Making the core fonts work

[Ivan Kozlov <kanichos@yandex.ru>]

Hello.

You should know that it is currently non-trivial to make the X.org server use fonts from a profile. You basically have to manually sift through the font files and find their ‘dirname’. The ‘fonts-dir’ union directories that Guix generates and installs into profiles have been useless since forever and in fact only get in the way; this is because the X.org server will not follow symbolic links to font files.

I was reading the Xserver(1) man page and noticed that it supports ‘font catalogue’ directories. They should contain symbolic links to actual font directories that will be added to the font path. This should allow a very nice solution.

Something like this:

(define (fontpath-file manifest)
  (define build
    #~(begin
        (use-modules (srfi srfi-1) (srfi srfi-26) (guix build utils))
        (let* ((top-font-dirs (filter file-exists?
                                      (map (cut string-append <>
                                                "/share/fonts")
                                           '#$(manifest-inputs manifest))))
               (font-dirs (append-map (lambda (dir)
                                        (find-files dir
                                                    (lambda (file stat)
                                                      (and (eq? 'directory (stat:type stat))
                                                           (file-exists? (string-append file "/fonts.dir"))))
                                                    #:directories? #t)) top-font-dirs)))
          (mkdir #$output)
          (chdir #$output)
          (if (null? font-dirs)
              (exit #t)
              (for-each (lambda (dir pri)
                          (symlink dir (string-append (basename dir) ":pri=" pri)))
                        font-dirs
                        (map number->string (iota (length font-dirs) 1)))))))
  (gexp->derivation "fontpath.d" build
                    #:modules '((guix build utils)
                                (srfi srfi-1)
                                (srfi srfi-26))
                    #:local-build? #t
                    #:substitutable? #f
                    #:properties
                    `((type . profile-hook)
                      (hook . fontpath-dir))))

This should be installed somewhere in the profile. Then you set the font path to "catalogue:$HOME/.guix-profile/share/fontpath.d" and everything works like a charm.

I am unqualified to make the actual patch that would add this functionality into Guix.