[pacman-dev] [RFC] adding a --sysroot option

[Andrew Gregory]

pacman's --root option is regularly (mis)used to use pacman to manage
a mounted guest system, typically one whose pacman installation is
currently broken.  We have a few configuration defaults in place to
make this sort of work, but support is incomplete.  Those defaults
only actually take effect if the settings haven't been set in
a configuration file, several options still default to the host system
resources, and using the guest's pacman configuration requires
updating all configured paths to the new mounted location.

Adding a --sysroot/--chroot option would allow pacman to properly
operate in a mounted guest system.  At the moment, there are two ways
we could accomplish this:  prefix all paths with the sysroot or just
call chroot(2).  Obviously, the problem with chroot(2) is that it
requires special privileges.  Unfortunately, I think my symbolic
user/group patch (https://patchwork.archlinux.org/patch/3694/) will
require chroot to work properly as I can't find any other way to look
up users/groups in a mounted guest.  So, we may have to implement both
approaches so that regular users can perform queries but privileged
users can perform transactions with proper symbolic name support.

apg