BepInEx.IL2CPP: Fix mutex checks

BepInEx.Core/Utility.cs

@@ -320,6 +320,23 @@ public static class Utility
         return ByteArrayToString(md5.Hash);
     }
 
+    /// <summary>
+    /// Hash a list of strings using MD5
+    /// </summary>
+    /// <param name="strings">Strings to hash</param>
+    /// <returns>MD5 of the strings</returns>
+    public static string HashStrings(params string[] strings)
+    {
+        using var md5 = MD5.Create();
+
+        foreach (var str in strings)
+            md5.TransformBlock(Encoding.UTF8.GetBytes(str), 0, str.Length, null, 0);
+
+        md5.TransformFinalBlock(new byte[0], 0, 0);
+
+        return ByteArrayToString(md5.Hash);
+    }
+
     /// <summary>
     ///     Convert the given array to a hex string.
     /// </summary>

BepInEx.IL2CPP/DoorstopEntrypoint.cs

@@ -2,6 +2,7 @@ using System;
 using System.Diagnostics;
 using System.IO;
 using System.Threading;
+using BepInEx;
 using BepInEx.IL2CPP;
 using BepInEx.Preloader.Core;
 
@@ -25,9 +26,10 @@ internal static class Entrypoint
             silentExceptionLog =
                 Path.Combine(Path.GetDirectoryName(EnvVars.DOORSTOP_PROCESS_PATH), silentExceptionLog);
 
-            mutex = new Mutex(false,
-                              Process.GetCurrentProcess().ProcessName + EnvVars.DOORSTOP_PROCESS_PATH +
-                              typeof(Doorstop.Entrypoint).FullName);
+            var mutexId = Utility.HashStrings(Process.GetCurrentProcess().ProcessName, EnvVars.DOORSTOP_PROCESS_PATH,
+                                              typeof(Entrypoint).FullName);
+
+            mutex = new Mutex(false, $"Global\\{mutexId}");
             mutex.WaitOne();
 
             UnityPreloaderRunner.PreloaderMain();