bug#18628: Emacs hangs trying to open "CON" file (on Windows)

[Lee Houghton]

Hello,

I don't know if this can really be counted as a bug, as CON is the
windows equivalent of /dev/stdin, (and of course I deserve it for
using Windows), but it is a frustrating problem, especially when I am
using helm-mode and trying to get my "config" directory and it decides
to read the "CON" file instead. I

t doesn't matter where you are in the file system, CON is also
omnipresent, and it also happens when trying to read files such as
CON.txt, as Windows considers it to be the same file as CON (though
this doesn't appear in the file listing).

Perhaps emacs should refuse to open this file. Or should this be
something I should forward to the helm-mode developers?

Regards,
Lee

To reproduce the problem:

Open the scratch buffer, execute (find-file "CON") and watch emacs hang.

The top of the stack is (I don't have debugging symbols for emacs,
only the Windows libraries):

ntdll.dll!_NtReadFile@36 () Unknown
KernelBase.dll!_ReadFile@20 () Unknown
msvcrt.dll!__read_nolock () Unknown
msvcrt.dll!__read () Unknown
emacs.exe!01022134() Unknown
[Frames below may be incorrect and/or missing, no symbols loaded for emacs.exe]

In GNU Emacs 24.3.1 (i386-mingw-nt6.2.9200)
 of 2013-03-17 on MARVIN
Windowing system distributor `Microsoft Corp.', version 6.2.9200
Configured using:
 `configure --with-gcc (4.7) --cflags
 -ID:/devel/emacs/libs/libXpm-3.5.8/include
 -ID:/devel/emacs/libs/libXpm-3.5.8/src
 -ID:/devel/emacs/libs/libpng-dev_1.4.3-1/include
 -ID:/devel/emacs/libs/zlib-dev_1.2.5-2/include
 -ID:/devel/emacs/libs/giflib-4.1.4-1/include
 -ID:/devel/emacs/libs/jpeg-6b-4/include
 -ID:/devel/emacs/libs/tiff-3.8.2-1/include
 -ID:/devel/emacs/libs/gnutls-3.0.9/include
 -ID:/devel/emacs/libs/libiconv-1.13.1-1-dev/include
 -ID:/devel/emacs/libs/libxml2-2.7.8/include/libxml2'

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

Major mode: Lisp Interaction

Minor modes in effect:
  helm-mode: t
  shell-dirtrack-mode: t
  helm-match-plugin-mode: t
  helm-occur-match-plugin-mode: t
  electric-pair-mode: t
  electric-indent-mode: t
  desktop-save-mode: t
  delete-selection-mode: t
  tooltip-mode: t
  mouse-wheel-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
  line-number-mode: t
  transient-mark-mode: t

Recent input:
y M-x r e p o r t <down> <down> <down> <down> <ret
urn>

Recent messages:
Loading delsel...done
Loading desktop...done
Loading electric...done
Helm completion enabled
Warning: desktop file appears to be in use by PID 11008.
Using it may cause conflicts.  Use it anyway? (y or n)  y
Desktop: 0 buffers restored.
For information about GNU Emacs and the GNU system, type C-h C-a.

Load-path shadows:
c:/Users/CTG/AppData/Roaming/.emacs.d/elpa/js2-mode-20140114/.dir-locals
hides c:/Users/CTG/Programs/emacs-24.3/lisp/gnus/.dir-locals

Features:
(shadow sort mail-extr emacsbug message rfc822 mml mml-sec mm-decode
mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader
sendmail rfc2047 rfc2045 ietf-drums mail-utils helm-mode helm-files rx
image-dired tramp tramp-compat tramp-loaddefs shell pcomplete
format-spec dired-x easymenu dired-aux ffap thingatpt helm-buffers
helm-elscreen helm-tags helm-bookmark helm-adaptive helm-info helm-net
browse-url xml url url-proxy url-privacy url-expand url-methods
url-history url-cookie url-domsuf url-util url-parse auth-source
gnus-util mm-util mail-prsvr password-cache url-vars mailcap helm-plugin
bookmark pp helm-locate helm-help helm-match-plugin helm-grep
helm-regexp grep helm-external helm-utils warnings dired helm advice
help-fns advice-preload cl-macs gv helm-source eieio byte-opt bytecomp
byte-compile cconv cl-lib scss-mode flymake compile comint ansi-color
ring derived edmacro kmacro helm-autoloads async-autoloads
js2-mode-autoloads finder-inf rainbow-mode-autoloads scss-mode-autoloads
package electric desktop delsel cus-start cus-load 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 register page
menu-bar rfn-eshadow timer select scroll-bar mouse jit-lock font-lock
syntax facemenu font-core frame cham georgian utf-8-lang misc-lang
vietnamese tibetan thai tai-viet lao korean japanese hebrew greek
romanian slovak czech european 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 w32 multi-tty emacs)