Merge pull request #13 from ashward/issue-12-sub-yarn

Fixes issue #12 - Fails to run on yarn sub-process

files/.jsig/index.js

@@ -1,7 +1,7 @@
 var ChildProcess = require("child_process");
 var Path = require("path");
 
-var jsigVersion = "0.1.5";
+var jsigVersion = "0.1.6";
 
 module.exports = {
   version: jsigVersion,

files/.jsig/jsig-yarn.js

@@ -9,38 +9,48 @@ var FS = require("fs");
 var jsig = require("./index");
 
 // Work out where the actual yarn installation is
-var yarnDir;
-
-try {
-  var yarnFile = ChildProcess.execSync("which yarn").toString().trim();
-
-  yarnDir = Path.dirname(FS.realpathSync(yarnFile));
-
-  // If 'yarn.js' isn't in the same dir as the yarn' script
-  // then we will try and parse its location from the script.
-  // This seems to happen in some Hmoebrew installations
-  if (!FS.existsSync(Path.resolve(yarnDir, "yarn.js"))) {
-    var yarnScript = FS.readFileSync(yarnFile).toString();
-
-    var match = yarnScript.match(/([^'"]+)\/yarn\.js/);
-
-    if (match) {
-      yarnDir = match[1];
-    } else {
-      throw new Error(
-        `Could not determine yarn.js path from yarn script ${yarnScript}`
-      );
+var yarnJsFile;
+
+if (process.env.jsig_yarn_js_file) {
+  // We're in a sub-process yarn, so use the original (top-level) one.
+  yarnJsFile = process.env.jsig_yarn_js_file;
+} else {
+  try {
+    var yarnFile = ChildProcess.execSync("which yarn").toString().trim();
+
+    var yarnDir = Path.dirname(FS.realpathSync(yarnFile));
+
+    // If 'yarn.js' isn't in the same dir as the yarn' script
+    // then we will try and parse its location from the script.
+    // This seems to happen in some Homebrew installations
+    if (!FS.existsSync(Path.resolve(yarnDir, "yarn.js"))) {
+      var yarnScript = FS.readFileSync(yarnFile).toString();
+
+      var match = yarnScript.match(/([^'"]+)\/yarn\.js/);
+
+      if (match) {
+        yarnDir = match[1];
+      } else {
+        throw new Error(
+          `Could not determine yarn.js path from yarn script ${yarnScript}`
+        );
+      }
     }
+
+    yarnJsFile = Path.resolve(yarnDir, "yarn.js");
+
+    // Store the actual Yarn dir in an env var so that child processes can pick it up
+    process.env.jsig_yarn_js_file = yarnJsFile;
+  } catch (e) {
+    //  TODO: Add a way of specifying the yarn executable
+    console.error(
+      "🛑   JSInstallGuard: Could not find yarn executable using 'which yarn'"
+    );
+    console.error("🛑   JSInstallGuard:", e.message);
+    process.exit(1);
   }
-} catch (e) {
-  //  TODO: Add a way of specifying the yarn executable
-  console.error(
-    "🛑   JSInstallGuard: Could not find yarn executable using 'which yarn'"
-  );
-  console.error("🛑   JSInstallGuard:", e.message);
-  process.exit(1);
 }
 
 jsig.init(false);
 
-require(Path.resolve(yarnDir, "yarn.js"));
+require(yarnJsFile);

package.json

@@ -1,6 +1,6 @@
 {
   "name": "jsinstallguard",
-  "version": "0.1.5",
+  "version": "0.1.6",
   "description": "Small security wrapper around the package manager which intercepts any preistall and postinstall scripts.",
   "main": "index.js",
   "scripts": {