#!/usr/bin/perl -wT

# Completely delete a PostgreSQL cluster. Fails if there is still a server
# process attached.
#
# (C) 2005-2009 Martin Pitt <mpitt@debian.org>
# (C) 2015-2021 Christoph Berg <myon@debian.org>
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.

use strict;
use warnings;
use Getopt::Long;
use PgCommon;

# untaint environment
$ENV{'PATH'} = '/bin:/usr/bin';
delete @ENV{'IFS', 'CDPATH', 'ENV', 'BASH_ENV'};

my $stopserver = 0;
exit 1 unless GetOptions ('stop-server' => \$stopserver, 'stop' => \$stopserver);

# command line options
if ($#ARGV != 1) {
    print "Usage: $0 [--stop] <version> <cluster>\n";
    exit 1;
}

my ($version) = $ARGV[0] =~ /^(\d+\.?\d+)$/;
my ($cluster) = $ARGV[1] =~ /^([-.\w]+)$/;
error 'invalid version' unless defined $version;
error 'invalid cluster name' unless defined $cluster;

my %info;
my $c; # configuration directory
my $startconf;

if (cluster_exists $version, $cluster) {
    %info = cluster_info ($version, $cluster);
    validate_cluster_owner \%info if ($info{pgdata} && -d $info{pgdata}); # ignore missing data directory

    if ($info{'running'}) {
	if ($stopserver) {
	    if ($info{'pgdata'} && -d $info{'pgdata'}) {
		if (system ('pg_ctlcluster', $version, $cluster, 'stop')) {
		    error 'could not stop server, aborting';
		}
	    } else {
		print STDERR "Warning: corrupted cluster: data directory does not exist any more, but server is still running; you have to manually kill the postgres process\n";
	    }
	} else {
	    error 'This cluster is still running. Stop it or supply the --stop option';
	}
    }
    $c = $info{'configdir'};
    $startconf = $info{'start'};
} else {
    $c = "/etc/postgresql/$version/$cluster";

    # check if we have a broken cluster, clean up if necessary
    -d $c or error 'specified cluster does not exist';
}

# disable systemd-enabled clusters
if (not exists $ENV{'PG_CLUSTER_CONF_ROOT'} and -d '/run/systemd/system') {
    if ($> == 0) {
        system "systemctl", "disable", "postgresql\@$version-$cluster";
        system "systemctl", "disable", "--now", "pg_receivewal\@$version-$cluster";
        system "systemctl", "disable", "--now", "pg_basebackup\@$version-$cluster.timer";
        system "systemctl", "disable", "--now", "pg_dump\@$version-$cluster.timer";
    }
}

if ($info{'pgdata'} && -d $info{'pgdata'}) {
    # remove custom wal directory
    if ($info{waldir} and -d $info{waldir}) {
        my $walowner = (stat($info{waldir}))[4];
        if (defined $walowner and $walowner == $info{owneruid}) {
            my $result = system 'rm', '-r', '--', $info{waldir};
            if ($result) {
                print STDERR "Warning: could not remove wal directory $info{waldir}";
            }
        } else {
            print STDERR "Warning: wal directory $info{waldir} is not owned by uid $info{owneruid}, not removing\n";
        }
    }

    # remove tablespace subdirectories that belong to our version
    for my $link (glob "$info{pgdata}/pg_tblspc/*") {
        next unless (-l $link);
        my $tblspc = readlink $link;
        my $tblspcowner = (stat($tblspc))[4];
        if (defined $tblspcowner and $tblspcowner == $info{owneruid}) {
            if ($version >= 9.0) {
                for my $dir (glob "$tblspc/PG_${version}_*") {
                    my $dirowner = (stat($dir))[4];
                    if (defined $dirowner and $dirowner == $info{owneruid}) {
                        my $result = system 'rm', '-r', '--', ($dir =~ /(.*)/); # untaint
                        if ($result) {
                            print STDERR "Warning: could not remove tablespace directory $dir";
                        }
                    } else {
                        print STDERR "Warning: tablespace subdirectory $dir (in tablespace linked from $link) is not owned by uid $info{owneruid}, not removing\n";
                    }
                }
            } else { # before 9.0
                if (open my $fh, '<', "$tblspc/PG_VERSION") {
                    my $v = <$fh>;
                    chomp $v;
                    close $fh;
                    if ($v eq $version) {
                        $tblspc =~ /(.*)/; # untaint
                        my $result = system "rm -r -- $1/*";
                    } else {
                        print STDERR "Warning: tablespace directory $tblspc (linked from $link) is from PostgreSQL version $v, not removing\n";
                    }
                } else {
                    print STDERR "Warning: tablespace directory $tblspc (linked from $link) is not a PostgreSQL directory, not removing\n";
                }
            }
        } else {
            print STDERR "Warning: tablespace directory $tblspc (linked from $link) is not owned by uid $info{owneruid}, not considering\n";
        }
    }

