FileTarget crashes if archive file pattern is the same as the log files

[asherber]

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Type (choose one):

• Bug

NLog version: latest master from GitHub

Platform: .Net 4.5

Current NLog config (xml or C#, if relevant)

var fileTarget = new FileTarget()
            {
                FileName = "${var:baseFileName}-${date:format=yyyyMMdd}.log",
                Layout = "${message}",
                //ArchiveFileName = "${var:baseFileName}.{#}.log",
                ArchiveFileName = "${var:baseFileName}-{#}.log",
                ArchiveNumbering = ArchiveNumberingMode.DateAndSequence,
                ArchiveEvery = FileArchivePeriod.Day,
                ArchiveDateFormat = "yyyyMMdd",
                MaxArchiveFiles = 7,
                ArchiveAboveSize = 1000,
            };

If the character before the replacement pattern {#} is a dash, NLog starts throwing exceptions at the point where the log should roll over.

Exception info from InternalLogger:

2016-05-04 22:17:15.9871 Error Error has been raised. Exception: System.ArgumentOutOfRangeException: Length cannot be less than zero.                                                                                                                                 
Parameter name: length                                                                                                             
   at System.String.Substring(Int32 startIndex, Int32 length)                                                                      
   at NLog.Targets.FileTarget.TryParseDateAndSequence(String archiveFileNameWithoutPath, String dateFormat, FileNameTemplate fileTe
mplate, DateTime& date, Int32& sequence) in P:\Visual Studio\NLog\src\NLog\Targets\FileTarget.cs:line 1416                         
   at NLog.Targets.FileTarget.<FindDateAndSequenceArchives>d__158.MoveNext() in P:\Visual Studio\NLog\src\NLog\Targets\FileTarget.c
s:line 1382                                                                                                                        
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)                                                            
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)                                                                 
   at NLog.Targets.FileTarget.ArchiveByDateAndSequence(String fileName, String pattern, LogEventInfo logEvent) in P:\Visual Studio\
NLog\src\NLog\Targets\FileTarget.cs:line 1303                                                                                      
   at NLog.Targets.FileTarget.DoAutoArchive(String fileName, LogEventInfo eventInfo) in P:\Visual Studio\NLog\src\NLog\Targets\File
Target.cs:line 1664                                                                                                                
   at NLog.Targets.FileTarget.ProcessLogEvent(LogEventInfo logEvent, String fileName, Byte[] bytesToWrite) in P:\Visual Studio\NLog
\src\NLog\Targets\FileTarget.cs:line 972                                                                                           
   at NLog.Targets.FileTarget.Write(LogEventInfo logEvent) in P:\Visual Studio\NLog\src\NLog\Targets\FileTarget.cs:line 909        
   at NLog.Targets.Target.Write(AsyncLogEventInfo logEvent) in P:\Visual Studio\NLog\src\NLog\Targets\Target.cs:line 467           

[asherber]

Slight correction: It's something about the combination of the punctuation in the FileName and ArchiveFileName that is the problem.

In the example config above, FileName and ArchiveFileName both have a dash before the last part of the filename, and the exception gets thrown. The same is true if I replace the dash in both properties with a period. But if either one is a period and the other one is a dash, then there is no exception and files get written as expected.

[304NotModified]

This is indeed a bug. Nlog tries to parse the date from current archived files, but failed.

[304NotModified]

Too had no time to look at this. If you could help writing an unit test, that would boost the development!

[asherber]

Sure, I"ll try.

[304NotModified]

Thanks! We use xunit1 and you can send a PR :)

[304NotModified]

working in this now

[304NotModified]

I think the problem is here that the archive filename is the same as the filename (only change is the sequence number). They are both in the same dir also.

I couldn't get the same exception, but I think I have solved the issue.

[asherber]

Thank you for picking this up.