Subject: `call-process-region' fails on Windows (in UNC default-directory)

From: Richard Copley <[email-masked]>
Date: Tue, 16 Jul 2013 22:28:40 +0100

C-x C-f \\localhost\share <return>
M-! dir <return>
;; => Opening process input file: invalid argument, //localhost/share/NUL:

When `call-process-region' calls `call-process', it passes NULL_DEVICE
for the INFILE argument. It should pass nil instead.  I’m not sure
why, but the error above doesn’t happen if default-directory is a path
with a drive letter.

(For some reason NULL_DEVICE is defined as "NUL:" in my `config.h'.)

In GNU Emacs 24.3.50.2 (i686-pc-mingw32)
 of 2013-07-16 on MACHINE
Bzr revision: 113435 [email-masked]
Windowing system distributor `Microsoft Corp.', version 6.2.9200
Configured using:
 `configure --prefix c:/emacs/emacs-113425
 --enable-locallisppath=%emacs_dir%/../site-lisp CPPFLAGS='-I
 G:/usr/include -I C:/GnuWin32/include' LDFLAGS='-L G:/usr/lib -L
 C:/GnuWin32/lib''

Important settings:
  value of $LANG: ENG
  locale-coding-system: cp1252
  default enable-multibyte-characters: t

Major mode: Dired by name

Minor modes in effect:
  shell-dirtrack-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
C-x C-f \ \ l o c a l h o s t \ s h a r e <return>
M-! d i r <return> M-x r - e - b <return>

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
(Shell command failed with error)
shell-command-on-region: Opening process input file: invalid argument,
//localhost/share/NUL:

Load-path shadows:
None found.

Features:
(shadow sort nadvice gnus-util mail-extr emacsbug message format-spec
rfc822 mml easymenu mml-sec mm-decode mm-bodies mm-encode mail-parse
rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045
ietf-drums mm-util mail-prsvr mail-utils shell pcomplete comint
ansi-color ring dired time-date tooltip ediff-hook vc-hooks
lisp-float-type mwheel dos-w32 ls-lisp w32-common-fns disp-table w32-win
w32-vars tool-bar dnd fontset image regexp-opt fringe tabulated-list
newcomment lisp-mode prog-mode register page menu-bar rfn-eshadow timer
select scroll-bar mouse jit-lock font-lock syntax facemenu font-core
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ethiopic indian cyrillic chinese case-table epa-hook jka-cmpr-hook help
simple abbrev minibuffer loaddefs button faces cus-face macroexp files
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget hashtable-print-readable backquote make-network-process
w32notify w32 multi-tty emacs)