[Fontconfig] robustness of the mmap cache branch

[Patrick Lam]

Matthias Clasen wrote:

> Btw, do you have any docs on the mmap cache file format ? I doesn't
> have to be anything grandiose, but a few notes like
> http://mail.gnome.org/archives/gtk-devel-list/2004-April/msg00065.html
> might be great to include in CVS.

I'll put together something better this weekend and include it in the
source, as well as posting it to the list.  Briefly, there's always a
line of signature identifying the machine and pointing to the next
block.  Then you have an FcCache data structure written in binary
format, followed by a chunk of memory which gets mmapped.  On a global
cache, you have a number of these dir chunks, prefaced by directory name.

pat