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#include "kernel/filesystem/vfs.hpp"
#include "kapi/system.hpp"
#include "kernel/devices/storage/management.hpp"
#include "kernel/filesystem/dentry.hpp"
#include "kernel/filesystem/devfs/filesystem.hpp"
#include "kernel/filesystem/filesystem.hpp"
#include "kernel/filesystem/mount.hpp"
#include "kernel/filesystem/mount_table.hpp"
#include "kernel/filesystem/open_file_description.hpp"
#include "kernel/filesystem/rootfs/filesystem.hpp"
#include <kstd/memory>
#include <optional>
#include <ranges>
#include <string_view>
namespace
{
constinit auto static active_vfs = std::optional<kernel::filesystem::vfs>{};
} // namespace
namespace kernel::filesystem
{
auto vfs::init() -> void
{
if (active_vfs)
{
kapi::system::panic("[FILESYSTEM] vfs has already been initialized.");
}
active_vfs.emplace(vfs{});
active_vfs->init_internal();
}
auto vfs::init_internal() -> void
{
auto root_fs = kstd::make_shared<rootfs::filesystem>();
root_fs->mount(nullptr);
auto root_fs_root_dentry = kstd::make_shared<dentry>(nullptr, root_fs->root_inode());
m_mount_table.add_mount(kstd::make_shared<mount>(nullptr, root_fs_root_dentry, root_fs, "", nullptr));
auto storage_mgmt = devices::storage::management::get();
if (auto boot_device = storage_mgmt.determine_boot_device())
{
auto boot_root_fs = kernel::filesystem::filesystem::probe_and_mount(boot_device);
if (boot_root_fs)
{
do_mount_internal("/", root_fs_root_dentry, boot_root_fs);
}
}
auto device_fs = kstd::make_shared<devfs::filesystem>();
device_fs->mount(nullptr);
do_mount_internal("/dev", root_fs_root_dentry, device_fs);
}
auto vfs::get() -> vfs &
{
if (!active_vfs)
{
kapi::system::panic("[FILESYSTEM] vfs has not been initialized.");
}
return *active_vfs;
}
auto vfs::open(std::string_view path) -> kstd::shared_ptr<open_file_description>
{
if (auto dentry = resolve_path(path))
{
return kstd::make_shared<open_file_description>(dentry->get_inode());
}
return nullptr;
}
auto vfs::do_mount(std::string_view path, kstd::shared_ptr<filesystem> const & filesystem) -> operation_result
{
if (!filesystem)
{
return operation_result::filesystem_null;
}
if (path.empty() || path.front() != '/' || (path.size() > 1 && path.back() == '/'))
{
return operation_result::invalid_path;
}
if (auto mount_point_dentry = resolve_path(path))
{
do_mount_internal(path, mount_point_dentry, filesystem);
return operation_result::success;
}
return operation_result::mount_point_not_found;
}
auto vfs::unmount(std::string_view path) -> operation_result
{
if (path.empty() || path.front() != '/' || (path.size() > 1 && path.back() == '/'))
{
return operation_result::invalid_path;
}
auto remove_result = m_mount_table.remove_mount(path);
if (remove_result == mount_table::operation_result::removed)
{
return operation_result::success;
}
if (remove_result == mount_table::operation_result::has_child_mounts)
{
return operation_result::unmount_failed;
}
return operation_result::mount_point_not_found;
}
auto vfs::do_mount_internal(std::string_view path, kstd::shared_ptr<dentry> const & mount_point_dentry,
kstd::shared_ptr<filesystem> const & fs) -> void
{
auto parent_mount = m_mount_table.find_longest_prefix_mount(path);
auto new_fs_root = kstd::make_shared<dentry>(mount_point_dentry, fs->root_inode());
auto new_mount = kstd::make_shared<mount>(mount_point_dentry, new_fs_root, fs, path, parent_mount);
m_mount_table.add_mount(new_mount);
}
auto vfs::resolve_path(std::string_view path) -> kstd::shared_ptr<dentry>
{
// TODO BA-FS26 implement full path resolution semantics.
// TODO BA-FS26 better path validation
// TODO BA-FS26 implement a path parser (maybe in libs?) and use it here and in do_mount
if (path.empty() || path.front() != '/')
return nullptr;
// TODO BA-FS26 longest match in mount_table -> jump into final fs directly
// TODO BA-FS26 performance optimization first check mounted_flag O(1) then check mount_table O(n)
auto best_mount = m_mount_table.find_longest_prefix_mount(path);
if (!best_mount)
{
kapi::system::panic("[FILESYSTEM] no root mount found.");
}
auto current_dentry = best_mount->root_dentry();
auto current_fs = best_mount->get_filesystem();
std::string_view remaining = path.substr(best_mount->get_mount_path().size());
auto path_parts =
std::views::split(remaining, '/') | std::views::filter([](auto const & part) { return !part.empty(); });
for (auto const & part : path_parts)
{
std::string_view part_view{part};
auto next_dentry = current_dentry->find_child(part_view);
if (!next_dentry)
{
auto found_inode = current_fs->lookup(current_dentry->get_inode(), part_view);
if (!found_inode)
return nullptr;
next_dentry = kstd::make_shared<dentry>(current_dentry, found_inode, part_view);
current_dentry->add_child(next_dentry);
}
current_dentry = next_dentry;
}
return current_dentry;
}
} // namespace kernel::filesystem
namespace kernel::tests::filesystem::vfs
{
auto deinit() -> void
{
active_vfs.reset();
}
} // namespace kernel::tests::filesystem::vfs
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