bug#4291: 23.1; doc-view-mode temporary directory vulnerable to denial of service

[David Bremner <bremner@unb.ca>]

By default doc-view-mode makes a directory /tmp/docview$uid .  Since
this is easily predictable, a malicious person could cause docview to
fail simply by creating a directory with the same name. 

In GNU Emacs 23.1.1 (i486-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2009-08-03 on raven, modified by Debian
Windowing system distributor `The X.Org Foundation', version 11.0.10603000
configured using `configure  '--build=i486-linux-gnu' '--host=i486-linux-gnu' '--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib' '--localstatedir=/var/lib' '--infodir=/usr/share/info' '--mandir=/usr/share/man' '--with-pop=yes' '--enable-locallisppath=/etc/emacs23:/etc/emacs:/usr/local/share/emacs/23.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/23.1/site-lisp:/usr/share/emacs/site-lisp:/usr/share/emacs/23.1/leim' '--with-x=yes' '--with-x-toolkit=athena' '--with-toolkit-scroll-bars' 'build_alias=i486-linux-gnu' 'host_alias=i486-linux-gnu' 'CFLAGS=-DDEBIAN -g -O2' 'LDFLAGS=-g' 'CPPFLAGS=''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_CA.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default-enable-multibyte-characters: t

Major mode: Fundamental

Minor modes in effect:
  diff-auto-refine-mode: t
  tool-bar-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
  global-auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
M-x C-g C-x C-f t e a SPC c s SPC 2 SPC SPC w i SPC 
c SPC SPC SPC SPC <return> M-x r e p SPC o SPC SPC 
r SPC SPC SPC <return>

Recent messages:
Loading /home/bremner/.emacs-custom.el (source)...
Loading epa-mail...done
Loading /home/bremner/.emacs-custom.el (source)...done
Loading /usr/share/emacs/site-lisp/haskell-mode/haskell-site-file.el (source)...done
For information about GNU Emacs and the GNU system, type C-h C-a.
Quit
Making completion list... [2 times]
File mode specification error: (file-error "Doing chmod" "operation not permitted" "/tmp/docview1000")
Loading vc-git...done
Making completion list... [3 times]