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#ifndef TEACHOS_KERNEL_FILESYSTEM_DEVICE_NUMBER_REGISTRY_HPP
#define TEACHOS_KERNEL_FILESYSTEM_DEVICE_NUMBER_REGISTRY_HPP
#include <kernel/filesystem/file_type.hpp>
#include <kapi/devices.hpp>
#include <kapi/filesystem.hpp>
#include <kapi/tracked_mutex.hpp>
#include <kstd/flat_map.hpp>
#include <kstd/memory.hpp>
#include <kstd/result.hpp>
#include <kstd/string.hpp>
#include <kstd/vector.hpp>
#include <cstdint>
namespace kernel::filesystem
{
struct device_number_registry_observer;
//! A registry to assign stable device numbers to published devices.
struct device_number_registry final : kapi::devices::facet_registry_observer
{
//! A single numbered device.
//!
//! Theses entries are used, for example, in devfs to provide access to devices.
struct entry
{
kapi::filesystem::device_number number;
file_type type;
kstd::string name;
kstd::weak_ptr<kapi::devices::device> device;
};
//! Construct a new device number registry, subscribing to the given facet registry.
//!
//! @param facet_registry The facet registry to back this device number registry.
explicit device_number_registry(kapi::devices::facet_registry & facet_registry);
//! Destroy this registry.
~device_number_registry() override;
device_number_registry(device_number_registry const &) = delete;
device_number_registry(device_number_registry &&) = delete;
auto operator=(device_number_registry const &) -> device_number_registry & = delete;
auto operator=(device_number_registry &&) -> device_number_registry & = delete;
//! Get the system global instance of the registry.
[[nodiscard]] auto static get() -> device_number_registry &;
//! Resolve a device number and file type to a device.
//!
//! @param number The device number.
//! @param type The expected file type of the device.
//! @return A device if a fitting entry is found, an error otherwise.
[[nodiscard]] auto resolve(kapi::filesystem::device_number number, file_type type) const
-> kstd::result<kstd::shared_ptr<kapi::devices::device>>;
//! Resolve a device to it's device number.
//!
//! @param device The device to find the number for.
//! @return The device number associated with the given device, or an error otherwise.
[[nodiscard]] auto number_of(kapi::devices::device const & device) const
-> kstd::result<kapi::filesystem::device_number>;
//! Get all currently registered devices.
//!
//! @return A range containing all currently registered devices numbers mappings.
[[nodiscard]] auto all() const -> kstd::vector<entry>;
//! Subscribe to device numbering events.
//!
//! Observers subscribed through this function are held through non-owning pointers. It is safe of an observer
//! subscribed through this function to be destroyed without being unsubscribed.
//!
//! @param observer The observer to notify.
auto subscribe(kstd::weak_ptr<device_number_registry_observer> observer) -> void;
private:
auto on_facet_published(kapi::capabilities::facet_id facet, kapi::devices::facet_registry::entry const & entry)
-> void override;
auto on_facet_withdrawn(kapi::capabilities::facet_id facet, kapi::devices::device & device) -> void override;
auto try_number(kapi::capabilities::facet_id facet, kapi::devices::facet_registry::entry const & published) -> void;
auto allocate_minor(file_type type, std::uint8_t major) const -> std::uint8_t;
mutable kapi::tracked_mutex m_lock{};
kstd::observer_ptr<kapi::devices::facet_registry> m_facet_registry;
mutable kstd::vector<entry> m_entries{};
kstd::vector<kstd::weak_ptr<device_number_registry_observer>> m_observers{};
};
//! The facet for types interested in observing numbering transactions on a device number registry.
struct device_number_registry_observer
{
//! Enable correct destruction through base pointers.
virtual ~device_number_registry_observer() = default;
//! Called after a device has been assigned a device number.
//!
//! @param numbered The newly numbered entry.
virtual auto on_device_numbered(device_number_registry::entry const & numbered) -> void = 0;
//! Called after a device's number has been withdrawn.
//!
//! @param unnumbered The entry that is no longer numbered.
virtual auto on_device_unnumbered(device_number_registry::entry const & unnumbered) -> void = 0;
};
} // namespace kernel::filesystem
#endif
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