Subject: 27.0.50; Suspicious code in flymake-proc around temporary directories
From: Philipp Stephani <[email-masked]>
To: [email-masked]
Date: Tue, 27 Nov 2018 17:37:05 +0100
List-Id: <debbugs-submit.debbugs.gnu.org>

I've noticed that the temporary directory code in flymake-proc has
issues with remote filenames.  For example:

$ emacs -Q -batch -l flymake-proc --eval='(print (flymake-proc-create-temp-with-folder-structure "/:/dir" nil))'

"/tmp/:/dir"

Clearly that's not what was intended.  Rather, this should create the
directory structure on the remote machine.

If we use that filename:

mkdir -p /tmp/:/dir

then stuff will generally work, but trying to remove it will cause an
endless loop and try to remove /dir and /:

$ emacs -Q -batch -l flymake-proc --eval='(flymake-proc--delete-temp-directory "/tmp/:/dir")'
Error [flymake-proc *scratch*]: Failed to delete dir /dir, error ignored
Error [flymake-proc *scratch*]: Failed to delete dir /, error ignored
Error [flymake-proc *scratch*]: Failed to delete dir /, error ignored
[...infinite loop...]
^C
lisp.h:1485: Emacs fatal error: assertion failed: 0 <= nchars
Aborted

The assertion failure seems to be a different issue, but this bug
focuses on the problematic behavior of flymake-proc.  The code for these
functions looks really suspicious and seems to make lots of incorrect
assumptions (about whether temporary-file-directory ends in a slash,
that all files are local, etc.).  Especially the infinite loop in
flymake-proc--delete-temp-directory causes trouble because the only way
out of it is sending a signal to the Emacs process.

In GNU Emacs 27.0.50 (build 46, x86_64-pc-linux-gnu, GTK+ Version 3.22.24)
 of 2018-11-27
Repository revision: e02d375cb6670e2306b9c67d7f6fd2dd1d1b2711
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.11906000
System Description: Debian GNU/Linux buster/sid

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Eager macro-expansion failure: (wrong-number-of-arguments (2 . 2) 4)

Configured using:
 'configure --without-threads --enable-gcc-warnings=warn-only
 --enable-gtk-deprecation-warnings --without-pop --with-mailutils
 --enable-checking --enable-check-lisp-object-type --with-modules
 'CFLAGS=-O0 -ggdb3''

Configured features:
XPM JPEG TIFF GIF PNG SOUND DBUS GSETTINGS GLIB NOTIFY INOTIFY GNUTLS
FREETYPE XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM MODULES JSON GMP

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  electric-indent-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
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc dired dired-loaddefs
format-spec rfc822 mml easymenu mml-sec epa derived epg epg-config
gnus-util rmail rmail-loaddefs time-date mm-decode mm-bodies mm-encode
mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047
rfc2045 ietf-drums mm-util mail-prsvr mail-utils phst pcase ffap
thingatpt url-parse auth-source cl-seq eieio eieio-core cl-macs
eieio-loaddefs password-cache json map url-vars subr-x rx gnutls puny
seq byte-opt gv bytecomp byte-compile cconv dbus xml cl-loaddefs cl-lib
elec-pair mule-util tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel term/x-win x-win term/common-win x-dnd tool-bar
dnd fontset image regexp-opt fringe tabulated-list replace newcomment
text-mode elisp-mode lisp-mode prog-mode register page menu-bar
rfn-eshadow isearch timer select scroll-bar mouse jit-lock font-lock
syntax facemenu font-core term/tty-colors frame cl-generic cham georgian
utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean
japanese eucjp-ms cp51932 hebrew greek romanian slovak czech european
ethiopic indian cyrillic chinese composite charscript charprop
case-table epa-hook jka-cmpr-hook help simple abbrev obarray minibuffer
cl-preloaded nadvice loaddefs button faces cus-face macroexp files
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget hashtable-print-readable backquote dbusbind inotify
dynamic-setting system-font-setting font-render-setting move-toolbar gtk
x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 109009 5313)
 (symbols 48 21762 1)
 (strings 32 32871 2004)
 (string-bytes 1 894311)
 (vectors 16 16454)
 (vector-slots 8 533506 11914)
 (floats 8 52 65)
 (intervals 56 230 0)
 (buffers 992 12))

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