Game support

[Mike Hearn]

On Tue, 06 Apr 2004 09:23:45 +0100, James Perry wrote:
> It's difficult to trace properly as PECrypt has debugger
> detection and behaves oddly if it detects breakpoints or
> whatever. But I narrowed it down to 3 Wine calls in the
> critical loop: SetEvent, WaitForSingleObject and ResetEvent.
> I tried wrapping each of these functions with
> __asm__("pushfl\n"); at the start and __asm__("popfl\n"); at
> the end to preserve the flags - with this, PECrypt works
> fine and the game gets as far as trying to initialise
> DirectX. Not exactly a neat fix though.

Did you have to do all of them, or is it just one function that needs this
treatment? Are you sure it's not that we need to set the flag before
jumping to the entrypoint? PECrypt sounds like it should run very early on
in the programs lifetime: how much stuff does it do before hitting this
bug?

> I never did trace exactly where the flag was getting
> clobbered, but I disassembled some basic libc functions and
> found that memcpy and memset both clear the direction flag.
> So it could be happening almost anywhere - looks like it is
> standard practise in UNIX to clobber this flag.

I wouldn't say standard practice in UNIX, more just a quirk of the GNU
implementations. If there is really widespread software that depends on
this behaviour though there is precedent for including a hack for it - see
the DllMain wrapper which preserves %ebx for an example.

thanks -mike