sh: Make sure defined functions can actually be called.

Add some conservative checks on function names:
- Disallow expansions or quoting characters; these can only be called via
  strange control characters
- Disallow '/'; these functions cannot be called anyway, as exec.c assumes
  they are pathnames
- Make the CTL* bytes work properly in function names.

These are syntax errors.

POSIX does not require us to support more than names (letters, digits and
underscores, not starting with a digit), but I do not want to restrict it
that much at this time.

Exp-run done by:	pav (with some other sh(1) changes)

bin/sh/parser.c

@@ -639,10 +639,14 @@ simplecmd(union node **rpp, union node *redir)
 			if (readtoken() != TRP)
 				synexpect(TRP);
 			funclinno = plinno;
-#ifdef notdef
-			if (! goodname(n->narg.text))
+			/*
+			 * - Require plain text.
+			 * - Functions with '/' cannot be called.
+			 */
+			if (!noexpand(n->narg.text) || quoteflag ||
+			    strchr(n->narg.text, '/'))
 				synerror("Bad function name");
-#endif
+			rmescapes(n->narg.text);
 			n->type = NDEFUN;
 			n->narg.next = command();
 			funclinno = 0;

tools/regression/bin/sh/parser/func1.0

@@ -0,0 +1,25 @@
+# $FreeBSD$
+# POSIX does not require these bytes to work in function names,
+# but making them all work seems a good goal.
+
+failures=0
+unset LC_ALL
+export LC_CTYPE=en_US.ISO8859-1
+i=128
+set -f
+while [ "$i" -le 255 ]; do
+	c=$(printf \\"$(printf %o "$i")")
+	ok=0
+	eval "$c() { ok=1; }"
+	$c
+	ok1=$ok
+	ok=0
+	"$c"
+	if [ "$ok" != 1 ] || [ "$ok1" != 1 ]; then
+		echo "Bad results for character $i" >&2
+		: $((failures += 1))
+	fi
+	unset -f $c
+	i=$((i+1))
+done
+exit $((failures > 0))