s/trailing NULL/trailing NUL/

lib/libc/gen/getcwd.c

@@ -155,7 +155,7 @@ getcwd(pt, size)
 		/*
 		 * Build pointer to the parent directory, allocating memory
 		 * as necessary.  Max length is 3 for "../", the largest
-		 * possible component name, plus a trailing NULL.
+		 * possible component name, plus a trailing NUL.
 		 */
 		if (bup + 3  + MAXNAMLEN + 1 >= eup) {
 			if ((up = reallocf(up, upsize *= 2)) == NULL)

lib/libc/gen/vis.c

@@ -159,7 +159,7 @@ vis(dst, c, flag, nextc)
  * strvis, strvisx - visually encode characters from src into dst
  *
  *	Dst must be 4 times the size of src to account for possible
- *	expansion.  The length of dst, not including the trailing NULL,
+ *	expansion.  The length of dst, not including the trailing NUL,
  *	is returned.
  *
  *	Strvisx encodes exactly len bytes from src into dst.