Re: [PATCH] man ptrace: add extended description of various ptrace quirks

From: Denys Vlasenko
Date: Fri Sep 30 2011 - 10:28:48 EST


On Thu, Sep 29, 2011 at 9:08 PM, Michael Kerrisk <mtk.manpages@xxxxxxxxx> wrote:
> So, I took your patch, and then did a global edit of the page to fix
> various pieces (in the existing text, as well as do some language
> clean-ups for the new text). In the process, I found a number of
> pieces that are still unclear (some in the old text, some in your new
> text). I also made some changes to your text that I'd like you to
> check. I've marked each of these with FIXME below. Could you please
> take a look at the FIXMEs, and write me a comment for each of these.
> (I appreciate that in some cases, especially for the existing text,
> you may not have a handy answer Denys, but if you (and others) can
> give any help, that would be great.)
>
> Rather than you writing a new patch to this version of the page, I
> think it might be easiest if you just replied to the FIXMEs inline
> below, then I can revise the page in the light of your comments.

Another group of commands makes the ptrace-stopped tracee run. They
have the form:

ptrace(PTRACE_cmd, pid, 0, sig);

where cmd is PTRACE_CONT, PTRACE_DETACH, PTRACE_SYSCALL, PTRACE_SIN-
GLESTEP, PTRACE_SYSEMU, or PTRACE_SYSEMU_SINGLESTEP.

Cosmetics: cmd is, of course, CONT, DETACH,..., not PTRACE_CONT,
PTRACE_DETACH...


If the tracee is
in signal-delivery-stop, sig is the signal to be injected (if it is
nonzero). Otherwise, sig may be ignored. (Recommended practice is to
always pass 0 in these cases.)

Looks like (my) text in last sentence is confusing. I meant:
"If you are resterting thracee from a ptrace-stop other than
signal-delivery-stop, recommended practice is to always pass
sig == 0".

--
vda
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