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package resize_fat::fat; # $Id$
use diagnostics;
use strict;
use resize_fat::any;
use resize_fat::io;
use resize_fat::c_rewritten;
1;
sub read($) {
my ($fs) = @_;
resize_fat::c_rewritten::read_fat(fileno $fs->{fd}, $fs->{fat_offset}, $fs->{fat_size}, $fs->{media});
@{$fs->{clusters}{count}}{qw(free bad used)} =
resize_fat::c_rewritten::scan_fat($fs->{nb_clusters}, $fs->{fs_type_size});
}
sub write($) {
my ($fs) = @_;
sysseek $fs->{fd}, $fs->{fat_offset}, 0 or die "write_fat: seek failed";
foreach (1..$fs->{nb_fats}) {
resize_fat::c_rewritten::write_fat(fileno $fs->{fd}, $fs->{fat_size});
}
}
#- allocates where all the clusters will be moved to. Clusters before cut_point
#- remain in the same position, however cluster that are part of a directory are
#- moved regardless (this is a mechanism to prevent data loss) (cut_point is the
#- first cluster that won't occur in the new fs)
sub allocate_remap {
my ($fs, $cut_point) = @_;
my ($cluster, $new_cluster);
my $remap = sub { resize_fat::c_rewritten::set_fat_remap($cluster, $new_cluster) };
my $get_new = sub {
$new_cluster = get_free($fs);
0 < $new_cluster && $new_cluster < $cut_point or die "no free clusters";
set_eof($fs, $new_cluster); #- mark as used
#-log::ld("resize_fat: [$cluster,", &next($fs, $cluster), "...]->$new_cluster...");
};
#- this must call allocate_fat_remap that zeroes the buffer allocated.
resize_fat::c_rewritten::allocate_fat_remap($fs->{nb_clusters} + 2);
$fs->{last_free_cluster} = 2;
for ($cluster = 2; $cluster < $fs->{nb_clusters} + 2; $cluster++) {
if ($cluster < $cut_point) {
if (resize_fat::c_rewritten::flag($cluster) == $resize_fat::any::DIRECTORY) {
&$get_new();
} else {
$new_cluster = $cluster;
}
&$remap();
} elsif (!is_empty(&next($fs, $cluster))) {
&$get_new();
&$remap();
}
}
}
#- updates the fat for the resized filesystem
sub update {
my ($fs) = @_;
for (my $cluster = 2; $cluster < $fs->{nb_clusters} + 2; $cluster++) {
if (resize_fat::c_rewritten::flag($cluster)) {
my $old_next = &next($fs, $cluster);
my $new = resize_fat::c_rewritten::fat_remap($cluster);
my $new_next = resize_fat::c_rewritten::fat_remap($old_next);
set_available($fs, $cluster);
is_eof($old_next) ?
set_eof($fs, $new) :
set_next ($fs, $new, $new_next);
}
}
}
sub endianness16($) { (($_[0] & 0xff) << 8) + ($_[0] >> 8); }
sub endianness($$) {
my ($val, $nb_bits) = @_;
my $r = 0;
for (; $nb_bits > 0; $nb_bits -= 8) {
$r <<= 8;
$r += $val & 0xff;
$val >>= 8;
}
$nb_bits < 0 and die "error: endianness only handle numbers divisible by 8";
$r;
}
*next = \&resize_fat::c_rewritten::next;
*set_next = \&resize_fat::c_rewritten::set_next;
sub get_free($) {
my ($fs) = @_;
foreach (my $i = 0; $i < $fs->{nb_clusters}; $i++) {
my $cluster = ($i + $fs->{last_free_cluster} - 2) % $fs->{nb_clusters} + 2;
is_available(&next($fs, $cluster)) and return $fs->{last_free_cluster} = $cluster;
}
die "no free clusters";
}
#- returns true if <cluster> represents an EOF marker
sub is_eof($) {
my ($cluster) = @_;
$cluster >= $resize_fat::bad_cluster_value;
}
sub set_eof($$) {
my ($fs, $cluster) = @_;
set_next ($fs, $cluster, $resize_fat::bad_cluster_value + 1);
}
#- returns true if <cluster> is empty. Note that this includes bad clusters.
sub is_empty($) {
my ($cluster) = @_;
$cluster == 0 || $cluster == $resize_fat::bad_cluster_value;
}
#- returns true if <cluster> is available.
sub is_available($) {
my ($cluster) = @_;
$cluster == 0;
}
sub set_available($$) {
my ($fs, $cluster) = @_;
set_next ($fs, $cluster, 0);
}
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