summaryrefslogtreecommitdiffstats
path: root/perl-install/partition_table/dos.pm
blob: a97fcf89ded5a4f6de833fbdd15b0e60951b050f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
package partition_table::dos;

use diagnostics;
use strict;
use vars qw(@ISA);

@ISA = qw(partition_table::raw);

use common;
use partition_table::raw;
use partition_table;
use fs::type;
use c;

my @fields = qw(active start_head start_sec start_cyl pt_type end_head end_sec end_cyl start size);
my $format = "C8 V2";
my $magic = "\x55\xAA";
my $nb_primary = 4;

my $offset = $common::SECTORSIZE - length($magic) - $nb_primary * common::psizeof($format);

sub use_pt_type { 1 }
sub hasExtended { 1 }

sub geometry_to_string {
    my ($geom) = @_;
    "$geom->{cylinders}/$geom->{heads}/$geom->{sectors}";
}

sub last_usable_sector { 
    my ($hd) = @_;
    #- do not use totalsectors, see docs/Partition-ends-after-end-of-disk.txt for more
    $hd->{geom}{sectors} * $hd->{geom}{heads} * $hd->{geom}{cylinders};
}

my $two_TB = 2 * 1024 * 1024 * 2048;
sub max_partition_start { $two_TB - 1 }
sub max_partition_size { $two_TB - 1 }

sub get_rawCHS {
    my ($part) = @_;

    exists $part->{start_cyl} or internal_error("get_rawCHS $part->{device}");

    [ $part->{start_cyl}, $part->{start_head}, $part->{start_sec} ],
      [ $part->{end_cyl}, $part->{end_head}, $part->{end_sec} ];
}
sub set_rawCHS {
    my ($part, $raw_chs_start, $raw_chs_end) = @_;   
    ($part->{start_cyl}, $part->{start_head}, $part->{start_sec}) = @$raw_chs_start;
    ($part->{end_cyl}, $part->{end_head}, $part->{end_sec}) = @$raw_chs_end;
}

sub compute_CHS {
    my ($hd, $part) = @_;
    my ($chs_start, $chs_end) = CHS_from_part_linear($hd->{geom}, $part);
    set_rawCHS($part, $chs_start ? CHS2rawCHS($hd->{geom}, $chs_start) : [0,0,0], 
	              $chs_end ? CHS2rawCHS($hd->{geom}, $chs_end) : [0,0,0]);
}

sub CHS_from_part_rawCHS {
    my ($part) = @_;

    $part->{start} || $part->{pt_type} or return;

    my ($raw_chs_start, $raw_chs_end) = get_rawCHS($part);
    rawCHS2CHS($raw_chs_start), rawCHS2CHS($raw_chs_end);
}

sub CHS_from_part_linear {
    my ($geom, $part) = @_;

    $part->{start} || $part->{pt_type} or return;

    sector2CHS($geom, $part->{start}), sector2CHS($geom, $part->{start} + $part->{size} - 1);
}

sub rawCHS2CHS {
    my ($chs) = @_;
    my ($c, $h, $s) = @$chs;
    [ $c | (($s & 0xc0) << 2), $h, ($s & 0x3f) - 1 ];
}

sub CHS2rawCHS {
    my ($geom, $chs) = @_;
    my ($c, $h, $s) = @$chs;
    if ($c > 1023) {
	#- no way to have a #cylinder >= 1024
	$c = 1023;
	$h = $geom->{heads} - 1;
	$s = $geom->{sectors} - 1;
    }
    [ $c & 0xff, $h, ($s + 1) | (($c >> 2) & 0xc0) ];
}

