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

[Kevin Ryde <user42@zip.com.au>]

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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().

I can't spot any obvious ill effect, only that a line of only

    (define

is tagged, perhaps depending on what was on the line before it.  In any
case doesn't sound good to look into possibly uninitialized parts of the
input buffer.  (Another helper skip_notinname() to try to be clearer
than a double-negative loop :-)

2010-02-19  Kevin Ryde  <user42@zip.com.au>

	* etags.c (Scheme_functions): Don't go past '\0' terminator.
	(skip_notinname): New helper.


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--- 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!"))

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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=''