From 4029ec9df72b2e059eff09d92fec8e9fba8732f4 Mon Sep 17 00:00:00 2001
From: Jujhar Singh <jujharsmc@gmail.com>
Date: Wed, 26 Aug 2020 19:14:54 +1200
Subject: [PATCH 1/3] Modify chrome.go to not rely on chrome stderr

---
 chrome.go | 66 ++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 43 insertions(+), 23 deletions(-)

diff --git a/chrome.go b/chrome.go
index b17b803..aa3cb12 100644
--- a/chrome.go
+++ b/chrome.go
@@ -1,15 +1,14 @@
 package lorca
 
 import (
-	"bufio"
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io"
 	"io/ioutil"
 	"log"
+	"net"
+	"net/http"
 	"os/exec"
-	"regexp"
 	"sync"
 	"sync/atomic"
 
@@ -47,6 +46,24 @@ type chrome struct {
 	bindings map[string]bindingFunc
 }
 
+type browserVersion struct {
+	Browser string `json:"Browser"`
+	ProtocolVersion string `json:"Protocol-Version"`
+	UserAgent string `json:"User-Agent"`
+	V8Version string `json:"V8-Version"`
+	WebkitVersion string `json:"Webkit-Version"`
+	WebSocketDebuggerUrl string `json:"webSocketDebuggerUrl"`
+}
+
+func getFreePort() (int, error) {
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		return 0, err
+	}
+	defer ln.Close()
+	return ln.Addr().(*net.TCPAddr).Port, nil
+}
+
 func newChromeWithArgs(chromeBinary string, args ...string) (*chrome, error) {
 	// The first two IDs are used internally during the initialization
 	c := &chrome{
@@ -55,24 +72,40 @@ func newChromeWithArgs(chromeBinary string, args ...string) (*chrome, error) {
 		bindings: map[string]bindingFunc{},
 	}
 
+	debugPort, err := getFreePort()
+	if err != nil {
+		return nil, err
+	}
+
 	// Start chrome process
+	args = append(args, fmt.Sprintf("--remote-debugging-port=%d", debugPort))
 	c.cmd = exec.Command(chromeBinary, args...)
-	pipe, err := c.cmd.StderrPipe()
+	if err := c.cmd.Start(); err != nil {
+		return nil, err
+	}
+
+	if err := c.cmd.Wait(); err != nil {
+		return nil, err
+	}
+
+	res, err := http.Get(fmt.Sprintf("http://127.0.0.1:%d/json/version", debugPort))
 	if err != nil {
 		return nil, err
 	}
-	if err := c.cmd.Start(); err != nil {
+
+	body, err := ioutil.ReadAll(res.Body)
+	if err != nil {
 		return nil, err
 	}
 
-	// Wait for websocket address to be printed to stderr
-	re := regexp.MustCompile(`^DevTools listening on (ws://.*?)\r?\n$`)
-	m, err := readUntilMatch(pipe, re)
+	browserVer := &browserVersion{}
+
+	err = json.Unmarshal(body, &browserVer)
 	if err != nil {
-		c.kill()
 		return nil, err
 	}
-	wsURL := m[1]
+
+	wsURL := browserVer.WebSocketDebuggerUrl
 
 	// Open a websocket
 	c.ws, err = websocket.Dial(wsURL, "", "http://127.0.0.1")
@@ -516,19 +549,6 @@ func (c *chrome) kill() error {
 	return nil
 }
 
-func readUntilMatch(r io.ReadCloser, re *regexp.Regexp) ([]string, error) {
-	br := bufio.NewReader(r)
-	for {
-		if line, err := br.ReadString('\n'); err != nil {
-			r.Close()
-			return nil, err
-		} else if m := re.FindStringSubmatch(line); m != nil {
-			go io.Copy(ioutil.Discard, br)
-			return m, nil
-		}
-	}
-}
-
 func contains(arr []string, x string) bool {
 	for _, n := range arr {
 		if x == n {

From 7378c0fe9d85fec6a8dd2b3560925a9653999b04 Mon Sep 17 00:00:00 2001
From: Jujhar Singh <jujharsmc@gmail.com>
Date: Wed, 26 Aug 2020 19:16:22 +1200
Subject: [PATCH 2/3] Remove --remote-debugging-port arg from ui.go

This argument is now located in chrome.go
---
 ui.go | 1 -
 1 file changed, 1 deletion(-)

diff --git a/ui.go b/ui.go
index bb4fa75..87f6bc1 100644
--- a/ui.go
+++ b/ui.go
@@ -76,7 +76,6 @@ func New(url, dir string, width, height int, customArgs ...string) (UI, error) {
 	args = append(args, fmt.Sprintf("--user-data-dir=%s", dir))
 	args = append(args, fmt.Sprintf("--window-size=%d,%d", width, height))
 	args = append(args, customArgs...)
-	args = append(args, "--remote-debugging-port=0")
 
 	chrome, err := newChromeWithArgs(ChromeExecutable(), args...)
 	done := make(chan struct{})

From 25ec0987a9adf881f7d8897ac6ca45ebaae08944 Mon Sep 17 00:00:00 2001
From: Jujhar Singh <jujharsmc@gmail.com>
Date: Wed, 26 Aug 2020 19:32:00 +1200
Subject: [PATCH 3/3] Remove c.cmd.Wait()

---
 chrome.go | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/chrome.go b/chrome.go
index aa3cb12..0efc6ee 100644
--- a/chrome.go
+++ b/chrome.go
@@ -84,10 +84,6 @@ func newChromeWithArgs(chromeBinary string, args ...string) (*chrome, error) {
 		return nil, err
 	}
 
-	if err := c.cmd.Wait(); err != nil {
-		return nil, err
-	}
-
 	res, err := http.Get(fmt.Sprintf("http://127.0.0.1:%d/json/version", debugPort))
 	if err != nil {
 		return nil, err