threads: pathname.d - with_file_id() issue

[Vladimir T. <vtz...@gm...>]

Hi Sam,

I am adding GC safe regions in pathname.d and came to the issue with  
check_file_reopen(truename,direction).

We have to following line:
     var void *ret = with_file_id(namez,(void*)&flags,&find_open_file);

Internally it calls stat() (GetFileInformationByHandle() and  
CreateFile() on Win32) so it definitely should be surrounded by GC  
safe region. However it also callbacks find_open_file() (declared in  
stream.d but used only from here) which accesses lisp heap - so no  
way to surround the whole "dynamic scope" of with_file_id() as GC safe.
Also accessing O(open_files) requires a global lock - it's commented  
as TODO item in stream.d.

I would "inline" the with_file_id() in check_file_open() - it is used  
only from here. However as I read the code - it looks like it is  
meant to be used from elsewhere as well? What would you recommend?

Vladimir