gtkclipblock

A hack to prevent GTK programs from interacting with the primary clipboard (aka "primary selection"). Supports GTK 2/3/4.

This was made to work around a Firefox bug, but may be useful for other purposes.

How to use

Method 1

1. add /usr/lib/libgtkclipblock.so to /etc/ld.so.preload
2. add GTKCLIPBLOCK_HOOK=1 to /etc/environment or ~/.config/environment.d/gtkclipblock.conf

This is the most effective method, but it's also the most invasive as it gets loaded by all processes.

It also has the benefit of working with setcap/setuid/setgid binaries.

Method 2

Launch the program like this: GTKCLIPBLOCK_HOOK=1 LD_PRELOAD=/usr/lib/libgtkclipblock.so /usr/bin/firefox.

This is less invasive than the first method, however there's a few caveats:

• environment variables are inherited by child processes, which may unwittingly load the library
• doesn't work with setcap/setuid/setgid binaries

For convenience, you can patch a specific program by modifying its .desktop file:

1. copy the .desktop file from /usr/share/applications to ~/.local/share/applications
2. modify the Exec= line
   • before: Exec=/usr/bin/firefox %u
   • after: Exec=/usr/bin/env GTKCLIPBLOCK_HOOK=1 LD_PRELOAD=/usr/lib/libgtkclipblock.so /usr/bin/firefox %u

For CLI use, you can create a bootstrap script:

Save this as ~/.local/bin/firefox (make sure to chmod +x it!):

#!/usr/bin/env sh

export LD_PRELOAD="/usr/lib/libgtkclipblock.so${LD_PRELOAD:+:$LD_PRELOAD}"
exec /usr/bin/firefox "$@"

Install from package

Available on the AUR.

Install from source

meson setup --prefix=/usr/local build
meson install -C build

Environment variables

env var	description	value
GTKCLIPBLOCK_HOOK	determines which GTK libraries should be hooked	0 (disables all; default), 1 (enables all); or a comma-separated list, e.g gtk2,gtk3,gtk4
GTKCLIPBLOCK_HOOK_DLFCN	if disabled, libraries loaded via dlopen() won't get hooked	0 (disabled), 1 (enabled; default)