no_comment

1 files changed, 167 insertions, 0 deletions

diff --git a/perl-install/resize_fat/fat.pm b/perl-install/resize_fat/fat.pm
new file mode 100644
index 000000000..e6039077a
--- /dev/null
+++ b/perl-install/resize_fat/fat.pm
@@ -0,0 +1,167 @@
+package resize_fat::fat;
+
+use diagnostics;
+use strict;
+
+use resize_fat::any;
+use resize_fat::io;
+
+1;
+
+sub read($) {
+    my ($fs) = @_;
+
+    @{$fs->{fats}} = map {
+	my $fat = eval { resize_fat::io::read($fs, $fs->{fat_offset} + $_ * $fs->{fat_size}, $fs->{fat_size}) };
+	$@ and die "reading fat #$_ failed";
+	vec($fat, 0, 8) == $fs->{media} or die "FAT $_ has invalid signature";
+	$fat;
+    } (0 .. $fs->{nb_fats} - 1);
+
+    $fs->{fat} = $fs->{fats}[0];
+
+    my ($free, $bad, $used) = (0, 0, 0);
+
+    for (my $i = 2; $i < $fs->{nb_clusters} + 2; $i++) {
+	my $cluster = &next($fs, $i);
+	if ($cluster == 0) { $free++; }
+	elsif ($cluster == $resize_fat::bad_cluster_value) { $bad++; }
+	else { $used++; }
+    }
+    @{$fs->{clusters}{count}}{qw(free bad used)} = ($free, $bad, $used);
+}
+
+sub write($) {
+    my ($fs) = @_;
+
+    sysseek $fs->{fd}, $fs->{fat_offset}, 0 or die "write_fat: seek failed";
+    foreach (1..$fs->{nb_fats}) {
+	syswrite $fs->{fd}, $fs->{fat} or die "write_fat: write failed";
+    }
+}
+
+
+
+#- allocates where all the clusters will be moved to. Clusters before cut_point
+#- remain in the same position, however cluster that are part of a directory are
+#- moved regardless (this is a mechanism to prevent data loss) (cut_point is the
+#- first cluster that won't occur in the new fs)
+sub allocate_remap {
+    my ($fs, $cut_point) = @_;
+    my ($cluster, $new_cluster);
+    my $remap = sub { $fs->{fat_remap}[$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...");
+    };
+
+    $fs->{fat_remap}[0] = 0;
+    $fs->{last_free_cluster} = 2;
+    for ($cluster = 2; $cluster < $fs->{nb_clusters} + 2; $cluster++) {
+	if ($cluster < $cut_point) {
+	    if ($fs->{fat_flag_map}[$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; $cluster++) {
+	 if ($fs->{fat_flag_map}[$cluster]) {
+	     my $old_next = &next($fs, $cluster);
+	     my $new      = $fs->{fat_remap}[$cluster];
+	     my $new_next = $fs->{fat_remap}[$old_next];
+
+	     set_available($fs, $cluster);
+
+	     is_eof($old_next) ?
+		 set_eof($fs, $new) :
+		 set_next($fs, $new, $new_next);
+	 }
+    }
+}
+
+
+#- - compares the two FATs (one's a backup that should match) - skips first entry
+#- - its just a signature (already checked above) NOTE: checks for cross-linking
+#- are done in count.c
+sub check($) {
+    my ($fs) = @_;
+    foreach (@{$fs->{fats}}) {
+	$_ eq $fs->{fats}[0] or die "FAT tables do not match";
+    }
+}
+
+sub endianness16($) { (($_[0] & 0xff) << 8) + ($_[0] >> 8); }
+sub endianness($$) {
+    my ($val, $nb_bits) = @_;
+    my $r = 0;
+    for (; $nb_bits > 0; $nb_bits -= 8) {
+	$r <<= 8;
+	$r += $val & 0xff;
+	$val >>= 8;
+    }
+    $nb_bits < 0 and die "error: endianness only handle numbers divisible by 8";
+    $r;
+}
+
+sub next($$) {
+    my ($fs, $cluster) = @_;
+    $cluster > $fs->{nb_clusters} + 2 and die "fat::next: cluster $cluster outside filesystem";
+    endianness(vec($fs->{fat}, $cluster, $fs->{fs_type_size}), $fs->{fs_type_size});
+
+}
+sub set_next($$$) {
+    my ($fs, $cluster, $new_v) = @_;
+    $cluster > $fs->{nb_clusters} + 2 and die "fat::set_next: cluster $cluster outside filesystem";
+    vec($fs->{fat}, $cluster, $fs->{fs_type_size}) = endianness($new_v, $fs->{fs_type_size});
+}
+
+
+sub get_free($) {
+    my ($fs) = @_;
+    foreach (my $i = 0; $i < $fs->{nb_clusters}; $i++) {
+        my $cluster = ($i + $fs->{last_free_cluster} - 2) % $fs->{nb_clusters} + 2;
+        is_available(&next($fs, $cluster)) and return $fs->{last_free_cluster} = $cluster;
+    }
+    die "no free clusters";
+}
+
+#-    returns true if <cluster> represents an EOF marker
+sub is_eof($) {
+    my ($cluster) = @_;
+    $cluster >= $resize_fat::bad_cluster_value;
+}
+sub set_eof($$) {
+    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);
+}