#!/usr/bin/perl -w

=head1 NAME

dpkg-preconfigure - let packages ask questions prior to their installation

=head1 SYNOPSIS

 dpkg-preconfigure [options] package.deb

 dpkg-preconfigure --apt

=head1 DESCRIPTION

B<dpkg-preconfigure> lets packages ask questions before they are installed.
It operates on a set of debian packages, and all packages that use debconf
will have their config script run so they can examine the system and ask
questions.

=head1 OPTIONS

=over 4

=item B<-f>I<type>, B<--frontend=>I<type>

Select the frontend to use.

=item B<-p>I<value>, B<--priority=>I<value>

Set the lowest priority of questions you are interested in. Any questions
with a priority below the selected priority will be ignored and their
default answers will be used.

=item B<--terse>

Enables terse output mode. This affects only some frontends.

=item B<--apt>

Run in apt mode. It will expect to read a set of package filenames from
stdin, rather than getting them as parameters. Typically this is used to
make apt run dpkg-preconfigure on all packages before they are installed.
To do this, add something like this to /etc/apt/apt.conf:

 // Pre-configure all packages before
 // they are installed.
 DPkg::Pre-Install-Pkgs {
 	"dpkg-preconfigure --apt --priority=low";
 };

=item B<-h>, B<--help>

Display usage help.

=back

=cut

=head1 SEE ALSO

L<debconf(7)>

=cut

# This program may be running from apt. If so, if it fails, apt is going to
# fail as well, which will make it hard for people to fix whatever the failure
# was. One thing someone encountered was perl failing to install. Apt then
# was re-run with perl unpacked and not configured, and modules weren't
# able to be loaded. As a sanity check, detect that case. If found, exit with
# an error message, but a return code of 0 so apt continues.
BEGIN {
	eval qq{
		use strict;
		use FileHandle;
		use Debconf::Log qw(:all);
		use Debconf::Db;
		use Debconf::Template;
		use Debconf::Config;
		use Debconf::AutoSelect qw(:all);
		use Debconf::Gettext;
		use Debconf::Path;
	};
	if ($@) {
		# Don't use gettext() on this because it may have failed to
		# load!
		print STDERR "debconf: Perl may be unconfigured ($@) -- aborting\n";
		exit 0;
	}
}

if (exists $ENV{DEBCONF_USE_CDEBCONF} and $ENV{DEBCONF_USE_CDEBCONF} ne '') {
    exec "/usr/lib/cdebconf/dpkg-preconfigure", @ARGV;
}

Debconf::Db->load;

my $apt=0;
Debconf::Config->getopt(
qq{Usage: dpkg-preconfigure [options] [debs]
       --apt			Apt mode.},
	"apt"			=> \$apt,
);

# In apt mode, need unbuffered output. Let's just enable it.
$|=1;

my @debs=@ARGV;
@ARGV=();

my $have_tty=1;

# If running from apt, read package filenames on stdin.
if ($apt) {
	while (<>) {
		chomp;
		push @debs, $_ if length $_;
	}
	
	exit unless @debs;
	
	# We have now reached the end of the first file on stdin.
	# Future reads from stdin should get input from the user, so re-open.
	$have_tty=0 unless open (STDIN, "/dev/tty");
}
elsif (! @debs) {
	print STDERR sprintf("dpkg-preconfigure: ".gettext("must specify some debs to preconfigure")), "\n";
	exit(1);
}

if (! Debconf::Path::find("apt-extracttemplates")) {
	warn gettext("delaying package configuration, since apt-utils is not installed");
	exit;
}

my $frontend=make_frontend();

if (! $have_tty && $frontend->need_tty) {
	print STDERR sprintf("dpkg-preconfigure: ".gettext("unable to re-open stdin: %s"), $!)."\n";
	exit 0;
}

# Use the external package scanner for speed. It takes a list of debs
# and outputs to stdout a table with these fields separated by spaces:
my ($package, $version, $template, $config);
# Note that it also handles making sure the current version of debconf can
# deal with the package, because apt-extracttemplates skips over any
# package that depends on a version of debconf newer than what is
# installed.
unless (open(INFO, "-|")) {
	# The kernel can accept command lines up to 20k worth of
	# characters. It has happened that the list of packages to
	# configure is more than that, which requires splitting it up into
	# multiple apt-extracttemplates runs.
	my $command_max=20000; # LINUX SPECIFIC!!
		# I could use POSIX::ARG_MAX, but that would be slow.
	my $static_len=length("apt-extracttemplates");
	my $len=$static_len;
	my @collect;
	my $progress=0;
	my $show_progress=($apt && @debs > 30 && -t STDERR);
	if ($show_progress) {
		STDERR->autoflush(1);
	}
	foreach my $deb (@debs) {
		$len += length($deb) + 1;
		if ($len < $command_max && @collect < 30) {
			push @collect, $deb;
		}
		else {
			if (system("apt-extracttemplates", @collect) != 0) {
				print STDERR sprintf("debconf: ".gettext("apt-extracttemplates failed: %s")."\n",$!);
			}
			if ($show_progress) {
				$progress += @collect;
				printf STDERR "\r".gettext("Extracting templates from packages: %d%%"), $progress * 100 / @debs;
			}
				
			@collect=($deb);
			$len=$static_len + length($deb) + 1;
		}
	}
	if (system("apt-extracttemplates", @collect) != 0) {
		print STDERR sprintf("debconf: ".gettext("apt-extracttemplates failed: %s")."\n",$!);
	}
	if ($show_progress) {
		$progress += @collect;
		printf STDERR "\r".gettext("Extracting templates from packages: %d%%")."\n", $progress * 100 / @debs;
	}
	exit;
}
# Why buffer here? Well, suppose 300 packages are being installed, and
# only the first and last use debconf. The first is preconfigured. Then
# the user watches their UI lock up until it scans all the way to the last..
# Blowing a bit of memory on a buffer seems like a saner approach.
my @buffer=<INFO>;
if ($apt && @buffer) {
	print gettext("Preconfiguring packages ...\n");
}
foreach my $line (@buffer) {
	($package, $version, $template, $config)=split /\s/, $line;
	
	# Load templates if any.
	if (defined $template && length $template) {
		eval q{
			Debconf::Template->load($template, $package)
		};
		unlink $template;
		if ($@) {
			print STDERR "$package ".sprintf(gettext("template parse error: %s"), $@)."\n";
			unlink $config;
			next;
		}
	}
}

foreach my $line (@buffer) {
	($package, $version, $template, $config)=split /\s/, $line;

	# Run config script if any.
	if (defined $config && length $config && -e $config) {
		debug user => sprintf("preconfiguring %s (%s)",$package,$version);
		chmod(0755, $config) or
			die sprintf(gettext("debconf: can't chmod: %s"), $!);
		$frontend->default_title($package);
		$frontend->info(undef);
		my $confmodule=make_confmodule($config, 'configure', $version);
		# Make sure any questions created are owned by the correct package.
		$confmodule->owner($package);
		1 while ($confmodule->communicate);
		# I could just exit, but it's good to be robust so
		# other packages can still be configured and installed.
		if ($confmodule->exitcode > 0) {
			print STDERR sprintf(
				gettext("%s failed to preconfigure, with exit status %s"),
				$package, $confmodule->exitcode)."\n";
		}
		unlink $config;
	}
}

$frontend->shutdown;

# Save state.
Debconf::Db->save;

=head1 AUTHOR

Joey Hess <joeyh@debian.org>

=cut