From 3b1920c060b9352654b3f2d429548bffcbbbc4a0 Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Thu, 13 Oct 2022 18:18:29 +0900
Subject: [PATCH] Add code to check whether a file is a hard link

---
 osu.Game/Database/RealmFileStore.cs | 48 +++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/osu.Game/Database/RealmFileStore.cs b/osu.Game/Database/RealmFileStore.cs
index 56ea8f23bc..4aa65dd50a 100644
--- a/osu.Game/Database/RealmFileStore.cs
+++ b/osu.Game/Database/RealmFileStore.cs
@@ -5,6 +5,8 @@ using System;
 using System.IO;
 using System.Linq;
 using System.Runtime.InteropServices;
+using System.Runtime.InteropServices.ComTypes;
+using Microsoft.Win32.SafeHandles;
 using osu.Framework;
 using osu.Framework.Extensions;
 using osu.Framework.IO.Stores;
@@ -77,6 +79,20 @@ namespace osu.Game.Database
             data.Seek(0, SeekOrigin.Begin);
         }
 
+        public static int GetFileLinkCount(string filePath)
+        {
+            int result = 0;
+            SafeFileHandle handle = CreateFile(filePath, FileAccess.Read, FileShare.Read, IntPtr.Zero, FileMode.Open, FileAttributes.Archive, IntPtr.Zero);
+
+            ByHandleFileInformation fileInfo;
+
+            if (GetFileInformationByHandle(handle, out fileInfo))
+                result = (int)fileInfo.NumberOfLinks;
+            CloseHandle(handle);
+
+            return result;
+        }
+
         [DllImport("Kernel32.dll", CharSet = CharSet.Unicode)]
         private static extern bool CreateHardLink(
             string lpFileName,
@@ -84,6 +100,38 @@ namespace osu.Game.Database
             IntPtr lpSecurityAttributes
         );
 
+        [StructLayout(LayoutKind.Sequential)]
+        private struct ByHandleFileInformation
+        {
+            public readonly uint FileAttributes;
+            public readonly FILETIME CreationTime;
+            public readonly FILETIME LastAccessTime;
+            public readonly FILETIME LastWriteTime;
+            public readonly uint VolumeSerialNumber;
+            public readonly uint FileSizeHigh;
+            public readonly uint FileSizeLow;
+            public readonly uint NumberOfLinks;
+            public readonly uint FileIndexHigh;
+            public readonly uint FileIndexLow;
+        }
+
+        [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
+        private static extern SafeFileHandle CreateFile(
+            string lpFileName,
+            [MarshalAs(UnmanagedType.U4)] FileAccess dwDesiredAccess,
+            [MarshalAs(UnmanagedType.U4)] FileShare dwShareMode,
+            IntPtr lpSecurityAttributes,
+            [MarshalAs(UnmanagedType.U4)] FileMode dwCreationDisposition,
+            [MarshalAs(UnmanagedType.U4)] FileAttributes dwFlagsAndAttributes,
+            IntPtr hTemplateFile);
+
+        [DllImport("kernel32.dll", SetLastError = true)]
+        private static extern bool GetFileInformationByHandle(SafeFileHandle handle, out ByHandleFileInformation lpFileInformation);
+
+        [DllImport("kernel32.dll", SetLastError = true)]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        private static extern bool CloseHandle(SafeHandle hObject);
+
         private bool checkFileExistsAndMatchesHash(RealmFile file)
         {
             string path = file.GetStoragePath();