GNU bug report logs - #55727
29.0.50; Incorrect zero symbol transcoding between applications

Previous Next

To add a comment to this bug, you must first unarchive it, by sending
a message to control AT debbugs.gnu.org, with unarchive 55727 in the body.
You can then email your comments to 55727 AT debbugs.gnu.org in the normal way.

Toggle the display of automated, internal messages from the tracker.

Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Петров Андрей <an.petrov <at> pay-lab.ru>
To: "bug-gnu-emacs <at> gnu.org" <bug-gnu-emacs <at> gnu.org>
Subject: 29.0.50; Incorrect zero symbol transcoding between applications
Date: Mon, 30 May 2022 13:08:52 +0000

Hello, team!

Please check the following behavior:

1. Start two instances of emacs -Q.
2. Switch to the "*scratch*" buffer of the first one and type the following:
   M-: (insert (format "%S"  "000\000000")) [RET]
   You should see "000^@000" string.
3. Copy the string into clipboard and paste into the other instance of
   Emacs (which you have started before).
   I get "000\0000" instead of "000\000000"
4. Try evaluating inserted text ("000\0000")
   C-c C-e
   I get "000^@0" instead of "000^@000".

It seems that "^@" is transcoded between applications into "\0"
 instead of "\000". If I do the same test inside single instance
 of Emacs I get the correct result.


In GNU Emacs 29.0.50 (build 3, x86_64-pc-linux-gnu, GTK+ Version 3.24.34, cairo version 1.17.6)
 of 2022-05-30 built on pva-msi
Repository revision: 004e6ae3f42bdc8cd632060f56dbf8c1ea850c4a
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101003
System Description: Arch Linux

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBOTF LIBSYSTEMD LIBXML2 M17N_FLT MODULES NOTIFY INOTIFY
PDUMPER PNG RSVG SECCOMP SOUND SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS
WEBP X11 XDBE XIM XINPUT2 XPM GTK3 ZLIB

Important settings:
  value of $LANG: ru_RU.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
  show-paren-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
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message mailcap yank-media rmc puny
dired dired-loaddefs rfc822 mml mml-sec password-cache epa derived epg
rfc6068 epg-config gnus-util text-property-search seq gv byte-opt
bytecomp byte-compile cconv mm-decode mm-bodies mm-encode mail-parse
rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045
ietf-drums mm-util mail-prsvr mail-utils time-date subr-x cl-loaddefs
cl-lib cyril-util iso-transl tooltip eldoc paren electric uniquify
ediff-hook vc-hooks lisp-float-type elisp-mode 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 lisp-mode prog-mode register
page tab-bar menu-bar rfn-eshadow isearch easymenu timer select
scroll-bar mouse jit-lock font-lock syntax font-core term/tty-colors
frame minibuffer nadvice simple cl-generic indonesian philippine 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 emoji-zwj charscript
charprop case-table epa-hook jka-cmpr-hook help abbrev obarray oclosure
cl-preloaded button loaddefs faces cus-face macroexp files window
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget keymap hashtable-print-readable backquote threads dbusbind
inotify lcms2 dynamic-setting system-font-setting font-render-setting
cairo move-toolbar gtk x-toolkit xinput2 x multi-tty
make-network-process emacs)

Memory information:
((conses 16 43966 8699)
 (symbols 48 5718 1)
 (strings 32 15667 1941)
 (string-bytes 1 509558)
 (vectors 16 11167)
 (vector-slots 8 162892 11831)
 (floats 8 23 52)
 (intervals 56 457 0)
 (buffers 992 11))


Best regards,
Andrey Petrov.

Message #8 received at 55727 <at> debbugs.gnu.org (full text, mbox):

From: Po Lu <luangruo <at> yahoo.com>
To: Петров Андрей <an.petrov <at> pay-lab.ru>
Cc: 55727 <at> debbugs.gnu.org
Subject: Re: bug#55727: 29.0.50; Incorrect zero symbol transcoding between
 applications
Date: Mon, 30 May 2022 21:42:51 +0800

Петров Андрей <an.petrov <at> pay-lab.ru> writes:

> Hello, team!
>
> Please check the following behavior:
>
> 1. Start two instances of emacs -Q.
> 2. Switch to the "*scratch*" buffer of the first one and type the following:
>    M-: (insert (format "%S"  "000\000000")) [RET]
>    You should see "000^@000" string.
> 3. Copy the string into clipboard and paste into the other instance of
>    Emacs (which you have started before).
>    I get "000\0000" instead of "000\000000"
> 4. Try evaluating inserted text ("000\0000")
>    C-c C-e
>    I get "000^@0" instead of "000^@000".
>
> It seems that "^@" is transcoded between applications into "\0"
>  instead of "\000". If I do the same test inside single instance
>  of Emacs I get the correct result.

