path: root/urpm/media.pm

package urpm::media;

# $Id$

use urpm 'file_from_local_url';
use urpm::msg;
use urpm::util;
use urpm::removable;
use urpm::lock;
use MDV::Distribconf;


our @PER_MEDIA_OPT = qw(
    downloader
    hdlist
    ignore
    key-ids
    list
    media_info_dir
    name
    noreconfigure
    priority-upgrade
    removable
    static
    synthesis
    update
    url
    verify-rpm
    virtual
    with_hdlist
);

sub only_media_opts {
    my ($m) = @_;
    my %m = map { $_ => $m->{$_} } grep { defined $m->{$_} } @PER_MEDIA_OPT;
    \%m;
}

sub read_private_netrc {
    my ($urpm) = @_;

    my @words = split(/\s+/, scalar cat_($urpm->{private_netrc}));
    my @l;
    my $e;
    while (@words) {
	my $keyword = shift @words;
	if ($keyword eq 'machine') {
	    push @l, $e = { machine => shift(@words) };
	} elsif ($keyword eq 'default') {
	    push @l, $e = { default => '' };
	} elsif ($keyword eq 'login' || $keyword eq 'password' || $keyword eq 'account') {
	    $e->{$keyword} = shift(@words);
	} else {
	    $urpm->{error}("unknown netrc command $keyword");
	}
    }
    @l;
}

sub read_config_add_passwords {
    my ($urpm, $config) = @_;

    my @netrc = read_private_netrc($urpm) or return;
    foreach (@{$config->{media}}) {
	my $u = urpm::download::parse_url_with_login($_->{url}) or next;
	if (my ($e) = grep { ($_->{default} || $_->{machine} eq $u->{machine}) && $_->{login} eq $u->{login} } @netrc) {
	    $_->{url} = sprintf('%s://%s:%s@%s%s', $u->{proto}, $u->{login}, $e->{password}, $u->{machine}, $u->{dir});
	} else {
	    $urpm->{log}("no password found for $u->{login}@$u->{machine}");
	}
    }
}

sub remove_passwords_and_write_private_netrc {
    my ($urpm, $config) = @_;

    my @l;
    foreach (@{$config->{media}}) {
	my $u = urpm::download::parse_url_with_login($_->{url}) or next;
	#- check whether a password is visible
	$u->{password} or next;

	push @l, $u;
	$_->{url} = sprintf('%s://%s@%s%s', $u->{proto}, $u->{login}, $u->{machine}, $u->{dir});
    }
    {
	my $fh = urpm::sys::open_safe($urpm, '>', $urpm->{private_netrc}) or return;
	foreach my $u (@l) {
	    printf $fh "machine %s login %s password %s\n", $u->{machine}, $u->{login}, $u->{password};
	}
    }
    chmod 0600, $urpm->{private_netrc};
}

#- handle deprecated way of saving passwords
sub recover_url_from_list {
    my ($urpm, $medium) = @_;

    #- /./ is end of url marker in list file (typically generated by a
    #- find . -name "*.rpm" > list
    #- for exportable list file.
    if (my @probe = map { m!^(.*)/\./! || m!^(.*)/[^/]*$! } cat_(statedir_list($urpm, $medium))) {
	$urpm->{log}("recovering url from " . statedir_list($urpm, $medium));
	($medium->{url}) = sort { length($a) <=> length($b) } @probe;
	$urpm->{modified} = 1; #- ensure urpmi.cfg is handled using only partially hidden url + netrc, since file list won't be generated anymore
    }
}

#- Loads /etc/urpmi/urpmi.cfg and performs basic checks.
#- Does not handle old format: <name> <url> [with <path_hdlist>]
#- options :
#-    - nocheck_access : don't check presence of hdlist and other files
sub read_config {
    my ($urpm, $b_nocheck_access, $b_auto_correct) = @_;
    return if $urpm->{media}; #- media already loaded
    $urpm->{media} = [];
    my $config = urpm::cfg::load_config($urpm->{config})
	or $urpm->{fatal}(6, $urpm::cfg::err);

    #- global options
    if (my $global = $config->{global}) {
	foreach my $opt (keys %$global) {
	    if (defined $global->{$opt} && !exists $urpm->{options}{$opt}) {
		$urpm->{options}{$opt} = $global->{$opt};
	    }
	}
    }

    #- per-media options

    read_config_add_passwords($urpm, $config);

    foreach my $m (@{$config->{media}}) {
	my $medium = only_media_opts($m);

	if (!$medium->{url}) {
	    #- recover the url the old deprecated way...
	    #- only useful for migration, new urpmi.cfg will use netrc
	    recover_url_from_list($urpm, $medium);
	    $medium->{url} or $urpm->{error}("unable to find url in list file $medium->{name}, medium ignored");
	}

	add_existing_medium($urpm, $medium, $b_nocheck_access, $b_auto_correct);
    }

    eval { require urpm::ldap; urpm::ldap::load_ldap_media($urpm) };

    #- load default values
    foreach (qw(post-clean verify-rpm)) {
	exists $urpm->{options}{$_} or $urpm->{options}{$_} = 1;
    }

    #- read MD5 sums (not in urpmi.cfg but in a separate file)
    foreach (@{$urpm->{media}}) {
	if (my $md5sum = urpm::md5sum::from_MD5SUM("$urpm->{statedir}/MD5SUM", statedir_hdlist_or_synthesis($urpm, $_, 's'))) {
	    $_->{md5sum} = $md5sum;
	}
    }

    #- remember global options for write_config
    $urpm->{global_config} = $config->{global};
}

#- if invalid, set {ignore}
sub check_existing_medium {
    my ($urpm, $medium, $b_nocheck_access, $b_auto_correct) = @_;

    if ($medium->{virtual}) {
	#- a virtual medium needs to have an url available without using a list file.
	if ($medium->{list}) {
	    $medium->{ignore} = 1;
	    $urpm->{error}(N("virtual medium \"%s\" should not have defined hdlist or list file, medium ignored",
			     $medium->{name}));
	} elsif (!$medium->{url}) {
	    $medium->{ignore} = 1;
	    $urpm->{error}(N("virtual medium \"%s\" should have a clear url, medium ignored",
			     $medium->{name}));
	}
    } else {
	if ($medium->{hdlist}) {
	    #- is this check really needed? keeping just in case
	    $medium->{hdlist} ne 'list' && $medium->{hdlist} ne 'pubkey' or
	      $medium->{ignore} = 1,
		$urpm->{error}(N("invalid hdlist name"));
	}
	if (!$medium->{ignore} && !$medium->{list}) {
	    unless (defined $medium->{url}) {
		$medium->{list} = "list.$medium->{name}";
		unless (-e statedir_list($urpm, $medium)) {
		    $medium->{ignore} = 1,
		      $urpm->{error}(N("unable to find list file for \"%s\", medium ignored", $medium->{name}));
		}
	    }
	}
    }


    #- check the presence of hdlist and list files if necessary.
    if (!$b_nocheck_access && !$medium->{ignore}) {
	if ($medium->{virtual} && -r hdlist_or_synthesis_for_virtual_medium($medium, 's')) {}
	elsif (-r statedir_hdlist_or_synthesis($urpm, $medium, 's')) {}
	elsif (-r statedir_hdlist($urpm, $medium)) {
	    $b_auto_correct and delete $urpm->{synthesis};
	    $urpm->{error}(N("\"synthesis\" should not be set (medium \"%s\")", $medium->{name}));
	} elsif (-r statedir_synthesis($urpm, $medium)) {
	    $medium->{synthesis} = 1;
	    $urpm->{error}(N("\"synthesis\" should be set (medium \"%s\")", $medium->{name}));
	} else {
	    $medium->{ignore} = 1;
	    $urpm->{error}(N("unable to access hdlist file of \"%s\", medium ignored", $medium->{name}));
	}
	if ($medium->{list} && -r statedir_list($urpm, $medium)) {}
	elsif ($medium->{url}) { 
	    if ($medium->{list}) {
		$b_auto_correct and delete $medium->{list}; #- remove buggy list
		$urpm->{error}(N("unable to access list file of \"%s\"", $medium->{name}));
	    }
	} else {
	    $medium->{ignore} = 1;
	    $urpm->{error}(N("unable to access list file of \"%s\", medium ignored", $medium->{name}));
	}
    }

    foreach my $field ('hdlist', 'list') {
	$medium->{$field} && $medium->{$field} ne '1' or next;
	if (grep { $_->{$field} eq $medium->{$field} } @{$urpm->{media}}) {
	    $medium->{ignore} = 1;
	    $urpm->{error}(
		$field eq 'hdlist'
		  ? N("medium \"%s\" trying to use an already used hdlist, medium ignored", $medium->{name})
		  : N("medium \"%s\" trying to use an already used list, medium ignored",   $medium->{name}));
	}
    }
}

sub _migrate__with_hdlist {
    my ($medium) = @_;

    grep { $_ eq '..' } split('/', $medium->{with_hdlist}) and return;

