SERVER-16703 Improve parsing of JS function bodies and expressions

7 files changed, 234 insertions, 22 deletions

diff --git a/src/mongo/dbtests/jstests.cpp b/src/mongo/dbtests/jstests.cpp
index 4a4ebb408a4..19f6ea37a2a 100644
--- a/src/mongo/dbtests/jstests.cpp
+++ b/src/mongo/dbtests/jstests.cpp
@@ -2139,20 +2139,11 @@ public:
         s->invoke("String(' return ')", 0, 0);
         ASSERT_EQUALS(" return ", s->getString("__returnValue"));
 
-        // This should fail so we set the expected __returnValue to undefined
-        s->invoke(";x = 5", 0, 0);
-        ASSERT_EQUALS("undefined", s->getString("__returnValue"));
-
         s->invoke("String(\"'return\")", 0, 0);
         ASSERT_EQUALS("'return", s->getString("__returnValue"));
 
         s->invoke("String('\"return')", 0, 0);
         ASSERT_EQUALS("\"return", s->getString("__returnValue"));
-
-        // A fail case
-        s->invoke("return$ = 0", 0, 0);
-        // Checks to confirm that the result is NaN
-        ASSERT(s->getNumber("__returnValue") != s->getNumber("__returnValue"));
     }
 };
 
diff --git a/src/mongo/scripting/SConscript b/src/mongo/scripting/SConscript
index f2e51237543..e81f2e4c705 100644
--- a/src/mongo/scripting/SConscript
+++ b/src/mongo/scripting/SConscript
@@ -101,6 +101,13 @@ elif usemozjs:
         'STATIC_JS_API=1',
     ])
 
+    scriptingEnv.JSHeader(
+        target='mozjs/mongohelpers_js.cpp',
+        source=[
+            'mozjs/mongohelpers.js'
+        ]
+    )
+
     scriptingEnv.Library(
         target='scripting',
         source=[
@@ -125,6 +132,8 @@ elif usemozjs:
             'mozjs/maxkey.cpp',
             'mozjs/minkey.cpp',
             'mozjs/mongo.cpp',
+            'mozjs/mongohelpers.cpp',
+            'mozjs/mongohelpers_js.cpp',
             'mozjs/nativefunction.cpp',
             'mozjs/numberint.cpp',
             'mozjs/numberlong.cpp',
diff --git a/src/mongo/scripting/mozjs/implscope.cpp b/src/mongo/scripting/mozjs/implscope.cpp
index 0c110ec546a..d594623a31e 100644
--- a/src/mongo/scripting/mozjs/implscope.cpp
+++ b/src/mongo/scripting/mozjs/implscope.cpp
@@ -240,6 +240,7 @@ MozJSImplScope::MozJSImplScope(MozJSScriptEngine* engine)
       _maxKeyProto(_context),
       _minKeyProto(_context),
       _mongoExternalProto(_context),
+      _mongoHelpersProto(_context),
       _mongoLocalProto(_context),
       _nativeFunctionProto(_context),
       _numberIntProto(_context),
@@ -276,6 +277,7 @@ MozJSImplScope::MozJSImplScope(MozJSScriptEngine* engine)
 
     // install global utility functions
     installGlobalUtils(*this);
+    _mongoHelpersProto.install(_global);
 }
 
 MozJSImplScope::~MozJSImplScope() {
@@ -420,22 +422,11 @@ bool hasFunctionIdentifier(StringData code) {
     return code[8] == ' ' || code[8] == '(';
 }
 
-// TODO: This function identification code is broken.  Fix it up to be more robust
-//
-// See: SERVER-16703 for more info
 void MozJSImplScope::_MozJSCreateFunction(const char* raw,
                                           ScriptingFunction functionNumber,
                                           JS::MutableHandleValue fun) {
-    std::string code = jsSkipWhiteSpace(raw);
-    if (!hasFunctionIdentifier(code)) {
-        if (code.find('\n') == std::string::npos && !hasJSReturn(code) &&
-            (code.find(';') == std::string::npos || code.find(';') == code.size() - 1)) {
-            code = "return " + code;
-        }
-        code = "function(){ " + code + "}";
-    }
-
-    code = str::stream() << "_funcs" << functionNumber << " = " << code;
+    std::string code = str::stream() << "_funcs" << functionNumber << " = "
+                                     << parseJSFunctionOrExpression(_context, StringData(raw));
 
