Re: Bizarre out of memory bug
Re: Bizarre out of memory bug
- Subject: Re: Bizarre out of memory bug
- From: Tim Seufert <email@hidden>
- Date: Fri, 27 May 2005 01:26:27 -0700
Things found through further experimentation:
1. Bonjour is a red herring. Alexey Proskuryakov suggested forcing
ssh to use IPv4 since ssh'ing to a Bonjour address will default to an
IPv6 connection. And indeed I find that the problem goes away with
"ssh -4 yobgorgle.local". Furthermore, if I ssh directly to
Yobgorgle's IPv6 address, the problem is present. So I think Bonjour
has been eliminated from culpability; it's really a question of
whether the SSH session uses IPv4 or IPv6.
2. To test bash I created a fresh user account on the problem machine
and did not alter its login shell setting. The result: bash works
fine inside an IPv6 ssh session. So this seems to be a tcsh problem.
3. Along those lines, further observation of tcsh's behavior
strongly suggests a bug in its command completion code. Pressing tab
with no characters typed is OK, but with one or more characters typed
tcsh will die immediately. If completion is not used, the only
commands which do not crash tcsh with an 'Out of memory' error are
those whose names are only 1 character, such as 'w'. Single-
character aliases work too, even if they expand to multiple characters.
Note, however, that all this applies only to the command name
itself. If I do something like this:
[yobgorgle:~] tas% l /Sys<tab>
I get the expected expansion to:
[yobgorgle:~] tas% l /System/
If I then press return, I get what I expect given that 'l' is an
alias to 'ls -l'.
So, arguments to commands don't cause the bug.
4. The bug goes away if I don't invoke Wilfredo Sanchez's example
tcsh setup (/usr/share/tcsh/examples/rc) in my .cshrc .
5. I still only get this when SSHing from the PowerBook to the G5.
Despite trying to configure the PowerBook with an identical login
name and UID/GID, identical network config, and identical .cshrc,
everything works fine when logging in to the PowerBook. Unless I
figure out what's unique about the G5's configuration, this may not
be easy to replicate reliably on other systems.
I think my next step is to try to build tcsh with debugging symbols,
attach to it with GDB when I log in, and step through the code to see
exactly where things go wrong. I may also try to track down exactly
which part of the example rc causes the problem. (Presumably it's
the section which sets up completion.)
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