That's not a bug.  Most programs cannot tolerate NUL bytes inside
selection strings, so the Emacs selection converter deliberately
replaces those inside a string with "\0" before sending the string to a
requestor.

When one Emacs instance owns the selection, the contents of the kill
ring are used directly when yanking text, so that conversion doesn't
take place.

Message #11 received at 55727 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Петров Андрей <an.petrov <at> pay-lab.ru>
Cc: 55727 <at> debbugs.gnu.org
Subject: Re: bug#55727: 29.0.50;
 Incorrect zero symbol transcoding between applications
Date: Mon, 30 May 2022 17:06:02 +0300

> From: Петров Андрей <an.petrov <at> pay-lab.ru>
> Date: Mon, 30 May 2022 13:08:52 +0000
> 
> 1. Start two instances of emacs -Q.
> 2. Switch to the "*scratch*" buffer of the first one and type the following:
>    M-: (insert (format "%S"  "000\000000")) [RET]
>    You should see "000^@000" string.
> 3. Copy the string into clipboard and paste into the other instance of
>    Emacs (which you have started before).
>    I get "000\0000" instead of "000\000000"
> 4. Try evaluating inserted text ("000\0000")
>    C-c C-e
>    I get "000^@0" instead of "000^@000".
> 
> It seems that "^@" is transcoded between applications into "\0"
>  instead of "\000". If I do the same test inside single instance
>  of Emacs I get the correct result.

Yes.  And it's a feature.  From select.el:

      ;; Most programs are unable to handle NUL bytes in strings.
      (setq str (string-replace "\0" "\\0" str))

Message #14 received at 55727 <at> debbugs.gnu.org (full text, mbox):

From: Петров Андрей <an.petrov <at> pay-lab.ru>
To: Po Lu <luangruo <at> yahoo.com>
Cc: "55727 <at> debbugs.gnu.org" <55727 <at> debbugs.gnu.org>
Subject: Re: bug#55727: 29.0.50; Incorrect zero symbol transcoding between
 applications
Date: Mon, 30 May 2022 14:27:43 +0000

Hi, Po.

OK, You can close the bug then.

Just tell me if Emacs have ready to use solution for passing binary
strings between applications in a form what can be correctly restored
 with `read' function. I found that output of `print' also can not be
transferred through application boundary.

С уважением,
Андрей Петров,
программист ООО Инпас-Софт.


________________________________________
От: Po Lu <luangruo <at> yahoo.com>
Отправлено: 30 мая 2022 г. 18:42:51
Кому: Петров Андрей
Копия: 55727 <at> debbugs.gnu.org
Тема: Re: bug#55727: 29.0.50; Incorrect zero symbol transcoding between applications

Петров Андрей <an.petrov <at> pay-lab.ru> writes:

> Hello, team!
>
> Please check the following behavior:
>
> 1. Start two instances of emacs -Q.
> 2. Switch to the "*scratch*" buffer of the first one and type the following:
>    M-: (insert (format "%S"  "000\000000")) [RET]
>    You should see "000^@000" string.
> 3. Copy the string into clipboard and paste into the other instance of
>    Emacs (which you have started before).
>    I get "000\0000" instead of "000\000000"
> 4. Try evaluating inserted text ("000\0000")
>    C-c C-e
>    I get "000^@0" instead of "000^@000".
>
> It seems that "^@" is transcoded between applications into "\0"
>  instead of "\000". If I do the same test inside single instance
>  of Emacs I get the correct result.

That's not a bug.  Most programs cannot tolerate NUL bytes inside
selection strings, so the Emacs selection converter deliberately
replaces those inside a string with "\0" before sending the string to a
requestor.

When one Emacs instance owns the selection, the contents of the kill
ring are used directly when yanking text, so that conversion doesn't
take place.

