jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2022, Undefine <undefine@undefine.pl>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#include <Kernel/Debug.h>
8#include <Kernel/FileSystem/FATFS/FileSystem.h>
9#include <Kernel/FileSystem/FATFS/Inode.h>
10
11namespace Kernel {
12
13ErrorOr<NonnullLockRefPtr<FileSystem>> FATFS::try_create(OpenFileDescription& file_description)
14{
15 return TRY(adopt_nonnull_lock_ref_or_enomem(new (nothrow) FATFS(file_description)));
16}
17
18FATFS::FATFS(OpenFileDescription& file_description)
19 : BlockBasedFileSystem(file_description)
20{
21}
22
23bool FATFS::is_initialized_while_locked()
24{
25 VERIFY(m_lock.is_locked());
26 return !m_root_inode.is_null();
27}
28
29ErrorOr<void> FATFS::initialize_while_locked()
30{
31 VERIFY(m_lock.is_locked());
32 VERIFY(!is_initialized_while_locked());
33
34 m_boot_record = TRY(KBuffer::try_create_with_size("FATFS: Boot Record"sv, m_logical_block_size));
35 auto boot_record_buffer = UserOrKernelBuffer::for_kernel_buffer(m_boot_record->data());
36 TRY(raw_read(0, boot_record_buffer));
37
38 if constexpr (FAT_DEBUG) {
39 dbgln("FATFS: oem_identifier: {}", boot_record()->oem_identifier);
40 dbgln("FATFS: bytes_per_sector: {}", boot_record()->bytes_per_sector);
41 dbgln("FATFS: sectors_per_cluster: {}", boot_record()->sectors_per_cluster);
42 dbgln("FATFS: reserved_sector_count: {}", boot_record()->reserved_sector_count);
43 dbgln("FATFS: fat_count: {}", boot_record()->fat_count);
44 dbgln("FATFS: root_directory_entry_count: {}", boot_record()->root_directory_entry_count);
45 dbgln("FATFS: media_descriptor_type: {}", boot_record()->media_descriptor_type);
46 dbgln("FATFS: sectors_per_track: {}", boot_record()->sectors_per_track);
47 dbgln("FATFS: head_count: {}", boot_record()->head_count);
48 dbgln("FATFS: hidden_sector_count: {}", boot_record()->hidden_sector_count);
49 dbgln("FATFS: sector_count: {}", boot_record()->sector_count);
50 dbgln("FATFS: sectors_per_fat: {}", boot_record()->sectors_per_fat);
51 dbgln("FATFS: flags: {}", boot_record()->flags);
52 dbgln("FATFS: fat_version: {}", boot_record()->fat_version);
53 dbgln("FATFS: root_directory_cluster: {}", boot_record()->root_directory_cluster);
54 dbgln("FATFS: fs_info_sector: {}", boot_record()->fs_info_sector);
55 dbgln("FATFS: backup_boot_sector: {}", boot_record()->backup_boot_sector);
56 dbgln("FATFS: drive_number: {}", boot_record()->drive_number);
57 dbgln("FATFS: volume_id: {}", boot_record()->volume_id);
58 }
59
60 if (boot_record()->signature != signature_1 && boot_record()->signature != signature_2) {
61 dbgln("FATFS: Invalid signature");
62 return EINVAL;
63 }
64
65 m_logical_block_size = boot_record()->bytes_per_sector;
66 set_block_size(m_logical_block_size);
67
68 u32 root_directory_sectors = ((boot_record()->root_directory_entry_count * sizeof(FATEntry)) + (m_logical_block_size - 1)) / m_logical_block_size;
69 m_first_data_sector = boot_record()->reserved_sector_count + (boot_record()->fat_count * boot_record()->sectors_per_fat) + root_directory_sectors;
70
71 TRY(BlockBasedFileSystem::initialize_while_locked());
72
73 FATEntry root_entry {};
74
75 root_entry.first_cluster_low = boot_record()->root_directory_cluster & 0xFFFF;
76 root_entry.first_cluster_high = boot_record()->root_directory_cluster >> 16;
77
78 root_entry.attributes = FATAttributes::Directory;
79 m_root_inode = TRY(FATInode::create(*this, root_entry));
80
81 return {};
82}
83
84Inode& FATFS::root_inode()
85{
86 return *m_root_inode;
87}
88
89BlockBasedFileSystem::BlockIndex FATFS::first_block_of_cluster(u32 cluster) const
90{
91 return ((cluster - first_data_cluster) * boot_record()->sectors_per_cluster) + m_first_data_sector;
92}
93
94}