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|
#!perl -w
#
# LabeledPartition -- a partition with ext2 or other label.
# Copyright (C) 2005 Erik van Konijnenburg
#
# 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.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
#
# descriptors contain:
# - label - string such as volume name for matching in /etc/fstab
# - uuid - similar but hex
# - path - the block special file where the label was found
# - type - what kind of superblock the label was found in.
#
# NOTE: consider delegating this whole mess to findfs from the
# e2fsprogs package. That package can probe for an extensive
# set of superblocks, knows about LVM, but does not make fs type
# information available via the command line.
#
use strict;
use warnings;
package LabeledPartition;
use base 'Obj';
sub fill {
my $self = shift;
$self->SUPER::fill();
$self->takeArgs ('label', 'uuid', 'path', 'type');
}
sub label { return $_[0]->{label}; }
sub uuid { return $_[0]->{uuid}; }
sub type { return $_[0]->{type}; }
sub path { return $_[0]->{path}; }
sub string {
my $self = shift;
my $label = ($self->label or '-');
my $uuid = ($self->uuid or '-');
my $type = $self->type;
my $path = $self->path;
return "labeled($type) $label, $uuid at $path";
}
#
# try -- return descriptor for labeled fs, or undef,
# trying a number of formats for superblock.
#
sub try ($) {
my ($path) = @_;
my $result = undef;
my $fh;
if (! open ($fh, "<", "$path")) {
return $result;
}
binmode ($fh);
$result = tryExt2 ($fh, $path) unless defined $result;
$result = tryReiser ($fh, $path) unless defined $result;
# ignore errors, could not have been very wrong
# if a working superblock came out of it.
close ($fh);
return $result;
}
#
# lets hope the sysadm labeled it in ascii not utf8.
# based on util-linux-2.12h mount; they have lots of other
# superblocks to match. Later.
#
sub tryExt2 ($$) {
my ($fh, $path) = @_;
my $result = undef;
if (! seek ($fh, 1024, 0)) {
return $result;
}
# undef on read error - is this worth a warning?
my $superBlock;
my $rc = read ($fh, $superBlock, 1024);
if (! defined ($rc) || $rc != 1024) {
return $result;
}
my ($magic, $uuid, $label) =
unpack
"x[56] v x[34] x[VVV] H[32] Z[16]",
$superBlock;
if ($magic == 0xEF53) {
$uuid = fancyUuid ($uuid);
$result = LabeledPartition->new (
type => "ext2",
label => $label,
uuid => $uuid,
path => $path,
);
}
return $result;
}
# fancyUuid - given a hex uuid, add hyphens at conventional place.
sub fancyUuid ($) {
my ($uuid) = @_;
$uuid =~ s/^(.{8})(.{4})(.{4})(.{4})(.{12})$/$1-$2-$3-$4-$5/;
return lc ($uuid);
}
sub tryReiser ($$) {
my ($fh, $path) = @_;
my $result = undef;
# offset in reisser 3.6 (3.5-3.5.10 had 8k)
if (! seek ($fh, (64*1024), 0)) {
return $result;
}
# undef on read error - is this worth a warning?
my $superBlock;
my $rc = read ($fh, $superBlock, 1024);
if (! defined ($rc) || $rc != 1024) {
return $result;
}
my ($magic, $uuid, $label) =
unpack
"x[52] Z[10] x[22] a[16] Z[16]",
$superBlock;
my $t = join ("", map { sprintf "%02x", ord($_) } split(//, $uuid));
if ($magic eq "ReIsEr2Fs" || $magic eq "ReIsEr3Fs") {
$uuid = fancyUuid ($uuid);
$result = LabeledPartition->new (
type => "reiserfs",
label => $label,
uuid => fancyUuid($t),
path => $path,
);
}
return $result;
}
1;
|
