"See_The_Changelog"

1 files changed, 106 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..c236b1617
--- /dev/null
+++ b/perl-install/resize_fat/boot_sector.pm
@@ -0,0 +1,106 @@
+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};
+    } 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 = (1 << $fs->{fs_type_size}) - 9;
+    
+    $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}";
+    }
+}