dirRename

fn dirRename(
    userdata: ?*anyopaque,
    old_dir: Dir,
    old_sub_path: []const u8,
    new_dir: Dir,
    new_sub_path: []const u8,
) Dir.RenameError!void {
    const ev: *Evented = @ptrCast(@alignCast(userdata));
    _ = ev;

    var old_path_buffer: [c.PATH_MAX]u8 = undefined;
    var new_path_buffer: [c.PATH_MAX]u8 = undefined;

    const old_sub_path_posix = try pathToPosix(old_sub_path, &old_path_buffer);
    const new_sub_path_posix = try pathToPosix(new_sub_path, &new_path_buffer);

    while (true) switch (c.errno(c.renameat(old_dir.handle, old_sub_path_posix, new_dir.handle, new_sub_path_posix))) {
        .SUCCESS => return,
        .INTR => {},
        .ACCES => return error.AccessDenied,
        .PERM => return error.PermissionDenied,
        .BUSY => return error.FileBusy,
        .DQUOT => return error.DiskQuota,
        .ISDIR => return error.IsDir,
        .IO => return error.HardwareFailure,
        .LOOP => return error.SymLinkLoop,
        .MLINK => return error.LinkQuotaExceeded,
        .NAMETOOLONG => return error.NameTooLong,
        .NOENT => return error.FileNotFound,
        .NOTDIR => return error.NotDir,
        .NOMEM => return error.SystemResources,
        .NOSPC => return error.NoSpaceLeft,
        .EXIST => return error.DirNotEmpty,
        .NOTEMPTY => return error.DirNotEmpty,
        .ROFS => return error.ReadOnlyFileSystem,
        .XDEV => return error.CrossDevice,
        .ILSEQ => return error.BadPathName,
        .FAULT => |err| return errnoBug(err),
        .INVAL => |err| return errnoBug(err),
        else => |err| return unexpectedErrno(err),
    };
}