no_comment

1 files changed, 36 insertions, 0 deletions

diff --git a/perl-install/resize_fat/info_sector.pm b/perl-install/resize_fat/info_sector.pm
new file mode 100644
index 000000000..3a6f7cfed
--- /dev/null
+++ b/perl-install/resize_fat/info_sector.pm
@@ -0,0 +1,36 @@
+package resize_fat::info_sector;
+
+use diagnostics;
+use strict;
+
+use common qw(:system);
+use resize_fat::io;
+
+my $format = "a484 I I I a16";
+my @fields = (
+    'unused',
+    'signature',		#- should be 0x61417272
+    'free_clusters',		#- -1 for unknown
+    'next_cluster',		#- most recently allocated cluster
+    'unused2',
+);
+
+1;
+
+
+sub read($) {
+    my ($fs) = @_;
+    my $info = resize_fat::io::read($fs, $fs->{info_offset}, psizeof($format));
+    @{$fs->{info_sector}}{@fields} = unpack $format, $info;
+    $fs->{info_sector}{signature} == 0x61417272 or die "Invalid information sector signature\n";
+}
+
+sub write($) {
+    my ($fs) = @_;
+    $fs->{info_sector}{free_clusters} = $fs->{clusters}->{count}->{free};
+    $fs->{info_sector}{next_cluster} = 2;
+
+    my $info = pack $format, @{$fs->{info_sector}}{@fields};
+
+    resize_fat::io::write($fs, $fs->{info_offset}, psizeof($format), $info);
+}