Messages in this thread | | | Date | Fri, 17 Mar 2006 06:44:21 -0500 | From | Chuck Ebbert <> | Subject | Re: [RFC] Proposed manpage additions for ptrace(2) |
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In-Reply-To: <20060316200201.GA20315@nevyn.them.org>
On Thu, 16 Mar 2006 15:02:01 -0500, Daniel Jacobowitz wrote:
> > PTRACE_O_TRACEFORK > > Stop the child at the next fork() call with SIGTRAP | > > PTRACE_EVENT_FORK << 8 and automatically start tracing > > the newly forked process, which will start with a > > SIGSTOP. The pid for the new process can be retrieved > > with PTRACE_GETEVENTMSG. > > > > PTRACE_O_TRACEVFORK > > Stop the child at the next vfork() call with SIGTRAP | > > PTRACE_EVENT_VFORK << 8 and automatically start tracing > > the the newly vforked process, which will start with a > > SIGSTOP. The pid for the new process can be retrieved > > with PTRACE_GETEVENTMSG. > > > > PTRACE_O_TRACECLONE > > Stop the child at the next clone() call with SIGTRAP | > > PTRACE_EVENT_CLONE << 8 and automatically start tracing > > the newly cloned process, which will start with a > > SIGSTOP. The pid for the new process can be retrieved > > with PTRACE_GETEVENTMSG. > > Specifically, the three kinds of cloning are distinguished as: > > if CLONE_VFORK -> PTRACE_EVENT_VFORK > else if clone exit signal == SIGCHLD -> PTRACE_EVENT_FORK > else PTRACE_EVENT_CLONE > > You need to do some juggling to get the actual clone flags.
It might be best to leave these descriptions in terms of C library functions rather than kernel-internal. Looking at sys_clone() and sys_fork() I can see what you mean but I'm not sure how to describe it to a programmer.
> BTW, I believe there are still some potential deadlocks between > the vfork event and the vfork done event; I used to regularly generate > unkillable processes working on this code.
I have a test program and didn't hit any problems yet. Maybe this was fixed?
-- Chuck "Penguins don't come from next door, they come from the Antarctic!"
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