Support meteor <command> for any dev_bundle/bin/<command> executable.

This will make it easier to use tools like https://yarnpkg.com/ with the
right version of Node, etc.

With this commit, here's all you have to do:

  meteor npm install -g yarnpkg

Then test that it works:

  meteor yarn info

Note that any commands registered by Meteor itself will not be honored.

History.md

@@ -48,6 +48,9 @@
   sensitive to non-reproducible factors in the external environment.
   https://github.com/meteor/meteor/pull/7668/commits/3313180a6ff33ee63602f7592a9506012029e919
 
+* The `meteor <command> ...` syntax will now work for any command
+  installed in `dev_bundle/bin`, except for Meteor's own commands.
+
 * The `meteor test` command now supports the `--no-release-check` flag.
   https://github.com/meteor/meteor/pull/7668/commits/7097f78926f331fb9e70a06300ce1711adae2850
 

tools/cli/dev-bundle-bin-commands.js

@@ -1,11 +1,8 @@
 // Note that this file is required before we install our Babel hooks in
 // ../tool-env/install-babel.js, so we can't use ES2015+ syntax here.
 
+var fs = require("fs");
 var path = require("path");
-var win32Extensions = {
-  node: ".exe",
-  npm: ".cmd"
-};
 
 // The dev_bundle/bin command has to come immediately after the meteor
 // command, as in `meteor npm` or `meteor node`, because we don't want to
@@ -14,22 +11,22 @@ var devBundleBinCommand = process.argv[2];
 var args = process.argv.slice(3);
 
 function getChildProcess() {
-  if (! win32Extensions.hasOwnProperty(devBundleBinCommand)) {
+  if (typeof devBundleBinCommand !== "string") {
     return Promise.resolve(null);
   }
 
   var helpers = require("./dev-bundle-bin-helpers.js");
 
-  if (process.platform === "win32") {
-    devBundleBinCommand += win32Extensions[devBundleBinCommand];
-  }
-
   return Promise.all([
     helpers.getDevBundle(),
     helpers.getEnv()
   ]).then(function (devBundleAndEnv) {
     var devBundleDir = devBundleAndEnv[0];
-    var cmd = path.join(devBundleDir, "bin", devBundleBinCommand);
+    var cmd = helpers.getCommand(devBundleBinCommand, devBundleDir);
+    if (! cmd) {
+      return null;
+    }
+
     var env = devBundleAndEnv[1];
     var child = require("child_process").spawn(cmd, args, {
       stdio: "inherit",

tools/cli/dev-bundle-bin-helpers.js

@@ -1,12 +1,65 @@
 var fs = require("fs");
 var path = require("path");
 var files = require("../fs/mini-files.js");
+var isWindows = process.platform === "win32";
+var extensions = isWindows ? [".cmd", ".exe"] : [""];
+var hasOwn = Object.prototype.hasOwnProperty;
 
 function getDevBundle() {
   return require("./dev-bundle.js");
 }
 exports.getDevBundle = getDevBundle;
 
+exports.getCommand = function (name, devBundleDir) {
+  var result = null;
+
+  // Strip leading and/or trailing whitespace.
+  name = name.replace(/^\s+|\s+$/g, "");
+
+  if (! isValidCommand(name, devBundleDir)) {
+    return result;
+  }
+
+  extensions.some(function (ext) {
+    var cmd = path.join(devBundleDir, "bin", name + ext);
+    try {
+      if (fs.statSync(cmd).isFile()) {
+        result = cmd;
+        return true;
+      }
+    } catch (e) {
+      return false;
+    }
+  });
+
+  return result;
+};
+
+function isValidCommand(name, devBundleDir) {
+  if (name === "node" ||
+      name === "npm") {
+    return true;
+  }
+
+  if (! name || name.charAt(0) === ".") {
+    // Disallow empty commands and commands that start with a period.
+    return false;
+  }
+
+  var meteorCommandsJsonPath =
+    path.join(devBundleDir, "bin", ".meteor-commands.json");
+
+  try {
+    var meteorCommands = require(meteorCommandsJsonPath);
+  } catch (e) {
+    return false;
+  }
+
+  // If `meteor <name>` is already a Meteor command, don't let anything in
+  // dev_bundle/bin override it.
+  return ! hasOwn.call(meteorCommands, name);
+}
+
 exports.getEnv = function (options) {
   var devBundle = options && options.devBundle;
   var devBundlePromise = typeof devBundle === "string"

tools/cli/main.js

@@ -291,6 +291,28 @@ require('./commands-packages-query.js');
 require('./commands-cordova.js');
 require('./commands-aliases.js');
 
+///////////////////////////////////////////////////////////////////////////////
+// Record all the top-level commands as JSON
+///////////////////////////////////////////////////////////////////////////////
+
+export const meteorCommandsJsonPath = files.pathJoin(
+  files.getDevBundle(), "bin", ".meteor-commands.json"
+);
+
+export function dumpMeteorCommands() {
+  const all = Object.create(null);
+  Object.keys(commands).forEach(name => all[name] = true);
+  const json = JSON.stringify(all, null, 2);
+  files.writeFile(meteorCommandsJsonPath, json + "\n");
+  return all;
+}
+
+if (files.inCheckout()) {
+  // If we're running Meteor from a checkout, dump the commands every
+  // time, so that the file remains up to date.
+  dumpMeteorCommands();
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Long-form help
 ///////////////////////////////////////////////////////////////////////////////