When running it without arguments it is supposed to read the local CUPS's
cupsd.conf and show a summary of the setting. in CUPS 2.3.1 it shows a mess
with a lot of HTML inside and this is due to the fact that when loading the
file via HTTP using the /admin/cups/cupsd.conf path the scheduler calls the
admin.cgi program which returns the admin front page of the web admin
interface. cupsctl then tries to interpret that as the config file and displays
garbage. Even worse is if you run cupsctl with command line argument (one of
the five switches or a key=value pair) to change a setting. It seems to load
cupsd.conf again and gets again the HTML code of the web interface page.
cupsctl tries to interpret this again, producing garbage, adds the
user-supplied setting and writes all this back into cupsd.conf. Then it tries
to restart the scheduler which fails due to the broken config file.
The problem is that in the file scheduler/client.conf, in the function
get_file() the URI from the client is at first checked whether it begins with
"/admin/" and in this case the CGI program admin.cgi is responsible. Only after
that the check for "/admin/conf/cupsd.conf" comes and is never reached.
I have changed the order now appropriately and this way cupsctl works again.
Note that the problem only occurs if the web interface is active and the
cupsctl command is issued by a non-root user.
This is a regression caused by issue #5652.
Bug: https://github.com/apple/cups/issues/5744
Gbp-Pq: Name 0005-Fix-scheduler-cupsd.conf-load.patch
su-fang