[Android-tools-devel] Bug#924591: this requires linking in libsparse, which is from Android sources

[Theodore Ts'o]

On Mon, Apr 22, 2019 at 10:19:46PM +0200, Hans-Christoph Steiner wrote:
> 
> I don't really know how fastboot in stretch provided the mke2fs support,
> but judging by the dependencies, it might have been that fastboot used
> to do the formatting itself, based on being linked to
> android-libext4-utils and android-libsparse.  The buster version of
> fastboot is clearly calling mk2efs, which in AOSP is built from an
> inline e2fsprogs fork.

Yes, that's correct.

>From running strings on the fastboot binary from Stretch, it's using
the statically linked-in make_ext4fs code.  The make_ext4fs was code
written years and years ago, back when Android senior management
(rumor has it was that it was Andy Rubin himself) didn't want to use
any GPL'ed code in userspace.  Fortunately, that's no longer the case.

The old make_ext4fs code was old, creaky, and didn't exactly work the
same way as mke2fs (since it was written as a clean-room
reimplementation from scratch).  As a result I was very happy when we
were finally able to take the make_ext4fs code and KILL IT WITH
FIRE[1].  :-)

[1] https://www.youtube.com/watch?v=Tnod9vtB4xA

Unfortunately, the focus was to make the make_ext4fs replacement work
with AOSP only.  I wasn't aware of Debian's native Android tools; but
even if I did, it's not clear that we could have gotten things working
within the scope of the intern project to drop make_ext4fs support and
port the necessary support code into e2fsprogs.

This change started landing in AOSP in November 2016 (it was a Fall
2016 intern project).  I'd have to check to be sure, but looking at
the Debian changelog, the AOSP release with the actual KILL IT WITH
FIRE commit probably landed in Debian sometime in late 2017.  Alas,
apparently no one had noticed the problem for well over a year.  So
I'm guessing Debian's fastboot, or at least its format command, is
rarely used by Debian users.  :-/

					- Ted