From 9bdd16c33939f2dc72db5e66255682f61d8e5916 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Henrik=20N=C3=B8rfjand=20Stengaard?= <hst@firstrealize.com>
Date: Mon, 16 Feb 2026 12:00:17 +0100
Subject: [PATCH] Fix fat load entries update end of entries when cluster
 doesnt contain end marker entry

---
 Library/DiscUtils.Fat/Directory.cs          |  2 +
 Tests/LibraryTests/Fat/FatFileSystemTest.cs | 70 ++++++++++++++++++++-
 2 files changed, 71 insertions(+), 1 deletion(-)

diff --git a/Library/DiscUtils.Fat/Directory.cs b/Library/DiscUtils.Fat/Directory.cs
index 5e7b2470..3de3d115 100644
--- a/Library/DiscUtils.Fat/Directory.cs
+++ b/Library/DiscUtils.Fat/Directory.cs
@@ -471,6 +471,8 @@ private void LoadEntries()
             {
                 AddEntryRaw(streamPos, entry);
             }
+
+            _endOfEntries = _dirStream.Position;
         }
 
         // Record any pending free entry
diff --git a/Tests/LibraryTests/Fat/FatFileSystemTest.cs b/Tests/LibraryTests/Fat/FatFileSystemTest.cs
index eb21c03c..34f93dab 100644
--- a/Tests/LibraryTests/Fat/FatFileSystemTest.cs
+++ b/Tests/LibraryTests/Fat/FatFileSystemTest.cs
@@ -608,4 +608,72 @@ public void CreateDirectoryWithExistingData()
 
         Assert.Empty(entries);
     }
-}
+
+    [Fact]
+    public void CreateFilesInSubdirectoryUsingFatFileSystemPerFile()
+    {
+        using var diskStream = new SparseMemoryStream();
+
+        diskStream.Position = 0;
+        using (var fsFormat = FatFileSystem.FormatFloppy(diskStream, FloppyDiskType.HighDensity, "FLOPPY_IMG "))
+        {
+            fsFormat.CreateDirectory("dir");            
+        }
+
+        for (var i = 0; i < 20; i++)
+        {
+            using (var fsCreate = new FatFileSystem(diskStream))
+            {
+                using (var fileStream = fsCreate.OpenFile($"dir{Path.DirectorySeparatorChar}file{i}.txt", FileMode.Create))
+                {
+                    fileStream.Write(new byte[10]);
+                }
+            }            
+        }
+
+        using var fsAssert = new FatFileSystem(diskStream);
+        {
+            var entries = fsAssert.GetFileSystemEntries("").ToList();
+            Assert.Single(entries);
+            Assert.Equal("dir", entries[0]);
+
+            entries = fsAssert.GetFileSystemEntries("dir").ToList();
+            Assert.Equal(20, entries.Count);
+            Assert.Equal(Enumerable.Range(0, 20).Select(i => $"dir\\file{i}.txt"), entries);
+        }
+    }
+
+    [Fact]
+    public void CreateFilesInSubdirectoryUsingOneFatFileSystem()
+    {
+        using var diskStream = new SparseMemoryStream();
+
+        diskStream.Position = 0;
+        using (var fsFormat = FatFileSystem.FormatFloppy(diskStream, FloppyDiskType.HighDensity, "FLOPPY_IMG "))
+        {
+            fsFormat.CreateDirectory("dir");            
+        }
+
+        using (var fsCreate = new FatFileSystem(diskStream))
+        {
+            for (var i = 0; i < 20; i++)
+            {
+                using (var fileStream = fsCreate.OpenFile($"dir{Path.DirectorySeparatorChar}file{i}.txt", FileMode.Create))
+                {
+                    fileStream.Write(new byte[10]);
+                }
+            }            
+        }
+
+        using var fsAssert = new FatFileSystem(diskStream);
+        {
+            var entries = fsAssert.GetFileSystemEntries("").ToList();
+            Assert.Single(entries);
+            Assert.Equal("dir", entries[0]);
+
+            entries = fsAssert.GetFileSystemEntries("dir").ToList();
+            Assert.Equal(20, entries.Count);
+            Assert.Equal(Enumerable.Range(0, 20).Select(i => $"dir\\file{i}.txt"), entries);
+        }
+    }
+}
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