    #- try to migrate to media_info_dir
    my $b = basename($medium->{with_hdlist});
    if ($b eq ($medium->{synthesis} ? 'synthesis.hdlist.cz' : 'hdlist.cz')) {
	$medium->{media_info_dir} = dirname(delete $medium->{with_hdlist});
	1;
    } else {
	0;
    }
}

#- probe medium to be used, take old medium into account too.
sub add_existing_medium {
    my ($urpm, $medium, $b_nocheck_access, $b_auto_correct) = @_;

    if (name2medium($urpm, $medium->{name})) {
	$urpm->{error}(N("trying to override existing medium \"%s\", skipping", $medium->{name}));
	return;
    }

    if ($medium->{with_hdlist} && _migrate__with_hdlist($medium)) {
	$urpm->{modified} = 1;
    }

    check_existing_medium($urpm, $medium, $b_nocheck_access, $b_auto_correct);

    #- probe removable device.
    probe_removable_device($urpm, $medium);

    #- clear URLs for trailing /es.
    $medium->{url} and $medium->{url} =~ s|(.*?)/*$|$1|;

    push @{$urpm->{media}}, $medium;
}

sub _set_synthesis_or_hdlist {
    my ($medium, $want_synthesis) = @_;

    $medium->{$want_synthesis ? 'synthesis' : 'hdlist'} = 1;
}

sub file_from_file_url {
    my ($url) = @_;
    $url =~ m!^(?:file:/)?(/.*)! && $1;
}

sub _synthesis_or_not {
    my ($medium, $prefer_synthesis) = @_;
    $medium->{synthesis} || !$medium->{hdlist} && $prefer_synthesis;
}
sub _url_with_hdlist_basename {
    my ($medium, $prefer_synthesis) = @_;

    $medium->{with_hdlist}
      ? basename($medium->{with_hdlist})
      : _synthesis_or_not($medium, $prefer_synthesis) ? 'synthesis.hdlist.cz' : 'hdlist.cz';
}
sub _hdlist_dir {
    my ($medium) = @_;
    my $base = file_from_local_url($medium->{url}) || $medium->{url};
    $medium->{with_hdlist}
      ? reduce_pathname("$base/$medium->{with_hdlist}/..")
      : $medium->{media_info_dir} && reduce_pathname("$base/$medium->{media_info_dir}");
}
sub _url_with_hdlist {
    my ($medium, $prefer_synthesis) = @_;

    my $base = file_from_local_url($medium->{url}) || $medium->{url};
    $medium->{with_hdlist}
      ? reduce_pathname("$base/$medium->{with_hdlist}")
      : _hdlist_dir($medium) . "/" . _url_with_hdlist_basename($medium, $prefer_synthesis);

}
sub hdlist_or_synthesis_for_virtual_medium {
    my ($medium, $prefer_synthesis) = @_;
    file_from_file_url($medium->{url}) && _url_with_hdlist($medium, $prefer_synthesis);
}

sub _hdlist {
    my ($medium) = @_;
    $medium->{hdlist} && $medium->{hdlist} ne '1'
      ? $medium->{hdlist} 
      : $medium->{name} && "hdlist.$medium->{name}.cz";
}

sub statedir_hdlist_or_synthesis {
    my ($urpm, $medium, $prefer_synthesis) = @_;
    "$urpm->{statedir}/" . (_synthesis_or_not($medium, $prefer_synthesis) ? 'synthesis.' : '') . _hdlist($medium);
}
sub statedir_hdlist {
    my ($urpm, $medium) = @_;
    "$urpm->{statedir}/" . _hdlist($medium);
}
sub statedir_synthesis {
    my ($urpm, $medium) = @_;
    "$urpm->{statedir}/synthesis." . _hdlist($medium);
}
sub statedir_list {
    my ($urpm, $medium) = @_;
    $medium->{list} && "$urpm->{statedir}/$medium->{list}";
}
sub statedir_descriptions {
    my ($urpm, $medium) = @_;
    $medium->{name} && "$urpm->{statedir}/descriptions.$medium->{name}";
}
sub statedir_names {
    my ($urpm, $medium) = @_;
    $medium->{name} && "$urpm->{statedir}/names.$medium->{name}";
}
sub cachedir_with_hdlist {
    my ($urpm, $medium, $prefer_synthesis) = @_;
    _url_with_hdlist($medium, $prefer_synthesis) && "$urpm->{cachedir}/partial/" . _url_with_hdlist_basename($medium, $prefer_synthesis);
}
sub cachedir_list {
    my ($urpm, $medium) = @_;
    $medium->{list} && "$urpm->{cachedir}/partial/$medium->{list}";
}
sub any_hdlist {
    my ($urpm, $medium) = @_;
    my $f = statedir_hdlist($urpm, $medium);
    if ($medium->{virtual} && !$medium->{synthesis}
	  || !-e $f && file_from_local_url($medium->{url}) && !$medium->{synthesis} && !$medium->{hdlist}) {
	$f = _url_with_hdlist($medium, '');
    }
    -e $f && $f;
}
sub any_synthesis {
    my ($urpm, $medium) = @_;
    my $f = $medium->{virtual} && !$medium->{hdlist}
      ? _url_with_hdlist($medium, 's')
      : statedir_synthesis($urpm, $medium);
    -e $f && $f;
}

sub name2medium {
    my ($urpm, $name) = @_;
    my ($medium) = grep { $_->{name} eq $name } @{$urpm->{media}};
    $medium;
}

#- probe device associated with a removable device.
sub probe_removable_device {
    my ($urpm, $medium) = @_;

    if ($medium->{url} && $medium->{url} =~ /^removable/) {
	#- try to find device name in url scheme, this is deprecated, use medium option "removable" instead
	if ($medium->{url} =~ /^removable_?([^_:]*)/) {
	    $medium->{removable} ||= $1 && "/dev/$1";
	}
    } else {
	delete $medium->{removable};
	return;
    }

    #- try to find device to open/close for removable medium.
    if (my $dir = file_from_local_url($medium->{url})) {
	my %infos;
	my @mntpoints = urpm::sys::find_mntpoints($dir, \%infos);
	if (@mntpoints > 1) {	#- return value is suitable for an hash.
	    $urpm->{log}(N("too many mount points for removable medium \"%s\"", $medium->{name}));
	    $urpm->{log}(N("taking removable device as \"%s\"", join ',', map { $infos{$_}{device} } @mntpoints));
	}
	if (urpm::removable::is_iso($medium->{removable})) {
	    $urpm->{log}(N("Medium \"%s\" is an ISO image, will be mounted on-the-fly", $medium->{name}));
	} elsif (@mntpoints) {
	    if ($medium->{removable} && $medium->{removable} ne $infos{$mntpoints[-1]}{device}) {
		$urpm->{log}(N("using different removable device [%s] for \"%s\"",
			       $infos{$mntpoints[-1]}{device}, $medium->{name}));
	    }
	    $medium->{removable} = $infos{$mntpoints[-1]}{device};
	} else {
	    $urpm->{error}(N("unable to retrieve pathname for removable medium \"%s\"", $medium->{name}));
	}
    } else {
	$urpm->{error}(N("unable to retrieve pathname for removable medium \"%s\"", $medium->{name}));
    }
}


sub write_MD5SUM {
    my ($urpm) = @_;

    #- write MD5SUM file
    my $fh = urpm::sys::open_safe($urpm, '>', "$urpm->{statedir}/MD5SUM") or return 0;
    foreach my $medium (grep { $_->{md5sum} } @{$urpm->{media}}) {
	my $s = basename(statedir_hdlist_or_synthesis($urpm, $medium, 's'));
	print $fh "$medium->{md5sum}  $s\n";
    }

    $urpm->{log}(N("wrote %s", "$urpm->{statedir}/MD5SUM"));

    delete $urpm->{md5sum_modified};
}

#- Writes the urpmi.cfg file.
sub write_urpmi_cfg {
    my ($urpm) = @_;

    #- avoid trashing exiting configuration if it wasn't loaded
    $urpm->{media} or return;

    my $config = {
	#- global config options found in the config file, without the ones
	#- set from the command-line
	global => $urpm->{global_config},
	media => [ map { only_media_opts($_) } grep { !$_->{external} } @{$urpm->{media}} ],
    };
    remove_passwords_and_write_private_netrc($urpm, $config);

    urpm::cfg::dump_config($urpm->{config}, $config)
	or $urpm->{fatal}(6, N("unable to write config file [%s]", $urpm->{config}));

    $urpm->{log}(N("wrote config file [%s]", $urpm->{config}));

    #- everything should be synced now.
    delete $urpm->{modified};
}

sub write_config {
    my ($urpm) = @_;

    write_urpmi_cfg($urpm);
    write_MD5SUM($urpm);
}

sub _tempignore {
    my ($medium, $ignore) = @_;
    $medium->{tempignore} = $medium->{ignore} = $ignore;
}

