Re: [PATCH] man ptrace: add extended description of various ptrace quirks
From: Michael Kerrisk
Date: Mon Oct 03 2011 - 01:35:43 EST
Hi Denys,
On Fri, Sep 30, 2011 at 4:28 PM, Denys Vlasenko
<vda.linux@xxxxxxxxxxxxxx> wrote:
> 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...
Yes. But what I did to fix is change the ptrace call to:
ptrace(cmd, pid, 0, sig);
(Having these constants shown without the "PTRACE_" prefix is a little
confusing.)
> 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".
Okay -- I made that change.
Thanks,
Michael
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Author of "The Linux Programming Interface"; http://man7.org/tlpi/
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