Re: Re: PLT pointer destroyed problem when loading IR32_32.DLL (Indeo codec)

[Christian Costa]

> Message du 18/03/04 00:51
> De : Marcus Meissner 
> A : Christian Costa 
> Copie à : wined 
> Objet : Re: PLT pointer destroyed problem when loading IR32_32.DLL (Indeo codec)
> On Wed, Mar 17, 2004 at 10:37:01PM +0000, Christian Costa wrote:
> > Hi,
> >
> > When executing the DllMain of the native IR32_32.DLL (VFW), Wine crashes.
> > After some investigations, I found that a part of the code uses the EBX 
> > register at one point without saving
> > and restore it afterwards. Since this register contains the PLT pointer 
> > for standard unix functions like libc ones, this
> > does not take a long time for Wine to crashing.
> > I tested with the ugly hack attached that saves and restores the EBX 
> > register between the call to DllMain and that fixed the problem and
> > the DLL works fine then.
>
> This might happen.
> That ebx can be scrapped?
> Your fix is not really ok, you must not modify the stackpointer in asm statements.
>
> Try using:
> __asm__ __volatile__ ("":::"ebx");
>
> after entry(), which tells the compiler that ebx has been scrapped.

Thanks for this! :-)

Christian

PLT pointer destroyed problem when loading IR32_32.DLL (Indeo codec)

[Marcus Meissner]

> > > Hi,
> > >
> > > When executing the DllMain of the native IR32_32.DLL (VFW), Wine crashes.
> > > After some investigations, I found that a part of the code uses the EBX 
> > > register at one point without saving
> > > and restore it afterwards. Since this register contains the PLT pointer 
> > > for standard unix functions like libc ones, this
> > > does not take a long time for Wine to crashing.
> > > I tested with the ugly hack attached that saves and restores the EBX 
> > > register between the call to DllMain and that fixed the problem and
> > > the DLL works fine then.
> >
> > This might happen.
> > That ebx can be scrapped?

Yes. I have seen such a case too, however in a windows WDM driver.

However, the Win32 ABI specifies that the registers should be saved across a
function call, so this is a bug in IR32_32.DLL I think.

googling gives something like:
 
 http://www.codeproject.com/cpp/calling_conventions_demystified.asp?print=tru...
 http://weblogs.asp.net/oldnewthing/archive/2004/01/08/48616.aspx

Ciao, Marcus