I guess overriding sendsig hook is better solution.

Jaromir

Emmanuel Dreyfus wrote:
> Hi
> 
> In the wonderful world of MacOS X, signals can be replaced by
> exceptions. Exceptions are Mach messages sent to a process to notify an
> exceptionnal condition.
> 
> For instance, when gdb traces a program, it does not wait for signals,
> it waits for Mach messages. This makes my job a bit complicated, but
> fortunately, trapsignal() can be emulation specific already. I just
> intercept signals at trapsignal() level I and transform them into
> exception, if the tracer process required so. The code for this already
> exists and it works. 
> 
> I have one special problem with the SIGTRAP emission in
> sys/kern/kern_exec:sys_execve(), for traced processes. It is currently
> done with psignal(), which offers no hook for emulations. What about the
> following patch?
> 
> Index: kern_exec.c
> ===================================================================
> RCS file: /cvsroot/src/sys/kern/kern_exec.c,v
> retrieving revision 1.176
> diff -U4 -r1.176 kern_exec.c
> --- kern_exec.c 17 Nov 2003 22:52:09 -0000      1.176
> +++ kern_exec.c 25 Nov 2003 17:03:47 -0000
> @@ -764,10 +764,20 @@
>         /* map the process's signal trampoline code */
>         if (exec_sigcode_map(p, pack.ep_es->es_emul))
>                 goto exec_abort;
>  
> -       if (p->p_flag & P_TRACED)
> +       if (p->p_flag & P_TRACED) {
> +#ifdef __HAVE_SIGINFO
> +               ksiginfo_t ksi;
> +
> +               KSI_INIT_TRAP(&ksi);
> +               ksi.ksi_signo = SIGTRAP;
> +               ksi.ksi_trap = TRAP_TRACE;
> +               (*p->p_emul->e_trapsignal)(l, &ksi);
> +#else
>                 psignal(p, SIGTRAP);
> +#endif
> +       }
>  
>         free(pack.ep_hdr, M_EXEC);
> 
> My concern is that I'm using trapsignal for a signal sent from somewhere
> else than a trap. Is it a serious problem?
> 
> Additionnaly, should we include more information with siginfo for this
> event? 
> 
> -- 
> Emmanuel Dreyfus
> Il y a 10 sortes de personnes dans le monde: ceux qui comprennent 
> le binaire et ceux qui ne le comprennent pas.
> manu@netbsd.org
> 

-- 
Jaromir Dolecek <jdolecek@NetBSD.org>            http://www.NetBSD.cz/
-=- We should be mindful of the potential goal, but as the Buddhist -=-
-=- masters say, ``You may notice during meditation that you        -=-
-=- sometimes levitate or glow.   Do not let this distract you.''   -=-