Re: [PATCH] ntdll/signal_i386.c: RtlCaptureContext locals + args are 12 bytes instead of 8 (return address + CONTEXT * arg + %eax local

[Alexandre Julliard]

Bernhard Loos  writes:
> @@ -1181,7 +1181,7 @@ __ASM_STDCALL_FUNC( RtlCaptureContext, 4,
>                      __ASM_CFI(".cfi_adjust_cfa_offset 4\n\t")
>                      "popl 0xc0(%eax)\n\t"      /* context->EFlags */
>                      __ASM_CFI(".cfi_adjust_cfa_offset -4\n\t")
> -
>                "leal 8(%esp),%edx\n\t"
> -
>                "leal 0xc(%esp),%edx\n\t"
>                "movl %edx,0xc4(%eax)\n\t" /* context->Esp */

That's not really more correct, it's supposed to return the caller frame
but there's no good way of doing that. What are you trying to fix?

[PATCH] ntdll/signal_i386.c: RtlCaptureContext locals + args are 12 bytes instead of 8 (return address + CONTEXT * arg + %eax local

[Bernhard Loos]

On Tue, Sep 27, 2011 at 4:33 PM, Alexandre Julliard  wrote:
> Bernhard Loos  writes:
> > @@ -1181,7 +1181,7 @@ __ASM_STDCALL_FUNC( RtlCaptureContext, 4,
> >                      __ASM_CFI(".cfi_adjust_cfa_offset 4\n\t")
> >                      "popl 0xc0(%eax)\n\t"      /* context->EFlags */
> >                      __ASM_CFI(".cfi_adjust_cfa_offset -4\n\t")
> > - "leal 8(%esp),%edx\n\t"
> > - "leal 0xc(%esp),%edx\n\t"
> >
> > "movl %edx,0xc4(%eax)\n\t" /* context->Esp */
>
> That's not really more correct, it's supposed to return the caller frame
> but there's no good way of doing that. What are you trying to fix?

Nothing specific. I noticed this yesterday, while trying to use this
function for RtlRaiseException, before you pointed out the register
problem.

Wouldn't it be better to rename this functions as it behaves
differently then the windows version so apps get an actual error
message instead of unexpected behavior?
> --
> Alexandre Julliard
> [e-mail]

[PATCH] ntdll/signal_i386.c: RtlCaptureContext locals + args are 12 bytes instead of 8 (return address + CONTEXT * arg + %eax local

[Alexandre Julliard]

Bernhard Loos  writes:
> Nothing specific. I noticed this yesterday, while trying to use this
> function for RtlRaiseException, before you pointed out the register
> problem.
>
> Wouldn't it be better to rename this functions as it behaves
> differently then the windows version so apps get an actual error
> message instead of unexpected behavior?

Not really. Retrieving the exact stack pointer is unlikely to be all
that useful anyway.