#!/usr/bin/perl -w
# Call a PostgreSQL client program with the version, cluster and default
# database specified in ~/.postgresqlrc or
# /etc/postgresql-common/user_clusters.
#
# (C) 2005-2009 Martin Pitt <mpitt@debian.org>
# (C) 2013 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 POSIX;

use lib '/usr/share/postgresql-common';
use PgCommon;

my ($version, $cluster, $db, $port, $host);

$host = $ENV{'PGHOST'};

# Check for PGCLUSTER in %ENV
if (defined $ENV{'PGCLUSTER'}) {
    ($version, $cluster) = split ('/', $ENV{'PGCLUSTER'}, 2);
    error 'Invalid version specified with $PGCLUSTER' unless version_exists $version;
    error 'No cluster specified with $PGCLUSTER' unless $cluster;
}

# Check for --cluster argument and filter it out, and check if --port is specified
my $port_specified = exists $ENV{'PGPORT'};
for (my $i = 0; $i <= $#ARGV; ++$i) {
    last if $ARGV[$i] eq '--';

    if ($ARGV[$i] eq '--cluster') {
        error '--cluster option needs an argument (<version>/<cluster>)' if ($i >= $#ARGV);

        ($version, $cluster) = split ('/', $ARGV[$i+1], 2);
	$host = undef; # --cluster overrides $PGHOST env var
        error 'Invalid version specified with --cluster' unless version_exists $version;
        error 'No cluster specified with --cluster' unless $cluster;

        splice @ARGV, $i, 2;
        last;
    }

    $port_specified = 1 if $ARGV[$i] =~ /^--port\b/ || $ARGV[$i] =~ /^-\w*p\w*\d*$/;
    $host = '.from.commandline' if $ARGV[$i] =~ /^--host\b/ || $ARGV[$i] =~ /^-\w*h\w*$/;
}

# Determine $version, $cluster, $db, $port from map files
($version, $cluster, $db) = user_cluster_map() unless $cluster;

# check if we have a network cluster
if (!$host && $cluster && !cluster_exists $version, $cluster) {
    if ($cluster =~ /^(\S+):(\d*)$/) {
	$host = $1;
	$port = $2 || 5432;
    } else {
	error 'Specified cluster does not exist locally and does not specify a remote cluster';
    }
}

if (!$host && $cluster) {
    $port = get_cluster_port($version, $cluster);

    unless ($ENV{'PGHOST'}) {
        # default to cluster specific Unix socket directory
        $ENV{'PGHOST'} = get_cluster_socketdir $version, $cluster;
    }
}

$ENV{'PGSYSCONFDIR'} = '/etc/postgresql-common' if !$ENV{'PGSYSCONFDIR'};
$ENV{'PGPORT'} = $port if $port && !$ENV{'PGPORT'};
$ENV{'PGDATABASE'} = $db if $db && !$ENV{'PGDATABASE'};
$ENV{'PGHOST'} = $host if $host && $host ne '.from.commandline';

# if we only have a port, but no version here, use the latest version
# TODO: this could be improved by better argument parsing and mapping back the
# port to a cluster version/name
if (!$version and $port_specified) {
    $version = get_newest_version;
}

unless ($version) {
    if (get_versions) {
	error 'No existing local cluster is suitable as a default target. Please see man pg_wrapper(1) how to specify one.';
    } else {
	error 'You must install at least one postgresql-client-<version> package.';
    }
}

error 'Invalid PostgreSQL cluster version' unless -d "/usr/lib/postgresql/$version";
my $cmdname = (split '/', $0)[-1];
my $cmd;

# for psql we always want the latest version, as this is backwards compatible
# to every major version that that we support
if ($cmdname =~ /^(psql|pg_isready)$/) {
    $cmd = get_program_path ($cmdname, get_newest_version);
} else {
    $cmd = get_program_path ($cmdname, $version);
}

