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1 files changed, 107 insertions, 0 deletions

diff --git a/perl-install/resize_fat/boot_sector.pm b/perl-install/resize_fat/boot_sector.pm
new file mode 100644
index 000000000..48e2a8d4e
--- /dev/null
+++ b/perl-install/resize_fat/boot_sector.pm
@@ -0,0 +1,107 @@
+package resize_fat::boot_sector;
+
+use diagnostics;
+use strict;
+
+use common qw(:common :system :constant);
+use resize_fat::io;
+use resize_fat::any;
+use resize_fat::directory;
+
+
+my $format = "a3 a8 S C S C S S C S S S I I I S S I S S a458 S";
+my @fields = (
+    'boot_jump',		#- boot strap short or near jump
+    'system_id',		#- Name - can be used to special case partition manager volumes
+    'sector_size',		#- bytes per logical sector
+    'cluster_size_in_sectors',	#- sectors/cluster
+    'nb_reserved',		#- reserved sectors
+    'nb_fats',			#- number of FATs
+    'nb_root_dir_entries',	#- number of root directory entries
+    'small_nb_sectors',		#- number of sectors: big_nb_sectors supersedes
+    'media',			#- media code
+    'fat16_fat_length',		#- sectors/FAT for FAT12/16
+    'sectors_per_track',
+    'nb_heads',
+    'nb_hidden',		#- (unused)
+    'big_nb_sectors',		#- number of sectors (if small_nb_sectors == 0)
+
+#- FAT32-only entries
+    'fat32_fat_length',		#- size of FAT in sectors
+    'fat32_flags',		#- bit8: fat mirroring,
+				#- low4: active fat
+    'fat32_version',		#- minor * 256 + major
+    'fat32_root_dir_cluster',
+    'info_offset_in_sectors',
+    'fat32_backup_sector',
+
+#- Common again...
+    'boot_code',		#- Boot code (or message)
+    'boot_sign',		#- 0xAA55
+);
+
+1;
+
+
+#- trimfs_init_boot_sector() - reads in the boot sector - gets important info out
+#- of boot sector, and puts in main structure - performs sanity checks - returns 1
+#- on success, 0 on failureparameters: filesystem an empty structure to fill.
+sub read($) {
+    my ($fs) = @_;
+
+    my $boot = eval { resize_fat::io::read($fs, 0, $SECTORSIZE) }; $@ and die "reading boot sector failed on device $fs->{fs_name}";
+    @{$fs}{@fields} = unpack $format, $boot;
+
+    $fs->{nb_sectors} = $fs->{small_nb_sectors} || $fs->{big_nb_sectors};
+    $fs->{cluster_size} = $fs->{cluster_size_in_sectors} * $fs->{sector_size};
+
+    $fs->{boot_sign} == 0xAA55 or die "Invalid signature for a MS-based filesystem.";
+    $fs->{nb_fats} == 2 or die "Weird number of FATs: $fs->{nb_fats}, not 2.",
+    $fs->{nb_sectors} < 32 and die "Too few sectors for viable file system\n";
+
+    if ($fs->{fat16_fat_length}) {
+	#- asserting FAT16, will be verified later on
+        $fs->{fs_type} = 'FAT16';
+	$fs->{fs_type_size} = 16;
+	$fs->{fat_length} = $fs->{fat16_fat_length};
+	$resize_fat::bad_cluster_value = 0xfff7; #- 2**16 - 1
+    } else {
+	$resize_fat::isFAT32 = 1;
+        $fs->{fs_type} = 'FAT32';
+        $fs->{fs_type_size} = 32;
+	$fs->{fat_length} = $fs->{fat32_fat_length};
+
+	$fs->{nb_root_dir_entries} = 0;
+	$fs->{info_offset} = $fs->{info_offset_in_sectors} * $fs->{sector_size};
+	$resize_fat::bad_cluster_value = 0xffffff7;
+    }
+
+    $fs->{fat_offset} = $fs->{nb_reserved} * $fs->{sector_size};
+    $fs->{fat_size} = $fs->{fat_length} * $fs->{sector_size};
+    $fs->{root_dir_offset} = $fs->{fat_offset} + $fs->{fat_size} * $fs->{nb_fats};
+    $fs->{root_dir_size} = $fs->{nb_root_dir_entries} * resize_fat::directory::entry_size();
+    $fs->{cluster_offset} = $fs->{root_dir_offset} + $fs->{root_dir_size} - 2 * $fs->{cluster_size};
+
+    $fs->{nb_fat_entries} = divide($fs->{fat_size}, $fs->{fs_type_size} / 8);
+
+    #- - 2 because clusters 0 & 1 doesn't exist
+    $fs->{nb_clusters} = divide($fs->{nb_sectors} * $fs->{sector_size} - $fs->{cluster_offset}, $fs->{cluster_size}) - 2;
+
+    $fs->{dir_entries_per_cluster} = divide($fs->{cluster_size}, psizeof($format));
+
+#-    $fs->{nb_clusters} >= resize_fat::any::min_cluster_count($fs) or die "error: not enough sectors for a $fs->{fs_type}\n";
+    $fs->{nb_clusters} <  resize_fat::any::max_cluster_count($fs) or die "error: too many sectors for a $fs->{fs_type}\n";
+}
+
+sub write($) {
+    my ($fs) = @_;
+    my $boot = pack($format, @{$fs}{@fields});
+
+    eval { resize_fat::io::write($fs, 0, $SECTORSIZE, $boot) }; $@ and die "writing the boot sector failed on device $fs->{fs_name}";
+
+    if ($resize_fat::isFAT32) {
+	#- write backup
+	eval { resize_fat::io::write($fs, $fs->{fat32_backup_sector} * $SECTORSIZE, $SECTORSIZE, $boot) };
+	$@ and die "writing the backup boot sector (#$fs->{fat32_backup_sector}) failed on device $fs->{fs_name}";
+    }
+}