[jira] [Created] (LOG4NET-658) ColoredConsoleAppender throws exception on .NET Core

["Martin Storø Nyfløtt (Jira)" <ji...@apache.org>]

Martin Storø Nyfløtt created LOG4NET-658:
--------------------------------------------

             Summary: ColoredConsoleAppender throws exception on .NET Core
                 Key: LOG4NET-658
                 URL: https://issues.apache.org/jira/browse/LOG4NET-658
             Project: Log4net
          Issue Type: Bug
          Components: Appenders
    Affects Versions: 2.0.8
         Environment: Windows, .NET Core 3.1
            Reporter: Martin Storø Nyfløtt


Moving from .NET Framework to .NET Core, I discovered that ColoredConsoleAppender starts logging the following error messages to my console if I reference it in a log4net.config:

 
{noformat}
log4net:ERROR Could not create Appender [ColoredConsoleAppender] of type [log4net.Appender.ColoredConsoleAppender]. Reported error follows.
System.NotSupportedException: No data is available for encoding 437. For information on defining a custom encoding, see the documentation for the Encoding.RegisterProvider method.
 at System.Text.Encoding.GetEncoding(Int32 codepage)
 at log4net.Appender.ColoredConsoleAppender.ActivateOptions()
 at log4net.Repository.Hierarchy.XmlHierarchyConfigurator.ParseAppender(XmlElement appenderElement)
log4net:ERROR Appender named [ColoredConsoleAppender] not found.{noformat}
 

The reason I am seeing this is because [ColoredConsoleAppender will call|https://github.com/apache/logging-log4net/blob/rel/2.0.12/src/log4net/Appender/ColoredConsoleAppender.cs#L462] GetConsoleOutputCP() in Kernel32.dll to get the current encoding being used in the console to configure a stream writer for writing to the console with the appropriate text encoding. In my case, this is 437 (OEM United States). When GetEncoding with this code-page, the exception above gets thrown because this encoding is not included out-of-the-box in .NET Core.

This can be reproduced by having an application with the following Main:

 
{code:java}
static void Main()
{
    var configurationPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "log4net.config");
    XmlConfigurator.Configure(new FileInfo(configurationPath));
}
{code}
 

and the following log4net.config:

 

 
{noformat}
<?xml version="1.0" encoding="utf-8"?><log4net>
  <appender name="ColoredConsoleAppender" type="log4net.Appender.ColoredConsoleAppender">
  </appender>  <root>
    <appender-ref ref="ColoredConsoleAppender" />
  </root>
</log4net>{noformat}
 

In order to go around this problem, I have added a reference to the Nuget package [System.Text.Encoding.CodePages|https://www.nuget.org/packages/System.Text.Encoding.CodePages/] and registered the code pages before I configure log4net:

 
{code:java}
static void Main()
{
    Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
    var configurationPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "log4net.config");
    XmlConfigurator.Configure(new FileInfo(configurationPath));
}
{code}
I think this is also how you would fix this in log4net. This is also a show-stopper from getting this functionality working on Linux (or anything non-Windows), since Kernel32.dll is a Windows-specific library.

 



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