`pathContentsGood` is used to assess the validity of a path as part of
derivation goals *in repair mode*.
When repair is used with a diverted store, i.e. a store where
fsPath(toRealPath(s)) != fsPath(s) for s a store path, this result in
utterly broken behavior because it will attempt to assess the goodness
of the *logical* store locations, most of the time: /nix/store/...
So, if you are repairing your system using a live NixOS ISO. Your ISO
contains a `/nix/store` (assumed to be good) and you repair your system
which is rooted at /mnt and contains its own /nix/store, that is, a Nix
store at /mnt/nix/store.
Performing the following operation `nix-store --verify --repair --store
/mnt` will assess the contents goodness of the ISO's Nix store.
To avoid this, we assess the path existence of the *physical path*, aka
the result of `store.toRealPath` applied to a *logical* store path
string representation and we verify the hash of the *physical path*.
The error messages are not taken care of in this CL as those are purely
cosmetic and helps the user understand what is going on.
Fixes#892.
Change-Id: Ib9e0153cb5683edcf37f1963ebf065ceba5e5dfb
Signed-off-by: Raito Bezarius <raito@lix.systems>
Raito Bezarius
ef94901156