Hello,
it would be awesome if somebody in the know could confirm or refute a suspicion
on ptrace() that we have.
The man page says:
Attachment and subsequent commands are per thread:
in a multi‐ threaded process, every thread can be individually attached to a
(potentially different) tracer, or left not attached and thus not debugged.
Therefore, "tracee" always means "(one) thread", never "a (possibly
multithreaded) process".
While the first sentence "Attachment ... [is] per thread" is quite general, the
rest talks only about the multi-threadedness of the *tracee*.
What about multithreaded *tracers*?
We suspect (and observe program behaviour that supports this) that having one
thread pA_t1 in a process A become the tracer of some tracee thread pB_t1, and
then a different thread of A, pA_t2 running a `ptrace(pB_t1, ...)` is illegal
and results in `ESRCH`.
Is this statement in true in general, or are there nuances?
Thanks,
Niklas
PS: We'd be happy to contribute these details to the man page based on an
answer :)
