Re: Bug in ulimit ?

[Stephane Chazelas <Stephane_Chazelas@yahoo.fr>]

On Tue, Apr 17, 2007 at 03:55:27AM -0700, Micah Cowan wrote:
[...]
> > ulimit -t
> > 
> > doesn't set the limit to 0 but to infinity (in effect, to the
> > hard limit).
> > 
> > It's ulimit -t 0
> > to set the limit to 0 (well actually, 1 second in that case).
> > 
> Originally responded to this directly, but then realized that the
> veracity of this statement is pertinent to the next message I sent as
> well, so it's worth addressing on-list, in case it isn't clear to others.
> 
> ulimit -t
> 
> doesn't set the limit _at_all_; it prints it (hence the "0", above).
[...]

Indeed sorry.

I can now see the same behavior as you did, and it doesn't seem
to be linked to zsh indeed.

The limit doesn't seem to get inherited by the child process:

~$ perl -MBSD::Resource -le 'setrlimit(RLIMIT_CPU,0,RLIM_INFINITY); print for getrlimit(RLIMIT_CPU); while (1) { ; }'
0
-1
zsh: cpu limit exceeded  perl -MBSD::Resource -le
(152)~$ perl -MBSD::Resource -le 'setrlimit(RLIMIT_CPU,0,RLIM_INFINITY); print for getrlimit(RLIMIT_CPU); if (fork) {wait} else {while (1) { ; }}'
0
-1
<Ctrl-C>

Which contradicts this note in setrlimit(2):

NOTES
       A child process created via fork(2) inherits its parents
       resource limits.  Resource limits are preserved across
       execve(2).


Though strictly speaking, stracing perl, there's no fork() system
call but a clone(). There is a call to libc's fork() function
(verified using ltrace), so it may be a libc issue. Maybe the
limits should be dupplicated in user space by glibc's fork()?

$ getconf GNU_LIBC_VERSION
glibc 2.3.6

-- 
Stéphane