#- read urpmi.cfg file as well as necessary synthesis files
#- options :
#-	root (deprecated, set directly $urpm->{root})
#-	cmdline_skiplist
#-      nocheck_access (used by read_config)
#-
#-	callback (urpmf)
#-	need_hdlist (for urpmf: to be able to have info not available in synthesis)
#-	nodepslist (for urpmq: we don't need the hdlist/synthesis)
#-	no_skiplist (urpmf)
#-      no_second_pass (urpmf)
#-
#-	synthesis (use this synthesis file, and only this synthesis file)
#-
#-	parallel
#-	usedistrib (otherwise uses urpmi.cfg)
#-	  media
#-	  excludemedia
#-	  sortmedia
#-
#-	  update
#-	  searchmedia
sub configure {
    my ($urpm, %options) = @_;

    clean($urpm);

    $options{parallel} && $options{usedistrib} and $urpm->{fatal}(1, N("Can't use parallel mode with use-distrib mode"));

    if ($options{parallel}) {
	require urpm::parallel;
	urpm::parallel::configure($urpm, $options{parallel});

	if (!$options{media} && $urpm->{parallel_handler}{media}) {
	    $options{media} = $urpm->{parallel_handler}{media};
	    $urpm->{log}->(N("using associated media for parallel mode: %s", $options{media}));
	}
    } else {
	#- nb: can't have both parallel and root
	$urpm->{root} = $options{root} if $options{root};
    }

    if ($urpm->{root} && ! -c "$urpm->{root}/dev/null") {
	mkdir "$urpm->{root}/dev";
	system("/bin/cp", "-a", '/dev/null', "$urpm->{root}/dev");
    }

    if ($options{synthesis}) {
	if ($options{synthesis} ne 'none') {
	    #- synthesis take precedence over media, update options.
	    $options{media} || $options{excludemedia} || $options{sortmedia} || $options{update} || $options{usedistrib} || $options{parallel} and
	      $urpm->{fatal}(1, N("--synthesis cannot be used with --media, --excludemedia, --sortmedia, --update, --use-distrib or --parallel"));
	    $urpm->parse_synthesis($options{synthesis});
	    #- synthesis disables the split of transaction (too risky and not useful).
	    $urpm->{options}{'split-length'} = 0;
	}
    } else {
        if ($options{usedistrib}) {
            $urpm->{media} = [];
            add_distrib_media($urpm, "Virtual", $options{usedistrib}, %options, 'virtual' => 1);
        } else {
	    read_config($urpm, $options{nocheck_access}, 1);
	    if (!$options{media} && $urpm->{options}{'default-media'}) {
		$options{media} = $urpm->{options}{'default-media'};
	    }
        }
	if ($options{media}) {
	    delete $_->{modified} foreach @{$urpm->{media} || []};
	    select_media($urpm, split /,/, $options{media});
	    foreach (@{$urpm->{media} || []}) {
		_tempignore($_, !$_->{modified});
	    }
	}
	if ($options{searchmedia}) {
	   select_media($urpm, $options{searchmedia}); #- Ensure this media has been selected
	   if (my $medium = name2medium($urpm, $options{searchmedia})) {
	       _tempignore($medium, 0);
	       $medium->{searchmedia} = 1;
	   }
	}
	if ($options{excludemedia}) {
	    delete $_->{modified} foreach @{$urpm->{media} || []};
	    foreach (select_media_by_name($urpm, [ split /,/, $options{excludemedia} ])) {
		$_->{modified} = 1;
		#- this is only a local ignore that will not be saved.
		_tempignore($_, 1);
	    }
	}
	if ($options{sortmedia}) {
	    my @sorted_media = map { select_media_by_name($urpm, [$_]) } split(/,/, $options{sortmedia});
	    my @remaining = difference2($urpm->{media}, \@sorted_media);
	    $urpm->{media} = [ @sorted_media, @remaining ];
	}
	_parse_media($urpm, 0, \%options) if !$options{nodepslist};
    }
    #- determine package to withdraw (from skip.list file) only if something should be withdrawn.
    if (!$options{nodepslist}) {
	_compute_flags_for_skiplist($urpm, $options{cmdline_skiplist}) if !$options{no_skiplist};
	_compute_flags_for_instlist($urpm);
    }
}

sub _parse_media {
    my ($urpm, $is_second_pass, $options) = @_;

    my $need_second_pass;
    foreach (grep { !$_->{ignore} && (!$options->{update} || $_->{update}) } @{$urpm->{media} || []}) {
	our $currentmedia = $_; #- hack for urpmf
	delete @$_{qw(start end)};
	my $want_hdlist = $options->{need_hdlist} || $is_second_pass; 
	if (!$want_hdlist && 
	      _parse_synthesis($urpm, $_, any_synthesis($urpm, $_), $options->{callback})) {
	    #- cool
	} elsif (_parse_hdlist($urpm, $_, any_hdlist($urpm, $_), $options->{callback})) {
	    $need_second_pass = 1 if !$is_second_pass && !$options->{no_second_pass};
	} else {
	    $options->{need_hdlist}
	      and $urpm->{error}(N("Note: no hdlist for medium \"%s\", unable to return any result for it", $_->{name}));

	    _parse_synthesis($urpm, $_, any_synthesis($urpm, $_), $options->{callback});
	}
	unless ($_->{ignore}) {
	    _check_after_reading_hdlist_or_synthesis($urpm, $_);
	}
	unless ($_->{ignore}) {
	    if ($_->{searchmedia}) {
		($urpm->{searchmedia}{start}, $urpm->{searchmedia}{end}) = ($_->{start}, $_->{end});
		$urpm->{log}(N("Search start: %s end: %s",
			       $urpm->{searchmedia}{start}, $urpm->{searchmedia}{end}));
		delete $_->{searchmedia};
	    }
	}
    }

    if ($need_second_pass) {
	require URPM::Build;
	$urpm->{log}(N("performing second pass to compute dependencies\n"));
	$urpm->unresolved_provides_clean;
	_parse_media($urpm, 1, $options);
    }
}

sub _compute_flags_for_skiplist {
    my ($urpm, $cmdline_skiplist) = @_;
    my %uniq;
    $urpm->compute_flags(
	get_packages_list($urpm->{skiplist}, $cmdline_skiplist),
	skip => 1,
	callback => sub {
	    my ($urpm, $pkg) = @_;
	    $pkg->is_arch_compat && ! exists $uniq{$pkg->fullname} or return;
	    $uniq{$pkg->fullname} = undef;
	    $urpm->{log}(N("skipping package %s", scalar($pkg->fullname)));
	},
    );
}

sub _compute_flags_for_instlist {
    my ($urpm) = @_;

    my %uniq;
    $urpm->compute_flags(
	get_packages_list($urpm->{instlist}),
	disable_obsolete => 1,
	callback => sub {
	    my ($urpm, $pkg) = @_;
	    $pkg->is_arch_compat && ! exists $uniq{$pkg->fullname} or return;
	    $uniq{$pkg->fullname} = undef;
	    $urpm->{log}(N("would install instead of upgrade package %s", scalar($pkg->fullname)));
	},
    );

}

#- add a new medium, sync the config file accordingly.
#- returns the new medium's name. (might be different from the requested
#- name if index_name was specified)
#- options: ignore, index_name, nolock, synthesis, update, virtual
sub add_medium {
    my ($urpm, $name, $url, $with_hdlist, %options) = @_;

    #- make sure configuration has been read.
    $urpm->{media} or die "caller should have used ->read_config or ->configure first";

    #- if a medium with that name has already been found, we have to exit now
    if (defined $options{index_name}) {
	my ($i, $basename) = ($options{index_name}, $name);
	while (1) {
	    ++$i;
	    $name = $basename . ($i == 1 ? '' : $i);
	    last if !name2medium($urpm, $name);
	}
    } else {
	name2medium($urpm, $name) and $urpm->{fatal}(5, N("medium \"%s\" already exists", $name));
    }

    $url =~ s,/*$,,; #- clear URLs for trailing /es.

