const F_LINUX_SPECIFIC_BASE: u32 = 1024;

/// fcntl syscall command
///
/// for linux-specific fcntl commands, see:
/// https://code.dragonos.org.cn/xref/linux-5.19.10/tools/include/uapi/linux/fcntl.h#8
#[derive(Debug, Copy, Clone, Eq, PartialEq, FromPrimitive, ToPrimitive)]
#[repr(u32)]
pub enum FcntlCommand {
    /// dup
    DupFd = 0,
    /// get close-on-exec
    GetFd = 1,
    /// set/clear close-on-exec
    SetFd = 2,
    /// get file flags
    GetFlags = 3,
    /// set file flags
    SetFlags = 4,
    /// get record locking info
    GetLock = 5,
    /// set record locking info (non-blocking)
    SetLock = 6,
    /// set record locking info (blocking)
    SetLockWait = 7,
    /// set owner
    SetOwn = 8,
    /// get owner
    GetOwn = 9,
    /// set signal to send on asynchronous I/O
    SetSig = 10,
    /// get signal to send on asynchronous I/O
    GetSig = 11,

    SetLease = F_LINUX_SPECIFIC_BASE,
    GetLease = F_LINUX_SPECIFIC_BASE + 1,

    /// Request nofications on a directory.
    /// See below for events that may be notified.
    Notify = F_LINUX_SPECIFIC_BASE + 2,

    /// Cancel a blocking posix lock; internal use only until we expose an
    /// asynchronous lock api to userspace
    CancelLock = F_LINUX_SPECIFIC_BASE + 5,
    /// Create a file descriptor with FD_CLOEXEC set.
    DupFdCloexec = F_LINUX_SPECIFIC_BASE + 6,

    /// Set pipe page size array
    SetPipeSize = F_LINUX_SPECIFIC_BASE + 7,
    /// Get pipe page size array
    GetPipeSize = F_LINUX_SPECIFIC_BASE + 8,

    /// Set seals
    AddSeals = F_LINUX_SPECIFIC_BASE + 9,
    /// Get seals
    GetSeals = F_LINUX_SPECIFIC_BASE + 10,

    /**
     * Set/Get write life time hints. {GET,SET}_RW_HINT operate on the
     * underlying inode, while {GET,SET}_FILE_RW_HINT operate only on
     * the specific file.
     */
    GetRwHint = F_LINUX_SPECIFIC_BASE + 11,
    SetRwHint = F_LINUX_SPECIFIC_BASE + 12,
    GetFileRwHint = F_LINUX_SPECIFIC_BASE + 13,
    SetFileRwHint = F_LINUX_SPECIFIC_BASE + 14,
}

bitflags! {

    ///  The constants AT_REMOVEDIR and AT_EACCESS have the same value.  AT_EACCESS is
    ///  meaningful only to faccessat, while AT_REMOVEDIR is meaningful only to
    ///  unlinkat.  The two functions do completely different things and therefore,
    ///  the flags can be allowed to overlap.  For example, passing AT_REMOVEDIR to
    ///  faccessat would be undefined behavior and thus treating it equivalent to
    ///  AT_EACCESS is valid undefined behavior.
    #[allow(clippy::bad_bit_mask)]
    pub struct AtFlags: i32 {
        /// 特殊值，用于指示openat应使用当前工作目录。
        const AT_FDCWD = -100;
        /// 不要跟随符号链接。
        const AT_SYMLINK_NOFOLLOW = 0x100;
        /// AtEAccess: 使用有效ID进行访问测试，而不是实际ID。
        const AT_EACCESS = 0x200;
        /// AtRemoveDir: 删除目录而不是取消链接文件。
        const AT_REMOVEDIR = 0x200;

        /// 跟随符号链接。
        /// AT_SYMLINK_FOLLOW: 0x400
        const AT_SYMLINK_FOLLOW = 0x400;
        /// 禁止终端自动挂载遍历。
        /// AT_NO_AUTOMOUNT: 0x800
        const AT_NO_AUTOMOUNT = 0x800;
        /// 允许空的相对路径名。
        /// AT_EMPTY_PATH: 0x1000
        const AT_EMPTY_PATH = 0x1000;
        /// statx()所需的同步类型。
        /// AT_STATX_SYNC_TYPE: 0x6000
        const AT_STATX_SYNC_TYPE = 0x6000;
        /// 执行与stat()相同的操作。
        /// AT_STATX_SYNC_AS_STAT: 0x0000
        const AT_STATX_SYNC_AS_STAT = 0x0000;
        /// 强制将属性与服务器同步。
        /// AT_STATX_FORCE_SYNC: 0x2000
        const AT_STATX_FORCE_SYNC = 0x2000;
        /// 不要将属性与服务器同步。
        /// AT_STATX_DONT_SYNC: 0x4000
        const AT_STATX_DONT_SYNC = 0x4000;
        /// 应用于整个子树。
        /// AT_RECURSIVE: 0x8000
        const AT_RECURSIVE = 0x8000;

        const AT_GETATTR_NOSEC = i32::MIN;
    }
}

/// for F_[GET|SET]FL
pub const FD_CLOEXEC: u32 = 1;

/// for POSIX fcntl() record locks
pub const F_RDLCK: i16 = 0;
pub const F_WRLCK: i16 = 1;
pub const F_UNLCK: i16 = 2;

/// userspace `struct flock` ABI (64-bit)
#[repr(C)]
#[derive(Clone, Copy, Debug)]
pub struct PosixFlock {
    pub l_type: i16,
    pub l_whence: i16,
    pub l_start: i64,
    pub l_len: i64,
    pub l_pid: i32,
}
