Re: A stack overflow problem.

[Ludovic Courtès]

address@hidden (R. Clayton) skribis:

>   $ guile
>   GNU Guile 2.0.9-deb+1-1
>   Copyright (C) 1995-2013 Free Software Foundation, Inc.
>
>   Guile comes with ABSOLUTELY NO WARRANTY; for details type `,show w'.
>   This program is free software, and you are welcome to redistribute it
>   under certain conditions; type `,show c' for details.
>
>   Enter `,help' for help.
>   scheme@(guile-user)> (define (naughty) (let ((i 1)) (naughty) i))
>   scheme@(guile-user)> (naughty)
>   <unnamed port>:1:31: In procedure naughty:
>   <unnamed port>:1:31: Throw to key `vm-error' with args `(vm-run "VM: Stack 
> overflow" ())'.
>
>   Entering a new prompt.  Type `,bt' for a backtrace or `,q' to continue.
>   scheme@(guile-user) [1]> ,q
>   scheme@(guile-user)> (naughty)
>   Aborted
>
>   $ echo $?
>   134
>
>   $
>
> I'm thinking the second call to naughty should give me another stack overflow,
> rather than aborting guile.  On the other hand, maybe I didn't reset the 
> system
> properly after the first stack overflow.  Which is it?  If it's the latter,
> what's the proper reset?

A little bit of stack space is needed to throw the exception.  To do
that, the VM in Guile 2.0 has a small reserve on its stack, which it
uses on the first overflow (see ‘vm_error_stack_overflow’ in vm.c.)

The problem here is that, when the second overflow occurs, that reserve
has already been used, so it just aborts.

Commit 70057f3 in ‘stable-2.0’ fixes that (will be in 2.0.10.)

Thanks!

Ludo’.