Fix launching Snap-based Chromiums

Author: pimterry

src/interceptors/chromium-based-interceptors.ts

@@ -1,17 +1,20 @@
 import _ from 'lodash';
+import * as path from 'path';
 import { generateSPKIFingerprint } from 'mockttp';
 
 import { HtkConfig } from '../config';
 
+import { delay } from '../util/promise';
+import { readFile, deleteFolder } from '../util/fs';
+import { listRunningProcesses, windowsClose, waitForExit } from '../util/process-management';
+import { getSnapConfigPath, isSnap } from '../util/snap';
+
 import {
     getBrowserDetails,
     launchBrowser,
     BrowserInstance,
     LaunchOptions
 } from '../browsers';
-import { delay } from '../util/promise';
-import { readFile, deleteFolder } from '../util/fs';
-import { listRunningProcesses, windowsClose, waitForExit } from '../util/process-management';
 import { HideWarningServer } from '../hide-warning-server';
 import { Interceptor } from '.';
 import { logError } from '../error-tracking';
@@ -20,6 +23,7 @@ import { WEBEXTENSION_INSTALL } from '../webextension';
 const getChromiumLaunchOptions = async (
     browser: string,
     config: HtkConfig,
+    profilePath: string | null | undefined,
     proxyPort: number,
     hideWarningServer: HideWarningServer,
     webExtensionEnabled: boolean
@@ -28,6 +32,7 @@ const getChromiumLaunchOptions = async (
     const spkiFingerprint = generateSPKIFingerprint(certificatePem);
 
     return {
+        profile: profilePath,
         browser,
         proxy: `https://127.0.0.1:${proxyPort}`,
         noProxy: [
@@ -95,10 +100,15 @@ abstract class FreshChromiumBasedInterceptor implements Interceptor {
 
         const browserDetails = await getBrowserDetails(this.config.configPath, this.variantName);
 
+        const profilePath = browserDetails && await isSnap(browserDetails.command)
+            ? path.join(await getSnapConfigPath(this.variantName), 'profile')
+            : undefined;
+
         const browser = await launchBrowser(hideWarningServer.hideWarningUrl,
             await getChromiumLaunchOptions(
                 browserDetails ? browserDetails.name : this.variantName,
                 this.config,
+                profilePath,
                 proxyPort,
                 hideWarningServer,
                 !!options.webExtensionEnabled
@@ -121,7 +131,7 @@ abstract class FreshChromiumBasedInterceptor implements Interceptor {
             if (process.platform === 'win32' && this.variantName === 'opera') return;
             await delay(1000); // No hurry, make sure the browser & related processes have all cleaned up
 
-            if (Object.keys(this.activeBrowsers).length === 0 && browserDetails && _.isString(browserDetails.profile)) {
+            if (Object.keys(this.activeBrowsers).length === 0 && typeof browserDetails?.profile === 'string') {
                 // If we were the last browser, and we have a profile path, and it's in our config
                 // (just in case something's gone wrong) -> delete the profile to reset everything.
 
@@ -269,6 +279,7 @@ abstract class ExistingChromiumBasedInterceptor implements Interceptor {
         const launchOptions = await getChromiumLaunchOptions(
             browserDetails ? browserDetails.name : this.variantName,
             this.config,
+            null, // Null profile path ensures we use the system default profile
             proxyPort,
             hideWarningServer,
             !!options.webExtensionEnabled
@@ -290,8 +301,7 @@ abstract class ExistingChromiumBasedInterceptor implements Interceptor {
 
         const browser = await launchBrowser("", {
             ...launchOptions,
-            skipDefaults: true,
-            profile: null // Enforce that we use the default profile
+            skipDefaults: true
         }, this.config.configPath);
 
         if (browser.process.stdout) browser.process.stdout.pipe(process.stdout);

src/interceptors/fresh-firefox.ts

@@ -243,7 +243,7 @@ export class FreshFirefox implements Interceptor {
         if (!browserDetails) throw new Error('Firefox could not be detected');
 
         const profilePath = await isSnap(browserDetails.command)
-            ? path.join(getSnapConfigPath('firefox'), 'profile')
+            ? path.join(await getSnapConfigPath('firefox'), 'profile')
             : path.join(this.config.configPath, 'firefox-profile');
 
         const firefoxPrefsFile = path.join(profilePath, 'prefs.js');

src/util/snap.ts

@@ -2,6 +2,7 @@ import os = require('os');
 import path = require('path');
 
 import fs = require('./fs');
+import { streamToBuffer } from './stream';
 
 export async function isSnap(bin: string) {
     if (os.platform() !== 'linux') return false;
@@ -14,24 +15,29 @@ export async function isSnap(bin: string) {
     // Most snaps directly run from the Snap bin folder:
     if (binPath.startsWith('/snap/bin/')) return true;
 
-    // Firefox is the only known example that doesn't - it uses a
-    // wrapper script, so we just look for that:
-    if (binPath === '/usr/bin/firefox') {
-        const content = await fs.readFile(binPath);
-        return content.includes('exec /snap/bin/firefox');
-    }
+    // If not, the command might be a wrapper script - both chromium-browser
+    // & firefox use these. Check the end and see if we recognize it:
+
+    const fileSize = await fs.statFile(binPath);
+    const stream = fs.createReadStream(binPath, { start: fileSize.size - 100 });
+    const lastChunkOfFile = (await streamToBuffer(stream)).toString('utf8');
 
-    return false;
+    return lastChunkOfFile.includes('exec /snap/bin/');
 }
 
 // For all Snaps, any data we want to inject needs to live inside the
 // Snap's data directory - we put it in a .httptoolkit folder.
-export const getSnapConfigPath = (appName: string) => {
-    return path.join(
+export async function getSnapConfigPath(appName: string) {
+    const snapDataPath = path.join(
         os.homedir(),
         'snap',
         appName,
-        'current',
-        '.httptoolkit'
+        'current'
     );
+
+    if (!await fs.canAccess(snapDataPath)) {
+        throw new Error(`Could not find Snap data path for ${appName}`);
+    }
+
+    return path.join(snapDataPath, '.httptoolkit');
 }