[Toybox] Tilde expansion test on android?

[enh]

On Wed, Jan 8, 2020 at 3:32 PM Rob Landley <rob at landley.net> wrote:
>
> Hello from Tokyo.
>
> I'm shoveling my way through shell variable expansion, and I've implemented 3 of
> the 8 types so far (tilde expansion, bracket expansion, and quote removal), and
> I'm adding tests/sh.test entries for each, and I've come to this one:
>
>   echo {~,~root}/pwd
>
> And I'm going... ok, I can get away with just saying ~ and comparing it with
> $HOME (which I did in the previous two tests), but if I want an actual username,
> the only one guaranteed-ish to be on the system is "root". But though root's
> home directory has been "/root" on every Linux distro I've used for the past
> decade, it's not actually _required_ by anything?

yeah, and it's just / for all users on Android, and /data for all uids
that correspond to apps (which is: all uids >= 10000).

> No, posix doesn't require a root user to exist, because Microsoft and IBM
> sabotaged it. Back during the cold war, the US federal government required Unix,
> C, and Posix compatibility for all its systems in Federal Information and
> Processing Standard 151 (http://www.opengroup.org/testing/fips/) meaning even
> Apple came out with Unix for the Mac (https://youtu.be/nwrTTXOg-KI) and thus
> having certified posix compatibility was _required_ to get big lucrative
> government contracts... so Microsoft and IBM got seats on the Posix committe and
> sabotaged it as much as possible to so they could declare NT and S/360 posix
> compatibile via half-assed "compatibility layers"
> (https://en.wikipedia.org/wiki/Microsoft_POSIX_subsystem) even though NT didn't
> have the concept of more than one user (which is why your word processor was
> allowed to format the hard drive).
>
> Anyway, Android _also_ doesn't have user accounts, because they used the UID
> mechanism to separate apps (each app running as a different UID) back before
> thhey started spraying the system down with SELinux everywhere. (Because Android
> shipped in 2007 and container infrastructure didn't start seriously going into
> the kernel until around 2010, and was properly _usable_ about 5 years after that.)
>
> Anyway, tl;dr: ~root isn't guaranteed to expand to /root but nothing _else_ is
> likely to consistently expand to anything, and I wanna write tilde expansion
> tests. Suggestions?

slap in another of our "wait, is this Android?" checks and skip this
test there? `[ $(id -u shell) -eq 2000 ]` would be an appropriately
uid-themed check.

> Rob
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