[PATCH 3/4] winegstreamer: Convert the Unix library to the __wine_unix_call interface.

[Emil Velikov]

Thanks for the elaborate answer Zebediah,

On Tue, 5 Oct 2021 at 17:57, Zebediah Figura (she/her)
<zfigura at codeweavers.com> wrote:

> * The syscall interface can be used to swap architecture boundaries. Mac
> dropped 32-bit, some enterprise Linux distributions want to do the same;
> this would allow us to no longer require 32-bit Unix libraries.
>

Due to the different struct sizes, paddings and alike, this means that
Wine will need to add a "compat_ioctl" style wrapper, correct?
I guess such code is planned, although I don't think it landed just yet.

> * This one hasn't been discussed, but we have a bug (47808) where an
> application (Cygwin) replaces the normal thread stack with one that's
> actually split into reserved/committed parts, but then libfreetype jumps
> several pages at once expecting it to all be committed. This is a moot
> point for libfreetype specifically, because we'll probably compile it
> with MinGW and keep it on the PE side (in theory it has the same
> problem, but Windows applications should emit chkstk or something
> similar here and MinGW indeed does so). On the other hand, another
> library could run into something similar.
>

That is an interesting way to workaround such "lovely" behaviour.
Sounds like prime contender for the hall of shame :-P

> >
> > In addition, did the team consider using linux kernel style ioctls?
> > These will allow you to preserve the type of the arguments, their
> > respective size, as well as access level. This should help with
> > out-of-bounds access and potentially writing into read-only memory,
> > say due to a bug or security vulnerability in the unix lib.
>
> I don't think it was thought of before. I don't think there was really
> any internal discussion about it either. I can definitely see the value
> in checking argument size—that's pretty easy to get wrong—although I'm
> not sure we can reasonably check access level.

Hope the team finds a way. Or at least get the infra in, so when the
eureka moment comes it won't involve updating dozens of modules.

-Emil