    #- creating the medium info.
    my $medium = { name => $name, 
		url => $url, 
		modified => !$options{ignore}, 
		downloader => $options{downloader}, 
		update => $options{update}, 
		ignore => $options{ignore},
		synthesis => $options{synthesis},
	    };
    if ($options{virtual}) {
	file_from_file_url($url) or $urpm->{fatal}(1, N("virtual medium needs to be local"));
	$medium->{virtual} = 1;
    } else {
	probe_removable_device($urpm, $medium);
    }

    if ($with_hdlist) {
	_set_synthesis_or_hdlist($medium, $with_hdlist =~ m!(?:^|/)synthesis\.!);
	$medium->{with_hdlist} = $with_hdlist;
	_migrate__with_hdlist($medium);
    }

    #- local media have priority, other are added at the end.
    my $inserted;
    my $ignore_text = $medium->{ignore} ? ' ' . N("(ignored by default)") : '';
    if (file_from_file_url($url)) {
	#- insert before first remote medium
	@{$urpm->{media}} = map {  
	    if (!file_from_file_url($_->{url}) && !$inserted) {
		$inserted = 1;
		$urpm->{info}(N("adding medium \"%s\" before remote medium \"%s\"", $name, $_->{name}) . $ignore_text);
		$medium, $_;
	    } else { $_ }
	} @{$urpm->{media}};
    }
    if (!$inserted) {
	$urpm->{info}(N("adding medium \"%s\"", $name) . $ignore_text);
	push @{$urpm->{media}}, $medium;
    }

    $urpm->{modified} = 1;

    $name;
}

#- add distribution media, according to url given.
#- returns the list of names of added media.
#- options :
#- - initial_number : when adding several numbered media, start with this number
#- - probe_with : force use of synthesis/hdlist/rpms instead of using both synthesis&hdlist
#- - ask_media : callback to know whether each media should be added
#- other options are passed to add_medium(): ignore, nolock, virtual
sub add_distrib_media {
    my ($urpm, $name, $url, %options) = @_;

    #- make sure configuration has been read.
    $urpm->{media} or die "caller should have used ->read_config or ->configure first";

    my $distribconf;

    if (my $dir = file_from_local_url($url)) {
	urpm::removable::try_mounting($urpm, $dir)
	    or $urpm->{error}(N("unable to mount the distribution medium")), return ();
	$distribconf = MDV::Distribconf->new($dir, undef);
	$distribconf->load
	    or $urpm->{error}(N("this location doesn't seem to contain any distribution")), return ();
    } else {
	unlink "$urpm->{cachedir}/partial/media.cfg";

	$distribconf = MDV::Distribconf->new($url, undef);
	$distribconf->settree('mandriva');

	$urpm->{log}(N("retrieving media.cfg file..."));
	if (urpm::download::sync($urpm, undef,
				 [ reduce_pathname($distribconf->getfullpath(undef, 'infodir') . '/media.cfg') ],
				 quiet => 1)) {
	    $distribconf->parse_mediacfg("$urpm->{cachedir}/partial/media.cfg")
		or $urpm->{error}(N("unable to parse media.cfg")), return();
	} else {
	    $urpm->{error}(N("...retrieving failed: %s", $@));
	    $urpm->{error}(N("unable to access the distribution medium (no media.cfg file found)"));
	    return ();
	}
    }

    #- cosmetic update of name if it contains spaces.
    $name =~ /\s/ and $name .= ' ';

    my @newnames;
    #- at this point, we have found a media.cfg file, so parse it
    #- and create all necessary media according to it.
    my $medium_index = $options{initial_number} || 1;

    foreach my $media ($distribconf->listmedia) {
        my $media_name = $distribconf->getvalue($media, 'name') || '';

        my $add_by_default = !$distribconf->getvalue($media, 'noauto');
        if ($options{ask_media}) {
            $options{ask_media}->($media_name, $add_by_default) or next;
        } else {
	    my $simple_rpms = !$distribconf->getvalue($media, 'debug_for') && 
	                      !$distribconf->getvalue($media, 'rpms');
	    $add_by_default || $simple_rpms or next;
	}

	my $is_update_media = $distribconf->getvalue($media, 'updates_for');

	push @newnames, add_medium($urpm,
	    $name ? "$media_name ($name$medium_index)" : $media_name,
	    reduce_pathname($distribconf->getfullpath($media, 'path')),
	    offset_pathname(
		$url,
		$distribconf->getpath($media, 'path'),
	    ) . '/' . $distribconf->getpath($media, $options{probe_with} eq 'synthesis' ? 'synthesis' : 'hdlist'),
	    index_name => $name ? undef : 0,
	    $add_by_default ? () : (ignore => 1),
	    %options,
	    # the following override %options
	    update => $is_update_media ? 1 : undef,
	);
	++$medium_index;
    }
    return @newnames;
}

#- deprecated, use select_media_by_name instead
sub select_media {
    my $urpm = shift;
    my $options = {};
    if (ref $_[0]) { $options = shift }
    foreach (select_media_by_name($urpm, [ @_ ], $options->{strict_match})) {
	#- select medium by setting the modified flag, do not check ignore.
	$_->{modified} = 1;
    }
}

sub select_media_by_name {
    my ($urpm, $names, $b_strict_match) = @_;

    my %wanted = map { $_ => 1 } @$names;

    #- first the exact matches
    my @l = grep { delete $wanted{$_->{name}} } @{$urpm->{media}};

    #- check if some arguments don't correspond to the medium name.
    #- in such case, try to find the unique medium (or list candidate
    #- media found).
    foreach (keys %wanted) {
	my $q = quotemeta;
	my (@found, @foundi);
	my $regex  = $b_strict_match ? qr/^$q$/  : qr/$q/;
	my $regexi = $b_strict_match ? qr/^$q$/i : qr/$q/i;
	foreach my $medium (@{$urpm->{media}}) {
	    $medium->{name} =~ $regex  and push @found, $medium;
	    $medium->{name} =~ $regexi and push @foundi, $medium;
	}
	@found = @foundi if !@found;

	if (@found == 0) {
	    $urpm->{error}(N("trying to select nonexistent medium \"%s\"", $_));
	} else {
	    if (@found > 1) {
		$urpm->{log}(N("selecting multiple media: %s", join(", ", map { qq("$_->{name}") } @found)));
	    }
	    #- changed behaviour to select all occurences by default.
	    push @l, @found;
	}
    }
    @l;
}

#- deprecated, use remove_media instead
sub remove_selected_media {
    my ($urpm) = @_;

    remove_media($urpm, [ grep { $_->{modified} } @{$urpm->{media}} ]);
}

sub remove_media {
    my ($urpm, $to_remove) = @_;

    foreach my $medium (@$to_remove) {
	$urpm->{info}(N("removing medium \"%s\"", $medium->{name}));

	#- mark to re-write configuration.
	$urpm->{modified} = 1;

	#- remove files associated with this medium.
	unlink grep { $_ } map { $_->($urpm, $medium) } \&statedir_hdlist, \&statedir_list, \&statedir_synthesis, \&statedir_descriptions, \&statedir_names;

	#- remove proxy settings for this media
	urpm::download::remove_proxy_media($medium->{name});
    }

    $urpm->{media} = [ difference2($urpm->{media}, $to_remove) ];
}

sub _probe_with_try_list {
    my ($urpm, $medium, $probe_with, $f) = @_;

    my $probe = sub {
	my ($synthesis, $media_info_dir) = @_;

	my $base = file_from_local_url($medium->{url}) || $medium->{url};
	my $url = reduce_pathname("$base/$media_info_dir") . '/' . ($synthesis ? 'synthesis.hdlist.cz' : 'hdlist.cz');
	$f->($url) or return;

	$urpm->{debug} and $urpm->{debug}("found hdlist/synthesis: $url");

	$medium->{media_info_dir} = $media_info_dir;
	if ($probe_with) {
	    _set_synthesis_or_hdlist($medium, $synthesis);
	}
	1;
    };


    my $want_synthesis = !$probe_with || $probe_with eq 'synthesis';
    my @media_info_dirs = ('media_info', '.');

    foreach my $media_info_dir (@media_info_dirs) {
	if ($probe->($want_synthesis, $media_info_dir)) {
	    return 1 if $probe_with;
	    last;
	}
    }
    if ($medium->{media_info_dir}) {
	#- try to have both synthesis and hdlist :-)
	if (file_from_file_url($medium->{url}) &&
	      !$probe->(!$want_synthesis, $medium->{media_info_dir})) {
	    #- sad, only one available.
	    _set_synthesis_or_hdlist($medium, $want_synthesis);
	}
	1;
    } else {
	foreach my $media_info_dir (@media_info_dirs) {
	    $probe->(!$want_synthesis, $media_info_dir)
	      and return 1;
	}
	'';
    }
}

sub may_reconfig_urpmi {
    my ($urpm, $medium) = @_;

    my $f;
    if (my $dir = file_from_local_url($medium->{url})) {
	$f = reduce_pathname("$dir/reconfig.urpmi");
    } else {
	unlink($f = "$urpm->{cachedir}/partial/reconfig.urpmi");
	urpm::download::sync($urpm, $medium, [ reduce_pathname("$medium->{url}/reconfig.urpmi") ], quiet => 1);
    }
    if (-s $f) {
	reconfig_urpmi($urpm, $f, $medium->{name});
    }
    unlink $f if !file_from_local_url($medium->{url});
}

#- read a reconfiguration file for urpmi, and reconfigure media accordingly
#- $rfile is the reconfiguration file (local), $name is the media name
#-
#- the format is similar to the RewriteRule of mod_rewrite, so:
#-    PATTERN REPLACEMENT [FLAG]
#- where FLAG can be L or N
#-
#- example of reconfig.urpmi:
#-    # this is an urpmi reconfiguration file
#-    /cooker /cooker/$ARCH
sub reconfig_urpmi {
    my ($urpm, $rfile, $name) = @_;
    -r $rfile or return;

