On Friday, May 23, 2014 10:48:11 AM Chet Ramey wrote:
> On 5/23/14, 10:17 AM, Ondrej Oprala wrote:
> > Hi, there've recently been a few bug reports against bash on RH BZ,
> > saying that bash can't handle infinite recursion the way zsh or ksh can.
> >
> > Looking at execute_cmd.c, there are the funcnest{,_max} variables
> > and a piece of code using them in execute_function().
> >
> > Will funcnest_max be set to non-0 in upstream code in the future?
> > Or is it just there for the downstream maintainers to set it if they
> > see it fit?
>
> Neither. The funcnest_max variable reflects the value of the FUNCNEST
> shell variable.
Oops Chet read your message right... I presumed you were aware of FUNCNEST,
and were talking about setting a non-zero default at compile-time. Can't
remember if that's ever been discussed.
> Users can set the maximum recursion level they want,
> without changing the bash code at all, but the default is still as much as
> the stack will give you (as it has been all along).
Yup, it's a good feature. Zsh and ksh don't "support infinite recursion", they
have hardcoded limits (1024 ksh93, 1000 zsh).
As a random aside... dash somehow has extremely lightweight function calls.
Glad it's not arbitrarily capped at 1k.
$ time dash -c 'f() { echo "$1"; f $(($1 + 1)); }; f 0' | tail -n 1
13776
real 0m0.035s
user 0m0.020s
sys 0m0.033s
$ time bash -c 'f() { echo "$1"; f $(($1 + 1)); }; f 0' | tail -n 1
8308
real 0m3.993s
user 0m4.032s
sys 0m0.165s
--
Dan Douglas