    # remove pgdata
    my $result = system 'rm', '-r', $info{'pgdata'};
    if ($result) {
        if (! -w ($info{'pgdata'} . '/..')) {
            error 'you might need to run this program with root privileges';
        }
        exit $result;
    }
} else {
    print STDERR "Warning: corrupted cluster: data directory does not exist\n";
}

# remove config
unlink $c.'/pg_hba.conf', $c.'/pg_ident.conf', $c.'/postgresql.conf',
    $c.'/start.conf', $c.'/log', $c.'/autovacuum_log', $c.'/pgdata',
    $c.'/environment', $c.'/pg_ctl.conf';
rmdir $_ foreach (map { /(.*)/ && $1 } glob "$c/*"); # remove empty conf.d directories

unlink $info{'logfile'} if defined ($info{'logfile'});
if ($info{'socketdir'} and $info{'socketdir'} !~ /^(\/tmp|\/var\/run\/postgresql)\/?$/) {
    rmdir $info{'socketdir'};
}
rmdir $c;
rmdir "/etc/postgresql/$version";
rmdir "/var/lib/postgresql/$version/$cluster";
rmdir "/var/lib/postgresql/$version";
unlink "/var/log/postgresql/postgresql-$version-$cluster.log";
# remove logrotated files
foreach my $f (</var/log/postgresql/postgresql-$version-$cluster.log.[1-9]*>) {
    unlink ($f =~ /(.*)/); # untaint
}

# remove stats_temp_directory
my $statstempdir = $info{config}->{stats_temp_directory};
if ($statstempdir) {
    my $statsowner = (stat($statstempdir))[4];
    if (defined $statsowner and defined $info{owneruid} and $statsowner == $info{owneruid}) {
        foreach my $f (<$statstempdir/*.stat>) {
            unlink ($f =~ /(.*)/); # untaint
        }
        rmdir $statstempdir;
    }
}

# notify systemd when an autostarted cluster went away
if (not exists $ENV{'PG_CLUSTER_CONF_ROOT'} and $startconf and $startconf eq 'auto' and -d '/run/systemd/system') {
    if ($> == 0) {
        system 'systemctl daemon-reload';
    } elsif (-t 1) {
        print "Warning: systemd was not informed about the removed cluster yet. Operations like \"service postgresql start\" might fail. To fix, run:\n";
        print "  sudo systemctl daemon-reload\n";
    }
}

# notify apt about the new cluster
if (not exists $ENV{'PG_CLUSTER_CONF_ROOT'} and $> == 0) {
    system "/usr/share/postgresql-common/pg_updateaptconfig";
}

exit 0;

__END__

=head1 NAME

pg_dropcluster - completely delete a PostgreSQL cluster

=head1 SYNOPSIS

B<pg_dropcluster> [B<--stop>] I<cluster-version> I<cluster-name>

=head1 DESCRIPTION

This program removes all files that belong to a given PostgreSQL cluster; that
includes the data, wal, and tablespace directories, the log file, and all configuration files that
were created by L<pg_createcluster(1)>. If the configuration directory
(C</etc/postgresql/>I<version>C</>I<cluster>) is empty after this, it is
removed as well.
An empty socket directory other than B</var/run/postgresql> or B</tmp> is
also removed.

Usually a cluster which still has a running server attached will not be
deleted. To override this, the B<--stop> option forces a server shutdown
before the files are removed.

=head1 SEE ALSO

L<pg_createcluster(1)>, L<pg_ctlcluster(1)>

=head1 AUTHOR

Martin Pitt L<E<lt>mpitt@debian.orgE<gt>>