dirCreateDir

fn dirCreateDir(
    userdata: ?*anyopaque,
    dir: Dir,
    sub_path: []const u8,
    permissions: Dir.Permissions,
) Dir.CreateDirError!void {
    const ev: *Evented = @ptrCast(@alignCast(userdata));
    _ = ev;

    var path_buffer: [c.PATH_MAX]u8 = undefined;
    const sub_path_posix = try pathToPosix(sub_path, &path_buffer);

    while (true) {
        switch (c.errno(c.mkdirat(dir.handle, sub_path_posix, permissions.toMode()))) {
            .SUCCESS => return,
            .INTR => {},
            .ACCES => return error.AccessDenied,
            .PERM => return error.PermissionDenied,
            .DQUOT => return error.DiskQuota,
            .EXIST => return error.PathAlreadyExists,
            .LOOP => return error.SymLinkLoop,
            .MLINK => return error.LinkQuotaExceeded,
            .NAMETOOLONG => return error.NameTooLong,
            .NOENT => return error.FileNotFound,
            .NOMEM => return error.SystemResources,
            .NOSPC => return error.NoSpaceLeft,
            .NOTDIR => return error.NotDir,
            .ROFS => return error.ReadOnlyFileSystem,
            .ILSEQ => return error.BadPathName,
            .BADF => |err| return errnoBug(err), // File descriptor used after closed.
            .FAULT => |err| return errnoBug(err),
            else => |err| return unexpectedErrno(err),
        }
    }
}