diff options
Diffstat (limited to 'kernel/src/filesystem/ext2/filesystem.cpp')
| -rw-r--r-- | kernel/src/filesystem/ext2/filesystem.cpp | 241 |
1 files changed, 200 insertions, 41 deletions
diff --git a/kernel/src/filesystem/ext2/filesystem.cpp b/kernel/src/filesystem/ext2/filesystem.cpp index eb9edc4..0ad5c97 100644 --- a/kernel/src/filesystem/ext2/filesystem.cpp +++ b/kernel/src/filesystem/ext2/filesystem.cpp @@ -1,13 +1,17 @@ #include "kernel/filesystem/ext2/filesystem.hpp" -#include "kernel/devices/block_device_utils.hpp" #include "kapi/devices/device.hpp" + +#include "kernel/devices/block_device_utils.hpp" +#include "kernel/filesystem/ext2/block_group_descriptor.hpp" #include "kernel/filesystem/ext2/inode.hpp" +#include "kernel/filesystem/ext2/linked_directory_entry.hpp" #include "kernel/filesystem/ext2/superblock.hpp" #include "kernel/filesystem/filesystem.hpp" #include "kernel/filesystem/inode.hpp" #include <kstd/memory> +#include <kstd/vector> #include <cstddef> #include <cstdint> @@ -17,56 +21,211 @@ namespace kernel::filesystem::ext2 { namespace { - // constexpr size_t SUPERBLOCK_OFFSET = 1024; - // constexpr uint16_t EXT2_MAGIC = 0xEF53; - - // // Mode bits - // constexpr uint16_t S_IFMT = 0xF000; - // constexpr uint16_t S_IFREG = 0x8000; - // constexpr uint16_t S_IFDIR = 0x4000; - - // auto S_ISREG(uint16_t mode) -> bool - // { - // return (mode & S_IFMT) == S_IFREG; - // } - // auto S_ISDIR(uint16_t mode) -> bool - // { - // return (mode & S_IFMT) == S_IFDIR; - // } - - // auto get_block_size(superblock const & superblock) -> size_t - // { - // return 1024U << superblock.log_block_size; - // } - - // auto get_inode_size(superblock const & superblock) -> size_t - // { - // return superblock.rev_level == 0 ? 128 : superblock.inode_size; - // } + auto S_ISREG(uint16_t mode) -> bool + { + return (mode & constants::mode_mask) == constants::mode_regular; + } + + auto S_ISDIR(uint16_t mode) -> bool + { + return (mode & constants::mode_mask) == constants::mode_directory; + } } // namespace - auto filesystem::mount(kstd::shared_ptr<kapi::devices::device> const & device) -> int + auto filesystem::mount(kstd::shared_ptr<kapi::devices::device> const & device) -> operation_result { - kernel::filesystem::filesystem::mount(device); // TODO BA-FS26 error handling? - // TODO BA-FS26 load proper root inode from ext2 metadata - // m_root_inode = inode{inode_kind::directory}; - - // TODO BA-FS26 implement - m_root_inode = kstd::make_shared<inode>(); - // devices::block_device_utils::read(device, nullptr, 0, 0); // TODO BA-FS26 just for testing - return 0; + kernel::filesystem::filesystem::mount(device); + + kernel::devices::block_device_utils::read(m_device, &m_superblock, constants::superblock_offset, + sizeof(m_superblock)); + + if (m_superblock.magic != constants::magic_number) + { + return operation_result::invalid_magic_number; + } + + auto const block_size = get_block_size(); + auto const blocks_per_group = m_superblock.blocks_per_group; + auto const num_block_groups = (m_superblock.blocks_count + blocks_per_group - 1) / blocks_per_group; + + m_block_group_descriptors = kstd::vector<block_group_descriptor>(num_block_groups); + + auto const block_group_descriptor_table_offset = block_size == 1024 ? 2 * block_size : block_size; + kernel::devices::block_device_utils::read(m_device, m_block_group_descriptors.data(), + block_group_descriptor_table_offset, + num_block_groups * sizeof(block_group_descriptor)); + + m_root_inode = read_inode(constants::root_inode_number); + + if (!m_root_inode || !m_root_inode->is_directory()) + { + return operation_result::invalid_root_inode; + } + return operation_result::success; } - auto filesystem::lookup(kstd::shared_ptr<kernel::filesystem::inode> const & /*parent*/, std::string_view name) + auto filesystem::lookup(kstd::shared_ptr<kernel::filesystem::inode> const & parent, std::string_view name) -> kstd::shared_ptr<kernel::filesystem::inode> { - // TODO BA-FS26 implement ext2 directory traversal and inode loading - if (name == "dev") + if (!parent || !parent->is_directory()) + { + return nullptr; + } + + auto * ext2_parent = static_cast<inode *>(parent.get()); + if (!ext2_parent) + { + return nullptr; + } + + auto const block_size = get_block_size(); + auto const & inode_data = ext2_parent->m_data; + kstd::vector<uint8_t> buffer(block_size); + + for (uint32_t i = 0; i < get_inode_block_count(inode_data); ++i) + { + auto const global_block_number = map_inode_block_index_to_global_block_number(i, inode_data); + auto const block_offset = global_block_number * block_size; + kernel::devices::block_device_utils::read(m_device, buffer.data(), block_offset, block_size); + + auto const * entry = reinterpret_cast<linked_directory_entry const *>(buffer.data()); + auto bytes_read = 0uz; + + while (bytes_read < block_size && entry->inode != 0) + { + auto const entry_name = std::string_view{entry->name.data(), entry->name_len}; + if (entry_name == name) + { + return read_inode(entry->inode); + } + + bytes_read += entry->rec_len; + entry = reinterpret_cast<linked_directory_entry const *>(buffer.data() + bytes_read); + } + } + + return nullptr; + } + + auto