jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2020-2022, Liav A. <liavalb@hotmail.co.il>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#include <AK/Debug.h>
8#include <LibPartition/MBRPartitionTable.h>
9
10#ifndef KERNEL
11# include <LibCore/DeprecatedFile.h>
12#endif
13
14namespace Partition {
15
16#define MBR_SIGNATURE 0xaa55
17#define MBR_PROTECTIVE 0xEE
18#define EBR_CHS_CONTAINER 0x05
19#define EBR_LBA_CONTAINER 0x0F
20
21#ifdef KERNEL
22ErrorOr<NonnullOwnPtr<MBRPartitionTable>> MBRPartitionTable::try_to_initialize(Kernel::StorageDevice& device)
23{
24 auto table = TRY(adopt_nonnull_own_or_enomem(new (nothrow) MBRPartitionTable(device)));
25#else
26ErrorOr<NonnullOwnPtr<MBRPartitionTable>> MBRPartitionTable::try_to_initialize(NonnullRefPtr<Core::DeprecatedFile> device_file)
27{
28 auto table = TRY(adopt_nonnull_own_or_enomem(new (nothrow) MBRPartitionTable(move(device_file))));
29#endif
30 if (table->contains_ebr())
31 return Error::from_errno(ENOTSUP);
32 if (table->is_protective_mbr())
33 return Error::from_errno(ENOTSUP);
34 if (!table->is_valid())
35 return Error::from_errno(EINVAL);
36 return table;
37}
38
39#ifdef KERNEL
40OwnPtr<MBRPartitionTable> MBRPartitionTable::try_to_initialize(Kernel::StorageDevice& device, u32 start_lba)
41{
42 auto table = adopt_nonnull_own_or_enomem(new (nothrow) MBRPartitionTable(device, start_lba)).release_value_but_fixme_should_propagate_errors();
43#else
44OwnPtr<MBRPartitionTable> MBRPartitionTable::try_to_initialize(NonnullRefPtr<Core::DeprecatedFile> device_file, u32 start_lba)
45{
46 auto table = adopt_nonnull_own_or_enomem(new (nothrow) MBRPartitionTable(move(device_file), start_lba)).release_value_but_fixme_should_propagate_errors();
47#endif
48 if (!table->is_valid())
49 return {};
50 return table;
51}
52
53bool MBRPartitionTable::read_boot_record()
54{
55#ifdef KERNEL
56 auto buffer = UserOrKernelBuffer::for_kernel_buffer(m_cached_header.data());
57 if (!m_device->read_block(m_start_lba, buffer))
58 return false;
59#else
60 m_device_file->seek(m_start_lba * m_block_size);
61 if (m_device_file->read(m_cached_header.data(), m_cached_header.size()) != 512)
62 return false;
63#endif
64 m_header_valid = true;
65 return m_header_valid;
66}
67
68#ifdef KERNEL
69MBRPartitionTable::MBRPartitionTable(Kernel::StorageDevice& device, u32 start_lba)
70 : PartitionTable(device)
71#else
72MBRPartitionTable::MBRPartitionTable(NonnullRefPtr<Core::DeprecatedFile> device_file, u32 start_lba)
73 : PartitionTable(move(device_file))
74#endif
75 , m_start_lba(start_lba)
76 , m_cached_header(ByteBuffer::create_zeroed(m_block_size).release_value_but_fixme_should_propagate_errors()) // FIXME: Do something sensible if this fails because of OOM.
77{
78 if (!read_boot_record() || !initialize())
79 return;
80
81 m_header_valid = true;
82
83 auto& header = this->header();
84 for (size_t index = 0; index < 4; index++) {
85 auto& entry = header.entry[index];
86 if (entry.offset == 0x00) {
87 continue;
88 }
89 MUST(m_partitions.try_empend(entry.offset, (entry.offset + entry.length) - 1, entry.type));
90 }
91 m_valid = true;
92}
93
94#ifdef KERNEL
95MBRPartitionTable::MBRPartitionTable(Kernel::StorageDevice& device)
96 : PartitionTable(device)
97#else
98MBRPartitionTable::MBRPartitionTable(NonnullRefPtr<Core::DeprecatedFile> device_file)
99 : PartitionTable(move(device_file))
100#endif
101 , m_start_lba(0)
102 , m_cached_header(ByteBuffer::create_zeroed(m_block_size).release_value_but_fixme_should_propagate_errors()) // FIXME: Do something sensible if this fails because of OOM.
103{
104 if (!read_boot_record() || contains_ebr() || is_protective_mbr() || !initialize())
105 return;
106
107 auto& header = this->header();
108 for (size_t index = 0; index < 4; index++) {
109 auto& entry = header.entry[index];
110 if (entry.offset == 0x00) {
111 continue;
112 }
113 MUST(m_partitions.try_empend(entry.offset, (entry.offset + entry.length) - 1, entry.type));
114 }
115 m_valid = true;
116}
117
118MBRPartitionTable::~MBRPartitionTable() = default;
119
120MBRPartitionTable::Header const& MBRPartitionTable::header() const
121{
122 return *(MBRPartitionTable::Header const*)m_cached_header.data();
123}
124
125bool MBRPartitionTable::initialize()
126{
127 auto& header = this->header();
128 dbgln_if(MBR_DEBUG, "Master Boot Record: mbr_signature={:#08x}", header.mbr_signature);
129 if (header.mbr_signature != MBR_SIGNATURE) {
130 dbgln("Master Boot Record: invalid signature");
131 return false;
132 }
133 return true;
134}
135
136bool MBRPartitionTable::contains_ebr() const
137{
138 for (int i = 0; i < 4; i++) {
139 if (header().entry[i].type == EBR_CHS_CONTAINER || header().entry[i].type == EBR_LBA_CONTAINER)
140 return true;
141 }
142 return false;
143}
144
145bool MBRPartitionTable::is_protective_mbr() const
146{
147 return header().entry[0].type == MBR_PROTECTIVE;
148}
149
150}