transform javascript to opcode using spidermonkey

Question

i am new to spider monkey and want to use it for transform java script file to sequence of byte code. i get spider monkey and build it in debug mode.

i want to use JS_CompileScript function in jsapi.h to compile javascript code and analysis this to get bytecode , but when in compile below code and run it , i get run time error. the error is "Unhandled exception at 0x0f55c020 (mozjs185-1.0.dll) in spiderMonkeyTest.exe: 0xC0000005: Access violation reading location 0x00000d4c." and i do not resolve it.

any body can help me to resolve this or introducing other solutions to get byte code from javascript code by using spider monkey ?

     // spiderMonkeyTest.cpp : Defines the entry point for the console application.
    //
    #define XP_WIN
    #include <iostream>
    #include <fstream>
    #include "stdafx.h"
    #include "jsapi.h"
    #include "jsanalyze.h"
    using namespace std;
    using namespace js;


    static JSClass global_class = { "global",
                                    JSCLASS_NEW_RESOLVE | JSCLASS_GLOBAL_FLAGS,
                                    JS_PropertyStub,
                                    NULL,
                                    JS_PropertyStub,
                                    JS_StrictPropertyStub,
                                    JS_EnumerateStub,
                                JS_ResolveStub,
                                JS_ConvertStub,
                                NULL,
                                JSCLASS_NO_OPTIONAL_MEMBERS
};





int _tmain(int argc, _TCHAR* argv[]) {

    /* Create a JS runtime. */
    JSRuntime *rt = JS_NewRuntime(16L * 1024L * 1024L);
    if (rt == NULL)
       return 1;

    /* Create a context. */
    JSContext *cx = JS_NewContext(rt, 8192);
    if (cx == NULL)
       return 1;
    JS_SetOptions(cx, JSOPTION_VAROBJFIX);

    JSScript *script;
    JSObject *obj;
    const char *js = "function a() { var tmp; tmp = 1 + 2; temp = temp * 2; alert(tmp); return 1; }";
    obj = JS_CompileScript(cx,JS_GetGlobalObject(cx),js,strlen(js),"code.js",NULL);
    script = obj->getScript();
    if (script == NULL)
       return JS_FALSE;   /* compilation error */
    js::analyze::Script *sc = new js::analyze::Script();
    sc->analyze(cx,script);

    JS_DestroyContext(cx);
    JS_DestroyRuntime(rt);

    /* Shut down the JS engine. */
    JS_ShutDown();

    return 1;
}

JavaMan · Accepted Answer · 2013-12-01 12:08:39Z

Which version of Spidermonkey are you using? I am using the one that comes with FireFox 10 so the API may be different.

You should create a new global object and initialize it by calling JS_NewCompartmentAndGlobalObject() and JS_InitStandardClasses() before compiling your script :

.....
 /*
 * Create the global object in a new compartment.
 * You always need a global object per context.
 */
global = JS_NewCompartmentAndGlobalObject(cx, &global_class, NULL);
if (global == NULL)
    return 1;
/*
 * Populate the global object with the standard JavaScript
 * function and object classes, such as Object, Array, Date.
 */
if (!JS_InitStandardClasses(cx, global))
  return 1;
......

Note, the function JS_NewCompartmentAndGlobalObject() is obsolete now, check the latest JSAPI documentation for the version your are using. Your JS_CompileScript() call just try to retrieve a global object which has not been created and probably this causes the exception.

Zam · Accepted Answer · 2014-01-10 20:37:35Z

0

how about using function "SaveCompiled" ? it will save object/op-code (compiled javascript) to file

answered Jan 10, 2014 at 20:37

Zam

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