    $urpm->{log}(N("reconfiguring urpmi for media \"%s\"", $name));

    my ($magic, @lines) = cat_($rfile);
    #- the first line of reconfig.urpmi must be magic, to be sure it's not an error file
    $magic =~ /^# this is an urpmi reconfiguration file/ or return undef;

    my @replacements;
    foreach (@lines) {
	chomp;
	s/^\s*//; s/#.*$//; s/\s*$//;
	$_ or next;
	my ($p, $r, $f) = split /\s+/, $_, 3;
	push @replacements, [ quotemeta $p, $r, $f || 1 ];
    }

    my $reconfigured = 0;
    my @reconfigurable = qw(url with_hdlist media_info_dir);

    my $medium = name2medium($urpm, $name) or return;
    my %orig = %$medium;

  URLS:
    foreach my $k (@reconfigurable) {
	foreach my $r (@replacements) {
	    if ($medium->{$k} =~ s/$r->[0]/$r->[1]/) {
		$reconfigured = 1;
		#- Flags stolen from mod_rewrite: L(ast), N(ext)
		if ($r->[2] =~ /L/) {
		    last;
		} elsif ($r->[2] =~ /N/) { #- dangerous option
		    redo URLS;
		}
	    }
	}
	#- check that the new url exists before committing changes (local mirrors)
	my $file = file_from_local_url($medium->{$k});
	if ($file && !-e $file) {
	    %$medium = %orig;
	    $reconfigured = 0;
	    $urpm->{log}(N("...reconfiguration failed"));
	    return;
	}
    }

    if ($reconfigured) {
	$urpm->{log}(N("reconfiguration done"));
	write_config($urpm);
    }
    $reconfigured;
}

sub _guess_hdlist_suffix {
    my ($url) = @_;
    $url =~ m!\bmedia/(\w+)/*\Z! && $1;
}

sub _hdlist_suffix {
    my ($medium) = @_;
    $medium->{with_hdlist} =~ /hdlist(.*?)(?:\.src)?\.cz$/ ? $1 : '';
}

sub _parse_hdlist_or_synthesis__when_not_modified {
    my ($urpm, $medium) = @_;

    delete @$medium{qw(start end)};

    _parse_synthesis($urpm, $medium, any_synthesis($urpm, $medium)) or
      _parse_hdlist($urpm, $medium, any_hdlist($urpm, $medium));

    _check_after_reading_hdlist_or_synthesis($urpm, $medium);
}

sub _parse_hdlist_or_synthesis__virtual {
    my ($urpm, $medium) = @_;

    delete $medium->{modified};
    $medium->{really_modified} = 1;
    $urpm->{md5sum_modified} = 1;

    _parse_hdlist_or_synthesis__when_not_modified($urpm, $medium);
}

#- names.<media_name> is used by external progs (namely for bash-completion)
sub generate_medium_names {
    my ($urpm, $medium) = @_;

    unlink statedir_names($urpm, $medium);

    if (my $fh = urpm::sys::open_safe($urpm, ">", statedir_names($urpm, $medium))) {
	foreach ($medium->{start} .. $medium->{end}) {
	    if (defined $urpm->{depslist}[$_]) {
		print $fh $urpm->{depslist}[$_]->name . "\n";
	    } else {
		$urpm->{error}(N("Error generating names file: dependency %d not found", $_));
	    }
	}
    } else {
	$urpm->{error}(N("Error generating names file: Can't write to file (%s)", $!));
    }
}


sub _read_existing_synthesis_and_hdlist_if_same_time_and_msize {
    my ($urpm, $medium) = @_;

    same_size_and_mtime(cachedir_with_hdlist($urpm, $medium, 's'),
			statedir_hdlist_or_synthesis($urpm, $medium, 's')) or return;

    _read_existing_synthesis_and_hdlist($urpm, $medium);

    1;
}

sub _read_existing_synthesis_and_hdlist_if_same_md5sum {
    my ($urpm, $medium, $retrieved_md5sum) = @_;

    #- if an existing hdlist or synthesis file has the same md5sum, we assume the
    #- files are the same.
    #- if local md5sum is the same as distant md5sum, this means there is no need to
    #- download hdlist or synthesis file again.
    $retrieved_md5sum && $medium->{md5sum} eq $retrieved_md5sum or return;

    _read_existing_synthesis_and_hdlist($urpm, $medium);

    1;
}

sub _read_existing_synthesis_and_hdlist {
    my ($urpm, $medium) = @_;

    unlink cachedir_with_hdlist($urpm, $medium, 's');

    $urpm->{info}(N("medium \"%s\" is up-to-date", $medium->{name}));

    #- the medium is now considered not modified.
    $medium->{modified} = 0;
    #- XXX we could link the new hdlist to the old one.
    #- (However links need to be managed. see bug #12391.)
    #- as previously done, just read synthesis file here, this is enough.
    if (!_parse_synthesis($urpm, $medium, statedir_synthesis($urpm, $medium))) {
	_parse_hdlist($urpm, $medium, statedir_hdlist($urpm, $medium));
	_check_after_reading_hdlist_or_synthesis($urpm, $medium);
    }

    1;
}

sub _parse_hdlist {
    my ($urpm, $medium, $hdlist_file, $o_callback) = @_;

    -e $hdlist_file or return;

    $urpm->{log}(N("examining hdlist file [%s]", $hdlist_file));
    ($medium->{start}, $medium->{end}) = 
      $urpm->parse_hdlist($hdlist_file, packing => 1, $o_callback ? (callback => $o_callback) : @{[]});
}

sub _parse_synthesis {
    my ($urpm, $medium, $synthesis_file, $o_callback) = @_;

    -e $synthesis_file or return;

    $urpm->{log}(N("examining synthesis file [%s]", $synthesis_file));
    ($medium->{start}, $medium->{end}) = 
      $urpm->parse_synthesis($synthesis_file, $o_callback ? (callback => $o_callback) : @{[]});
}
sub _parse_hdlist_or_synthesis {
    my ($urpm, $medium, $hdlist_or, $prefer_synthesis, $o_callback) = @_;

    if (_synthesis_or_not($medium, $prefer_synthesis)) {
	_parse_synthesis($urpm, $medium, $hdlist_or, $o_callback);
    } else {
	_parse_hdlist($urpm, $medium, $hdlist_or, $o_callback);
    }
}

sub _build_hdlist_using_rpm_headers {
    my ($urpm, $medium) = @_;

    $urpm->{log}(N("building hdlist [%s]", statedir_hdlist($urpm, $medium)));
    #- finish building operation of hdlist.
    $urpm->build_hdlist(start  => $medium->{start},
			end    => $medium->{end},
			dir    => "$urpm->{cachedir}/headers",
			hdlist => statedir_hdlist($urpm, $medium),
		    );
}

sub _build_synthesis {
    my ($urpm, $medium) = @_;

    eval { $urpm->build_synthesis(
	start     => $medium->{start},
	end       => $medium->{end},
	synthesis => statedir_synthesis($urpm, $medium),
    ) };
    if (my $err = $@) {
	chomp($err);
	$urpm->{error}(N("Unable to build synthesis file for medium \"%s\". Your hdlist file may be corrupted.", $medium->{name}));
	$urpm->{error}($err);
	unlink statedir_synthesis($urpm, $medium);
    } else {
	$urpm->{log}(N("built hdlist synthesis file for medium \"%s\"", $medium->{name}));
    }
    #- keep in mind we have a modified database, sure at this point.
    $urpm->{md5sum_modified} = 1;
}

sub is_valid_medium {
    my ($medium) = @_;
    defined $medium->{start} && defined $medium->{end};
}

sub _check_after_reading_hdlist_or_synthesis {
    my ($urpm, $medium) = @_;

    if (!is_valid_medium($medium)) {
	$urpm->{error}(N("problem reading hdlist or synthesis file of medium \"%s\"", $medium->{name}));
	$medium->{ignore} = 1;
    }
}

sub _get_list_or_pubkey__local {
    my ($urpm, $medium, $name) = @_;

    my $path = _hdlist_dir($medium) . "/$name" . _hdlist_suffix($medium);
    -e $path or $path = file_from_local_url($medium->{url}) . "/media_info/$name";
    if (-e $path) {
	$urpm->{log}(N("copying [%s] for medium \"%s\"...", $path, $medium->{name}));
	copy_and_own($path, "$urpm->{cachedir}/partial/$name")
	  or $urpm->{error}(N("...copying failed")), return;
    }
    1;
}

sub _get_list_or_pubkey__remote {
    my ($urpm, $medium, $name) = @_;

    my $found;
    if (_hdlist_suffix($medium)) {
	my $local_name = $name . _hdlist_suffix($medium);

	if (urpm::download::sync($urpm, $medium, [_hdlist_dir($medium) . "/$local_name"], 
				 quiet => 1)) {
	    rename("$urpm->{cachedir}/partial/$local_name", "$urpm->{cachedir}/partial/$name");
	    $found = 1;
	}
    }
    if (!$found) {
	urpm::download::sync($urpm, $medium, [_hdlist_dir($medium) .  "/$name"], quiet => 1)
	    or unlink "$urpm->{cachedir}/partial/$name";
    }
}

sub get_descriptions_local {
    my ($urpm, $medium) = @_;

    unlink statedir_descriptions($urpm, $medium);

    my $dir = file_from_local_url($medium->{url});
    my $description_file = "$dir/media_info/descriptions"; #- new default location
    -e $description_file or $description_file = "$dir/../descriptions";
    -e $description_file or return;