     JS::CompileOptions co(_context);
     setCompileOptions(&co);
diff --git a/src/mongo/scripting/mozjs/implscope.h b/src/mongo/scripting/mozjs/implscope.h
index 6bd0c6c7411..30106006d43 100644
--- a/src/mongo/scripting/mozjs/implscope.h
+++ b/src/mongo/scripting/mozjs/implscope.h
@@ -46,6 +46,7 @@
 #include "mongo/scripting/mozjs/maxkey.h"
 #include "mongo/scripting/mozjs/minkey.h"
 #include "mongo/scripting/mozjs/mongo.h"
+#include "mongo/scripting/mozjs/mongohelpers.h"
 #include "mongo/scripting/mozjs/nativefunction.h"
 #include "mongo/scripting/mozjs/numberint.h"
 #include "mongo/scripting/mozjs/numberlong.h"
@@ -194,6 +195,10 @@ public:
         return _mongoExternalProto;
     }
 
+    WrapType<MongoHelpersInfo>& getMongoHelpersProto() {
+        return _mongoHelpersProto;
+    }
+
     WrapType<MongoLocalInfo>& getMongoLocalProto() {
         return _mongoLocalProto;
     }
@@ -310,6 +315,7 @@ private:
     WrapType<MaxKeyInfo> _maxKeyProto;
     WrapType<MinKeyInfo> _minKeyProto;
     WrapType<MongoExternalInfo> _mongoExternalProto;
+    WrapType<MongoHelpersInfo> _mongoHelpersProto;
     WrapType<MongoLocalInfo> _mongoLocalProto;
     WrapType<NativeFunctionInfo> _nativeFunctionProto;
     WrapType<NumberIntInfo> _numberIntProto;
diff --git a/src/mongo/scripting/mozjs/mongohelpers.cpp b/src/mongo/scripting/mozjs/mongohelpers.cpp
new file mode 100644
index 00000000000..b27163ce7a3
--- /dev/null
+++ b/src/mongo/scripting/mozjs/mongohelpers.cpp
@@ -0,0 +1,94 @@
+/**
+ * Copyright (C) 2015 MongoDB Inc.
+ *
+ * This program is free software: you can redistribute it and/or  modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * As a special exception, the copyright holders give permission to link the
+ * code of portions of this program with the OpenSSL library under certain
+ * conditions as described in each individual source file and distribute
+ * linked combinations including the program with the OpenSSL library. You
+ * must comply with the GNU Affero General Public License in all respects
+ * for all of the code used other than as permitted herein. If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so. If you do not
+ * wish to do so, delete this exception statement from your version. If you
+ * delete this exception statement from all source files in the program,
+ * then also delete it in the license file.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/scripting/mozjs/mongohelpers.h"
+
+#include <jsapi.h>
+
+#include "mongo/scripting/engine.h"
+#include "mongo/scripting/mozjs/implscope.h"
+#include "mongo/scripting/mozjs/objectwrapper.h"
+#include "mongo/scripting/mozjs/valuereader.h"
+#include "mongo/scripting/mozjs/valuewriter.h"
+
+namespace mongo {
+namespace JSFiles {
+extern const JSFile mongohelpers;
+}  // namespace JSFiles
+
+namespace mozjs {
+
+const char* const MongoHelpersInfo::className = "MongoHelpers";
+
+namespace {
+const char kExportsObjectName[] = "exportToMongoHelpers";
+const char kReflectName[] = "Reflect";
+}  // namespace
+
+std::string parseJSFunctionOrExpression(JSContext* cx, const StringData input) {
+    JS::RootedValue jsStrOut(cx);
+    JS::RootedValue jsStrIn(cx);
+
+    ValueReader(cx, &jsStrIn).fromStringData(input);
+    ObjectWrapper helpersWrapper(cx, getScope(cx)->getMongoHelpersProto().getProto());
+
+    helpersWrapper.callMethod("functionExpressionParser", JS::HandleValueArray(jsStrIn), &jsStrOut);
+
+    return ValueWriter(cx, jsStrOut).toString();
+}
+
+void MongoHelpersInfo::postInstall(JSContext* cx, JS::HandleObject global, JS::HandleObject proto) {
+    ObjectWrapper protoWrapper(cx, proto);
+    ObjectWrapper globalWrapper(cx, global);
+
+    // Initialize the reflection API and move it under the MongoHelpers object
+    uassert(ErrorCodes::JSInterpreterFailure,
+            "Error initializing javascript reflection API",
+            JS_InitReflect(cx, global));
+    JS::RootedValue reflectValue(cx);
+    globalWrapper.getValue(kReflectName, &reflectValue);
+    globalWrapper.deleteProperty(kReflectName);
+    protoWrapper.setValue(kReflectName, reflectValue);
+
+    JS::RootedValue exports(cx);
+    getScope(cx)->execSetup(JSFiles::mongohelpers);
+    globalWrapper.getValue(kExportsObjectName, &exports);
+    globalWrapper.deleteProperty(kExportsObjectName);
+
+    ObjectWrapper exportsWrapper(cx, exports);
+    JS::RootedValue copyExport(cx);
+    exportsWrapper.enumerate([&](JS::HandleId _id) {
+        exportsWrapper.getValue(_id, &copyExport);
+        protoWrapper.setValue(_id, copyExport);
+    });
+}
+
+}  // namespace mozjs
+}  // namespace mongo
diff --git a/src/mongo/scripting/mozjs/mongohelpers.h b/src/mongo/scripting/mozjs/mongohelpers.h
new file mode 100644