# returns (cylinder, head, sector)
sub sector2CHS {
    my ($geom, $start) = @_;
    my ($s, $h);
    ($start, $s) = divide($start, $geom->{sectors});
    ($start, $h) = divide($start, $geom->{heads});
    [ $start, $h, $s ];
}

sub is_geometry_valid_for_the_partition_table {
    my ($hd, $geom, $no_log) = @_;

    every {
	my ($chs_start_v1, $chs_end_v1) = map { join(',', @$_) } CHS_from_part_rawCHS($_) or next;
	my ($chs_start_v2, $chs_end_v2) = map { join(',', @$_) } map { [ min($_->[0], 1023), $_->[1], $_->[2] ] } CHS_from_part_linear($geom, $_);
	if (!$no_log) {
	    $chs_start_v1 eq $chs_start_v2 or log::l("is_geometry_valid_for_the_partition_table failed for ($_->{device}, $_->{start}): $chs_start_v1 vs $chs_start_v2 with geometry " . geometry_to_string($geom));
	    $chs_end_v1 eq $chs_end_v2 or log::l("is_geometry_valid_for_the_partition_table failed for ($_->{device}, " . ($_->{start} + $_->{size} - 1) . "): $chs_end_v1 vs $chs_end_v2 with geometry " . geometry_to_string($geom));
	}
	$chs_start_v1 eq $chs_start_v2 && $chs_end_v1 eq $chs_end_v2;
    } @{$hd->{primary}{normal} || []};
}

#- from parted, thanks!
my @valid_nb_sectors = (63, 61, 48, 32, 16);
my @valid_nb_heads = (255, 240, 192, 128, 96, 64, 61, 32, 17, 16);

sub guess_geometry_from_partition_table {
    my ($hd) = @_;

    my @chss = map { CHS_from_part_rawCHS($_) } @{$hd->{primary}{normal} || []} or return { empty => 1 };
    my ($nb_heads, $nb_sectors) = (max(map { $_->[1] } @chss) + 1, max(map { $_->[2] } @chss) + 1);    
    my $geom = { sectors => $nb_sectors, heads => $nb_heads };
    partition_table::raw::compute_nb_cylinders($geom, $hd->{totalsectors});
    log::l("guess_geometry_from_partition_table $hd->{device}: " . geometry_to_string($geom));

    member($geom->{sectors}, @valid_nb_sectors) or return { invalid => 1 };
    $geom;
}

sub geometry_from_edd {
    my ($hd, $edd_dir) = @_;

    my $sectors = cat_("$edd_dir/legacy_sectors_per_track") or return;
    my $heads = cat_("$edd_dir/legacy_max_head") or return;

    my $geom = { sectors => 0 + $sectors, heads => 1 + $heads, from_edd => 1 };
    is_geometry_valid_for_the_partition_table($hd, $geom, 0) or return;
    partition_table::raw::compute_nb_cylinders($geom, $hd->{totalsectors});

    log::l("geometry_from_edd $hd->{device} $hd->{volume_id}: " . geometry_to_string($geom));
    
    $geom;
}


sub try_every_geometry {
    my ($hd) = @_;

    my $geom = {};
    foreach (@valid_nb_sectors) {
	$geom->{sectors} = $_;
	foreach (@valid_nb_heads) {
	    $geom->{heads} = $_;
	    if (is_geometry_valid_for_the_partition_table($hd, $geom, 1)) {
		partition_table::raw::compute_nb_cylinders($geom, $hd->{totalsectors});
		log::l("try_every_geometry $hd->{device}: found " . geometry_to_string($geom));
		return $geom;
	    }
	}
    }
    log::l("$hd->{device}: argh! no geometry exists for this partition table");
    undef;
}

sub set_best_geometry_for_the_partition_table {
    my ($hd) = @_;

    my $guessed_geom = guess_geometry_from_partition_table($hd);
    if ($guessed_geom->{empty}) {
	log::l("$hd->{device}: would need looking at BIOS info to find out geometry") if !$hd->{geom}{from_edd};
	return;
    } 
    my $default_ok = is_geometry_valid_for_the_partition_table($hd, $hd->{geom}, 0);
    if ($guessed_geom->{invalid}) {
	log::l("$hd->{device}: no valid geometry guessed from partition table");
	$default_ok and return;
	$guessed_geom = try_every_geometry($hd) or return;
    }
    
