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#include "kernel/filesystem/ext2/filesystem.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/string>
#include <kstd/vector>
#include <cstddef>
#include <cstdint>
#include <string_view>
namespace kernel::filesystem::ext2
{
namespace
{
constexpr size_t SUPERBLOCK_OFFSET = 1024;
constexpr uint16_t MAGIC_NUMBER = 0xEF53;
constexpr uint32_t ROOT_INODE_NUMBER = 2;
constexpr size_t DIRECT_BLOCK_COUNT = 12;
// 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;
}
} // namespace
auto filesystem::mount(kstd::shared_ptr<kapi::devices::device> const & device) -> int
{
kernel::filesystem::filesystem::mount(device);
kernel::devices::block_device_utils::read(m_device, &m_superblock, SUPERBLOCK_OFFSET, sizeof(m_superblock));
if (m_superblock.magic != MAGIC_NUMBER)
{
return -1;
}
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(ROOT_INODE_NUMBER);
// TODO BA-FS26 check if root inode is valid and is a directory ??
return 0;
}
auto filesystem::lookup(kstd::shared_ptr<kernel::filesystem::inode> const & parent, std::string_view name)
-> 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 block_size = get_block_size();
auto const & inode_data = ext2_parent->m_data;
kstd::vector<uint8_t> buffer(block_size);
for (size_t i = 0; i < DIRECT_BLOCK_COUNT && inode_data.block[i] != 0; ++i)
{
kernel::devices::block_device_utils::read(m_device, buffer.data(), inode_data.block[i] * block_size, block_size);
size_t offset = 0;
while (offset < block_size)
{
auto * entry = reinterpret_cast<linked_directory_entry const *>(buffer.data() + offset);
if (entry->inode == 0)
break;
// Stop if the directory entry is malformed to avoid overruns/loops.
// if (entry->rec_len < sizeof(linked_directory_entry) || offset + entry->rec_len > block_size)
// {
// break;
// }
std::string_view entry_name(reinterpret_cast<char const *>(entry->name.data()), entry->name_len);
if (entry_name == name)
{
return read_inode(entry->inode);
}
offset += entry->rec_len;
}
}
return nullptr;
// TODO BA-FS26 implement ext2 directory traversal and inode loading
if (name == "dev")
{
// TODO BA-FS26 just for testing
return nullptr;
}
return kstd::make_shared<inode>();
}
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())
{
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 * get_inode_size();
auto new_inode = kstd::make_shared<inode>();
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::get_block_size() -> size_t
{
return 1024U << m_superblock.log_block_size;
}
auto filesystem::get_inode_size() -> size_t
{
return m_superblock.rev_level == 0 ? 128 : m_superblock.inode_size;
}
} // namespace kernel::filesystem::ext2
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