    $urpm->{log}(N("copying description file of \"%s\"...", $medium->{name}));
    if (copy_and_own($description_file, statedir_descriptions($urpm, $medium))) {
	$urpm->{log}(N("...copying done"));
    } else {
	$urpm->{error}(N("...copying failed"));
	$medium->{ignore} = 1;
    }
}
sub get_descriptions_remote {
    my ($urpm, $medium) = @_;

    unlink "$urpm->{cachedir}/partial/descriptions";

    if (-e statedir_descriptions($urpm, $medium)) {
	urpm::util::move(statedir_descriptions($urpm, $medium), "$urpm->{cachedir}/partial/descriptions");
    }
    urpm::download::sync($urpm, $medium, [ reduce_pathname("$medium->{url}/media_info/descriptions") ], quiet => 1) 
	or #- try older location
	  urpm::download::sync($urpm, $medium, [ reduce_pathname("$medium->{url}/../descriptions") ], quiet => 1);

    if (-e "$urpm->{cachedir}/partial/descriptions") {
	urpm::util::move("$urpm->{cachedir}/partial/descriptions", statedir_descriptions($urpm, $medium));
    }
}
sub get_hdlist_or_synthesis__local {
    my ($urpm, $medium, $callback) = @_;

    my $f = cachedir_with_hdlist($urpm, $medium, 's');
    unlink $f;
    $urpm->{log}(N("copying [%s] for medium \"%s\"...", _url_with_hdlist($medium, 's'), $medium->{name}));
    $callback and $callback->('copy', $medium->{name});
    if (copy_and_own(_url_with_hdlist($medium, 's'), $f)) {
	$callback and $callback->('done', $medium->{name});
	$urpm->{log}(N("...copying done"));
	if (file_size($f) < 20) {
	    $urpm->{error}(N("copy of [%s] failed (file is suspiciously small)", $f));
	    0;
	} else {
	    1;
	}
    } else {
	$callback and $callback->('failed', $medium->{name});
	#- force error, reported afterwards
	unlink $f;
	0;
    }
}
sub get_hdlist_or_synthesis__remote {
    my ($urpm, $medium, $callback, $quiet) = @_;

    if (urpm::download::sync($urpm, $medium, [ _url_with_hdlist($medium, 's') ],
			     quiet => $quiet, callback => $callback) &&
			       file_size(cachedir_with_hdlist($urpm, $medium, 's')) >= 20) {
	1;
    } else {
	chomp(my $err = $@);
	$urpm->{error}(N("...retrieving failed: %s", $err));
	0;
    }
}

sub get_hdlist_or_synthesis_and_check_md5sum__local {
    my ($urpm, $medium, $retrieved_md5sum, $callback) = @_;

    get_hdlist_or_synthesis__local($urpm, $medium, $callback) or return;

    #- keep checking md5sum of file just copied ! (especially on nfs or removable device).
    if ($retrieved_md5sum) {
	$urpm->{log}(N("computing md5sum of copied source hdlist (or synthesis)"));
	urpm::md5sum::compute(cachedir_with_hdlist($urpm, $medium, 's')) eq $retrieved_md5sum or
	  $urpm->{error}(N("copy of [%s] failed (md5sum mismatch)", _url_with_hdlist($medium, 's'))), return;
    }

    1;
}
sub get_hdlist_or_synthesis_and_check_md5sum__remote {
    my ($urpm, $medium, $retrieved_md5sum, $callback, $quiet) = @_;

    get_hdlist_or_synthesis__remote($urpm, $medium, $callback, $quiet) or return;

    #- check downloaded file has right signature.
    if ($retrieved_md5sum) {
	$urpm->{log}(N("computing md5sum of retrieved source hdlist (or synthesis)"));
	urpm::md5sum::compute(cachedir_with_hdlist($urpm, $medium, 's')) eq $retrieved_md5sum or
	    $urpm->{error}(N("...retrieving failed: md5sum mismatch")), return;
    }
    1;
}

sub _read_rpms_from_dir {
    my ($urpm, $medium, $clean_cache) = @_;

    my $dir = file_from_local_url($medium->{url});

    require File::Glob;
    $medium->{rpm_files} = [ File::Glob::glob("$dir/*.rpm") ];

    #- check files contains something good!
    if (!@{$medium->{rpm_files}}) {
	$urpm->{error}(N("no rpm files found from [%s]", $dir));
	$medium->{ignore} = 1;
	return;
    }

    #- we need to rebuild from rpm files the hdlist.

    $urpm->{log}(N("reading rpm files from [%s]", $dir));
    my @unresolved_before = grep {
	! defined $urpm->{provides}{$_};
    } keys %{$urpm->{provides} || {}};
    $medium->{start} = @{$urpm->{depslist}};

    eval {
	$medium->{headers} = [ $urpm->parse_rpms_build_headers(
	    dir   => "$urpm->{cachedir}/headers",
	    rpms  => $medium->{rpm_files},
	    clean => $$clean_cache,
	    packing => 1,
	) ];
    };
    if ($@) {
	$urpm->{error}(N("unable to read rpm files from [%s]: %s", $dir, $@));
	delete $medium->{headers}; #- do not propagate these.
	return;
    }

    $medium->{end} = $#{$urpm->{depslist}};
    if ($medium->{start} > $medium->{end}) {
	#- an error occured (provided there are files in input.)
	delete $medium->{start};
	delete $medium->{end};
	$urpm->{fatal}(9, N("no rpms read"));
    }

    #- make sure the headers will not be removed for another media.
    $$clean_cache = 0;

    my @unresolved = grep {
	! defined $urpm->{provides}{$_};
    } keys %{$urpm->{provides} || {}};
    @unresolved_before == @unresolved or $medium->{need_second_pass} = 1;

    delete $medium->{synthesis}; #- when building hdlist by ourself, drop synthesis property.
    1;
}

#- options: callback, force, nomd5sum, nopubkey, probe_with
sub _update_medium__parse_if_unmodified__local {
    my ($urpm, $medium, $clean_cache, $options) = @_;

    my $dir = file_from_local_url($medium->{url});

    if (!-d $dir) {
	#- the directory given does not exist and may be accessible
	#- by mounting some other directory. Try to figure it out and mount
	#- everything that might be necessary.
	urpm::removable::try_mounting($urpm,
	    $options->{probe_with} ne 'rpms' && _hdlist_dir($medium)
	      ? _hdlist_dir($medium) : $dir,
	    #- in case of an iso image, pass its name
	    urpm::removable::is_iso($medium->{removable}) && $medium->{removable},
	) or $urpm->{error}(N("unable to access medium \"%s\",
this could happen if you mounted manually the directory when creating the medium.", $medium->{name})), return 'unmodified';
    }

    #- try to probe for possible with_hdlist parameter, unless
    #- it is already defined (and valid).
    if (!_hdlist_dir($medium) && $options->{probe_with} ne 'rpms') {
	_probe_with_try_list($urpm, $medium, $options->{probe_with}, sub {
	    my ($url) = @_;
	    -e $url or return;
	    if (file_size($url) >= 20) {
		1;
	    } else {
		$urpm->{error}(N("invalid hdlist file %s for medium \"%s\"", $url, $medium->{name}));
		0;
	    }
	});
    }

    if ($medium->{virtual}) {
	#- syncing a virtual medium is very simple, just try to read the file in order to
	#- determine its type, once a with_hdlist has been found (but is mandatory).
	_parse_hdlist_or_synthesis__virtual($urpm, $medium);
	1;
    } elsif ($options->{probe_with} eq 'rpms' || !_hdlist_dir($medium)) {
	#- build hdlist/synthesis from rpms
	_read_rpms_from_dir($urpm, $medium, $clean_cache);
    } elsif (_hdlist_dir($medium)) {
	    my ($retrieved_md5sum);

	    if (!$options->{nomd5sum} && file_size(_hdlist_dir($medium) . '/MD5SUM') > 32) {
		$retrieved_md5sum = urpm::md5sum::from_MD5SUM__or_warn($urpm, _hdlist_dir($medium) . '/MD5SUM', 
								       _url_with_hdlist_basename($medium, 's'));
		if (urpm::md5sum::on_local_medium($urpm, $medium, $options->{force})) {
		    _read_existing_synthesis_and_hdlist_if_same_md5sum($urpm, $medium, $retrieved_md5sum)
		      and return 'unmodified';
		}
	    }

	    if (get_hdlist_or_synthesis_and_check_md5sum__local($urpm, $medium, $retrieved_md5sum, $options->{callback})) {

		    $medium->{md5sum} = $retrieved_md5sum if $retrieved_md5sum;

