Fix subfolder race condition.

Author: Lunaretic

xivModdingFramework/Helpers/IOUtil.cs

@@ -799,17 +799,21 @@ public static byte[] GetImageSharpPixels(Image<Rgba32> img)
 
         public static string GetUniqueSubfolder(string basePath, string prefix = "")
         {
-            var id = 0;
-            var path = Path.GetFullPath(Path.Combine(basePath, prefix + id.ToString()));
-            while (Directory.Exists(path))
+            lock (_SubfolderLock)
             {
-                id++;
-                path = Path.GetFullPath(Path.Combine(basePath, prefix + id.ToString()));
+                var id = 0;
+                var path = Path.GetFullPath(Path.Combine(basePath, prefix + id.ToString()));
+                while (Directory.Exists(path))
+                {
+                    id++;
+                    path = Path.GetFullPath(Path.Combine(basePath, prefix + id.ToString()));
+                }
+                Directory.CreateDirectory(path);
+                return path;
             }
-            Directory.CreateDirectory(path);
-
-            return path;
         }
+
+        public static object _SubfolderLock = new object();
         public static string GetFrameworkTempSubfolder(string prefix = "")
         {
             var basePath = GetFrameworkTempFolder();