valgrind-developers

[Valgrind-developers] Cancelling syscalls

[Filipe C. <fi...@gm...>]

Hi,

I'm implementing some Darwin syscalls but I'm having a small problem...

There's a system call that related to code signing. I want to disable 
the call if the parameters are such and such. Otherwise, I get the 
current process (valgrind) marked as "KILL if invalid" and, of course, 
marked as invalid (the code that is running is not the signed code).

I already implemented the handling of the required fcntl to add the code 
signatures and the system call itself (#169, csops).

How can I bypass the system call if the parameters are such and such?

something like:
PRE(...)
{
...
if (ARG2 == VKI_KILL_IF_INVALID)
   dont_execute_syscall();
...
}

Thanks in advance,

   Filipe Cabecinhas

Re: [Valgrind-developers] Cancelling syscalls

[Nicholas N. <n.n...@gm...>]

On Wed, Apr 1, 2009 at 2:37 AM, Filipe Cabecinhas <fi...@gm...> wrote:
>
> How can I bypass the system call if the parameters are such and such?
>
> something like:
> PRE(...)
> {
> ...
> if (ARG2 == VKI_KILL_IF_INVALID)
>   dont_execute_syscall();
> ...
> }

I think you want the SET_STATUS_{Success,Failure,from_SysRes} macros
in coregrind/m_syswrap/priv_types_n_macros.h.  They're used in various
places, eg. the wrapper for exit().

Nick