#!/usr/bin/perl -wT

# Rename a PostgreSQL cluster
#
# (C) 2014-2015 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 PgCommon;
use Getopt::Long;
use POSIX;

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

if (@ARGV != 3) {
    print "Usage: $0 [OPTIONS] <version> <old cluster name> <new cluster name>\n";
    exit 1;
}

my ($version) = $ARGV[0] =~ /^(\d+\.\d+)$/;
my ($oldcluster) = $ARGV[1] =~ /^([-.\w]+)$/;
my ($newcluster) = $ARGV[2] =~ /^([-.\w]+)$/;
if ($newcluster =~ /-/ and -t 1) {
    print "Warning: cluster names containing dashes (-) will cause problems when running from systemd. Continuing anyway\n";
}

error "Old and new name must be different"
    if ($oldcluster eq $newcluster);
error "specified cluster $version $oldcluster does not exist"
    unless (cluster_exists $version, $oldcluster);
error "target cluster $version $newcluster already exists"
    if (cluster_exists $version, $newcluster);
my %info = cluster_info ($version, $oldcluster);

# stopping old cluster, so that we notice early when there are still
# connections
if ($info{'running'}) {
    print "Stopping cluster $version $oldcluster ...\n";
    my @argv = ('pg_ctlcluster', $version, $oldcluster, 'stop', '--');
    push @argv, ('-t', '5') if $version >= '8.4';
    error "Could not stop cluster" if system @argv;
}

# Arguments: <string>, <from>, <to>
sub strrepl {
    my ($s, $f, $t) = @_;
    $s =~ s/\b\Q$f\E\b/$t/g;
    return $s;
}

# rename config directory
my $olddir = "$PgCommon::confroot/$version/$oldcluster";
my $newdir = "$PgCommon::confroot/$version/$newcluster";
rename $olddir, $newdir or error "Could not rename config directory $olddir: $!";

# adapt paths to configuration files
my %c = read_cluster_conf_file $version, $newcluster, 'postgresql.conf';
if ($c{hba_file}) {
    PgCommon::set_conf_value $version, $newcluster, 'postgresql.conf', 'hba_file',
        strrepl($c{hba_file}, $oldcluster, $newcluster);
}
if ($c{ident_file}) {
    PgCommon::set_conf_value $version, $newcluster, 'postgresql.conf', 'ident_file',
        strrepl($c{ident_file}, $oldcluster, $newcluster);
}
if ($c{external_pid_file}) {
    PgCommon::set_conf_value $version, $newcluster, 'postgresql.conf', 'external_pid_file',
        strrepl($c{external_pid_file}, $oldcluster, $newcluster);
}

# rename data directory
if ($info{pgdata}) {
    my $newpgdata = strrepl ($info{pgdata}, $oldcluster, $newcluster);
    if ($info{pgdata} ne $newpgdata) {
        rename $info{pgdata}, $newpgdata or
            error "Could not rename data directory $info{pgdata}: $!";
        PgCommon::set_conf_value $version, $newcluster, 'postgresql.conf',
            'data_directory', $newpgdata;
    }
}

# rename stats_temp_directory
if ($info{statstempdir}) {
    my $newstatstempdir = strrepl ($info{statstempdir}, $oldcluster, $newcluster);
    if ($info{statstempdir} ne $newstatstempdir) {
        PgCommon::set_conf_value $version, $newcluster, 'postgresql.conf',
            'stats_temp_directory', $newstatstempdir;
        if (-d $info{statstempdir}) {
            rename $info{statstempdir}, $newstatstempdir or
                error "Could not rename stats temp directory $info{statstempdir}: $!";
        }
    }
}

# rename old log files
my $logdir = "/var/log/postgresql";
if (opendir LOG, $logdir) {
    while (my $logfile = readdir LOG) {
        next unless $logfile =~ /^(\Qpostgresql-$version-$oldcluster.log\E.*)/;
        $logfile = $1; # untaint
        my $f = strrepl ($logfile, $oldcluster, $newcluster);
        rename "$logdir/$logfile", "$logdir/$f" or error "rename $logdir/$logfile: $!";
    }
    closedir LOG;
}

# start cluster if it was running before
if ($info{'running'}) {
    print "Starting cluster $version $newcluster ...\n";
    my @argv = ('pg_ctlcluster', $version, $newcluster, 'start');
    error "Could not start cluster" if system @argv;
}

__END__

=head1 NAME

pg_renamecluster - rename a PostgreSQL cluster

=head1 SYNOPSIS

B<pg_renamecluster> I<version> I<oldname> I<newname>

=head1 DESCRIPTION

B<pg_renamecluster> changes the name of a PostgreSQL cluster, i. e. the name of
the config directory in /etc/postgresql/I<version>/ along with the data
directory in /var/lib/postgresql/I<version>/.  Existing log files in
/var/log/postgresql/ are also renamed.  The cluster is stopped and started for
the operation.

The following B<postgresql.conf> config options are updated to refer to the
changed path names: B<data_directory>, B<hba_file>, B<ident_file>,
B<external_pid_file>, B<stats_temp_directory>.

Cluster names are a Debian convention, the name is not explicitly known to the
cluster itself.  From the PostgreSQL viewpoint, the name is merely a substring
of various path names.

=head1 OPTIONS

None.

=head1 SEE ALSO

L<pg_createcluster(8)>, L<pg_dropcluster(8)>, L<pg_lsclusters(1)>, L<pg_wrapper(1)>

=head1 AUTHOR

Christoph Berg L<E<lt>myon@debian.orgE<gt>>