Current File : //usr/share/perl5/Debconf/Client/ConfModule.pm
#!/usr/bin/perl
=head1 NAME
Debconf::Client::ConfModule - client module for ConfModules
=head1 SYNOPSIS
use Debconf::Client::ConfModule ':all';
version('2.0');
my $capb=capb('backup');
input("medium", "foo/bar");
my @ret=go();
if ($ret[0] == 30) {
# Back button pressed.
...
}
...
=head1 DESCRIPTION
This is a module to ease writing ConfModules for Debian's configuration
management system. It can communicate with a FrontEnd via the debconf
protocol (which is documented in full in the debconf_specification in
Debian policy).
The design is that each command in the protocol is represented by one
function in this module (with the name lower-cased). Call the function and
pass in any parameters you want to follow the command. If the function is
called in scalar context, it will return any textual return code. If it is
called in list context, an array consisting of the numeric return code and
the textual return code will be returned.
This module uses Exporter to export all functions it defines. To import
everything, simply import ":all".
=over 4
=cut
package Debconf::Client::ConfModule;
use warnings;
use strict;
use base qw(Exporter);
# List all valid commands here.
our @EXPORT_OK=qw(version capb stop reset title input beginblock endblock go
unset set get register unregister clear
start_frontend fset fget subst purge metaget visible exist
settitle info progress data x_loadtemplatefile);
# Import :all to get everything.
our %EXPORT_TAGS = (all => [@EXPORT_OK]);
# Set up valid command lookup hash.
my %commands;
map { $commands{uc $_}=1; } @EXPORT_OK;
# Unbuffered output is required.
$|=1;
=item import
Ensure that a FrontEnd is running. It's a little hackish. If
DEBIAN_HAS_FRONTEND is set, a FrontEnd is assumed to be running.
If not, one is started up automatically and stdin and out are
connected to it. Note that this function is always run when the
module is loaded in the usual way.
=cut
sub import {
if (! $ENV{DEBIAN_HAS_FRONTEND}) {
$ENV{PERL_DL_NONLAZY}=1;
if (exists $ENV{DEBCONF_USE_CDEBCONF} and
$ENV{DEBCONF_USE_CDEBCONF} ne '') {
exec "/usr/lib/cdebconf/debconf", $0, @ARGV;
} else {
exec "/usr/share/debconf/frontend", $0, @ARGV;
}
}
# Make the Exporter still work.
Debconf::Client::ConfModule->export_to_level(1, @_);
# A truly gross hack. This is only needed if
# /usr/share/debconf/confmodule is loaded, and then this
# perl module is used. In that case, this module needs to write
# to fd #3, rather than stdout. See changelog 0.3.74.
if (exists $ENV{DEBCONF_REDIR} && $ENV{DEBCONF_REDIR}) {
open(STDOUT, ">&", 3);
}
}
=item stop
The frontend doesn't send a return code here, so we cannot try to read it
or we'll block.
=cut
sub stop {
print "STOP\n";
return;
}
=item AUTOLOAD
Creates handler functions for commands on the fly.
=cut
sub AUTOLOAD {
my $command = uc our $AUTOLOAD;
$command =~ s|.*:||; # strip fully-qualified portion
die "Unsupported command `$command'."
unless $commands{$command};
no strict 'refs';
*$AUTOLOAD = sub {
my $c=join (' ', $command, @_);
# Newlines in input can really badly confuse the protocol, so
# detect and warn.
if ($c=~m/\n/) {
warn "Warning: Newline present in parameters passed to debconf.\n";
warn "This will probably cause strange things to happen!\n";
}
print "$c\n";
my $ret=<STDIN>;
chomp $ret;
my @ret=split(/\s/, $ret, 2);
if ($ret[0] eq '1') {
# escaped data
local $_;
my $unescaped='';
for (split /(\\.)/, $ret[1]) {
s/\\(.)/$1 eq "n" ? "\n" : $1/eg;
$unescaped.=$_;
}
$ret[0]='0';
$ret[1]=$unescaped;
}
return @ret if wantarray;
return $ret[1];
};
goto &$AUTOLOAD;
}
=back
=head1 SEE ALSO
The debconf specification
(/usr/share/doc/debian-policy/debconf_specification.txt.gz).
=head1 AUTHOR
Joey Hess <joeyh@debian.org>
=cut
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