    if ($guessed_geom->{heads} == $hd->{geom}{heads} && $guessed_geom->{sectors} == $hd->{geom}{sectors}) {
	# cool!
    } else {
	my $guessed_ok = is_geometry_valid_for_the_partition_table($hd, $guessed_geom, 0);
	if ($default_ok && $guessed_ok) {
	    #- oh my!?
	    log::l("$hd->{device}: both guessed and default are valid??? " . geometry_to_string($hd->{geom}) . " vs " . geometry_to_string($guessed_geom));	    
	} elsif ($default_ok) {
	    log::l("$hd->{device}: keeping default geometry " . geometry_to_string($hd->{geom}));	    
	} elsif ($guessed_ok) {
	    log::l("$hd->{device}: using guessed geometry " . geometry_to_string($guessed_geom) . " instead of " . geometry_to_string($hd->{geom}));
	    put_in_hash($hd->{geom}, $guessed_geom);
	} else {
	    log::l("$hd->{device}: argh! no valid geometry found");	    
	}
    }
}

sub read_one {
    my ($hd, $sector) = @_;
    my $tmp;

    my $F = partition_table::raw::openit($hd) 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{pt_type} = 'BIOS_GRUB' if $h{pt_type} == 0 && $h{size} > 0;
	fs::type::set_pt_type(\%h, $h{pt_type});
	\%h;
    } (1..$nb_primary);

    #- check magic number
    sysread $F, $tmp, length $magic or die "error reading magic number on disk $hd->{device}";
    $tmp eq $magic or die "bad magic number on disk $hd->{device}";

    if (c::get_disk_type($hd->{file}) ne "msdos") {
	# libparted may have ignored it because of overlapping partitions or other error
	# while it is actually a partition table.
	$hd->{fs_type_from_magic} and die "unpartitionned disk";
	my $primary = partition_table::raw::pt_info_to_primary($hd, [ @pt ]);
       foreach my $i (@{$primary->{normal}}) {
          if ($i->{active} && $i->{active} != 0x80 || 
             $hd->{totalsectors} && $i->{start} > $hd->{totalsectors}) {
                die "Invalid DOS partition table";
          }
       }
    }

    [ @pt ];
}

# prepare to write the partition table (and extended ones)
sub start_write {
    my ($hd) = @_;

    log::l("partition::dos::write $hd->{device}");

    #- handle testing for writing partition table on file only!
    my $F;
    if ($::testing) {
	my $file = "/tmp/partition_table_$hd->{device}";
	open $F, ">$file" or die "error opening test file $file";
    } else {
	$F = partition_table::raw::openit($hd, 2) or die "error opening device $hd->{device} for writing";
    }
    $F;
}

# write the partition table (and extended ones)
# for each entry, it uses fields: start, size, pt_type, active
sub write {
    my ($hd, $F, $sector, $pt) = @_;

    if (!$::testing) {
        c::lseek_sector(fileno($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; $_->{pt_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 end_write {
    my ($hd, $F) = @_;
    close $F;
}

sub need_to_tell_kernel {
    my ($hd) = @_;
    # Whenever udevd receives a change event for a raw disk device it is watching, it asks the kernel to
    # rescan the partition table on that device by calling the BLKRRPART ioctl. This is only successful
    # if none of the partitions on that device are currently mounted. So if any partitions are mounted,
    # we need to tell the kernel what has changed ourselves.
    # The udev/rules.d/60-block.rules file causes the raw disk devices to be watched by udev. This file is
    # not present in the cut-down system used to run the classic installer, so we always need to tell the
    # kernel in that case.
    # diskdrake will not let the user delete an individual partition that is mounted, but will let the
    # user clear all partitions. So initialize() records if any partitions were mounted and we take note
    # of that here.
    return ! -e '/usr/lib/udev/rules.d/60-block.rules' || delete $hd->{hadMountedPartitions} || any { $_->{isMounted} } partition_table::get_normal_parts($hd);
}

sub empty_raw { { raw => [ ({}) x $nb_primary ] } }

sub initialize { 
    my ($class, $hd) = @_;
    # Remember whether any existing partitions are mounted, for use by need_to_tell_kernel().
    $hd->{hadMountedPartitions} = 1 if any { $_->{isMounted} } partition_table::get_normal_parts($hd);
    $hd->{primary} = empty_raw();
    bless $hd, $class;
}

1;