findMongoPids: use pgrep where available

ps corrupts some non-ASCII characters on OS X.  pgrep doesn't, but isn't
available everywhere.

Fixes #3999.

tools/run-mongo.js

@@ -124,8 +124,26 @@ if (process.platform === 'win32') {
     var fut = new Future;
 
     // 'ps ax' should be standard across all MacOS and Linux.
+    // However, ps on OS X corrupts some non-ASCII characters in arguments,
+    // such as т (CYRILLIC SMALL LETTER TE), leading to this function
+    // failing to properly match pathnames with those characters.  #3999
+    //
+    // pgrep appears to do a better job (and has output that is roughly
+    // similar; it lacks a few fields that we don't care about).  Plus,
+    // it can do some of the grepping for us.
+    //
+    // However, 'pgrep' only started shipping with OS X 10.8 (and may be less
+    // common on Linux too), so we check to see if it exists and fall back to
+    // 'ps' if we can't find it.
     child_process.exec(
-      'ps ax',
+      'if type pgrep >/dev/null 2>&1; then ' +
+        // -lf means to display and match against full argument lists.
+        // pgrep exits 1 if no processes match the argument; we're OK
+        // considering this as a success, but we don't want other errors
+        // to be ignored.  Note that this is sh not bash, so we can't use
+        // [[.
+        'pgrep -lf mongod; test "$?" -eq 0 -o "$?" -eq 1;' +
+        'else ps ax; fi',
       // we don't want this to randomly fail just because you're running lots of
       // processes. 10MB should be more than ps ax will ever spit out; the default
       // is 200K, which at least one person hit (#2158).

tools/tests/mongo.js

@@ -19,3 +19,38 @@ selftest.define("mongo failover", ["slow"], function () {
   run.expectEnd();
   run.expectExit(0);
 });
+
+var testMeteorMongo = function (appDir) {
+  var s = new Sandbox();
+  s.createApp(appDir, 'standard-app');
+  s.cd(appDir);
+
+  var run = s.run();
+  run.waitSecs(15);
+  run.match(appDir);
+  run.match('proxy');
+  run.match('Started MongoDB');
+
+  var mongoRun = s.run('mongo');
+  mongoRun.match('MongoDB shell');
+  mongoRun.match('connecting to: 127.0.0.1');
+  // Note: when mongo shell's input is not a tty, there is no prompt.
+  mongoRun.write('db.version()\n');
+  mongoRun.match(/2\.6\.\d+/);
+  mongoRun.stop();
+};
+
+selftest.define("meteor mongo", function () {
+  testMeteorMongo('asdfzasdf');
+});
+
+// Regression test for #3999.  Note the Cyrillic character in the pathname.
+//
+// XXX This test fails on Windows for two different reasons:
+// - With the Unicode directory name, `meteor run` fails to start mongod
+// - If you change appDir to not have the Unicode character, the reads
+//   from the mongo shell process seem to be randomly corrupted
+// https://github.com/meteor/windows-preview/issues/145
+selftest.define("meteor mongo in unicode dir", function () {
+  testMeteorMongo('asdf\u0442asdf');
+});