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($$) { my ($val, $nb_bits) = @_; my $r = 0; for (; $nb_bits > 0; $nb_bits -= 8) { $r = $r << 8; $r += $val & 0xff; $val = $val >> 8; } $nb_bits < 0 and die "error: endianness only handle numbers divisible by 8"; $r; } *next = \&resize_fat::c_rewritten::next; *set_next = \&resize_fat::c_rewritten::set_next; sub get_free($) { my ($fs) = @_; for (my $i = 0; $i < $fs->{nb_clusters}; $i++) { my $cluster = ($i + $fs->{last_free_cluster} - 2) % $fs->{nb_clusters} + 2; is_available(&next($fs, $cluster)) and return $fs->{last_free_cluster} = $cluster; } die "no free clusters"; } #- returns true if <cluster> represents an EOF marker sub is_eof($) { my ($cluster) = @_; $cluster >= $resize_fat::bad_cluster_value; } sub set_eof($$) { 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); }