On Wed, Aug 31, 2016 at 12:21 PM, Andrew Eikum aeikum@codeweavers.com wrote:
On Wed, Aug 31, 2016 at 02:12:23AM -0700, John Sheu wrote:
TL;WR: I'd like to share a struct definition between ntdll and kernel32, passed through the PEB. Is this kosher according to Wine style/design, and if so, which header should I stick it in?
I don't know anything about the particular issue you're working on, so I can just speak generally.
We try to avoid creating internal, Wine-only APIs. Sometimes it's necessary, and when we do that, the header goes in <include/wine/>. One example is "gdi_driver.h" which defines the interface between e.g. user32 and the graphics drivers.
Are the structures you need declared publicly in the win32 API, even as opaque pointers? If so, they may belong in <include/winternl.h>.
A specific proposal about what changes you'd like might bring more detailed responses.
Thanks Andrew!
A little more elaboration, on what I already wrote:
ntdll and kernel32 will have to jointly manage ownership of the storage array that FLS data is stored in, because it can be deleted either
1. When a thread is shutdown, in the LdrShutdownThread path. 2. When a fiber is deleted, in when DeleteFiber is called.
In addition, (3) if the thread is aborted (through NtTerminateProcess), the storage array isn't deleted on thread abort, since (behavior confirmed by conformance tests) the FLS data is used later when FlsFree is called.
So we have cases where in (1) ntdll deletes the FLS data array, (2) kernel32 deletes the FLS data array, and (3) ntdll passes ownership of the data array to kernel32. Thus both dlls will have to have to jointly manage ownership of the array.
--
The question is how we manage this. One option is to introduce additional function call entry points to either ntdll or kernel32, called by the other, to manages FLS lifetime. I see though that the list of entry points is pretty tightly defined in the .spec files for each DLL, and the convention may be (correct me if I'm wrong) not to introduce "weird" private Wine-only APIs to the list. The other option is to use some internal structs, pointed to by the PEB and TEB structures. That's the approach I'd like to go with.
My proposal would be:
1. Define a common struct to hold the FLS data array, that would be: struct FlsSlots { LIST_ENTRY fls_link; void fls_slots[SLOT_COUNT]; }; 2. TEB.FlsSlots right now is a void** member; make this a struct FlsSlots* member instead. 3. Link the FlsSlots struct into PEB.FlsListHead.
This would require that struct FlsSlots be defined somewhere -- either in wine/include, as mentioned, or in <include/winternl.h>. Since it isn't declared publicly in the win32 API, even as an opaque pointer -- I'm leaning toward the former. Maybe in "wine/include/fls.h" ?
Thanks, -John Sheu