On 10/06, Jan Kratochvil wrote:
>
> On Tue, 06 Oct 2009 22:05:16 +0200, Oleg Nesterov wrote:
> > For example, the tracee reports PTRACE_EVENT_EXEC and stops. In this
> > case SIGNR has no effect after PTRACE_CONT/DETACH/etc.
> >
> > SIGNR does not ignored after the tracee reported syscall entry/exit or
> > signal.
>
> OK, if only such exceptional cases as PTRACE_EVENT_EXEC that should not matter
> I think.
Also PTRACE_EVENT_FORK and friends.
> It should work also for PTRACE_SINGLESTEP.
Heh. Yes, but with one exception.
- the tracee has a hanlder for, say, SIGHUP
- the tracee deques SIGHUP, reports to the tracer,
and stops.
- the tracer does ptrace(SINGLESTEP, SIGHUP)
// it could use another signr, this works.
// but the tracer must have a handler or
// everething is OK.
- the tracee delivers SIGHUP to itself, handle_signal()
notices TIF_SINGLESTEP and calls ptrace_notify().
Now, the tracee reports SIGTRAP, but the next time the tracer does
ptrace(WHATEVER, SIGNR) SIGNR will be ignored.
Oleg.
