Trying to understand what ptrace_report_signal() should do, a couple
of questions...
Why does utrace_signal_handler() set ->signal_handler when !stepping?
If I understand correctly, the logic is
if (stepping)
make sure that before return to user-space
UTRACE_SIGNAL_HANDLER will be reported.
This is understandable. More or less.
else
make sure that UTRACE_SIGNAL_REPORT is not
possible before we return to user-space,
UTRACE_SIGNAL_HANDLER should be used instead.
Why? I mean, why this is useful?
Another question. How can ->report_signal(info) change info->si_signo
(or other data in *info) when we have multiple engines? I mean, how
can engines cooperate if they want to change ->si_signo.
For example, ptrace_report_signal() sets ->si_signo = SIGTRAP. But
if we have another engine attached before ptrace-engine, then its
->report_signal() was already called. This means that engine can't
know about this SIGTRAP?
In short. If any engine changes *info, how should it take into account
other engines attached before?
ptrace also changes *info via ->last_siginfo. IOW, the owner of engine
plays with info, not ->report_signal(). I assume that ptrace is the only
engine which "has rights" to play with *info outside of ->report_signal(),
right?
Oleg.