index 00000000000..75a90117d70
--- /dev/null
+++ b/src/mongo/scripting/mozjs/mongohelpers.h
@@ -0,0 +1,53 @@
+/**
+ * Copyright (C) 2015 MongoDB Inc.
+ *
+ * This program is free software: you can redistribute it and/or  modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * As a special exception, the copyright holders give permission to link the
+ * code of portions of this program with the OpenSSL library under certain
+ * conditions as described in each individual source file and distribute
+ * linked combinations including the program with the OpenSSL library. You
+ * must comply with the GNU Affero General Public License in all respects
+ * for all of the code used other than as permitted herein. If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so. If you do not
+ * wish to do so, delete this exception statement from your version. If you
+ * delete this exception statement from all source files in the program,
+ * then also delete it in the license file.
+ */
+
+#pragma once
+
+#include "mongo/scripting/mozjs/wraptype.h"
+
+namespace mongo {
+namespace mozjs {
+
+/**
+ * The "MongoHelpers" Javascript object.
+ *
+ * The MongoHelpers object is a special hidden object to attach internal-use
+ * javascript code to the global object so that we can do things like access the
+ * javascript parser through SpiderMonkey's reflection API, and parse function
+ * bodies/expressions from the server code.
+ */
+struct MongoHelpersInfo : public BaseInfo {
+    static void postInstall(JSContext* cx, JS::HandleObject global, JS::HandleObject proto);
+    static const InstallType installType = InstallType::Private;
+    static const char* const className;
+};
+
+std::string parseJSFunctionOrExpression(JSContext* cx, StringData input);
+
+}  // namespace mozjs
+}  // namespace mongo
diff --git a/src/mongo/scripting/mozjs/mongohelpers.js b/src/mongo/scripting/mozjs/mongohelpers.js
new file mode 100644
index 00000000000..7864d417d62
--- /dev/null
+++ b/src/mongo/scripting/mozjs/mongohelpers.js
@@ -0,0 +1,68 @@
+/**
+ * Copyright (C) 2015 MongoDB Inc.
+ *
+ * This program is free software: you can redistribute it and/or  modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * As a special exception, the copyright holders give permission to link the
+ * code of portions of this program with the OpenSSL library under certain
+ * conditions as described in each individual source file and distribute
+ * linked combinations including the program with the OpenSSL library. You
+ * must comply with the GNU Affero General Public License in all respects
+ * for all of the code used other than as permitted herein. If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so. If you do not
+ * wish to do so, delete this exception statement from your version. If you
+ * delete this exception statement from all source files in the program,
+ * then also delete it in the license file.
+ */
+
+// This file has JavaScript functions that should be attached to the MongoHelpers object
+
+// The contents of exportToMongoHelpers will be copied into the MongoHelpers object and
+// this dictionary will be removed from the global scope.
+exportToMongoHelpers = {
+    // This function accepts an expression or function body and returns a function definition
+   'functionExpressionParser': function functionExpressionParser(fnSrc) {
+        var parseTree;
+        try {
+            parseTree = this.Reflect.parse(fnSrc);
+        } catch(e) {
+            if (e == 'SyntaxError: function statement requires a name') {
+                return fnSrc;
+            } else if (e == 'SyntaxError: return not in function') {
+                return 'function() { ' + fnSrc + ' }';
+            } else {
+                throw(e);
+            }
+        }
+        // Input source is a series of expressions. we should prepend the last one with return
+        var lastStatement = parseTree.body.length - 1;
+        var lastStatementType = parseTree.body[lastStatement].type;
+        if (lastStatementType == 'ExpressionStatement') {
+            var lines = fnSrc.split('\n');
+            var loc = parseTree.body[lastStatement].loc.start;
+            var mod_line = lines[loc.line - 1];
+            mod_line = mod_line.substr(0, loc.column) + 'return ' + mod_line.substr(loc.column);
+            lines[loc.line - 1] = mod_line;
+            fnSrc = 'function() { ' + lines.join('\n') + ' }'
+            return fnSrc;
+        } else if(lastStatementType == 'FunctionDeclaration') {
+            return fnSrc;
+        } else {
+            return 'function() { ' + fnSrc + ' }';
+        }
+    }
+}
+
+// WARNING: Anything outside the exportToMongoHelpers dictionary will be available in the
+// global scope and visible to users!