Tempt fate and stop index from converting a const char * into a char *.

I've made a seperate version (c_index() etc) that use const/const, but
I'm not sure it's worth it considering there is one file in the tree
that uses index on const strings (kern_linker.c) and it's easily adjusted
to scan the strings directly (and is perhaps more efficient that way).

sys/kern/kern_linker.c

@@ -345,7 +345,7 @@ linker_make_file(const char* pathname, void* priv, struct linker_file_ops* ops)
     int namelen;
     const char *filename;
 
-    filename = rindex(pathname, '/');
+    filename = c_rindex(pathname, '/');
     if (filename && filename[1])
 	filename++;
     else
@@ -993,7 +993,7 @@ linker_search_path(const char *name)
     enum vtype		type;
 
     /* qualified at all? */
-    if (index(name, '/'))
+    if (c_index(name, '/'))
 	return(linker_strdup(name));
 
     /* traverse the linker path */

sys/libkern/index.c

@@ -33,21 +33,33 @@
  * $FreeBSD$
  */
 
-#include <string.h>
+#include <sys/param.h>
+#include <sys/libkern.h>
 
 char *
-#ifdef STRCHR
-strchr(p, ch)
-#else
 index(p, ch)
-#endif
-	register const char *p, ch;
+	char *p;
+	int ch;
 {
 	for (;; ++p) {
 		if (*p == ch)
-			return((char *)p);
+			return(p);
 		if (!*p)
-			return((char *)NULL);
+			return(NULL);
+	}
+	/* NOTREACHED */
+}
+
+const char *
+c_index(p, ch)
+	const char *p;
+	int ch;
+{
+	for (;; ++p) {
+		if (*p == ch)
+			return(p);
+		if (!*p)
+			return(NULL);
 	}
 	/* NOTREACHED */
 }

sys/libkern/rindex.c

@@ -33,23 +33,35 @@
  * $FreeBSD$
  */
 
-#include <stddef.h>
-#include <string.h>
+#include <sys/param.h>
+#include <sys/libkern.h>
 
 char *
-#ifdef STRRCHR
-strrchr(p, ch)
-#else
 rindex(p, ch)
-#endif
-	register const char *p;
-	register int ch;
+	char *p;
+	int ch;
 {
-	register char *save;
+	char *save;
 
 	for (save = NULL;; ++p) {
 		if (*p == ch)
-			save = (char *)p;
+			save = p;
+		if (!*p)
+			return(save);
+	}
+	/* NOTREACHED */
+}
+
+const char *
+c_rindex(p, ch)
+	const char *p;
+	int ch;
+{
+	const char *save;
+
+	for (save = NULL;; ++p) {
+		if (*p == ch)
+			save = p;
 		if (!*p)
 			return(save);
 	}

sys/sys/libkern.h

@@ -72,8 +72,10 @@ int	 locc __P((int, char *, u_int));
 void	 qsort __P((void *base, size_t nmemb, size_t size,
 		    int (*compar)(const void *, const void *)));
 u_long	 random __P((void));
-char	*index __P((const char *, int));
-char	*rindex __P((const char *, int));
+char	*index __P((char *, int));
+char	*rindex __P((char *, int));
+const char *c_index __P((const char *, int));
+const char *c_rindex __P((const char *, int));
 int	 scanc __P((u_int, const u_char *, const u_char *, int));
 int	 skpc __P((int, int, char *));
 void	 srandom __P((u_long));