On Tue, 2017-08-22 at 10:38 +0200, Denys Vlasenko wrote:
> On Mon, Aug 21, 2017 at 8:38 PM, Ben Hutchings <b...@decadent.org.uk>
> wrote:
> > On Mon, 2017-08-21 at 19:40 +0200, Denys Vlasenko wrote:
> > > > On Mon, Aug 14, 2017 at 5:12 PM, Ben Hutchings <b...@decadent.or
> > > > g.uk> wrote:
> > > > On Mon, 2017-08-14 at 16:42 +0200, Denys Vlasenko wrote:
> > > > > > > run-init
> > > > > 
> > > > > This tool is doing this:
> > > > 
> > > > [...]
> > > > > There is the "switch_root" tool in util-linux which does the
> > > > > crucial part of this functionality - deleting / remounting /
> > > > > chrooting.
> > > > > It is in bbox too.
> > > > 
> > > > initramfs-tools used to use switch_root if possible, but it
> > > > didn't
> > > > support the -d (drop capabilities) option.  Later on we needed
> > > > validation of the init filename to support symlinks (e.g.
> > > > /sbin/init ->
> > > > /lib/systemd/systemd), so I added and used the -n (dry run)
> > > > option to
> > > > run-init.  busybox would need to support both of these.
> > > 
> > > I added run-init to busybox just now, but I don't see -n option
> > > in
> > > klibc-2.0.4 source. Can you point me to the source code with -n?
> > 
> > It's not upstream yet, but in a Debian patch:
> > https://sources.debian.net/src/klibc/2.0.4-9/debian/patches/run-ini
> > t-add-dry-run-mode.patch/
> 
> Done:
> 
> $ ./busybox run-init
> BusyBox v1.28.0.git (2017-08-21 18:55:09 CEST) multi-call binary.
> 
> Usage: run-init [-d CAP,CAP...] [-n] [-c CONSOLE_DEV] NEW_ROOT
> NEW_INIT [ARGS]
> 
> Free initramfs and switch to another root fs:
> chroot to NEW_ROOT, delete all in /, move NEW_ROOT to /,
> execute NEW_INIT. PID must be 1. NEW_ROOT must be a mountpoint.
> 
>     -c DEV    Reopen stdio to DEV after switch
>     -d CAPS   Drop capabilities
>     -n        Dry run

Great.  Once these changes are in the Debian package, I can update
initramfs-tools to make klibc-utils optional.

Ben.

-- 
Ben Hutchings
Make three consecutive correct guesses and you will be considered an
expert.

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