implement cat thing for realpath and rename too: if flag, call external

Build.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
-srcversion='$MirOS: src/bin/mksh/Build.sh,v 1.679 2015/05/01 16:08:26 tg Exp $'
+srcversion='$MirOS: src/bin/mksh/Build.sh,v 1.680 2015/07/05 15:45:16 tg Exp $'
 #-
 # Copyright (c) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
 #		2011, 2012, 2013, 2014, 2015
@@ -2646,6 +2646,8 @@ MKSH_NOPWNAM			skip PAM calls, for -static on glibc or Solaris
 MKSH_NO_CMDLINE_EDITING		disable command line editing code entirely
 MKSH_NO_DEPRECATED_WARNING	omit warning when deprecated stuff is run
 MKSH_NO_EXTERNAL_CAT		omit hack to skip cat builtin when flags passed
+MKSH_NO_EXTERNAL_REALPATH	same for realpath builtin
+MKSH_NO_EXTERNAL_RENAME		same for rename builtin
 MKSH_NO_LIMITS			omit ulimit code
 MKSH_NO_SIGSETJMP		define if sigsetjmp is broken or not available
 MKSH_NO_SIGSUSPEND		use sigprocmask+pause instead of sigsuspend

exec.c

@@ -23,7 +23,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/exec.c,v 1.153 2015/07/05 14:43:05 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/exec.c,v 1.154 2015/07/05 15:45:17 tg Exp $");
 
 #ifndef MKSH_DEFAULT_EXECSHELL
 #define MKSH_DEFAULT_EXECSHELL	"/bin/sh"
@@ -607,16 +607,21 @@ comexec(struct op *t, struct tbl * volatile tp, const char **ap,
 				subst_exstat = 0;
 				break;
 			}
+#if !defined(MKSH_NO_EXTERNAL_CAT) || \
+    !defined(MKSH_NO_EXTERNAL_REALPATH) || \
+    !defined(MKSH_NO_EXTERNAL_RENAME)
+		} else if (
 #ifndef MKSH_NO_EXTERNAL_CAT
-		} else if (tp->val.f == c_cat) {
+		    tp->val.f == c_cat ||
-			/*
+#endif
-			 * if we have any flags, do not use the builtin
+#ifndef MKSH_NO_EXTERNAL_REALPATH
-			 * in theory, we could allow -u, but that would
+		    tp->val.f == c_realpath ||
-			 * mean to use ksh_getopt here and possibly ad-
+#endif
-			 * ded complexity and more code and isn't worth
+#ifndef MKSH_NO_EXTERNAL_RENAME
-			 * additional hassle (and the builtin must call
+		    tp->val.f == c_rename ||
-			 * ksh_getopt already but can't come back here)
+#endif
-			 */
+		    0) {
+			/* if we have any flags, do not use the builtin */
 			if (ap[1] && ap[1][0] == '-' && ap[1][1] != '\0' &&
 			    /* argument, begins with -, is not - or -- */
 			    (ap[1][1] != '-' || ap[1][2] != '\0'))

mksh.1

@@ -1,4 +1,4 @@
-.\" $MirOS: src/bin/mksh/mksh.1,v 1.369 2015/07/05 15:22:41 tg Exp $
+.\" $MirOS: src/bin/mksh/mksh.1,v 1.370 2015/07/05 15:45:18 tg Exp $
 .\" $OpenBSD: ksh.1,v 1.160 2015/07/04 13:27:04 feinerer Exp $
 .\"-
 .\" Copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
@@ -3957,6 +3957,12 @@ it's also checked for existence and whether it is a directory; otherwise,
 returns 0 if the pathname either exists or can be created immediately,
 i.e. all but the last component exist and are directories.
 .Pp
+Unless compiled with
+.Dv MKSH_NO_EXTERNAL_REALPATH ,
+if any options are given and this is not a direct builtin call, an external
+.Xr realpath 1
+utility is invoked instead.
+.Pp
 .It Xo
 .Ic rename
 .Op Fl \-
@@ -3971,6 +3977,11 @@ This builtin is intended for emergency situations where
 .Pa /bin/mv
 becomes unusable, and directly calls
 .Xr rename 2 .
+Unless compiled with
+.Dv MKSH_NO_EXTERNAL_RENAME ,
+if any options are given and this is not a direct builtin call, an external
+.Xr rename 1
+utility is invoked instead.
 .Pp
 .It Ic return Op Ar status
 Returns from a function or