voidnsrun

voidnsrun is utility for launching programs in an isolated namespace with alternative /usr tree. Its primary goal is to run glibc programs in musl-libc Void Linux environments or vice-versa.

It creates a new private mount namespace, transparently substitutes /usr and some other directories with directories from your alternative root using bind mounts, and launches your program.

Installation

Just clone the repo, and then:

$ make
$ sudo make install

Note that installed binary must be owned by root and have suid bit. make install should handle it.

Usage

voidnsrun [OPTIONS] PROGRAM [ARGS]

Options:
	-m <path>: add bind mount
	-r <path>: altroot path. If this option is not present,
	           VOIDNSRUN_DIR environment variable is used.
	-h:        print this help
	-v:        print version

voidnsrun needs to know the path to your alternative root directory and it can read it from the VOIDNSRUN_DIR environment variable or you can use -r argument to specify it.

You may want to add something like this to your ~/.bashrc or similar script:

export VOIDNSRUN_DIR=/glibc

By default, voidnsrun binds these paths from alternative root to the new namespace:

• /usr
• /var/db/xbps
• /etc/xbps.d

But if you're launching xbps-install, xbps-remove or xbps-reconfigure and using voidnsrun version 1.1 or newer, this is what it will bind:

• /usr
• /var
• /etc

If you want to bind something else, use the -m argument.

Example

Let's imagine you want to use some proprietary glibc app on your musl-libc Void Linux box. Let it be Vivaldi browser for the example. You unpacked it to /opt/vivaldi and it doesn't work, obviously.

First, you need to perform an alternative glibc base system installation to a separate new directory:

# mkdir /glibc
# XBPS_ARCH=x86_64 xbps-install --repository=http://alpha.de.repo.voidlinux.org/current -r /glibc -S base-voidstrap

Export path to this installation for voidnsrun:

export VOIDNSRUN_DIR=/glibc

Try launching your app:

voidnsrun /opt/vivaldi/vivaldi

It won't work just yet:

/opt/vivaldi/vivaldi: error while loading shared libraries: libgobject-2.0.so.0: cannot open shared object file: No such file or directory

Now you need to install all its dependencies into your glibc installation. Use xlocate from xtools package to find a package responsible for a file (or just guess it):

$ xlocate libgobject-2.0.so.0
Signal-Desktop-1.38.1_1	/usr/lib/signal-desktop/resources/app.asar.unpacked/node_modules/sharp/vendor/lib/libgobject-2.0.so -> /usr/lib/signal-desktop/resources/app.asar.unpacked/node_modules/sharp/vendor/lib/libgobject-2.0.so.0.5600.4
Signal-Desktop-1.38.1_1	/usr/lib/signal-desktop/resources/app.asar.unpacked/node_modules/sharp/vendor/lib/libgobject-2.0.so.0 -> /usr/lib/signal-desktop/resources/app.asar.unpacked/node_modules/sharp/vendor/lib/libgobject-2.0.so.0.5600.4
Signal-Desktop-1.38.1_1	/usr/lib/signal-desktop/resources/app.asar.unpacked/node_modules/sharp/vendor/lib/libgobject-2.0.so.0.5600.4
glib-2.66.2_1	/usr/lib/libgobject-2.0.so.0 -> /usr/lib/libgobject-2.0.so.0.6600.2
glib-2.66.2_1	/usr/lib/libgobject-2.0.so.0.6600.2
glib-devel-2.66.2_1	/usr/share/gdb/auto-load/usr/lib/libgobject-2.0.so.0.6600.2-gdb.py
libglib-devel-2.66.2_1	/usr/lib/libgobject-2.0.so -> /usr/lib/libgobject-2.0.so.0

Sync repos and install glib. You can use voidnsrun for this purpose too.

$ sudo voidnsrun -r /glibc xbps-install -Su
$ sudo voidnsrun -r /glibc xbps-install glib

Try launching vivaldi again:

$ voidnsrun /opt/vivaldi/vivaldi
/opt/vivaldi/vivaldi: error while loading shared libraries: libnss3.so: cannot open shared object file: No such file or directory

As you can see, it no longer complains about missing libgobject-2.0.so.0, now it's libnss3.so. Repeat steps above for all missing dependencies, and in the end, it will work. (If it's not, then something's still missing. In particular, make sure to install fonts related packages: xorg-fonts, freetype, fontconfig, libXft.)

FAQ

Q: sudo voidnsrun xbps-install exits with "environment variable VOIDNSRUN_DIR not found" error

A: Add this line to /etc/sudoers:

Defaults env_keep += "VOIDNSRUN_DIR"

Q: Why applications launched with voidnsrun do not see my fonts?

A: If you installed fonts on your main system, applications that run in the mount namespace can't see them because of custom /usr directory. You need to install them again into the altroot directory.

Changelog

1.1

• Bind whole /etc and /var when launching xbps-install, xbps-remove or xbps-reconfigure.

1.0

• Initial release.

License

BSD-2c