bug#68531: 29.1; garbage inserted in the buffer when starting Emacs in xterm

bug#68531: 29.1; garbage inserted in the buffer when starting Emacs in xterm

[Vincent Lefevre]

1. Create a large file "foo", e.g. with
     echo `seq 10000000` > foo

2. In an xterm, connect to the machine via ssh (AFAIK to introduce
   a delay in the transmissions).

3. Type (without <RET>):
     /usr/bin/emacs -nw -Q --eval="(setq large-file-warning-threshold
     100000000)" foo

4. Type <RET> twice very quickly.

I sometimes get garbage near the beginning of the buffer, after a
blank line (due to <RET>):

11;rgb:0000/0000/00001 2 3 4 5 6 7 8 [...]

I could reproduce this bug in Debian/stable (emacs-nox 1:28.2+1-15),
Debian/unstable (emacs-gtk 1:29.1+1-5), and Android with Termux
(GNU Emacs 29.1).

Without -Q, the bug occurs more easily: no need to be particularly
fast (I get it with <RET> to validate the command + <next> or <end>),
and the file may be smaller.


In GNU Emacs 29.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.38,
 cairo version 1.16.0) of 2023-08-30, modified by Debian built on
 x86-csail-01
System Description: Debian GNU/Linux trixie/sid

Configured using:
 'configure --build x86_64-linux-gnu --prefix=/usr
 --sharedstatedir=/var/lib --libexecdir=/usr/libexec
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --with-libsystemd --with-pop=yes
 --enable-locallisppath=/etc/emacs:/usr/local/share/emacs/29.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/29.1/site-lisp:/usr/share/emacs/site-lisp
 --with-sound=alsa --without-gconf --with-mailutils
 --with-native-compilation --build x86_64-linux-gnu --prefix=/usr
 --sharedstatedir=/var/lib --libexecdir=/usr/libexec
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --with-libsystemd --with-pop=yes
 --enable-locallisppath=/etc/emacs:/usr/local/share/emacs/29.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/29.1/site-lisp:/usr/share/emacs/site-lisp
 --with-sound=alsa --without-gconf --with-mailutils
 --with-native-compilation --with-cairo --with-x=yes
 --with-x-toolkit=gtk3 --with-toolkit-scroll-bars 'CFLAGS=-g -O2
 -ffile-prefix-map=/build/reproducible-path/emacs-29.1+1=. -fstack-protector-strong
 -Wformat -Werror=format-security -Wall' 'CPPFLAGS=-Wdate-time
 -D_FORTIFY_SOURCE=2' LDFLAGS=-Wl,-z,relro'

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

Important settings:
  value of $LC_COLLATE: POSIX
  value of $LC_CTYPE: C.UTF-8
  value of $LC_TIME: en_DK.utf8
  value of $LANG: C.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Fundamental

Minor modes in effect:
  tooltip-mode: t
  global-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 puny dired
dired-loaddefs rfc822 mml mml-sec password-cache epa derived epg rfc6068
epg-config gnus-util text-property-search time-date mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader cl-loaddefs
comp comp-cstr warnings icons subr-x rx cl-seq cl-macs cl-extra
help-mode cl-lib sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr
mail-utils term/xterm xterm byte-opt gv bytecomp byte-compile rmc
iso-transl tooltip cconv 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 seq 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 theme-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 native-compile emacs)

Memory information:
((conses 16 88507 8738)
 (symbols 48 7330 0)
 (strings 32 22637 3837)
 (string-bytes 1 698149)
 (vectors 16 15139)
 (vector-slots 8 289259 10490)
 (floats 8 35 230)
 (intervals 56 268 0)
 (buffers 984 12))

bug#68531: 29.1; garbage inserted in the buffer when starting Emacs in xterm

[Eli Zaretskii]

> Cc: Vincent Lefevre <vincent@vinc17.net>
> From: Vincent Lefevre <vincent@vinc17.net>
> Date: Wed, 17 Jan 2024 15:32:04 +0100
> 
> 
> 1. Create a large file "foo", e.g. with
>      echo `seq 10000000` > foo
> 
> 2. In an xterm, connect to the machine via ssh (AFAIK to introduce
>    a delay in the transmissions).
> 
> 3. Type (without <RET>):
>      /usr/bin/emacs -nw -Q --eval="(setq large-file-warning-threshold
>      100000000)" foo
> 
> 4. Type <RET> twice very quickly.
> 
> I sometimes get garbage near the beginning of the buffer, after a
> blank line (due to <RET>):
> 
> 11;rgb:0000/0000/00001 2 3 4 5 6 7 8 [...]

It's not garbage, it's Emacs querying the terminal about its
background mode, see xterm--report-background-handler.  I'm guessing
Emacs fails to read the response because visiting that file takes too
much time.

Try playing with the value of xterm-query-timeout.  Or avoid visiting
files with such humongously long lines from the command line.