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#include <kernel/filesystem/ext2/filesystem.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>
#include <string_view>
#include <unistd.h>
namespace kernel::filesystem::ext2
{
auto filesystem::mount(kstd::shared_ptr<kernel::filesystem::inode> const & backing_inode) -> operation_result
{
kernel::filesystem::filesystem::mount(backing_inode);
m_backing_inode->read(&m_superblock, constants::superblock_offset, sizeof(m_superblock));
if (m_superblock.magic != constants::magic_number)
{
return operation_result::invalid_magic_number;
}
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);
m_backing_inode->read(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) const
-> kstd::shared_ptr<kernel::filesystem::inode>
{
if (!parent || !parent->is_directory())
{
return nullptr;
}
auto * ext2_parent = static_cast<inode *>(parent.get());
if (!ext2_parent)
{
return nullptr;
}
auto const & inode_data = ext2_parent->data();
kstd::vector<uint8_t> buffer(block_size());
for (uint32_t i = 0; i < 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();
m_backing_inode->read(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) const -> kstd::shared_ptr<inode>
{
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())
{
return nullptr;
}
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 * inode_size();
auto new_inode_data = inode_data{};
m_backing_inode->read(&new_inode_data, inode_offset, sizeof(inode_data));
return kstd::make_shared<inode>(this, new_inode_data);
}
auto filesystem::map_inode_block_index_to_global_block_number(size_t inode_block_index, inode_data data) const
-> ssize_t
{
if (inode_block_index < constants::direct_block_count)
{
return data.block.at(inode_block_index);
}
inode_block_index -= constants::direct_block_count;
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_singly_indirect_block_number(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);
return read_doubly_indirect_block_number(doubly_indirect_block_number, inode_block_index);
}
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);
return read_triply_indirect_block_number(triply_indirect_block_number, inode_block_index);
}
return -1;
}
auto filesystem::read_singly_indirect_block_number(uint32_t singly_indirect_block_number,
size_t block_index_in_singly_indirect_block) const -> size_t
{
if (singly_indirect_block_number == 0)
{
return 0;
}
return read_block_number_at_index(singly_indirect_block_number, block_index_in_singly_indirect_block);
}
auto filesystem::read_doubly_indirect_block_number(uint32_t doubly_indirect_block_number,
size_t block_index_in_doubly_indirect_block) const -> size_t
{
if (doubly_indirect_block_number == 0)
{
return 0;
}
auto const singly_indirect_block_index_in_doubly_indirect_block =
block_index_in_doubly_indirect_block / block_numbers_per_singly_indirect_block();
auto const block_index_in_singly_indirect_block =
block_index_in_doubly_indirect_block % 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);
return read_singly_indirect_block_number(singly_indirect_block_number, block_index_in_singly_indirect_block);
}
auto filesystem::read_triply_indirect_block_number(uint32_t triply_indirect_block_number,
size_t block_index_in_triply_indirect_block) const -> size_t
{
if (triply_indirect_block_number == 0)
{
return 0;
}
auto const doubly_indirect_block_index_in_triply_indirect_block =
block_index_in_triply_indirect_block / block_numbers_per_doubly_indirect_block();
auto const block_index_in_doubly_indirect_block =
block_index_in_triply_indirect_block % 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);
return read_doubly_indirect_block_number(doubly_indirect_block_number, block_index_in_doubly_indirect_block);
}
auto filesystem::read_block_number_at_index(uint32_t block_number, size_t index) const -> uint32_t
{
uint32_t block_number_buffer = 0;
auto const block_start_offset = block_number * block_size();
auto const number_start_address = block_start_offset + index * sizeof(uint32_t);
m_backing_inode->read(&block_number_buffer, number_start_address, sizeof(uint32_t));
return block_number_buffer;
}
auto filesystem::block_numbers_per_block() const -> size_t
{
return block_size() / sizeof(uint32_t);
}
auto filesystem::block_numbers_per_singly_indirect_block() const -> size_t
{
return block_numbers_per_block();
}
auto filesystem::block_numbers_per_doubly_indirect_block() const -> size_t
{
return block_numbers_per_singly_indirect_block() * block_numbers_per_block();
}
auto filesystem::block_numbers_per_triply_indirect_block() const -> size_t
{
return block_numbers_per_doubly_indirect_block() * block_numbers_per_block();
}
auto filesystem::block_size() const -> size_t
{
return constants::base_block_size << m_superblock.log_block_size;
}
auto filesystem::revision_level() const -> uint32_t
{
return m_superblock.rev_level;
}
auto filesystem::inode_size() const -> uint16_t
{
return revision_level() == constants::good_old_revision ? 128 : m_superblock.inode_size;
}
auto filesystem::inode_block_count(inode_data const & data) const -> uint32_t
{
return data.blocks / (2 << m_superblock.log_block_size);
}
auto filesystem::block_group_descriptor_table_offset() const -> size_t
{
return block_size() == 1024 ? 2 * block_size() : block_size();
}
} // namespace kernel::filesystem::ext2
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