[Debconf-devel] Bug#709928: debconf: "uninitialized value in concatenation", missing /var/cache/debconf

[Jeremiah Mahler]

Package: debconf
Version: 1.5.50
Severity: important
Tags: patch

Dear Maintainer,

I received the following "Use of unitialized value in concatentation"
error when I tried to upgrade/install any package.

  root at bishop:~# apt-get install --reinstall nmap
  Reading package lists... Done
  Building dependency tree       
  Reading state information... Done
  The following package was automatically installed and is no longer required:
    libgtk2-ruby
  Use 'apt-get autoremove' to remove it.
  0 upgraded, 0 newly installed, 1 reinstalled, 0 to remove and 2 not upgraded.
  Need to get 0 B/4,003 kB of archives.
  After this operation, 0 B of additional disk space will be used.
  Use of uninitialized value in concatenation (.) or string at /usr/share/perl5/Debconf/DbDriver/File.pm line 44, <DEBCONF_CONFIG> chunk 3.
  Use of uninitialized value in -e at /usr/share/perl5/Debconf/DbDriver/File.pm line 46, <DEBCONF_CONFIG> chunk 3.
  Use of uninitialized value in pattern match (m//) at /usr/share/perl5/Debconf/DbDriver/File.pm line 47, <DEBCONF_CONFIG> chunk 3.
  Use of uninitialized value $directory in -d at /usr/share/perl5/Debconf/DbDriver/File.pm line 48, <DEBCONF_CONFIG> chunk 3.
  Use of uninitialized value $directory in concatenation (.) or string at /usr/share/perl5/Debconf/DbDriver/File.pm line 49, <DEBCONF_CONFIG> chunk 3.
  debconf: DbDriver "config": mkdir :No such file or directory
  (Reading database ... 340051 files and directories currently installed.)
  Preparing to replace nmap 6.25-0.1 (using .../nmap_6.25-0.1_amd64.deb) ...
  Unpacking replacement nmap ...
  Processing triggers for man-db ...
  Use of uninitialized value in concatenation (.) or string at /usr/share/perl5/Debconf/DbDriver/File.pm line 44, <DEBCONF_CONFIG> chunk 3.
  Use of uninitialized value in -e at /usr/share/perl5/Debconf/DbDriver/File.pm line 46, <DEBCONF_CONFIG> chunk 3.
  Use of uninitialized value in pattern match (m//) at /usr/share/perl5/Debconf/DbDriver/File.pm line 47, <DEBCONF_CONFIG> chunk 3.
  Use of uninitialized value $directory in -d at /usr/share/perl5/Debconf/DbDriver/File.pm line 48, <DEBCONF_CONFIG> chunk 3.
  Use of uninitialized value $directory in concatenation (.) or string at /usr/share/perl5/Debconf/DbDriver/File.pm line 49, <DEBCONF_CONFIG> chunk 3.
  debconf: DbDriver "config": mkdir :No such file or directory
  dpkg: error processing man-db (--unpack):
   subprocess installed post-installation script returned error exit status 1
  Errors were encountered while processing:
   man-db
  E: Sub-process /usr/bin/dpkg returned an error code (1)
  root at bishop:~#

The cause was found to be related to a missing "/var/cache/debconf" directory.

  rm -fr /var/cache/debconf
  apt-get install <some package>
  (error)

The module

  /usr/share/perl5/Debconf/DbDriver/File.pm

uses 'abs_path' to resolve "/var/cache/debconf" but if the directory
is missing it will return an undefined value resulting in the errors
described.  In the module it can be seen that it will create the missing
directory if needed, but this step is performed after the error.
Moving the directory creation to an earlier point resolves the
problem (patch attached).
 
-- System Information:
Debian Release: jessie/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'testing'), (500, 'stable'), (500, 'oldstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 3.8-2-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages debconf depends on:
ii  perl-base  5.14.2-21

Versions of packages debconf recommends:
ii  apt-utils     0.9.8.1
ii  debconf-i18n  1.5.50

Versions of packages debconf suggests:
pn  debconf-doc                <none>
pn  debconf-utils              <none>
ii  libgtk2-perl               2:1.247-2
pn  libnet-ldap-perl           <none>
pn  libqtcore4-perl            <none>
pn  libqtgui4-perl             <none>
pn  libterm-readline-gnu-perl  <none>
ii  perl                       5.14.2-21
ii  whiptail                   0.52.15-1

-- no debconf information
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