feature(@embark/core): store IPC files in a dir within os.tmpdir()

This PR replaces #1202.

When embark is running on Linux and macOS, unix socket files are used for
geth's and embark's IPC files. A problem can arise if a DApp is in a deeply
nested directory structure such that character-length of the path to a socket
file exceeds the maximum supported length. See #450.

Also, if the DApp context is a Linux container running on a Windows Docker
host, and if the DApp is mounted from the host's file system, there is a
problem: unix socket files are incompatible with the Windows file system.

Solve both problems at once by storing a DApp's `.ipc` files in a directory
within `os.tmpdir()`. Introduce `ipcPath()` in `core/fs.js` and use a truncated
SHA-512 hash of the DApp's path in the name of the temporary directory created
for that purpose so that DApps won't collide (with an acceptably low
probability of collision).

src/lib/core/fs.js

@@ -144,6 +144,19 @@ function diagramPath() {
   return anchoredPath(env.DIAGRAM_PATH, ...arguments);
 }
 
+function ipcPath(basename, usePipePathOnWindows = false) {
+  if (!(basename && typeof basename === 'string')) {
+    throw new TypeError('first argument must be a non-empty string');
+  }
+  if (process.platform === 'win32' && usePipePathOnWindows) {
+    return `\\\\.\\pipe\\${basename}`;
+  }
+  return utils.joinPath(
+    tmpDir(`embark-${utils.sha512(dappPath()).slice(0, 8)}`),
+    basename
+  );
+}
+
 function pkgPath() {
   return anchoredPath(env.PKG_PATH, ...arguments);
 }
@@ -195,6 +208,7 @@ module.exports = {
   embarkPath,
   existsSync,
   ensureFileSync,
+  ipcPath,
   mkdirp,
   mkdirpSync,
   move,

src/lib/core/ipc.js

@@ -1,12 +1,12 @@
-const fs = require('./fs.js');
+const fs = require('./fs');
 const ipc = require('node-ipc');
 const {parse, stringify} = require('flatted/cjs');
+const utils = require('../utils/utils');
 
 class IPC {
-
   constructor(options) {
     this.logger = options.logger;
-    this.socketPath = options.socketPath || fs.dappPath(".embark/embark.ipc");
+    this.socketPath = options.socketPath || fs.ipcPath('embark.ipc');
     this.ipcRole = options.ipcRole;
     ipc.config.silent = true;
     this.connected = false;
@@ -39,7 +39,7 @@ class IPC {
   }
 
   serve() {
-    fs.mkdirpSync(fs.dappPath(".embark"));
+    fs.mkdirpSync(utils.dirname(this.socketPath));
     ipc.serve(this.socketPath, () => {});
     ipc.server.start();
 

src/lib/core/processes/processManager.js

@@ -1,4 +1,3 @@
-
 const ProcessState = {
   Unstarted: 'unstarted',
   Starting: 'starting',

src/lib/modules/blockchain_process/gethClient.js

@@ -1,4 +1,5 @@
 const async = require('async');
+const fs = require('../../core/fs');
 const GethMiner = require('./miner');
 const semver = require('semver');
 const constants = require('../../constants');
@@ -50,7 +51,7 @@ class GethClient {
   needKeepAlive() {
     // TODO: check version also (geth version < 1.8.15)
     if (this.isDev) {
-      // Trigger regular txs due to a bug in geth (< 1.8.15) and stuck transactions in --dev mode.   
+      // Trigger regular txs due to a bug in geth (< 1.8.15) and stuck transactions in --dev mode.
       return true;
     }
     return false;
@@ -78,6 +79,8 @@ class GethClient {
       cmd.push("--verbosity=" + config.verbosity);
     }
 
+    cmd.push(`--ipcpath=${fs.ipcPath('geth.ipc', true)}`);
+
     return cmd;
   }
 

src/lib/modules/blockchain_process/miner.js

@@ -1,4 +1,5 @@
 const async = require('async');
+const fs = require('../../core/fs');
 const NetcatClient = require('netcat/client');
 
 //Constants
@@ -43,14 +44,7 @@ class GethMiner {
       }
     }
 
-    const isWin = process.platform === "win32";
-
-    let ipcPath;
-    if (isWin) {
-      ipcPath = '\\\\.\\pipe\\geth.ipc';
-    } else {
-      ipcPath = this.datadir + '/geth.ipc';
-    }
+    const ipcPath = fs.ipcPath('geth.ipc', true);
 
     this.client = new NetcatClient();
     this.client.unixSocket(ipcPath)

src/lib/utils/host.ts

@@ -1,30 +1,29 @@
-const isDocker = (() => {
-  let isDockerProcess;
-
-  const hostname = require("os").hostname();
-  const pattern = new RegExp(
-    "[0-9]+\:[a-z_-]+\:\/docker\/" + hostname + "[0-9a-z]+", "i",
-  );
+const {execSync} = require("child_process");
+const {hostname} = require("os");
 
+const isDocker = (() => {
+  // assumption: an Embark container is always a Linux Docker container, though
+  // the Docker host may be Linux, macOS, or Windows
+  if (process.platform !== "linux") { return false; }
   try {
-    isDockerProcess = require("child_process")
-    .execSync(
-      "cat /proc/self/cgroup",
-      {stdio: ["ignore", "pipe", "ignore"]},
-    )
-    .toString().match(pattern) !== null;
+    return (
+      new RegExp(`[0-9]+\:[a-z_-]+\:\/docker\/${hostname()}[0-9a-z]+`, "i")
+    ).test(
+      execSync(
+        "cat /proc/self/cgroup",
+        {stdio: ["ignore", "pipe", "ignore"]},
+      ).toString(),
+    );
   } catch (e) {
-    isDockerProcess = false;
+    return false;
   }
-
-  return isDockerProcess;
 })();
 
 const defaultHost = isDocker ? "0.0.0.0" : "localhost";
 
-// when we"re runing in Docker, we can expect (generally, in a development
+// when we're runing in Docker, we can expect (generally, in a development
 // scenario) that the user would like to connect to the service in the
-// container via the **host"s** loopback address, so this helper can be used to
+// container via the **host's** loopback address, so this helper can be used to
 // swap 0.0.0.0 for localhost in code/messages that pertain to client-side
 function canonicalHost(host: string): string {
   return isDocker && host === "0.0.0.0" ? "localhost" : host;

src/lib/utils/utils.js

@@ -390,6 +390,15 @@ function sha3(arg) {
   return Web3.utils.sha3(arg);
 }
 
+function sha512(arg) {
+  if (typeof arg !== 'string') {
+    throw new TypeError('argument must be a string');
+  }
+  const crypto = require('crypto');
+  const hash = crypto.createHash('sha512');
+  return hash.update(arg).digest('hex');
+}
+
 function soliditySha3(arg) {
   const Web3 = require('web3');
   return Web3.utils.soliditySha3(arg);
@@ -640,6 +649,7 @@ module.exports = {
   getExternalContractUrl,
   toChecksumAddress,
   sha3,
+  sha512,
   soliditySha3,
   normalizeInput,
   buildUrl,

src/test/fs.js

@@ -31,6 +31,7 @@ describe('fs', () => {
     'dappPath',
     'diagramPath',
     'embarkPath',
+    'ipcPath',
     'pkgPath',
     'tmpDir'
   ];