FileTarget - Validate File CreationTimeUtc when non-Windows

src/NLog/Internal/FileAppenders/BaseFileAppender.cs

@@ -337,24 +337,19 @@ private FileStream TryCreateFileStream(bool allowFileSharedWriting)
 
         private void UpdateCreationTime()
         {
-            if (File.Exists(this.FileName))
+            FileInfo fileInfo = new FileInfo(this.FileName);
+            if (fileInfo.Exists)
             {
-#if !SILVERLIGHT
-                this.CreationTimeUtc = File.GetCreationTimeUtc(this.FileName);
-#else
-                this.CreationTimeUtc = File.GetCreationTime(this.FileName);
-#endif
+                this.CreationTimeUtc = FileCharacteristicsHelper.ValidateFileCreationTime(fileInfo, (f) => f.GetCreationTimeUtc(), (f) => f.GetLastWriteTimeUtc()).Value;
             }
             else
             {
                 File.Create(this.FileName).Dispose();
+                this.CreationTimeUtc = DateTime.UtcNow;
 
 #if !SILVERLIGHT
-                this.CreationTimeUtc = DateTime.UtcNow;
                 // Set the file's creation time to avoid being thwarted by Windows' Tunneling capabilities (https://support.microsoft.com/en-us/kb/172190).
                 File.SetCreationTimeUtc(this.FileName, this.CreationTimeUtc);
-#else
-                this.CreationTimeUtc = File.GetCreationTime(this.FileName);
 #endif
             }
         }

src/NLog/Internal/FileAppenders/FileAppenderCache.cs

@@ -416,11 +416,12 @@ public Mutex GetArchiveMutex(string fileName)
             {
                 try
                 {
-                    result = appender.GetFileCreationTimeUtc();
+                    result = FileCharacteristicsHelper.ValidateFileCreationTime(appender, (f) => f.GetFileCreationTimeUtc(), (f) => f.CreationTimeUtc, (f) => f.GetFileLastWriteTimeUtc());
                     if (result.HasValue)
                     {
                         // Check if cached value is still valid, and update if not (Will automatically update CreationTimeSource)
-                        if (result.Value != appender.CreationTimeUtc)
+                        DateTime cachedTimeUtc = appender.CreationTimeUtc;
+                        if (result.Value != cachedTimeUtc)
                         {
                             appender.CreationTimeUtc = result.Value;
                         }
@@ -439,7 +440,8 @@ public Mutex GetArchiveMutex(string fileName)
                 var fileInfo = new FileInfo(filePath);
                 if (fileInfo.Exists)
                 {
-                    return Time.TimeSource.Current.FromSystemTime(fileInfo.GetCreationTimeUtc());
+                    result = FileCharacteristicsHelper.ValidateFileCreationTime(fileInfo, (f) => f.GetCreationTimeUtc(), (f) => f.GetLastWriteTimeUtc()).Value;
+                    return Time.TimeSource.Current.FromSystemTime(result.Value);
                 }
             }
 

src/NLog/Internal/FileAppenders/UnixMultiProcessFileAppender.cs

@@ -76,6 +76,17 @@ BaseFileAppender IFileAppenderFactory.Open(string fileName, ICreateFileParameter
 
         public UnixMultiProcessFileAppender(string fileName, ICreateFileParameters parameters) : base(fileName, parameters)
         {
+            UnixFileInfo fileInfo = null;
+            bool fileExists = false;
+            try
+            {
+                fileInfo = new UnixFileInfo(fileName);
+                fileExists = fileInfo.Exists;
+            }
+            catch
+            {
+            }
+
             int fd = Syscall.open(fileName, OpenFlags.O_CREAT | OpenFlags.O_WRONLY | OpenFlags.O_APPEND, (FilePermissions)(6 | (6 << 3) | (6 << 6)));
             if (fd == -1)
             {
@@ -93,21 +104,18 @@ public UnixMultiProcessFileAppender(string fileName, ICreateFileParameters param
 
             try
             {
-                bool fileExists = File.Exists(fileName);
-
                 this.file = new UnixStream(fd, true);
 
                 long filePosition = this.file.Position;
                 if (fileExists || filePosition > 0)
                 {
-                    this.CreationTimeUtc = File.GetCreationTimeUtc(this.FileName);
-                    if (this.CreationTimeUtc < DateTime.UtcNow - TimeSpan.FromSeconds(2) && filePosition == 0)
+                    if (fileInfo != null)
+                    {
+                        this.CreationTimeUtc = FileCharacteristicsHelper.ValidateFileCreationTime(fileInfo, (f) => File.GetCreationTimeUtc(f.FullName), (f) => { f.Refresh(); return f.LastStatusChangeTimeUtc; }, (f) => DateTime.UtcNow).Value;
+                    }
+                    else
                     {
-                        // File wasn't created "almost now". 
-                        Thread.Sleep(50);
-                        // Having waited for a short amount of time usually means the file creation process has continued
-                        // code execution just enough to the above point where it has fixed up the creation time.
-                        this.CreationTimeUtc = File.GetCreationTimeUtc(this.FileName);
+                        this.CreationTimeUtc = FileCharacteristicsHelper.ValidateFileCreationTime(fileName, (f) => File.GetCreationTimeUtc(f), (f) => DateTime.UtcNow).Value;
                     }
                 }
                 else

src/NLog/Internal/FileCharacteristicsHelper.cs

@@ -33,6 +33,7 @@
 
 namespace NLog.Internal
 {
+    using System;
     using System.IO;
 
     /// <summary>
@@ -64,5 +65,23 @@ public static FileCharacteristicsHelper CreateHelper(bool forcedManaged)
         /// <param name="fileStream">The file stream.</param>
         /// <returns>The file characteristics, if the file information was retrieved successfully, otherwise null.</returns>
         public abstract FileCharacteristics GetFileCharacteristics(string fileName, FileStream fileStream);
+
+        public static DateTime? ValidateFileCreationTime<T>(T fileInfo, Func<T, DateTime?> primary, Func<T, DateTime?> fallback, Func<T, DateTime?> finalFallback = null)
+        {
+            DateTime? fileCreationTime = primary(fileInfo);
+            if (fileCreationTime.HasValue && fileCreationTime.Value.Year < 1980)
+            {
+                // Non-Windows-FileSystems doesn't always provide correct CreationTime/BirthTime
+                if (!PlatformDetector.IsDesktopWin32)
+                {
+                    fileCreationTime = fallback(fileInfo);
+                    if (finalFallback != null && (!fileCreationTime.HasValue || fileCreationTime.Value.Year < 1980))
+                    {
+                        fileCreationTime = finalFallback(fileInfo);
+                    }
+                }
+            }
+            return fileCreationTime;
+        }
     }
 }