Return result of directory creation, so that the game may handle creation errors

Assets/Scripts/Modules/SystemModule.Interop.cs

@@ -151,11 +151,11 @@ public partial class SystemModule: CallbackHandler<SystemModule>
     }
     
     [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
-    private delegate void SysMkDirCallback(IntPtr target, [MarshalAs(UnmanagedType.LPStr)] string path);
+    private delegate bool SysMkDirCallback(IntPtr target, [MarshalAs(UnmanagedType.LPStr)] string path);
 
     [MonoPInvokeCallback(typeof(SysMkDirCallback))]
-    private static void Callback_SysMkDir(IntPtr target, string path)
+    private static bool Callback_SysMkDir(IntPtr target, string path)
     {
-        GetSelf(target).MkDir(path);
+        return GetSelf(target).MkDir(path);
     }
 }

Assets/Scripts/Modules/SystemModule.cs

@@ -70,6 +70,8 @@ public partial class SystemModule
 
     private int FileOpenWrite(string path)
     {
+        // TODO: we could use this method to redirect user config & save data to a platform-specific user storage
+        
         int i = FindFileHandle();
         try
         {
@@ -155,15 +157,17 @@ public partial class SystemModule
         return File.Exists(path) ? 1 : -1;
     }
 
-    private void MkDir(string path)
+    private bool MkDir(string path)
     {
         try
         {
-            Directory.CreateDirectory(path);
+            var info = Directory.CreateDirectory(path);
+            return info.Exists;
         }
-        catch
+        catch (Exception ex)
         {
-            Debug.LogWarning($"Could not create directory: {path}");
+            Debug.LogWarning($"Could not create directory {path}, reason: {ex.Message}");
+            return false;
         }
     }
 }

engine/UniQuake/sys_uniquake.c

@@ -18,7 +18,7 @@ typedef struct unity_syscalls_s
 	int(*SysFileRead)(void *target, int handle, void *dest, int count);
 	int(*SysFileWrite)(void *target, int handle, const void *data, int count);
 	int(*SysFileTime)(void *target, const char *path);
-	void(*SysMkDir)(void *target, const char *path);
+	qboolean(*SysMkDir)(void *target, const char *path);
 } unity_syscalls_t;
 
 const unity_syscalls_t *unity_syscalls;
@@ -94,11 +94,8 @@ int	Sys_FileTime(const char *path)
 
 void Sys_mkdir(const char *path)
 {
-	unity_syscalls->SysMkDir(unity_syscalls->target, path);
-
-	// TODO: handle creation errors
-	/*if (GetLastError() != ERROR_ALREADY_EXISTS)
-		Sys_Error("Unable to create directory %s", path);*/
+	if (!unity_syscalls->SysMkDir(unity_syscalls->target, path))
+		Sys_Error("Unable to create directory %s", path);
 }
 
 void Sys_Sleep_New(unsigned long msecs)