--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,31 @@
 2009-09-02  Eric Blake  <ebb9@byu.net>
 
+	errno: use consistently
+	* lib/c-stack.c (ENOTSUP): <errno.h> guarantees a definition.
+	* lib/canonicalize-lgpl.c (ENAMETOOLONG): Likewise.
+	* lib/canonicalize.c (ELOOP): Likewise.
+	* lib/inet_ntop.c (EAFNOSUPPORT): Likewise.
+	* lib/inet_pton.c (EAFNOSUPPORT): Likewise.
+	* lib/lchown.c (EOPNOTSUPP): Likewise.
+	* lib/openat-priv.h (ENOSYS, EOPNOTSUPP): Likewise.
+	* lib/savewd.c (ESTALE): Likewise.
+	* lib/settime.c (ENOSYS): Likewise.
+	* lib/utimens.c (ENOSYS): Likewise.
+	* lib/xgethostname.c (ENAMETOOLONG): Likewise.
+	* lib/chdir-safer.c (ELOOP): Likewise.
+	(chdir_no_follow): Use HAVE_READLINK, not ELOOP, as witness.
+	* modules/c-stack (Depends-on): Add errno.
+	* modules/canonicalize (Depends-on): Likewise.
+	* modules/chdir-safer (Depends-on): Likewise.
+	* modules/fdopendir (Depends-on): Likewise.
+	* modules/inet_ntop (Depends-on): Likewise.
+	* modules/inet_pton (Depends-on): Likewise.
+	* modules/lchown (Depends-on): Likewise.
+	* modules/openat (Depends-on): Likewise.
+	* modules/savewd (Depends-on): Likewise.
+	* modules/settime (Depends-on): Likewise.
+	* m4/chdir-safer.m4 (gl_CHDIR_SAFER): Check for readlink.
+
 	fts: avoid leaking fds
 	* modules/fts (Depends-on): Add cloexec.
 	* lib/fts.c (opendirat, diropen, fts_build): Set close-on-exec

--- a/lib/c-stack.c
+++ b/lib/c-stack.c
@@ -46,9 +46,6 @@
 #define _(msgid) gettext (msgid)
 
 #include <errno.h>
-#ifndef ENOTSUP
-# define ENOTSUP EINVAL
-#endif
 
 #include <signal.h>
 #if ! HAVE_STACK_T && ! defined stack_t

--- a/lib/canonicalize-lgpl.c
+++ b/lib/canonicalize-lgpl.c
@@ -1,5 +1,5 @@
 /* Return the canonical absolute name of a given file.
-   Copyright (C) 1996-2003, 2005-2008 Free Software Foundation, Inc.
+   Copyright (C) 1996-2003, 2005-2009 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    This program is free software: you can redistribute it and/or modify
@@ -50,9 +50,6 @@
 #include <errno.h>
 #ifndef _LIBC
 # define __set_errno(e) errno = (e)
-# ifndef ENAMETOOLONG
-#  define ENAMETOOLONG EINVAL
-# endif
 #endif
 
 #ifdef _LIBC

--- a/lib/canonicalize.c
+++ b/lib/canonicalize.c
@@ -38,9 +38,6 @@
 #include "xalloc.h"
 #include "xgetcwd.h"
 
-#ifndef ELOOP
-# define ELOOP 0
-#endif
 #ifndef __set_errno
 # define __set_errno(Val) errno = (Val)
 #endif

--- a/lib/chdir-safer.c
+++ b/lib/chdir-safer.c
@@ -1,6 +1,6 @@
 /* much like chdir(2), but safer
 
-   Copyright (C) 2005-2006, 2008 Free Software Foundation, Inc.
+   Copyright (C) 2005-2006, 2008-2009 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -29,8 +29,8 @@
 #include <sys/stat.h>
 #include "same-inode.h"
 
-#ifndef ELOOP
-# define ELOOP 0
+#ifndef HAVE_READLINK
+# define HAVE_READLINK 0
 #endif
 
 /* Like chdir, but fail if DIR is a symbolic link to a directory (or
@@ -51,9 +51,9 @@
      they are the same file; if they are different files, set errno to
      ELOOP (the same value that open uses for symlinks with
      O_NOFOLLOW) so the caller can report a failure.
-     Skip this check if ELOOP == 0, which should be the case
+     Skip this check if HAVE_READLINK == 0, which should be the case
      on any system that lacks symlink support.  */
-  if (ELOOP && ! HAVE_WORKING_O_NOFOLLOW)
+  if (HAVE_READLINK && ! HAVE_WORKING_O_NOFOLLOW)
     {
       struct stat sb1;
       result = lstat (dir, &sb1);

