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Serenity Operating System
1/*
2 * Copyright (c) 2020, Liav A. <liavalb@hotmail.co.il>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright notice, this
9 * list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation
13 * and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
18 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
22 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
23 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <AK/ByteBuffer.h>
28#include <Kernel/Devices/EBRPartitionTable.h>
29
30#define EBR_DEBUG
31
32namespace Kernel {
33
34EBRPartitionTable::EBRPartitionTable(NonnullRefPtr<BlockDevice> device)
35 : m_device(move(device))
36{
37}
38
39EBRPartitionTable::~EBRPartitionTable()
40{
41}
42
43const MBRPartitionHeader& EBRPartitionTable::header() const
44{
45 return *reinterpret_cast<const MBRPartitionHeader*>(m_cached_mbr_header);
46}
47
48const EBRPartitionExtension& EBRPartitionTable::ebr_extension() const
49{
50 return *reinterpret_cast<const EBRPartitionExtension*>(m_cached_ebr_header);
51}
52
53int EBRPartitionTable::index_of_ebr_container() const
54{
55 for (int i = 0; i < 4; i++) {
56 if (header().entry[i].type == EBR_CHS_CONTAINER || header().entry[i].type == EBR_LBA_CONTAINER)
57 return i;
58 }
59 ASSERT_NOT_REACHED();
60}
61
62bool EBRPartitionTable::initialize()
63{
64 if (!m_device->read_block(0, m_cached_mbr_header)) {
65 return false;
66 }
67 auto& header = this->header();
68
69 m_ebr_container_id = index_of_ebr_container() + 1;
70
71#ifdef EBR_DEBUG
72 klog() << "EBRPartitionTable::initialize: MBR_signature=0x" << String::format("%x", header.mbr_signature);
73#endif
74
75 if (header.mbr_signature != MBR_SIGNATURE) {
76 klog() << "EBRPartitionTable::initialize: bad MBR signature 0x" << String::format("%x", header.mbr_signature);
77 return false;
78 }
79
80 auto& ebr_entry = header.entry[m_ebr_container_id - 1];
81 if (!m_device->read_block(ebr_entry.offset, m_cached_ebr_header)) {
82 return false;
83 }
84 size_t index = 1;
85 while (index < 128) { // Unlikely to encounter a disk with 128 partitions in this configuration...
86 if (ebr_extension().next_chained_ebr_extension.offset == 0 && ebr_extension().next_chained_ebr_extension.type == 0) {
87 break;
88 }
89 index++;
90 if (!m_device->read_block(ebr_extension().next_chained_ebr_extension.offset, m_cached_ebr_header)) {
91 return false;
92 }
93 }
94
95 m_ebr_chained_extensions_count = index;
96
97 klog() << "EBRPartitionTable::initialize: Extended partitions count - " << m_ebr_chained_extensions_count;
98
99 return true;
100}
101
102RefPtr<DiskPartition> EBRPartitionTable::get_non_extended_partition(unsigned index)
103{
104 auto& header = this->header();
105 auto& entry = header.entry[index - 1];
106
107#ifdef EBR_DEBUG
108 klog() << "EBRPartitionTable::partition: status=0x" << String::format("%x", entry.status) << " offset=0x" << String::format("%x", entry.offset);
109#endif
110
111 if (entry.offset == 0x00) {
112#ifdef EBR_DEBUG
113 klog() << "EBRPartitionTable::partition: missing partition requested index=" << index;
114#endif
115
116 return nullptr;
117 }
118
119#ifdef EBR_DEBUG
120 klog() << "EBRPartitionTable::partition: found partition index=" << index << " type=" << String::format("%x", entry.type);
121#endif
122
123 return DiskPartition::create(m_device, entry.offset, (entry.offset + entry.length));
124}
125
126RefPtr<DiskPartition> EBRPartitionTable::get_extended_partition(unsigned index)
127{
128
129 unsigned relative_index = index - m_ebr_container_id;
130 auto& header = this->header();
131
132#ifdef EBR_DEBUG
133 klog() << "EBRPartitionTable::partition: relative index " << relative_index;
134#endif
135
136 auto& ebr_entry = header.entry[m_ebr_container_id - 1];
137#ifdef EBR_DEBUG
138 klog() << "EBRPartitionTable::partition: Extended partition, offset 0x" << String::format("%x", ebr_entry.offset) << ", type " << String::format("%x", ebr_entry.type);
139#endif
140
141 if (!m_device->read_block(ebr_entry.offset, m_cached_ebr_header)) {
142 return nullptr;
143 }
144 size_t i = 0;
145 while (i < relative_index) {
146#ifdef EBR_DEBUG
147 klog() << "EBRPartitionTable::partition: logical partition, relative offset 0x" << String::format("%x", ebr_extension().entry.offset) << ", type " << String::format("%x", ebr_extension().entry.type);
148 klog() << "EBRPartitionTable::partition: next logical partition, relative offset 0x" << String::format("%x", ebr_extension().next_chained_ebr_extension.offset) << ", type " << String::format("%x", ebr_extension().next_chained_ebr_extension.type);
149#endif
150 if (ebr_extension().next_chained_ebr_extension.offset == 0 && ebr_extension().next_chained_ebr_extension.type == 0) {
151 break;
152 }
153
154 i++;
155 if (!m_device->read_block(ebr_extension().next_chained_ebr_extension.offset, m_cached_ebr_header)) {
156 return nullptr;
157 }
158 }
159
160#ifdef EBR_DEBUG
161 klog() << "EBRPartitionTable::partition: status=" << String::format("%x", ebr_extension().entry.status) << " offset=" << String::format("%x", ebr_extension().entry.offset + ebr_entry.offset);
162#endif
163
164 if (ebr_extension().entry.offset == 0x00) {
165#ifdef EBR_DEBUG
166 klog() << "EBRPartitionTable::partition: missing partition requested index=" << index;
167#endif
168
169 return nullptr;
170 }
171
172#ifdef EBR_DEBUG
173 klog() << "EBRPartitionTable::partition: found partition index=" << index << " type=" << String::format("%x", ebr_extension().entry.type);
174#endif
175
176 return DiskPartition::create(m_device, ebr_extension().entry.offset + ebr_entry.offset, (ebr_extension().entry.offset + ebr_entry.offset + ebr_extension().entry.length));
177}
178
179bool EBRPartitionTable::index_is_extended_partition(unsigned index) const
180{
181 return !(m_ebr_container_id > index || index > (m_ebr_container_id + m_ebr_chained_extensions_count));
182}
183
184RefPtr<DiskPartition> EBRPartitionTable::partition(unsigned index)
185{
186 ASSERT(index >= 1 && index <= m_ebr_chained_extensions_count + 4);
187
188 auto& header = this->header();
189 if (header.mbr_signature != MBR_SIGNATURE) {
190 klog() << "EBRPartitionTable::initialize: bad MBR signature - not initalized? 0x" << String::format("%x", header.mbr_signature);
191 return nullptr;
192 }
193 if (index_is_extended_partition(index))
194 return get_extended_partition(index);
195 if (index > 4)
196 return get_non_extended_partition(index - m_ebr_chained_extensions_count);
197 return get_non_extended_partition(index);
198}
199
200}