FileTarget - Handle archive file already exists by appending should n…

…ot just truncate file, but delete file if possible
NLog · Jun 28, 2018 · 776de3b · 776de3b
1 parent efc08aa
commit 776de3b
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Showing 2 changed files with 27 additions and 3 deletions.
diff --git a/src/NLog/Targets/FileTarget.cs b/src/NLog/Targets/FileTarget.cs
@@ -1295,19 +1295,40 @@ private void ArchiveFile(string fileName, string archiveFileName)
                     //todo maybe needs a better filelock behaviour
 
                     //copy to archive file.
-                    using (FileStream fileStream = File.Open(fileName, FileMode.Open))
+                    var fileShare = FileShare.ReadWrite;
+                    if (EnableFileDelete)
+                    {
+                        fileShare |= FileShare.Delete;
+                    }
+
+                    using (FileStream fileStream = File.Open(fileName, FileMode.Open, FileAccess.ReadWrite, fileShare))
                     using (FileStream archiveFileStream = File.Open(archiveFileName, FileMode.Append))
                     {
                         fileStream.CopyAndSkipBom(archiveFileStream, Encoding);
                         //clear old content
                         fileStream.SetLength(0);
+
+                        if (EnableFileDelete)
+                        {
+                            // Attempt to delete file to reset File-Creation-Time (Delete under file-lock)
+                            if (!DeleteOldArchiveFile(fileName))
+                            {
+                                fileShare &= ~FileShare.Delete;  // Retry after having released file-lock
+                            }
+                        }
+
                         fileStream.Close(); // This flushes the content, too.
 #if NET3_5
                         archiveFileStream.Flush();
 #else
                         archiveFileStream.Flush(true);
 #endif
                     }
+
+                    if ((fileShare & FileShare.Delete) == FileShare.None)
+                    {
+                        DeleteOldArchiveFile(fileName); // Attempt to delete file to reset File-Creation-Time
+                    }
                 }
                 else
                 {

diff --git a/tests/NLog.UnitTests/Targets/FileTargetTests.cs b/tests/NLog.UnitTests/Targets/FileTargetTests.cs
@@ -3934,7 +3934,6 @@ private void HandleArchiveFileAlreadyExistsTest(Encoding encoding, bool hasBom)
                 // set log file access times the same way as when this issue comes up.
                 Directory.CreateDirectory(tempDir);
 
-
                 File.WriteAllText(logFile, "some content" + Environment.NewLine, encoding);
                 var oldTime = DateTime.Now.AddDays(-2);
                 File.SetCreationTime(logFile, oldTime);
@@ -3959,7 +3958,9 @@ private void HandleArchiveFileAlreadyExistsTest(Encoding encoding, bool hasBom)
                     ArchiveFileName = archiveFileNamePattern,
                     ArchiveNumbering = ArchiveNumberingMode.Date,
                     ArchiveDateFormat = archiveDateFormat,
-                    Encoding = encoding
+                    Encoding = encoding,
+                    Layout = "${message}",
+                    WriteBom = hasBom,
                 };
 
 
@@ -3972,10 +3973,12 @@ private void HandleArchiveFileAlreadyExistsTest(Encoding encoding, bool hasBom)
                 var logger = LogManager.GetLogger("HandleArchiveFileAlreadyExistsTest");
                 // write, this should append.
                 logger.Info("log to force archiving");
+                logger.Info("log to same file");
 
                 LogManager.Configuration = null;    // Flush
 
                 AssertFileContents(archiveFileName, "message already in archive" + Environment.NewLine + "some content" + Environment.NewLine, encoding, hasBom);
+                AssertFileContents(logFile, "log to force archiving" + Environment.NewLine + "log to same file" + Environment.NewLine, encoding, hasBom);
             }
             finally
             {