From 59f66ff4807b3c382367aadd1eaa87beef80e1f4 Mon Sep 17 00:00:00 2001
From: Michael Bucari-Tovo <mbucari1@gmail.com>
Date: Fri, 14 Nov 2025 13:43:54 -0700
Subject: [PATCH] Fix subdirectory create failing on root drive (#1432)

This appears to be a bug in .NET. Someone started to fix it in a PR, but it went stale and was auto-closed.

https://github.com/dotnet/runtime/pull/117519
---
 Source/FileManager/FileUtility.cs            | 22 ++++++++++++++++++++
 Source/LibationFileManager/PictureStorage.cs |  5 +++--
 Source/LibationSearchEngine/SearchEngine.cs  |  3 ++-
 3 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/Source/FileManager/FileUtility.cs b/Source/FileManager/FileUtility.cs
index 137b817f..387178a1 100644
--- a/Source/FileManager/FileUtility.cs
+++ b/Source/FileManager/FileUtility.cs
@@ -263,5 +263,27 @@ namespace FileManager
 
 			return foundFiles;
 		}
+
+		/// <summary>
+		/// Creates a subdirectory or subdirectories on the specified path.
+		/// The specified path can be relative to this instance of the <see cref="DirectoryInfo"/> class.
+		/// <para/>
+		/// Fixes an issue with <see cref="DirectoryInfo.CreateSubdirectory(string)"/> where it fails when the parent <see cref="DirectoryInfo"/> is a drive root.
+		/// </summary>
+		/// <param name="path">The specified path. This cannot be a different disk volume or Universal Naming Convention (UNC) name.</param>
+		/// <returns>The last directory specified in <paramref name="path"/></returns>
+		public static DirectoryInfo CreateSubdirectoryEx(this DirectoryInfo parent, string path)
+		{
+			if (parent.Root.FullName != parent.FullName || Path.IsPathRooted(path))
+				return parent.CreateSubdirectory(path);
+
+			// parent is a drive root and subDirectory is relative
+			//Solves a problem with DirectoryInfo.CreateSubdirectory where it fails
+			//If the parent DirectoryInfo is a drive root.
+			var fullPath = Path.GetFullPath(Path.Combine(parent.FullName, path));
+			var directoryInfo = new DirectoryInfo(fullPath);
+			directoryInfo.Create();
+			return directoryInfo;
+		}
 	}
 }
diff --git a/Source/LibationFileManager/PictureStorage.cs b/Source/LibationFileManager/PictureStorage.cs
index 582d55d8..dccd4d42 100644
--- a/Source/LibationFileManager/PictureStorage.cs
+++ b/Source/LibationFileManager/PictureStorage.cs
@@ -1,4 +1,5 @@
-using System;
+using FileManager;
+using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.IO;
@@ -42,7 +43,7 @@ namespace LibationFileManager
     {
         // not customizable. don't move to config
         private static string ImagesDirectory { get; }
-            = new DirectoryInfo(Configuration.Instance.LibationFiles).CreateSubdirectory("Images").FullName;
+            = new DirectoryInfo(Configuration.Instance.LibationFiles).CreateSubdirectoryEx("Images").FullName;
 
 		private static string getPath(PictureDefinition def)
 			=> Path.Combine(ImagesDirectory, $"{def.PictureId}{def.Size}.jpg");
diff --git a/Source/LibationSearchEngine/SearchEngine.cs b/Source/LibationSearchEngine/SearchEngine.cs
index b922175b..f1bd1075 100644
--- a/Source/LibationSearchEngine/SearchEngine.cs
+++ b/Source/LibationSearchEngine/SearchEngine.cs
@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Linq;
 using DataLayer;
 using Dinah.Core;
+using FileManager;
 using LibationFileManager;
 using Lucene.Net.Analysis.Standard;
 using Lucene.Net.Documents;
@@ -279,6 +280,6 @@ namespace LibationSearchEngine
 
         // not customizable. don't move to config
         private static string SearchEngineDirectory { get; }
-            = new System.IO.DirectoryInfo(Configuration.Instance.LibationFiles).CreateSubdirectory("SearchEngine").FullName;
+            = new System.IO.DirectoryInfo(Configuration.Instance.LibationFiles).CreateSubdirectoryEx("SearchEngine").FullName;
     }
 }