Re: ostree and fontconfig

[Colin Walters <walters verbum org>]

On Mon, Feb 23, 2015, at 10:06 AM, Daniel Drake wrote:
> It would make more sense to have the fontconfig
> cache at (say) /usr/lib/fontconfig/cache, where it will be included in
> ostree updates. There is a fontconfig ./configure argument to set
> this.

Right, see:
https://git.gnome.org/browse/gnome-continuous/tree/manifest.json#n139

> Secondly, even though the fontconfig cache is now shipped in the
> ostree, fontconfig rejects it. The fontconfig cache files are
> per-directory, and each cache file embeds the mtime of the directory
> it was generated against. If the mtime embedded in the cache does not
> match the directory mtime on the system, it goes ahead and regenerates
> the caches in the user's home directory - no different from the
> original problem.

I think we may need to recommend that build systems ensure that
file timestamps are 0.  This is related to the "reproducible build"
projects going on, e.g.:

https://wiki.debian.org/ReproducibleBuilds/Howto#Files_in_data.tar_contain_timestamps

In this vein, we could add a parameter to gtk-update-icon-cache
to treat input directory timestamps as 0, regardless of the tempdir
cache.  Alternatively, build systems could recursively set the timestamp
to 0.