[Debconf-devel] Bug#930370: debconf: Overriding debconf db with file fails with a message "access to disallowed key Filename in restricted hash"

[Jiri Palecek]

Package: debconf
Version: 1.5.71
Severity: normal

Dear Maintainer,

while trying to debug some difficulties with unattended package
installation, I came accross an interesting problem. While debconf(7)
says you can use DEBCONF_DB_OVERRIDE like this:

DEBCONF_DB_FALLBACK=File{Filename:/root/config.dat Backup:no}

when trying it actually, i got an error message:

# LC_MESSAGES=C DEBCONF_DEBUG=developer DEBCONF_DB_OVERRIDE="File{Filename:config2.dat.Lwzkvd}" DEBIAN_FRONTEND=noninteractive dpkg --auto-deconfigure -i ../linux-*_"$DATE"_*.deb
... blah blah...
Attempt to access disallowed key 'Filename' in a restricted hash at /usr/share/perl5/Debconf/DbDriver.pm line 35.

It does work, though, without the "Filename:" part. What gives?

Another problem, and the reason I am actually experimentig with this, is
that it actually doesn't work unattended, because it somehow disregards
what is in the config file. ie:

debconf (developer): <-- FSET linux-image-4.19.36-bughunt+/preinst/overwriting-modules-4.19.36-bughunt+ seen false
debconf (developer): --> 0 false
debconf (developer): <-- SUBST linux-image-4.19.36-bughunt+/preinst/overwriting-modules-4.19.36-bughunt+ modules_base /lib/modules
debconf (developer): --> 0
debconf (developer): <-- SUBST linux-image-4.19.36-bughunt+/preinst/overwriting-modules-4.19.36-bughunt+ package linux-image-4.19.36-bughunt+
debconf (developer): --> 0
debconf (developer): <-- INPUT critical linux-image-4.19.36-bughunt+/preinst/overwriting-modules-4.19.36-bughunt+
debconf (developer): --> 30 question skipped
debconf (developer): <-- GO
debconf (developer): --> 0 ok
debconf (developer): <-- GET linux-image-4.19.36-bughunt+/preinst/overwriting-modules-4.19.36-bughunt+
debconf (developer): --> 0 true

I need false on the last line, but still get true (the
default). However, the config2.dat.... contains

Name: linux-image-4.19.36-bughunt+/preinst/overwriting-modules-4.19.36-bughunt+
Template: linux-image-4.19.36-bughunt+/preinst/overwriting-modules-4.19.36-bughunt+
Value: false

Maybe you could help me with that.

Regards
    Jiri Palecek

-- System Information:
Debian Release: 10.0
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'unstable-debug'), (500, 'testing-debug'), (500, 'unstable'), (1, 'experimental-debug'), (1, 'experimental')
Architecture: i386 (i686)

Kernel: Linux 4.19.36-bughunt+ (SMP w/2 CPU cores)
Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE
Locale: LANG=cs_CZ, LC_CTYPE=cs_CZ (charmap=ISO-8859-2), LANGUAGE=cs_CZ (charmap=ISO-8859-2)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages debconf depends on:
ii  perl-base  5.28.1-6

Versions of packages debconf recommends:
ii  apt-utils     1.8.2
ii  debconf-i18n  1.5.71

Versions of packages debconf suggests:
ii  debconf-doc                1.5.71
pn  debconf-kde-helper         <none>
ii  debconf-utils              1.5.71
ii  dialog                     1.3-20190211-1
pn  libgtk3-perl               <none>
pn  libnet-ldap-perl           <none>
ii  libterm-readline-gnu-perl  1.36-1
ii  perl                       5.28.1-6
ii  whiptail                   0.52.20-4

-- debconf information:
  debconf-apt-progress/preparing:
  debconf-apt-progress/media-change:
  debconf-apt-progress/info:
* debconf/frontend: Dialog
  debconf-apt-progress/title:
* debconf/priority: low