bug#5601: 23.1; etags Scheme_functions past \0 terminator

["Francesco Potortì" <pot@gnu.org>]

>In etags.c Scheme_functions, I think the loop
>
>    while (notinname (*bp))
>      bp++;
>
>will take bp past the '\0' string terminator, because '\0' is a
>notinname().

Yes, it appears so.  This is a long-standing bug.  Thanks for spotting
it.

>(Another helper skip_notinname() to try to be clearer
>than a double-negative loop :-)

I don't think a helper function is granted here.  There is a single use
of this construct in the file, and a lot of different constructs: we
have not a helper function for each of them.  Let's try to stick to the
comomn ones only, else we will only add to the confusion.  So, please do
not define a helper function for this case.

Again, I can do the change myself, or else you can do it yourself, as
you like.

>2010-02-19  Kevin Ryde  <user42@zip.com.au>
>
>	* etags.c (Scheme_functions): Don't go past '\0' terminator.
>	(skip_notinname): New helper.
>
>--- etags.c.~3.93.~	2009-11-29 08:42:32.000000000 +1100
>+++ etags.c	2010-02-19 11:04:42.000000000 +1100
>@@ -4989,6 +4989,16 @@
>  *          (set! xyzzy
>  * Original code by Ken Haase (1985?)
>  */
>+
>+static char *
>+skip_notinname (char *cp)
>+{
>+  /* '\0' is a notinname(), don't continue past it */
>+  while (*cp && notinname (*cp))
>+    cp++;
>+  return cp;
>+}
>+
> static void
> Scheme_functions (inf)
>      FILE *inf;
>@@ -5001,8 +5011,7 @@
> 	{
> 	  bp = skip_non_spaces (bp+4);
> 	  /* Skip over open parens and white space */
>-	  while (notinname (*bp))
>-	    bp++;
>+	  bp = skip_notinname (bp);
> 	  get_tag (bp, NULL);
> 	}
>       if (LOOKING_AT (bp, "(SET!") || LOOKING_AT (bp, "(set!"))
>
>
>
>In GNU Emacs 23.1.1 (i486-pc-linux-gnu, GTK+ Version 2.16.5)
> of 2009-09-14 on raven, modified by Debian
>configured using `configure  '--build=i486-linux-gnu' '--host=i486-linux-gnu' '--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib' '--localstatedir=/var/lib' '--infodir=/usr/share/info' '--mandir=/usr/share/man' '--with-pop=yes' '--enable-locallisppath=/etc/emacs23:/etc/emacs:/usr/local/share/emacs/23.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/23.1/site-lisp:/usr/share/emacs/site-lisp:/usr/share/emacs/23.1/leim' '--with-x=yes' '--with-x-toolkit=gtk' '--with-toolkit-scroll-bars' 'build_alias=i486-linux-gnu' 'host_alias=i486-linux-gnu' 'CFLAGS=-DDEBIAN -g -O2' 'LDFLAGS=-g' 'CPPFLAGS=''