readlink(path, buf, sizeof buf-1). Never forget that -1.

src/lib/libc/stdlib/realpath.c

@@ -35,7 +35,7 @@
  */
 
 #if defined(LIBC_SCCS) && !defined(lint)
-static char *rcsid = "$OpenBSD: realpath.c,v 1.3 1997/06/20 20:37:45 deraadt Exp $";
+static char *rcsid = "$OpenBSD: realpath.c,v 1.4 1998/05/18 09:55:19 deraadt Exp $";
 #endif /* LIBC_SCCS and not lint */
 
 #include <sys/param.h>
@@ -105,7 +105,7 @@ loop:
 				errno = ELOOP;
 				goto err1;
 			}
-			n = readlink(p, resolved, MAXPATHLEN);
+			n = readlink(p, resolved, MAXPATHLEN-1);
 			if (n < 0)
 				goto err1;
 			resolved[n] = '\0';