# libreadline is a lot better than libedit, so prefer that
if ($cmdname eq 'psql') {
    my @readlines;
    # non-multiarch path
    @readlines = sort(</lib/libreadline.so.?>);

    unless (@readlines) {
	# get multiarch dir for our architecture
	if (open PS, '-|', '/usr/bin/ldd', $cmd) {
	    my $out;
	    read PS, $out, 10000;
	    close PS;
	    if ($out =~ m!/libreadline.so!) {
		# already linked against libreadline
		@readlines = ();
	    }
	    else
	    {
		my ($lib_path) = $out =~ m!(/lib/.*)/libedit.so!;

		@readlines = sort(<$lib_path/libreadline.so.?>);
	    }
	}
    }

    if (@readlines) {
	$ENV{'LD_PRELOAD'} = ($ENV{'LD_PRELOAD'} or '') . ':' . $readlines[-1];
    }
}

error "pg_wrapper: $cmdname was not found in /usr/lib/postgresql/$version/bin" unless $cmd;
unshift @ARGV, $cmd;
exec @ARGV;

__END__

=head1 NAME

pg_wrapper - wrapper for PostgreSQL client commands

=head1 SYNOPSIS

I<client-program> [B<--cluster> I<version>/I<cluster>] [...]

(I<client-program>: B<psql>, B<createdb>, B<dropuser>, and all other client
programs installed in C</usr/lib/postgresql/>I<version>C</bin>).

=head1 DESCRIPTION

This program is run only as a link to names which correspond to PostgreSQL
programs in C</usr/lib/postgresql/>I<version>C</bin>. It determines the
configured cluster and database for the user and calls the appropriate version
of the desired program to connect to that cluster and database, supplying any
specified options to that command.

The target cluster is selected by the following means, in descending order of
precedence:

=over

=item 1.

explicit specification with the B<--host> option

=item 2.

explicit specification with the B<--cluster> option

=item 3.

if the B<PGHOST> environment variable is set, no further cluster selection is
performed. The default PostgreSQL version and port number (from the command
line, the environment variable B<PGPORT>, or default 5432) will be used.

=item 4.

explicit specification with the B<PGCLUSTER> environment variable

=item 5.

matching entry in C<~/.postgresqlrc> (see L<postgresqlrc(5)>), if that
file exists

=item 6.

matching entry in C</etc/postgresql-common/user_clusters> (see
L<user_clusters(5)>), if that file exists

=item 7.

If only one local cluster exists, that one will be selected.

=item 8.

If several local clusters exist, the one listening on the default port 5432
will be selected.

=back

If none of these rules match, B<pg_wrapper> aborts with an error.

For B<psql> and B<pg_isready>, B<pg_wrapper> will always use the binary from
the newest PostgreSQL version installed, as these are downwards compatible.

=head1 OPTIONS

=over

=item B<--cluster> I<version>B</>I<cluster>

I<cluster> is either the name of a local cluster, or takes the form
I<host>:I<port> for a remote cluster. If I<port> is left empty (i. e. you just
specify I<host:>), it defaults to 5432.

=back

=head1 ENVIRONMENT

=over

=item B<PGCLUSTER>

If C<$PGCLUSTER> is set, its value (of the form I<version>/I<cluster>)
specifies the desired cluster, similar to the B<--cluster> option. However, if
B<--cluster> is specified, it overrides the value of C<$PGCLUSTER>.

=item B<PG_CLUSTER_CONF_ROOT>

This specifies an alternative base directory for cluster configurations. This
is usually C</etc/postgresql/>, but for testing/development purposes you can
change this to point to e. g. your home directory, so that you can use the
postgresql-common tools without root privileges.

=item B<PGSYSCONFDIR>

This is the location of PostgreSQL's and postgresql-common's global
configuration (e. g. C<pg_service.conf>, L<user_clusters(5)>). The default is
C</etc/postgresql-common/>.

=back

=head1 FILES

=over

=item C</etc/postgresql-common/user_clusters>

stores the default cluster and database for users and groups as set by
the administrators. 

=item C<$HOME/.postgresqlrc>

stores defaults set by the user himself.

=back

=head1 SEE ALSO

L<user_clusters(5)>, L<postgresqlrc(5)>

=head1 AUTHOR

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