explicitely checks for instances of DirectWriteRolloverStrategy instead of DirectFileRolloverStrategy like its Builder does.

I opened a PR (https://github.com/apache/logging-log4j2/pull/331) that fixes this behavior.