Hello,

the attached file adds the e-book management program calibre. Eventually,
I will put it into ebook.scm. Comments are welcome, in particular concerning
the xdg issue.

The program works for downloading and reading ebooks, but it has problems
with mounting my attached e-reader. The problem seems to be that the guix
calibre is not allowed to connect to my debian dbus:
Udisks mount call failed:
Traceback (most recent call last):
  File "/gnu/store/jdpva5h8jb5d9xirzya1ivsvbl2vnpps-calibre-2.19.0/lib/calibre/calibre/devices/usbms/device.py", line 600, in do_mount
    mount(node)
  File "/gnu/store/jdpva5h8jb5d9xirzya1ivsvbl2vnpps-calibre-2.19.0/lib/calibre/calibre/devices/udisks.py", line 180, in mount
    u.mount(node_path)
  File "/gnu/store/jdpva5h8jb5d9xirzya1ivsvbl2vnpps-calibre-2.19.0/lib/calibre/calibre/devices/udisks.py", line 133, in mount
    dbus_interface=self.FILESYSTEM))
  File "/gnu/store/2f06bpk30myjx186f7mj86pc69k6jzi1-python2-dbus-1.2.0/lib/python2.7/site-packages/dbus/proxies.py", line 145, in __call__
    **keywords)
  File "/gnu/store/2f06bpk30myjx186f7mj86pc69k6jzi1-python2-dbus-1.2.0/lib/python2.7/site-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
DBusException: org.freedesktop.UDisks2.Error.NotAuthorized: Not authorized to perform operation (polkit authority not available and caller is not uid 0)

Do you have an idea how to solve this?

In the meantime, one may mount the e-reader by hand.

Andreas