--- a/lib/inet_ntop.c
+++ b/lib/inet_ntop.c
@@ -1,6 +1,6 @@
 /* inet_ntop.c -- convert IPv4 and IPv6 addresses from binary to text form
 
-   Copyright (C) 2005, 2006, 2008  Free Software Foundation, Inc.
+   Copyright (C) 2005, 2006, 2008, 2009  Free Software Foundation, Inc.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -42,10 +42,6 @@
 #include <string.h>
 #include <errno.h>
 
-#ifndef EAFNOSUPPORT
-# define EAFNOSUPPORT EINVAL
-#endif
-
 #define NS_IN6ADDRSZ 16
 #define NS_INT16SZ 2
 

--- a/lib/inet_pton.c
+++ b/lib/inet_pton.c
@@ -1,6 +1,6 @@
 /* inet_pton.c -- convert IPv4 and IPv6 addresses from text to binary form
 
-   Copyright (C) 2006, 2008 Free Software Foundation, Inc.
+   Copyright (C) 2006, 2008, 2009 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -41,10 +41,6 @@
 #include <string.h>
 #include <errno.h>
 
-#ifndef EAFNOSUPPORT
-# define EAFNOSUPPORT EINVAL
-#endif
-
 #define NS_INADDRSZ 4
 #define NS_IN6ADDRSZ 16
 #define NS_INT16SZ 2

--- a/lib/lchown.c
+++ b/lib/lchown.c
@@ -30,16 +30,6 @@
 #include <errno.h>
 #include <sys/stat.h>
 
-/* Some systems don't have EOPNOTSUPP.  */
-#ifndef EOPNOTSUPP
-# ifdef ENOTSUP
-#  define EOPNOTSUPP ENOTSUP
-# else
-/* Some systems don't have ENOTSUP either.  */
-#  define EOPNOTSUPP EINVAL
-# endif
-#endif
-
 /* Work just like chown, except when FILE is a symbolic link.
    In that case, set errno to EOPNOTSUPP and return -1.
    But if autoconf tests determined that chown modifies

--- a/lib/openat-priv.h
+++ b/lib/openat-priv.h
@@ -1,6 +1,6 @@
 /* Internals for openat-like functions.
 
-   Copyright (C) 2005, 2006 Free Software Foundation, Inc.
+   Copyright (C) 2005, 2006, 2009 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -23,26 +23,6 @@
 #define OPENAT_BUFFER_SIZE 512
 char *openat_proc_name (char buf[OPENAT_BUFFER_SIZE], int fd, char const *file);
 
-/* Some systems don't have ENOSYS.  */
-#ifndef ENOSYS
-# ifdef ENOTSUP
-#  define ENOSYS ENOTSUP
-# else
-/* Some systems don't have ENOTSUP either.  */
-#  define ENOSYS EINVAL
-# endif
-#endif
-
-/* Some systems don't have EOPNOTSUPP.  */
-#ifndef EOPNOTSUPP
-# ifdef ENOTSUP
-#  define EOPNOTSUPP ENOTSUP
-# else
-/* Some systems don't have ENOTSUP either.  */
-#  define EOPNOTSUPP EINVAL
-# endif
-#endif
-
 /* Trying to access a BUILD_PROC_NAME file will fail on systems without
    /proc support, and even on systems *with* ProcFS support.  Return
    nonzero if the failure may be legitimate, e.g., because /proc is not

--- a/lib/savewd.c
+++ b/lib/savewd.c
@@ -1,6 +1,6 @@
 /* Save and restore the working directory, possibly using a child process.
 
-   Copyright (C) 2006, 2007 Free Software Foundation, Inc.
+   Copyright (C) 2006, 2007, 2009 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -34,10 +34,6 @@
 #include "dirname.h"
 #include "fcntl-safer.h"
 
-#ifndef ESTALE
-# define ESTALE -1
-#endif
-
 /* Save the working directory into *WD, if it hasn't been saved
    already.  Return true if a child has been forked to do the real
    work.  */

--- a/lib/settime.c
+++ b/lib/settime.c
@@ -1,6 +1,6 @@
 /* settime -- set the system clock
 
-   Copyright (C) 2002, 2004, 2005, 2006, 2007 Free Software
+   Copyright (C) 2002, 2004, 2005, 2006, 2007, 2009 Free Software
    Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
@@ -27,16 +27,6 @@
 
 #include <errno.h>
 
-/* Some systems don't have ENOSYS.  */
-#ifndef ENOSYS
-# ifdef ENOTSUP
-#  define ENOSYS ENOTSUP
-# else
-/* Some systems don't have ENOTSUP either.  */
-#  define ENOSYS EINVAL
-# endif
-#endif
-
 /* Set the system time.  */
 
 int

--- a/lib/utimens.c
+++ b/lib/utimens.c
@@ -1,7 +1,7 @@
 /* Set file access and modification times.
 
