From 4dc67c027b96d0d75d12c4ec64d7f1e418710c81 Mon Sep 17 00:00:00 2001
From: Qstick <qstick@gmail.com>
Date: Sat, 30 Jan 2021 22:20:39 -0500
Subject: [PATCH] Fixed accounting for zero terminator in long path limitation

Fixes #5763

Co-Authored-By: Taloth <Taloth@users.noreply.github.com>
---
 src/NzbDrone.Common/Disk/LongPathSupport.cs | 63 ++++++++++++++++++++-
 1 file changed, 62 insertions(+), 1 deletion(-)

diff --git a/src/NzbDrone.Common/Disk/LongPathSupport.cs b/src/NzbDrone.Common/Disk/LongPathSupport.cs
index ef4bd3f7c..f971175a6 100644
--- a/src/NzbDrone.Common/Disk/LongPathSupport.cs
+++ b/src/NzbDrone.Common/Disk/LongPathSupport.cs
@@ -1,15 +1,76 @@
-using System;
+using System;
+using System.IO;
+using NzbDrone.Common.EnvironmentInfo;
 
 namespace NzbDrone.Common.Disk
 {
     public static class LongPathSupport
     {
+        private static int MAX_PATH;
+        private static int MAX_NAME;
+
         public static void Enable()
         {
             // Mono has an issue with enabling long path support via app.config.
             // This works for both mono and .net on Windows.
             AppContext.SetSwitch("Switch.System.IO.UseLegacyPathHandling", false);
             AppContext.SetSwitch("Switch.System.IO.BlockLongPaths", false);
+
+            DetectLongPathLimits();
+        }
+
+        private static void DetectLongPathLimits()
+        {
+            if (!int.TryParse(Environment.GetEnvironmentVariable("MAX_PATH"), out MAX_PATH))
+            {
+                if (OsInfo.IsLinux)
+                {
+                    MAX_PATH = 4096;
+                }
+                else
+                {
+                    try
+                    {
+                        Path.GetDirectoryName($@"C:\{new string('a', 300)}\ab");
+                        MAX_PATH = 4096;
+                    }
+                    catch
+                    {
+                        MAX_PATH = 260 - 1;
+                    }
+                }
+            }
+
+            if (!int.TryParse(Environment.GetEnvironmentVariable("MAX_NAME"), out MAX_NAME))
+            {
+                MAX_NAME = 255;
+            }
+        }
+
+        public static int MaxFilePathLength
+        {
+            get
+            {
+                if (MAX_PATH == 0)
+                {
+                    DetectLongPathLimits();
+                }
+
+                return MAX_PATH;
+            }
+        }
+
+        public static int MaxFileNameLength
+        {
+            get
+            {
+                if (MAX_NAME == 0)
+                {
+                    DetectLongPathLimits();
+                }
+
+                return MAX_NAME;
+            }
         }
     }
 }