You don't need to strdup here... The Mac file creation rountines use the global MCfiletype to apply the given attribtue to the stackfile on creation. The filetype of stackfiles is stored in MCstackfiletype... So here, MCfiletype is just being temporarily switched. i.e.
```
oldfiletype = MCfiletype
MCfiletype = MCstackfiletype
... do file creation ...
MCfiletype = oldfiletype
```
Since the ... do file creation ... stuff won't touch the filetype globals (except to read), you can just swap around the pointers.