Some JS and Haskell stuff


Vulgr UI - React

Vulgr is a project I've been working on, on and off, for a while. The goal is to build a dependency analysis platform - analyze your gradle/node/whatever dependencies to see whether they contain known vulnerabilities or bugs, reading from whatever data sources (CVE database, github issues, etc...) that make sense.

This week, I did some work on how this information could be displayed to users on a web interface, e.g.:

This is built with react and material-ui. The code for the card is located at AnalysisSummaryCard.js. Following is the code for the status icon's in the card, nice, flexible re-usable component!

'use strict';

import React, {PropTypes} from 'react';
import ReactTooltip from 'react-tooltip';

let statusIcon = (iconType, attributes, style) => {
  return (
    <i className='material-icons md-36' {...attributes}

let tooltippableStatusIcon = (iconType, tooltipInfo, style) => {
  let tooltip = function () {
    if (tooltipInfo) {
      return (
        <ReactTooltip place='top'
          <span ><strong>{tooltipInfo.message}</strong></span>
    } else {
      return null;

  let tooltippedAttributes = () => {
    return tooltipInfo ? {'data-tip': '', 'data-for':} : [];

  return (
      { tooltip() }
      { statusIcon(iconType, tooltippedAttributes(), style) }

export const StatusIcon = ({iconType, tooltipInfo, style}) => {
  return tooltippableStatusIcon(iconType, tooltipInfo, style);

StatusIcon.propTypes = {
  iconType: PropTypes.string.isRequired,
  tooltipInfo: PropTypes.shape({
    id: PropTypes.string.isRequired,
    type: PropTypes.string.isRequired,
    message: PropTypes.string.isRequired
  style: PropTypes.object

export default StatusIcon;

Here is an example of its use to render the error icon, first a function to wrap up the JSX:

let createStatusIcon = (iconType, tooltipInfo, style) => {
  return (
      style={style} />

Concrete usage:

let errorIcon = () => {
  let icon = 'error';
  let marginLeft = 10;
  let tooltipInfo = buildTooltipInfo('analysis-card-error-tooltip', 'error', 'Error!', {marginLeft});
  let style = {color: 'red', float: 'left', marginLeft};
  return createStatusIcon(icon, tooltipInfo, style);

Pretty flexible! The color and style can easily be changed so the icon can fit in without much hassle in components with complex styles, or can be greyed out, etc...

I use Angular and bootstrap at work, so far react and material have been a dream in comparison.

Haskell Criu RPC Client

I've been toying about with criu for the last few weeks. I decided to write some bindings to it in haskell.

Criu's RPC API 1 uses protobuf. I used the proto-lens library to generate lenses and data types. This gives a pretty nice foundation to build upon - the project for generation is on github, haskell-criu-rpc-types 2.

With that foundation, I threw together a quick client:

{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ScopedTypeVariables #-}
module Criu (
  module Proto.Criu.Rpc
  , module Lens.Family2
  , callCriu
  , callCriu'
  ) where

import Control.Exception.Base (IOException, bracket, try)
import Lens.Family2 ((.~))
import Data.ProtoLens (decodeMessage, encodeMessage)
import Proto.Criu.Rpc
import Network.Socket (Family(AF_UNIX), SocketType(SeqPacket), SockAddr(SockAddrUnix), close, connect, socket)
import Network.Socket.ByteString (recv, send)

-- | Send request to criu socket. Can throw exceptions.
callCriu :: FilePath -> Criu_req -> IO (Either String Criu_resp)
callCriu fp req = do
  resp <- withSocket $ \sock -> do
    connect sock (SockAddrUnix fp)
    send sock (encodeMessage req)
    recv sock 1024
  pure (decodeMessage resp :: Either String Criu_resp)
  withSocket f = bracket
    (socket AF_UNIX SeqPacket 0)
    (\sock -> f sock)

-- | Send a request to criu, but wrap up IOExceptions in Either.
callCriu' :: FilePath -> Criu_req -> IO (Either String Criu_resp)
callCriu' fp req = do
  eitherResp <- try (callCriu fp req)
  case eitherResp of
    Right resp -> pure resp
    Left (e :: IOException) -> pure . Left . show $ e

Both callCriu and callCriu' expect the path to the criu socket and a Criu_req type.

To build the actual Criu_req expected by the calls is is pretty straightforward. In ghci:

> build (type' .~ CHECK) :: Criu_req
Criu_req {
  _Criu_req'type' = CHECK
  , _Criu_req'opts = Nothing
  , _Criu_req'notifySuccess = Nothing
  , _Criu_req'keepOpen = Nothing
  , _Criu_req'features = Nothing

build (type' .~ CHECK) :: Criu_req builds a request for a criu check. So, an actual call looks as follows:

> callCriu' "criu_service.socket" (build (type' .~ CHECK) :: Criu_req)
Right (
  Criu_resp {
    _Criu_resp'type' = CHECK
    , _Criu_resp'success = True
    , _Criu_resp'dump = Nothing
    , _Criu_resp'restore = Nothing
    , _Criu_resp'notify = Nothing
    , _Criu_resp'ps = Nothing
    , _Criu_resp'crErrno = Nothing
    , _Criu_resp'features = Nothing
    , _Criu_resp'crErrmsg = Nothing

From the service logs:

$ criu service
Warn  (cr-service.c:1023): Binding to local dir address!
Warn  (cr-check.c:827): Skipping cgroup namespaces check
Looks good.

Success! Lots to improve, but a good start. I'll do a more in-depth post on this once it matures.


See for more information. 2: It's also on hackage,, however I'm not sure what the standard is for libraries that generate their code.