Message #19 received at 55727-done <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Петров Андрей <an.petrov <at> pay-lab.ru>
Cc: luangruo <at> yahoo.com, 55727-done <at> debbugs.gnu.org
Subject: Re: bug#55727: 29.0.50;
 Incorrect zero symbol transcoding between applications
Date: Mon, 30 May 2022 18:42:49 +0300

> Cc: "55727 <at> debbugs.gnu.org" <55727 <at> debbugs.gnu.org>
> From: Петров Андрей <an.petrov <at> pay-lab.ru>
> Date: Mon, 30 May 2022 14:27:43 +0000
> 
> OK, You can close the bug then.

Done.

> Just tell me if Emacs have ready to use solution for passing binary
> strings between applications in a form what can be correctly restored
>  with `read' function. I found that output of `print' also can not be
> transferred through application boundary.

Did you consider encoding it in base64?

Message #22 received at 55727-done <at> debbugs.gnu.org (full text, mbox):

From: Петров Андрей <an.petrov <at> pay-lab.ru>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: "luangruo <at> yahoo.com" <luangruo <at> yahoo.com>,
 "55727-done <at> debbugs.gnu.org" <55727-done <at> debbugs.gnu.org>
Subject: Re: bug#55727: 29.0.50; Incorrect zero symbol transcoding between
 applications
Date: Mon, 30 May 2022 16:23:46 +0000

Hi, Eli!

Looks like I have to use hex, base64 or other ASCII encodings.
It seems that I will use something like this:

(defun my-escape-char (c)
  (insert (if (< c ?\s) (format "\\%03o" c) c)))

(print "000\000000" 'my-escape-char)


Best regards,
Andrey Petrov.
________________________________________
От: Eli Zaretskii <eliz <at> gnu.org>
Отправлено: 30 мая 2022 г. 20:42:49
Кому: Петров Андрей
Копия: luangruo <at> yahoo.com; 55727-done <at> debbugs.gnu.org
Тема: Re: bug#55727: 29.0.50; Incorrect zero symbol transcoding between applications

> Cc: "55727 <at> debbugs.gnu.org" <55727 <at> debbugs.gnu.org>
> From: Петров Андрей <an.petrov <at> pay-lab.ru>
> Date: Mon, 30 May 2022 14:27:43 +0000
>
> OK, You can close the bug then.

Done.

> Just tell me if Emacs have ready to use solution for passing binary
> strings between applications in a form what can be correctly restored
>  with `read' function. I found that output of `print' also can not be
> transferred through application boundary.

Did you consider encoding it in base64?

Message #25 received at 55727 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Петров Андрей <an.petrov <at> pay-lab.ru>
Cc: luangruo <at> yahoo.com, 55727 <at> debbugs.gnu.org
Subject: Re: bug#55727: 29.0.50; Incorrect zero symbol transcoding between
 applications
Date: Mon, 30 May 2022 21:09:49 +0300

> From: Петров Андрей <an.petrov <at> pay-lab.ru>
> CC: "luangruo <at> yahoo.com" <luangruo <at> yahoo.com>, "55727-done <at> debbugs.gnu.org"
> 	<55727-done <at> debbugs.gnu.org>
> Date: Mon, 30 May 2022 16:23:46 +0000
> 
> Hi, Eli!
> 
> Looks like I have to use hex, base64 or other ASCII encodings.
> It seems that I will use something like this:
> 
> (defun my-escape-char (c)
>   (insert (if (< c ?\s) (format "\\%03o" c) c)))
> 
> (print "000\000000" 'my-escape-char)

Emacs has base64-encode-region and base64-decode-region, so you could
use that instead.

Message #28 received at 55727-done <at> debbugs.gnu.org (full text, mbox):

From: Po Lu <luangruo <at> yahoo.com>
To: Петров Андрей <an.petrov <at> pay-lab.ru>
Cc: "55727 <at> debbugs.gnu.org" <55727-done <at> debbugs.gnu.org>
Subject: Re: bug#55727: 29.0.50; Incorrect zero symbol transcoding between
 applications
Date: Tue, 31 May 2022 08:16:51 +0800

Петров Андрей <an.petrov <at> pay-lab.ru> writes:

> Hi, Po.
>
> OK, You can close the bug then.

Thanks, closed.

> Just tell me if Emacs have ready to use solution for passing binary
> strings between applications in a form what can be correctly restored
>  with `read' function. I found that output of `print' also can not be
> transferred through application boundary.

You could encode the data in a format such as base64, or alternatively
pass it as input to a subprocess.  Selections are probably the wrong
thing to use for this.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.