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package partition_table_dos;
use diagnostics;
use strict;
use vars qw(@ISA);
@ISA = qw(partition_table_raw);
use common qw(:common :system :file);
use partition_table_raw;
use c;
my @fields = qw(active start_head start_sec start_cyl type end_head end_sec end_cyl start size);
my $format = "C8 I2";
my $magic = "\x55\xAA";
my $nb_primary = 4;
my $offset = $common::SECTORSIZE - length($magic) - $nb_primary * common::psizeof($format);
sub hasExtended { 1 }
sub compute_CHS($$) {
my ($hd, $e) = @_;
my @l = qw(cyl head sec);
@$e{map { "start_$_" } @l} = $e->{start} || $e->{type} ? CHS2rawCHS(sector2CHS($hd, $e->{start})) : (0,0,0);
@$e{map { "end_$_" } @l} = $e->{start} || $e->{type} ? CHS2rawCHS(sector2CHS($hd, $e->{start} + $e->{size} - 1)) : (0,0,0);
1;
}
sub CHS2rawCHS($$$) {
my ($c, $h, $s) = @_;
$c = min($c, 1023); #- no way to have a #cylinder >= 1024
($c & 0xff, $h, $s | ($c >> 2 & 0xc0));
}
# returns (cylinder, head, sector)
sub sector2CHS($$) {
my ($hd, $start) = @_;
my ($s, $h);
($start, $s) = divide($start, $hd->{geom}{sectors});
($start, $h) = divide($start, $hd->{geom}{heads});
($start, $h, $s + 1);
}
sub read($$) {
my ($hd, $sector) = @_;
my $tmp;
local *F; partition_table_raw::openit($hd, *F) or die "failed to open device";
c::lseek_sector(fileno(F), $sector, $offset) or die "reading of partition in sector $sector failed";
my @pt = map {
sysread F, $tmp, psizeof($format) or die "error while reading partition table in sector $sector";
my %h; @h{@fields} = unpack $format, $tmp;
\%h;
} (1..$nb_primary);
#- check magic number
sysread F, $tmp, length $magic or die "error reading magic number";
$tmp eq $magic or die "bad magic number";
[ @pt ];
}
# write the partition table (and extended ones)
# for each entry, it uses fields: start, size, type, active
sub write($$$;$) {
my ($hd, $sector, $pt) = @_;
local *F; partition_table_raw::openit($hd, *F, 2) or die "error opening device $hd->{device} for writing";
c::lseek_sector(fileno(F), $sector, $offset) or return 0;
@$pt == $nb_primary or die "partition table does not have $nb_primary entries";
foreach (@$pt) {
compute_CHS($hd, $_);
local $_->{start} = $_->{local_start} || 0;
$_->{active} ||= 0; $_->{type} ||= 0; $_->{size} ||= 0; #- for no warning
syswrite F, pack($format, @$_{@fields}), psizeof($format) or return 0;
}
syswrite F, $magic, length $magic or return 0;
1;
}
sub clear_raw { { raw => [ ({}) x $nb_primary ] } }
1;
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