filesystem::read_inode(uint32_t inode_number) -> kstd::shared_ptr<inode> + { + auto const block_size = get_block_size(); + auto const inodes_per_group = m_superblock.inodes_per_group; + auto const block_group_index = (inode_number - 1) / inodes_per_group; + auto const inode_index_within_group = (inode_number - 1) % inodes_per_group; + + if (block_group_index >= m_block_group_descriptors.size()) { - // TODO BA-FS26 just for testing return nullptr; } - return kstd::make_shared<inode>(); + auto const & block_group_descriptor = m_block_group_descriptors.at(block_group_index); + auto const inode_table_start_block = block_group_descriptor.inode_table; + auto const inode_table_offset = static_cast<size_t>(inode_table_start_block) * block_size; + auto const inode_offset = inode_table_offset + inode_index_within_group * get_inode_size(); + + auto new_inode = kstd::make_shared<inode>(this); + kernel::devices::block_device_utils::read(m_device, &new_inode->m_data, inode_offset, sizeof(inode_data)); + + // TODO BA-FS26 improve inode_kind really needed? or just map it to the mode bits? + if (S_ISREG(new_inode->m_data.mode)) + { + new_inode->m_kind = inode::inode_kind::regular; + } + else if (S_ISDIR(new_inode->m_data.mode)) + { + new_inode->m_kind = inode::inode_kind::directory; + } + else + { + // TODO BA-FS26 really correct?? + return nullptr; + } + + return new_inode; + } + + auto filesystem::map_inode_block_index_to_global_block_number(uint32_t inode_block_index, inode_data data) -> uint32_t + { + if (inode_block_index < constants::direct_block_count) + { + return data.block.at(inode_block_index); + } + inode_block_index -= constants::direct_block_count; + + auto const block_size = get_block_size(); + auto const numbers_per_block = block_size / sizeof(uint32_t); + + auto const block_numbers_per_singly_indirect_block = numbers_per_block; + auto const block_numbers_per_doubly_indirect_block = numbers_per_block * block_numbers_per_singly_indirect_block; + auto const block_numbers_per_triply_indirect_block = numbers_per_block * block_numbers_per_doubly_indirect_block; + + if (inode_block_index < block_numbers_per_singly_indirect_block) + { + auto const singly_indirect_block_number = data.block.at(constants::singly_indirect_block_index); + return read_block_number_at_index(singly_indirect_block_number, inode_block_index); + } + inode_block_index -= block_numbers_per_singly_indirect_block; + + if (inode_block_index < block_numbers_per_doubly_indirect_block) + { + auto const doubly_indirect_block_number = data.block.at(constants::doubly_indirect_block_index); + auto const singly_indirect_block_index_in_doubly_indirect_block = + inode_block_index / block_numbers_per_singly_indirect_block; + auto const singly_indirect_block_number = read_block_number_at_index( + doubly_indirect_block_number, singly_indirect_block_index_in_doubly_indirect_block); + + auto const block_index_in_singly_indirect_block = inode_block_index % block_numbers_per_singly_indirect_block; + return read_block_number_at_index(singly_indirect_block_number, block_index_in_singly_indirect_block); + } + inode_block_index -= block_numbers_per_doubly_indirect_block; + + if (inode_block_index < block_numbers_per_triply_indirect_block) + { + auto const triply_indirect_block_number = data.block.at(constants::triply_indirect_block_index); + auto const doubly_indirect_block_index_in_triply_indirect_block = + inode_block_index / block_numbers_per_doubly_indirect_block; + auto const doubly_indirect_block_number = read_block_number_at_index( + triply_indirect_block_number, doubly_indirect_block_index_in_triply_indirect_block); + + auto const remaining_block_numbers = inode_block_index % block_numbers_per_doubly_indirect_block; + + auto const singly_indirect_block_index_in_doubly_indirect_block = + remaining_block_numbers / block_numbers_per_singly_indirect_block; + auto const singly_indirect_block_number = read_block_number_at_index( + doubly_indirect_block_number, singly_indirect_block_index_in_doubly_indirect_block); + + auto const block_index_in_singly_indirect_block = + remaining_block_numbers % block_numbers_per_singly_indirect_block; + return read_block_number_at_index(singly_indirect_block_number, block_index_in_singly_indirect_block); + } + + return 0; // TODO BA-FS26 really correct?? + } + + auto filesystem::read_block_number_at_index(uint32_t block_number, uint32_t index) -> uint32_t + { + uint32_t block_number_buffer = 0; + + auto const block_start_offset = block_number * get_block_size(); + auto const number_start_address = block_start_offset + index * sizeof(uint32_t); + kernel::devices::block_device_utils::read(m_device, &block_number_buffer, number_start_address, sizeof(uint32_t)); + + return block_number_buffer; + } + + auto filesystem::get_block_size() -> size_t + { + return constants::base_block_size << m_superblock.log_block_size; + } + + auto filesystem::get_inode_size() -> size_t + { + return m_superblock.rev_level == 0 ? 128 : m_superblock.inode_size; + } + + auto filesystem::get_inode_block_count(inode_data const & data) -> uint32_t + { + return data.blocks / (2 << m_superblock.log_block_size); } } // namespace kernel::filesystem::ext2 |