bug#48462: Corrupt, un-repairable store after power cut during upgrade

[elaexuotee]

Hey Guix,

Recently, during in the middle of a `guix package -m .guix/manifest.scm`, my
machine had power failure. After rebotting, I simply reran the above and
it completed without error.

However, it appears that some of files in the store items are corrupt:

    $ vim
    vim: error while loading shared libraries: 
/gnu/store/6z2g9ybl3fkx6bdfg226mz8rpc0g53jx-gtk+-2.24.32/lib/libgdk-x11-2.0.so.0:
 file too short

    $ file -L 
/gnu/store/6z2g9ybl3fkx6bdfg226mz8rpc0g53jx-gtk+-2.24.32/lib/libgdk-x11-2.0.so.0
    
/gnu/store/6z2g9ybl3fkx6bdfg226mz8rpc0g53jx-gtk+-2.24.32/lib/libgdk-x11-2.0.so.0:
 empty

As an extra bit of annoyance, the handy verify and repair tools fail to see a
problem:

    $ command -v vim | xargs readlink -f
    /gnu/store/h9q2fik60axj9sai5b66cjk2sfl37ij1-vim-full-8.2.2689/bin/vim

    $ sudo guix build --repair vim-full
    /gnu/store/h9q2fik60axj9sai5b66cjk2sfl37ij1-vim-full-8.2.2689

    $ sudo guix build --repair --no-grafts vim-full
    path `/gnu/store/73p5rzka1cb9dx9fy059lmkf1jg6sv95-gtk+-2.24.32' is 
corrupted or missing!
    found corrupted or missing path 
`/gnu/store/73p5rzka1cb9dx9fy059lmkf1jg6sv95-gtk+-2.24.32' in the output 
closure of `/gnu/store/qyp10sss1ascp70yshs87zdzr1lg71f8-vim-full-8.2.2689.drv'
    substituting /gnu/store/73p5rzka1cb9dx9fy059lmkf1jg6sv95-gtk+-2.24.32...
    downloading from 
https://mirror.brielmaier.net/nar/lzip/73p5rzka1cb9dx9fy059lmkf1jg6sv95-gtk%2B-2.24.32
 ...
     gtk%2B-2.24.32  6.4MiB          152KiB/s 00:43 [##################] 100.0%

    /gnu/store/d21m63am0pxw77883h0y1jmy9iiazvvx-vim-full-8.2.2689

    $ sudo guix gc --verify=repair,contents
    ...

    $ vim
    vim: error while loading shared libraries: 
/gnu/store/6z2g9ybl3fkx6bdfg226mz8rpc0g53jx-gtk+-2.24.32/lib/libgdk-x11-2.0.so.0:
 file too short

Even going in with a crude hammer doesn't fix things:

    $ sudo mount -o rw,remount /gnu/store

    $ sudo mv /gnu/store/6z2g9ybl3fkx6bdfg226mz8rpc0g53jx-gtk+-2.24.32 .

    $ sudo guix build --repair vim-full
    path `/gnu/store/6z2g9ybl3fkx6bdfg226mz8rpc0g53jx-gtk+-2.24.32' is 
corrupted or missing!
    found corrupted or missing path 
`/gnu/store/6z2g9ybl3fkx6bdfg226mz8rpc0g53jx-gtk+-2.24.32' in the output 
closure of `/gnu/store/z2q3zna20cn32if3v271x4xavd70ml5z-vim-full-8.2.2689.drv'
    path `/gnu/store/73p5rzka1cb9dx9fy059lmkf1jg6sv95-gtk+-2.24.32' is 
corrupted or missing!
    substituting /gnu/store/73p5rzka1cb9dx9fy059lmkf1jg6sv95-gtk+-2.24.32...
    downloading from 
https://mirror.brielmaier.net/nar/lzip/73p5rzka1cb9dx9fy059lmkf1jg6sv95-gtk%2B-2.24.32
 ...
     gtk%2B-2.24.32  6.4MiB          134KiB/s 00:49 [##################] 100.0%

    applying 17 grafts for 
/gnu/store/lm9xqz82q4cwlqs79i0pq77z6cfsx3rw-gtk+-2.24.32.drv ...
    grafting '/gnu/store/73p5rzka1cb9dx9fy059lmkf1jg6sv95-gtk+-2.24.32' -> 
'/gnu/store/6z2g9ybl3fkx6bdfg226mz8rpc0g53jx-gtk+-2.24.32'...
    successfully built 
/gnu/store/lm9xqz82q4cwlqs79i0pq77z6cfsx3rw-gtk+-2.24.32.drv
    gnu/store/h9q2fik60axj9sai5b66cjk2sfl37ij1-vim-full-8.2.2689

    $ vim
    vim: error while loading shared libraries: 
/gnu/store/6z2g9ybl3fkx6bdfg226mz8rpc0g53jx-gtk+-2.24.32/lib/libgdk-x11-2.0.so.0:
 file too short

It seems like the above graft is going badly:

    $ file -L 
/gnu/store/73p5rzka1cb9dx9fy059lmkf1jg6sv95-gtk+-2.24.32/lib/libgtk-x11-2.0.so.0
    
/gnu/store/73p5rzka1cb9dx9fy059lmkf1jg6sv95-gtk+-2.24.32/lib/libgtk-x11-2.0.so.0:
 ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), statically linked, not 
stripped

    $ file -L 
/gnu/store/6z2g9ybl3fkx6bdfg226mz8rpc0g53jx-gtk+-2.24.32/lib/libgdk-x11-2.0.so.0
    
/gnu/store/6z2g9ybl3fkx6bdfg226mz8rpc0g53jx-gtk+-2.24.32/lib/libgdk-x11-2.0.so.0:
 empty

Some questions:

  1) Am I just missing something obvious?
  2) How could grafting end up producing empty files in the output?
  3) Is the store supposed to be robust against power failures?