src: fix Windows segfault with --eval

When specifing a parameter that requries an additional argument on the
command line, node would segfault.  This appears to be specific to
Windows, adjusted command line argument parsing to hold a nullptr
terminal.

Adding unit test for crash on missing arguments.

PR-URL: #6938
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

src/node_main.cc

@@ -3,7 +3,7 @@
 #ifdef _WIN32
 int wmain(int argc, wchar_t *wargv[]) {
   // Convert argv to to UTF8
-  char** argv = new char*[argc];
+  char** argv = new char*[argc + 1];
   for (int i = 0; i < argc; i++) {
     // Compute the size of the required buffer
     DWORD size = WideCharToMultiByte(CP_UTF8,
@@ -35,6 +35,7 @@ int wmain(int argc, wchar_t *wargv[]) {
       exit(1);
     }
   }
+  argv[argc] = nullptr;
   // Now that conversion is done, we can finally start.
   return node::Start(argc, argv);
 }

test/parallel/test-cli-eval.js

@@ -40,11 +40,11 @@ child.exec(nodejs + ' --eval "console.error(42)"',
         assert.equal(stderr, '');
       });
 
-  child.exec(cmd + "'[]'",
+  child.exec(cmd + "'[]'", common.mustCall(
       function(err, stdout, stderr) {
         assert.equal(stdout, '[]\n');
         assert.equal(stderr, '');
-      });
+      }));
 });
 
 // assert that module loading works
@@ -59,6 +59,12 @@ child.exec(nodejs + ' --eval "require(\'./test/parallel/test-cli-eval.js\')"',
       assert.equal(status.code, 42);
     });
 
+// Missing argument should not crash
+child.exec(nodejs + ' -e', common.mustCall(function(status, stdout, stderr) {
+  assert.notStrictEqual(status, null);
+  assert.strictEqual(status.code, 9);
+}));
+
 // empty program should do nothing
 child.exec(nodejs + ' -e ""', function(status, stdout, stderr) {
   assert.equal(stdout, '');