[AC21.4] Fix stack overflow in mapconcat

[Vin Shelton]

APPROVE COMMIT 21.4

Steve Youngs <steve at sxemacs.org> writes:

> Hi Vin!
>
> This patch fixes a stack overflow bug in mapconcat.  The recipe to
> reproduce the bug is...
>
> (let ((str (make-string 1600000 ?x))) 
>   (mapconcat 
>    #'(lambda (el) 
>        el)
>    (list str) ""))
>
>
> 21.4 patch:
> ChangeLog files diff command: cvs -q diff -U 0
> Files affected:               src/ChangeLog
> Source files diff command:    cvs -q diff -uN
> Files affected:               src/fns.c
>
> Index: src/ChangeLog
> ===================================================================
> RCS file: /pack/xemacscvs/XEmacs/xemacs/src/ChangeLog,v
> retrieving revision 1.290.2.113
> diff -u -p -U0 -r1.290.2.113 ChangeLog
> --- src/ChangeLog	20 Nov 2006 18:29:42 -0000	1.290.2.113
> +++ src/ChangeLog	7 Dec 2006 17:58:48 -0000
> @@ -0,0 +1,8 @@
> +2006-12-08  Nelson Ferreira  <njsf at sxemacs.org>
> +
> +	* src/fns.c (XMALLOC_OR_ALLOCA,free_malloced_ptr,XMALLOC_UNBIND):
> +	relocated the definitions to be used sooner in file.
> +	(concat,plists_differ,mapcar1,Fmapconcat,Fmapcar): Use
> +	XMALLOC_OR_ALLOCA macro instead of alloca to prevent stack
> +	overflow.

Hi Steve and Nelson,

Thanks for the patch.  The number of chars I had to put in the string
differed, but I did eventually see a real crash.  This patch has been
committed and will appear in the soon-to-be-released 21.4.20,
"Double Solitaire".

  - Vin