[Fontconfig] Next steps for a reproducible Fontconfig?

[Alexander Larsson]

On Tue, Apr 2, 2019 at 2:35 PM Akira TAGOH <akira at tagoh.org> wrote:
>
> Thanks for testing, Alex.

Doing some more testing, and I think I have found an issue.

On the host i regenerate caches with your branch, getting FC_DEBUG=16
output (among other output):

  cache: /6ba42ae0000f58711b5caaf10d690066-le64.cache-7 (dir:
/usr/share/fonts/cantarell, salt: (null))
  cache: /6ba42ae0000f58711b5caaf10d690066-le64.cache-7 (dir:
/usr/share/fonts/cantarell, salt: (null))
  charsets 5 -> 1 leaves 75 -> 15
  cache: /6ba42ae0000f58711b5caaf10d690066-le64.cache-7 (dir:
/usr/share/fonts/cantarell, salt: (null))

In the flatpak-generated config in the sandbox have:
    <remap-dir as-path="/usr/share/fonts">/run/host/fonts</remap-dir>
    <dir>/run/host/fonts</dir>

Then, running fc-list in the sandbox prints:

  cache: /85bba0c73358da0b93a259c9d2b16b14-le64.cache-7 (dir:
/run/host/fonts/cantarell (mapped to /usr/share/fonts//cantarell),
salt: (null))
  cache: /85bba0c73358da0b93a259c9d2b16b14-le64.cache-7 (dir:
/run/host/fonts/cantarell (mapped to /usr/share/fonts//cantarell),
salt: (null))
  charsets 5 -> 1 leaves 75 -> 15
  cache: /85bba0c73358da0b93a259c9d2b16b14-le64.cache-7 (dir:
/run/host/fonts/cantarell (mapped to /usr/share/fonts//cantarell),
salt: (null))
  FcDirCacheWriteDir dir "/run/host/fonts/cantarell" file
"/home/alex/.var/app/org.gnome.eog/cache/fontconfig//85bba0c73358da0b93a259c9d2b16b14-le64.cache-7"

Note how these get different checksums, meaning that the host cache is
not used. I think this is due to the double-slash in "mapped to
/usr/share/fonts//cantarell".