Microsoft should provide a static linked /init - Process

[hackerswork]

With a static linked bash and a static linked busybox it is possible to reduce the WSL - system
to the bare minimum with only three executeables: /init, /bin/bash and the busybox - system
(executable and symlinks in /bin /usr/bin /usr/sbin /sbin).

With a static linked init - process we could get rid of /lib64 and /lib/x64_86-linux-gnu.
This in turn would allow to construct or use a distribution (with busybox as bootstrap) without any dependencies.

Appendix: How to make a minimal WSL - system

I assume you have built or downloaded a static linked bash (bash) and a busybox - system
(busybox and busybox.tar) and is available in C:\Install

cd /

cp /mnt/c/Install/bash /
cp /mnt/c/Install/busybox /

exec /bash

/busybox rm -rf /boot
/busybox rm -rf /bin
/busybox rm -rf /usr
/busybox rm -rf /sbin
/busybox rm -rf /etc/*
/busybox ln -s /run/resolvconf/resolv.conf /etc
/busybox tar -xf /mnt/c/Install/busybox.tar

cp /bash /bin/bash

At this point, the busybox - system is working

Now:
Empty /var
Empty /lib but leave /lib/x64_86-linux-gnu

Conclusion: In order to play with the WSL - system it should be as standalone as possible

[stehufntdev]

Thanks for the feedback. There's a related discussion in #8 if you are interested, and here's the short summary:

For now WSL is scoped to delivering a solid bash shell but there are many other exciting potential applications of the technology, including allowing people to select their distro of choice.

[benhillis]

We've changed the init daemon over to be a statically linked, this will be available in a Windows Insider build soon.

[therealkenc]

Nice 💯. Of course, this is a bad case of "careful what you wish for". Now I can't LD_PRELOAD the thing. Stashing the old binary while I still can 😉.

[DDoSolitary]

I can confirm that it works on the latest insider build, thanks!

[jstarks]

@therealkenc Out of curiosity, what are you LD_PRELOADing?

[therealkenc]

@jstarks - It was more of a tounge-in-cheek hypothesis rather than something I got around to trying. This stems from taking the briefest of looks back in August #2372 (message). As long as init was calling into dynamic glibc I figured it should be possible get in underneath and watch the library calls fly by, either by proxy or by swapping out glibc outright. It would not surprise me in the least if you say that is now not possible, regardless of whether I have set the old binary to the side.

[Biswa96]

How can I get BusyBox binary with bash applet in-build? Or do I compile it myself? I want to make a symbolic link from bash to busybox. So that the tar.gz file will have only one file.

[fcicq]

@Biswa96 hint is enable IF_FEATURE_BASH_IS_ASH, I guess you have to do the compile.

[Biswa96]

@benhillis LxssManager.dll doesn't add the file creation time of init during resource extraction. LxssManager.dll only set the 755 permission and LXATTRB attribute with EaBuffer.