		    #- check if the files are equal... and no force copy...
		    if (!$options->{force}) {
			_read_existing_synthesis_and_hdlist_if_same_time_and_msize($urpm, $medium)
			  and return 'unmodified';
		    }
		    1;
	    } else {
		    #- if copying hdlist has failed, try to build it directly.
		    if ($urpm->{options}{'build-hdlist-on-error'}) {
			#- no available hdlist/synthesis, try to build it from rpms
			_read_rpms_from_dir($urpm, $medium, $clean_cache);
		    } else {
			$urpm->{error}(N("unable to access hdlist file of \"%s\", medium ignored", $medium->{name}));
			$medium->{ignore} = 1;
			'';
		    }
	    }
    }
}

#- options: callback, force, nomd5sum, nopubkey, probe_with, quiet
sub _update_medium__parse_if_unmodified__remote {
    my ($urpm, $medium, $options) = @_;
    my ($retrieved_md5sum);

    #- examine if a distant MD5SUM file is available.
    #- this will only be done if $with_hdlist is not empty in order to use
    #- an existing hdlist or synthesis file, and to check if download was good.
    #- if no MD5SUM is available, do it as before...
    if (_hdlist_dir($medium)) {
	#- we can assume at this point a basename is existing, but it needs
	#- to be checked for being valid, nothing can be deduced if no MD5SUM
	#- file is present.

	unlink "$urpm->{cachedir}/partial/MD5SUM";
	if (!$options->{nomd5sum} && 
	      urpm::download::sync($urpm, $medium, 
				   [ reduce_pathname(_hdlist_dir($medium) . '/MD5SUM') ],
				   quiet => 1) && file_size("$urpm->{cachedir}/partial/MD5SUM") > 32) {
	    if (urpm::md5sum::on_local_medium($urpm, $medium, $options->{force} >= 2)) {
		$retrieved_md5sum = urpm::md5sum::from_MD5SUM__or_warn($urpm, "$urpm->{cachedir}/partial/MD5SUM", 
								       _url_with_hdlist_basename($medium, 's'));
		_read_existing_synthesis_and_hdlist_if_same_md5sum($urpm, $medium, $retrieved_md5sum)
		  and return 'unmodified';
	    }
	}
    }

    #- try to probe for possible with_hdlist parameter, unless
    #- it is already defined (and valid).
    $urpm->{log}(N("retrieving source hdlist (or synthesis) of \"%s\"...", $medium->{name}));
    $options->{callback} and $options->{callback}('retrieve', $medium->{name});
    my $error = sub {
	my ($msg) = @_;
	$urpm->{error}($msg);
	unlink cachedir_with_hdlist($urpm, $medium, 's');
	$options->{callback} and $options->{callback}('failed', $medium->{name});
    };
    if (!_hdlist_dir($medium)) {
	my $err;
	_probe_with_try_list($urpm, $medium, $options->{probe_with}, sub {
	    my ($url) = @_;
	    my $f = "$urpm->{cachedir}/partial/" . basename($url);
	    $options->{force} and unlink $f;
	    if (urpm::download::sync($urpm, $medium, [ $url ],
				     quiet => $options->{quiet}, callback => $options->{callback}) && file_size($f) >= 20) {
		$urpm->{log}(N("found probed hdlist (or synthesis) as %s", $url));
		1;
	    } else {
		chomp($err = $@);
		0;
	    }
	}) or do {
	    $error->(N("no hdlist file found for medium \"%s\"", $medium->{name}));
	    $urpm->{error}(N("...retrieving failed: %s", $err));
	    return;
	};
    } else {
	if ($options->{force}) {
	    unlink cachedir_with_hdlist($urpm, $medium, 's');
	} else {
	    #- try to sync (copy if needed) local copy after restored the previous one.
	    #- this is useful for rsync (?)
	    if (-e statedir_hdlist_or_synthesis($urpm, $medium, 's')) {
		copy_and_own(
		    statedir_hdlist_or_synthesis($urpm, $medium, 's'),
		    cachedir_with_hdlist($urpm, $medium, 's'),
		) or $error->(N("...copying failed")), return;
	    }
	}
	if (get_hdlist_or_synthesis_and_check_md5sum__remote($urpm, $medium, $retrieved_md5sum, $options->{callback}, $options->{quiet})) {
	    $options->{callback} and $options->{callback}('done', $medium->{name});

	    $medium->{md5sum} = $retrieved_md5sum if $retrieved_md5sum;

	    if (!$options->{force}) {
		_read_existing_synthesis_and_hdlist_if_same_time_and_msize($urpm, $medium)
		  and return 'unmodified';
	    }
	} else {
	    $error->(N("unable to access hdlist file of \"%s\", medium ignored", $medium->{name}));
	    $medium->{ignore} = 1;
	    return;
	}
    }
    1;
}

sub _get_pubkey_and_descriptions {
    my ($urpm, $medium, $nopubkey) = @_;

    my $local = file_from_local_url($medium->{url});

    ($local ? \&get_descriptions_local : \&get_descriptions_remote)->($urpm, $medium);

    #- examine if a pubkey file is available.
    if (!$nopubkey && !$medium->{'key-ids'}) {
	($local ? \&_get_list_or_pubkey__local : \&_get_list_or_pubkey__remote)->($urpm, $medium, 'pubkey');
    }
}

sub _read_cachedir_pubkey {
    my ($urpm, $medium) = @_;
    -s "$urpm->{cachedir}/partial/pubkey" or return;

    $urpm->{log}(N("examining pubkey file of \"%s\"...", $medium->{name}));

    my $_rpm_lock = urpm::lock::rpm_db($urpm, 'exclusive');

    my %key_ids;
    $urpm->import_needed_pubkeys(
	[ $urpm->parse_armored_file("$urpm->{cachedir}/partial/pubkey") ],
	root => $urpm->{root}, 
	callback => sub {
	    my (undef, undef, $_k, $id, $imported) = @_;
	    if ($id) {
		$key_ids{$id} = undef;
		$imported and $urpm->{log}(N("...imported key %s from pubkey file of \"%s\"",
					     $id, $medium->{name}));
	    } else {
		$urpm->{error}(N("unable to import pubkey file of \"%s\"", $medium->{name}));
	    }
	});
    if (keys(%key_ids)) {
	$medium->{'key-ids'} = join(',', keys %key_ids);
    }

    unlink "$urpm->{cachedir}/partial/pubkey";
}

sub _write_rpm_list {
    my ($urpm, $medium) = @_;

    @{$medium->{rpm_files} || []} or return;

    $medium->{list} ||= "list.$medium->{name}";

    #- write list file.
    $urpm->{log}(N("writing list file for medium \"%s\"", $medium->{name}));
    my $listfh = urpm::sys::open_safe($urpm, '>', cachedir_list($urpm, $medium)) or return;
    print $listfh basename($_), "\n" foreach @{$medium->{rpm_files}};
    1;
}

#- options: callback, force, nomd5sum, probe_with, quiet
#- (from _update_medium__parse_if_unmodified__local and _update_medium__parse_if_unmodified__remote)
sub _update_medium_first_pass {
    my ($urpm, $medium, $clean_cache, %options) = @_;

    #- we should create the associated synthesis file if it does not already exist...
    file_size(statedir_synthesis($urpm, $medium)) >= 20
      or $medium->{must_build_synthesis} = 1;

    unless ($medium->{modified}) {
	#- the medium is not modified, but to compute dependencies,
	#- we still need to read it and all synthesis will be written if
	#- an unresolved provides is found.
	#- to speed up the process, we only read the synthesis at the beginning.
	_parse_hdlist_or_synthesis__when_not_modified($urpm, $medium);
	return 1;
    }

    #- always delete a remaining list file or pubkey file in cache.
    foreach (qw(list pubkey)) {
	unlink "$urpm->{cachedir}/partial/$_";
    }

    #- check for a reconfig.urpmi file (if not already reconfigured)
    if (!$medium->{noreconfigure}) {
	may_reconfig_urpmi($urpm, $medium);
    }

    my @unresolved_before = grep { ! defined $urpm->{provides}{$_} } keys %{$urpm->{provides} || {}};

    {
	my $rc = 
	  file_from_local_url($medium->{url})
	    ? _update_medium__parse_if_unmodified__local($urpm, $medium, $clean_cache, \%options)
	    : _update_medium__parse_if_unmodified__remote($urpm, $medium, \%options);

	if (!$rc || $rc eq 'unmodified') {
	    return $rc;
	}
    }

    #- build list file according to hdlist.
    if (!$medium->{headers} && !$medium->{virtual} && file_size(cachedir_with_hdlist($urpm, $medium, 's')) < 20) {
	$urpm->{error}(N("no hdlist file found for medium \"%s\"", $medium->{name}));
	return;
    }

    if (!$medium->{virtual}) {
	if ($medium->{headers}) {
	    _write_rpm_list($urpm, $medium) or return;

	    if (-e statedir_list($urpm, $medium)) {
		$urpm->{info}(N("updated medium \"%s\"", $medium->{name}));
	    }
	    unlink statedir_hdlist($urpm, $medium);
	    unlink statedir_synthesis($urpm, $medium);
	    unlink statedir_list($urpm, $medium);
	    urpm::util::move(cachedir_list($urpm, $medium), statedir_list($urpm, $medium));
	} else {
	    #- read first pass hdlist or synthesis, try to open as synthesis, if file
	    #- is larger than 1MB, this is probably an hdlist else a synthesis.
	    #- anyway, if one tries fails, try another mode.
	    $options{callback} and $options{callback}('parse', $medium->{name});

