file_descriptor.h

Go to the documentation of this file.

 
#pragma once
 
#include <cstdint>
#include <memory>
 
#include "contur/core/error.h"
 
#include "contur/fs/inode.h"
 
namespace contur {

    struct FileDescriptor
    {
        std::int32_t value = -1;

        [[nodiscard]] constexpr bool valid() const noexcept
        {
            return value >= 0;
        }

        friend constexpr bool operator==(FileDescriptor lhs, FileDescriptor rhs) noexcept
        {
            return lhs.value == rhs.value;
        }
    };

    enum class OpenMode : std::uint8_t
    {
        None = 0,
        Read = 1U << 0,
        Write = 1U << 1,
        Create = 1U << 2,
        Truncate = 1U << 3,
        Append = 1U << 4,
    };

    [[nodiscard]] constexpr OpenMode operator|(OpenMode lhs, OpenMode rhs) noexcept
    {
        return static_cast<OpenMode>(static_cast<std::uint8_t>(lhs) | static_cast<std::uint8_t>(rhs));
    }

    [[nodiscard]] constexpr OpenMode operator&(OpenMode lhs, OpenMode rhs) noexcept
    {
        return static_cast<OpenMode>(static_cast<std::uint8_t>(lhs) & static_cast<std::uint8_t>(rhs));
    }

    [[nodiscard]] constexpr bool hasOpenMode(OpenMode value, OpenMode flag) noexcept
    {
        return static_cast<std::uint8_t>(value & flag) != 0;
    }

    struct OpenFileState
    {
        InodeId inodeId = INVALID_INODE_ID;

        std::size_t offset = 0;

        OpenMode mode = OpenMode::None;
    };

    class FileDescriptorTable final
    {
        public:
        FileDescriptorTable();
        ~FileDescriptorTable();
 
        FileDescriptorTable(const FileDescriptorTable &) = delete;
        FileDescriptorTable &operator=(const FileDescriptorTable &) = delete;
        FileDescriptorTable(FileDescriptorTable &&) noexcept;
        FileDescriptorTable &operator=(FileDescriptorTable &&) noexcept;

        [[nodiscard]] Result<FileDescriptor> open(OpenFileState state);

        [[nodiscard]] Result<void> close(FileDescriptor fd);

        [[nodiscard]] Result<OpenFileState> get(FileDescriptor fd) const;

        [[nodiscard]] Result<void> set(FileDescriptor fd, OpenFileState state);

        [[nodiscard]] bool contains(FileDescriptor fd) const noexcept;

        [[nodiscard]] std::size_t openCount() const noexcept;
 
        private:
        struct Impl;
        std::unique_ptr<Impl> impl_;
    };
 
} // namespace contur