Yo Hal! On Tue, 30 May 2017 16:44:48 -0700 Hal Murray <hmur...@megapathdsl.net> wrote:
> gdb doesn't work when ntpd is started automatically at boot time.
OK.
> strace solved that one.
Yes, we keep coming back to strace.
> There is another problem in this area. That's translating a stack
> trace in the middle of libc into a syscall. It's not simple, even
> with symbols for libc. Mostly, I could guess. I think I had to look
> at the source at least once.
And even if it works, ISC_PLATFORM_USEBACKTRACE is not going to
give you any symbols.
> strace gives you exactly what you want with a huge overhead which
> probably isn't practical on a busy server. It might be possible to
> modify it to keep a buffer of the last N syscalls and dump the buffer
> when the program being traced crashes.
Modifying strace is beyond what I would personally consider...
> > I remain a fan of ripping out unused and useless code.
>
> I generally agree. This code is currently unused. But is it useless?
I'll know in a few days. If I can get it to compile.
> An alternative would be to debug it and set things up to use it. I
> know about three cases where it might be very helpful.
> SIGSYS or a seccomp trap.
> SIGBUS, usually an address fault.
> The ASSERT handler.
And all 3 are supposedly tied into ISC_PLATFORM_USEBACKTRACE, at least
in a few cases. Is there something that would be more modern and easier
to hook in those handlers?
> Since I seem to be the only one interested in that code, I have a
> simple solution. Find somebody else to maintain the seccomp list.
I'm interested in seccomp. The few times I was about to fix a syscall
you beat me to it. I certainly want to give you tools that work to
help there.
> Then I'll shut up and you can dump that code and we can stop wasting
> time on discussions like this.
No matter who/when takes up seccomp next, they'll need better tools, and
I'm all for that. I just need to make sure ISC_PLATFORM_USEBACKTRACE
is pointless before looking for alternatives.
RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com Tel:+1 541 382 8588
Veritas liberabit vos. -- Quid est veritas?
"If you can’t measure it, you can’t improve it." - Lord Kelvin
pgp_GNT2uxaBh.pgp
Description: OpenPGP digital signature
_______________________________________________ devel mailing list devel@ntpsec.org http://lists.ntpsec.org/mailman/listinfo/devel