	    _parse_hdlist_or_synthesis($urpm, $medium, cachedir_with_hdlist($urpm, $medium, 's'), 's');

	    if (is_valid_medium($medium)) {
		$options{callback} && $options{callback}('done', $medium->{name});
	    } else {
		$urpm->{error}(N("unable to parse hdlist file of \"%s\"", $medium->{name}));
		$options{callback} and $options{callback}('failed', $medium->{name});
		delete $medium->{md5sum};

		#- we have to read back the current synthesis file unmodified.
		if (!_parse_synthesis($urpm, $medium, statedir_synthesis($urpm, $medium))) {
		    $urpm->{error}(N("problem reading synthesis file of medium \"%s\"", $medium->{name}));
		    $medium->{ignore} = 1;
		}
		return;
	    }

	    if (-e statedir_hdlist_or_synthesis($urpm, $medium, 's')) {
		$urpm->{info}(N("updated medium \"%s\"", $medium->{name}));
	    }


	    unlink statedir_list($urpm, $medium);
	    unlink statedir_hdlist($urpm, $medium);
	    unlink statedir_synthesis($urpm, $medium);
	    #- use newly created file.
	    urpm::util::move(cachedir_with_hdlist($urpm, $medium, 's'),
			     statedir_hdlist_or_synthesis($urpm, $medium, 's'));

	    if ($medium->{list}) {
		delete $medium->{list};
		$urpm->{modified} = 1;
	    }
	}

	#- make sure to rebuild base files and clear medium modified state.
	$medium->{modified} = 0;
	$medium->{really_modified} = 1;
	$urpm->{md5sum_modified} = 1;
	
	#- and create synthesis file associated.
	$medium->{must_build_synthesis} = !_synthesis_or_not($medium, 's');
    }

    {
	my @unresolved_after = grep { ! defined $urpm->{provides}{$_} } keys %{$urpm->{provides} || {}};
	if (@unresolved_before != @unresolved_after) {
	    $medium->{need_second_pass} = 1;
	    $urpm->{debug} and $urpm->{debug}(sprintf qq(medium "%s" has unresolved dependencies: %s), 
			   $medium->{name}, 
			   join(' ', difference2(\@unresolved_after, \@unresolved_before)));
	}
    }

    1;
}

sub _update_medium_first_pass_failed {
    my ($urpm, $medium) = @_;

    !$medium->{virtual} or return;

    #- an error has occured for updating the medium, we have to remove temporary files.
    unlink(glob("$urpm->{cachedir}/partial/*"));
}

#- take care of modified medium only, or all if all have to be recomputed.
sub _update_medium_second_pass {
    my ($urpm, $medium, $callback) = @_;

    $callback and $callback->('parse', $medium->{name});

    #- a modified medium is an invalid medium, we have to read back the previous hdlist
    #- or synthesis which has not been modified by first pass above.

	if ($medium->{headers} && !$medium->{modified}) {
	    $urpm->{log}(N("reading headers from medium \"%s\"", $medium->{name}));
	    ($medium->{start}, $medium->{end}) = $urpm->parse_headers(dir     => "$urpm->{cachedir}/headers",
								      headers => $medium->{headers},
								  );
	} elsif (_parse_hdlist($urpm, $medium, any_hdlist($urpm, $medium))) {
	    $medium->{must_build_synthesis} = 1;
	} else {
	    _parse_synthesis($urpm, $medium, any_synthesis($urpm, $medium));
	}

    $callback && $callback->('done', $medium->{name});
}

sub _build_hdlist_synthesis {
    my ($urpm, $medium) = @_;

    if ($medium->{headers} && !$medium->{modified}) {
	_build_hdlist_using_rpm_headers($urpm, $medium);
	#- synthesis needs to be created, since the medium has been built from rpm files.
	_build_synthesis($urpm,  $medium);
    } elsif ($medium->{synthesis}) {
    } else {
	#- check if the synthesis file can be built.
	if ($medium->{must_build_synthesis} && !$medium->{modified} && !$medium->{virtual}) {
	    _build_synthesis($urpm, $medium);
	}
    }
}

sub _update_media__handle_some_flags {
    my ($urpm, $forcekey, $all) = @_;

    foreach my $medium (grep { !$_->{ignore} } @{$urpm->{media}}) {
	$forcekey and delete $medium->{'key-ids'};

	if ($medium->{static}) {
	    #- don't ever update static media
	    $medium->{modified} = 0;
	} elsif ($all) {
	    #- if we're rebuilding all media, mark them as modified (except removable ones)
	    $medium->{modified} ||= $medium->{url} !~ m!^removable!;
	}
    }
}

#- Update the urpmi database w.r.t. the current configuration.
#- Takes care of modifications, and tries some tricks to bypass
#- the recomputation of base files.
#- Recognized options :
#-   all         : all medias are being rebuilt
#-   callback    : UI callback
#-   forcekey    : force retrieval of pubkey
#-   force       : try to force rebuilding base files
#-   noclean     : keep old files in the header cache directory
#-   nomd5sum    : don't verify MD5SUM of retrieved files
#-   nopubkey    : don't use rpm pubkeys
#-   probe_with  : probe synthesis or hdlist (or none)
#-   quiet       : download hdlists quietly
sub update_media {
    my ($urpm, %options) = @_;

    $urpm->{media} or return; # verify that configuration has been read

    $options{nopubkey} ||= $urpm->{options}{nopubkey};
    if (!$options{nopubkey} && !$urpm->{keys}) {
	#- get gpg-pubkey signature.
	my $_rpm_lock = urpm::lock::rpm_db($urpm);
	$urpm->{log}(qq(getting "gpg-pubkey"s from rpmdb));
	$urpm->parse_pubkeys(root => $urpm->{root});
    }

    #- examine each medium to see if one of them needs to be updated.
    #- if this is the case and if not forced, try to use a pre-calculated
    #- hdlist file, else build it from rpm files.
    clean($urpm);

    _update_media__handle_some_flags($urpm, $options{forcekey}, $options{all});

    my $clean_cache = !$options{noclean};
    foreach my $medium (grep { !$_->{ignore} } @{$urpm->{media}}) {
	_update_medium_first_pass($urpm, $medium, \$clean_cache, %options)
	  or _update_medium_first_pass_failed($urpm, $medium);
    }

    #- some unresolved provides may force to rebuild all synthesis,
    #- a second pass will be necessary.
    my $need_second_pass = 
      (grep { $_->{need_second_pass} } @{$urpm->{media}})
	#- second pass not useful if not a single media allowed to build a synthesis
	&& (grep { !$_->{virtual} } @{$urpm->{media}}) 
	#- second pass not useful if only synthesis available
	&& (grep { !$_->{synthesis} } @{$urpm->{media}});  
    if ($need_second_pass) {
	$urpm->{log}(N("performing second pass to compute dependencies\n"));
	$urpm->unresolved_provides_clean;
    }

    foreach my $medium (grep { !$_->{ignore} } @{$urpm->{media}}) {
	if ($need_second_pass) {
	    #- second pass consists in reading again synthesis or hdlists.
	    _update_medium_second_pass($urpm, $medium, $options{callback});
	}
	_build_hdlist_synthesis($urpm, $medium);

	if ($medium->{really_modified}) {
	    _get_pubkey_and_descriptions($urpm, $medium, $options{nopubkey});
	    _read_cachedir_pubkey($urpm, $medium);
	    generate_medium_names($urpm, $medium);
	}
    }

    if ($urpm->{modified}) {
	if ($options{noclean}) {
	    #- clean headers cache directory to remove everything that is no longer
	    #- useful according to the depslist.
	    urpm::remove_obsolete_headers_in_cache($urpm);
	}
	#- write config files in any case
	write_config($urpm);
	urpm::download::dump_proxy_config();
    } elsif ($urpm->{md5sum_modified}) {
	#- NB: in case of $urpm->{modified}, write_MD5SUM is called in write_config above
	write_MD5SUM($urpm);
    }
}

#- clean params and depslist computation zone.
sub clean {
    my ($urpm) = @_;

    $urpm->{depslist} = [];
    $urpm->{provides} = {};

    foreach (@{$urpm->{media} || []}) {
	delete $_->{start};
	delete $_->{end};
    }
}


#- get the list of packages that should not be upgraded or installed,
#- typically from the inst.list or skip.list files.
sub get_packages_list {
    my ($file, $o_extra) = @_;
    my $val = [];
    open(my $f, '<', $file) or return [];
    foreach (<$f>, split /,/, $o_extra || '') {
	chomp; s/#.*$//; s/^\s*//; s/\s*$//;
	next if $_ eq '';
	push @$val, $_;
    }
    $val;
}

1;