-   Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008 Free Software
-   Foundation, Inc.
+   Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Free
+   Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by the
@@ -44,16 +44,6 @@
 };
 #endif
 
-/* Some systems don't have ENOSYS.  */
-#ifndef ENOSYS
-# ifdef ENOTSUP
-#  define ENOSYS ENOTSUP
-# else
-/* Some systems don't have ENOTSUP either.  */
-#  define ENOSYS EINVAL
-# endif
-#endif
-
 #ifndef __attribute__
 # if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 8)
 #  define __attribute__(x)

--- a/lib/xgethostname.c
+++ b/lib/xgethostname.c
@@ -1,7 +1,7 @@
 /* xgethostname.c -- return current hostname with unlimited length
 
-   Copyright (C) 1992, 1996, 2000, 2001, 2003, 2004, 2005, 2006 Free
-   Software Foundation, Inc.
+   Copyright (C) 1992, 1996, 2000, 2001, 2003, 2004, 2005, 2006, 2009
+   Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -29,10 +29,6 @@
 
 #include "xalloc.h"
 
-#ifndef ENAMETOOLONG
-# define ENAMETOOLONG 0
-#endif
-
 #ifndef INITIAL_HOSTNAME_LENGTH
 # define INITIAL_HOSTNAME_LENGTH 34
 #endif

--- a/m4/chdir-safer.m4
+++ b/m4/chdir-safer.m4
@@ -1,5 +1,5 @@
-#serial 3
-dnl Copyright (C) 2005, 2006 Free Software Foundation, Inc.
+#serial 4
+dnl Copyright (C) 2005, 2006, 2009 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -7,4 +7,5 @@
 AC_DEFUN([gl_CHDIR_SAFER],
 [
   AC_LIBOBJ([chdir-safer])
+  AC_CHECK_FUNCS_ONCE([readlink])
 ])

--- a/modules/c-stack
+++ b/modules/c-stack
@@ -8,6 +8,7 @@
 
 Depends-on:
 gettext-h
+errno
 exitfail
 unistd
 raise

--- a/modules/canonicalize
+++ b/modules/canonicalize
@@ -9,6 +9,7 @@
 
 Depends-on:
 areadlink-with-size
+errno
 file-set
 filenamecat
 hash-triple

--- a/modules/chdir-safer
+++ b/modules/chdir-safer
@@ -7,6 +7,7 @@
 m4/chdir-safer.m4
 
 Depends-on:
+errno
 fchdir
 fcntl-h
 open

--- a/modules/fdopendir
+++ b/modules/fdopendir
@@ -8,8 +8,9 @@
 m4/fdopendir.m4
 
 Depends-on:
+dirent
+errno
 extensions
-dirent
 fchdir
 openat-die
 save-cwd

--- a/modules/inet_ntop
+++ b/modules/inet_ntop
@@ -9,6 +9,7 @@
 socklen
 sys_socket
 arpa_inet
+errno
 netinet_in
 extensions
 

--- a/modules/inet_pton
+++ b/modules/inet_pton
@@ -10,6 +10,7 @@
 socklen
 sys_socket
 arpa_inet
+errno
 netinet_in
 extensions
 

--- a/modules/lchown
+++ b/modules/lchown
@@ -7,6 +7,7 @@
 
 Depends-on:
 chown
+errno
 sys_stat
 unistd
 

--- a/modules/openat
+++ b/modules/openat
@@ -16,6 +16,7 @@
 
 Depends-on:
 dirname
+errno
 extensions
 fchdir
 fdopendir

--- a/modules/savewd
+++ b/modules/savewd
@@ -8,6 +8,7 @@
 
 Depends-on:
 dirname
+errno
 exit
 fchdir
 fcntl-safer

--- a/modules/settime
+++ b/modules/settime
@@ -7,6 +7,7 @@
 
 Depends-on:
 clock-time
+errno
 extensions
 sys_time
 timespec

--- a/modules/utimens
+++ b/modules/utimens
@@ -9,6 +9,7 @@
 m4/utimes.m4
 
 Depends-on:
+errno
 sys_time
 time