jsj_jsobject.c

caffeine-monkey java实现的js模拟引擎

 * possible that a JS error was actually triggered by Java at some point, in
 * which case the original Java exception is thrown.
 */
static void
throw_any_pending_js_error_as_a_java_exception(JSJavaThreadState *jsj_env)
{
    CapturedJSError *error;
    JNIEnv *jEnv;
    jstring message_jstr, linebuf_jstr, filename_jstr;
    jint index, lineno;
    JSErrorReport *report;
    JSContext *cx;
    jsval pending_exception; 
    jobject java_obj;
    int dummy_cost;
    JSBool is_local_refp;
    JSType primitive_type;
    jthrowable java_exception;

    message_jstr = linebuf_jstr = filename_jstr = java_exception = NULL;

    /* Get the Java JNI environment */
    jEnv = jsj_env->jEnv;

    cx = jsj_env->cx;
    /* Get the pending JS exception if it exists */
    if (cx&&JS_IsExceptionPending(cx)) {
        if (!JS_GetPendingException(cx, &pending_exception))
            goto out_of_memory;

        /* Find out the JSTYPE of this jsval. */
        primitive_type = JS_TypeOfValue(cx, pending_exception);
        
        /* Convert jsval exception to a java object and then use it to
           create an instance of JSException. */ 
        if (!jsj_ConvertJSValueToJavaObject(cx, jEnv, 
                                            pending_exception, 
                                            jsj_get_jlObject_descriptor(cx, jEnv),
                                            &dummy_cost, &java_obj, 
                                            &is_local_refp))
            goto done;
        
        java_exception = (*jEnv)->NewObject(jEnv, njJSException, 
                                            njJSException_JSException_wrap,
                                            primitive_type, java_obj);
        if (is_local_refp)
            (*jEnv)->DeleteLocalRef(jEnv, java_obj);
        if (!java_exception) 
            goto out_of_memory;
        
        /* Throw the newly-created JSException */
        if ((*jEnv)->Throw(jEnv, java_exception) < 0) {
            JS_ASSERT(0);
            jsj_LogError("Couldn't throw JSException\n");
            goto done;
        }    
        JS_ClearPendingException(cx);
        return;
    }
    if (!jsj_env->pending_js_errors) {
#ifdef DEBUG
        /* Any exception should be cleared as soon as it's detected, so there
           shouldn't be any pending. */
        if ((*jEnv)->ExceptionOccurred(jEnv)) {
            /* A Java exception occurred, but nobody in JS-land noticed. */
            JS_ASSERT(0);
            (*jEnv)->ExceptionClear(jEnv);
        }
#endif
        return;
    }

    /* Get the deepest (oldest) saved JS error */
    /* XXX - What's the right thing to do about newer errors ?
       For now we just throw them away */
    error = jsj_env->pending_js_errors;
    while (error->next)
        error = error->next;
    
    /*
     * If the JS error was originally the result of a Java exception, rethrow
     * the original exception.
     */
    if (error->java_exception) {
        (*jEnv)->Throw(jEnv, error->java_exception);
        goto done;
    }

    /* Propagate any JS errors that did not originate as Java exceptions into
       Java as an instance of netscape.javascript.JSException */

    /* First, marshall the arguments to the JSException constructor */
    message_jstr = NULL;
    if (error->message) {
        message_jstr = (*jEnv)->NewStringUTF(jEnv, error->message);
        if (!message_jstr)
            goto out_of_memory;
    }

    report = &error->report;

    filename_jstr = NULL;
    if (report->filename) {
        filename_jstr = (*jEnv)->NewStringUTF(jEnv, report->filename);
        if (!filename_jstr)
            goto out_of_memory;
    }

    linebuf_jstr = NULL;
    if (report->linebuf) {
        linebuf_jstr = (*jEnv)->NewStringUTF(jEnv, report->linebuf);
        if (!linebuf_jstr)
            goto out_of_memory;
    }

    lineno = report->lineno;
    index = report->linebuf ? report->tokenptr - report->linebuf : 0;

    /* Call the JSException constructor */
    java_exception = (*jEnv)->NewObject(jEnv, njJSException, njJSException_JSException,
                                        message_jstr, filename_jstr, lineno, linebuf_jstr, index);
    if (!java_exception)
        goto out_of_memory;

    /* Throw the newly-created JSException */
    if ((*jEnv)->Throw(jEnv, java_exception) < 0) {
        JS_ASSERT(0);
        jsj_UnexpectedJavaError(cx, jEnv, "Couldn't throw JSException\n");
    }
    goto done;

out_of_memory:
    /* No recovery possible */
    JS_ASSERT(0);
    jsj_LogError("Out of memory while attempting to throw JSException\n");

done:
    jsj_ClearPendingJSErrors(jsj_env);
    /*
     * Release local references to Java objects, since some JVMs seem reticent
     * about collecting them otherwise.
     */
    if (message_jstr)
        (*jEnv)->DeleteLocalRef(jEnv, message_jstr);
    if (filename_jstr)
        (*jEnv)->DeleteLocalRef(jEnv, filename_jstr);
    if (linebuf_jstr)
        (*jEnv)->DeleteLocalRef(jEnv, linebuf_jstr);
    if (java_exception)
        (*jEnv)->DeleteLocalRef(jEnv, java_exception);
}

/*
 * This function is called up returning from Java back into JS as a result of
 * a thrown netscape.javascript.JSException, which itself must have been caused
 * by a JS error when Java called into JS.  The original JS error is
 * reconstituted from the JSException and re-reported as a JS error.
 *
 * Returns JS_FALSE if an internal error occurs, JS_TRUE otherwise.
 */
JSBool
jsj_ReportUncaughtJSException(JSContext *cx, JNIEnv *jEnv, jthrowable java_exception)
{
    JSBool success;
    JSErrorReport report;
    const char *linebuf, *filename, *message, *tokenptr;
    jint lineno, token_index;
    jstring linebuf_jstr, filename_jstr, message_jstr;

    /* Initialize everything to NULL */
    memset(&report, 0, sizeof(JSErrorReport));
    success = JS_FALSE;
    filename_jstr = linebuf_jstr = message_jstr = NULL;
    filename = message = linebuf = tokenptr = NULL;

    lineno = (*jEnv)->GetIntField(jEnv, java_exception, njJSException_lineno);
    report.lineno = lineno;

    filename_jstr = (*jEnv)->GetObjectField(jEnv, java_exception, njJSException_filename);
    if ((*jEnv)->ExceptionOccurred(jEnv)) {
        jsj_UnexpectedJavaError(cx, jEnv, "Unable to access filename field of a JSException");
        goto done;
    }
    if (filename_jstr)
        filename = (*jEnv)->GetStringUTFChars(jEnv, filename_jstr, 0);
    report.filename = filename;

    linebuf_jstr = (*jEnv)->GetObjectField(jEnv, java_exception, njJSException_source);
    if ((*jEnv)->ExceptionOccurred(jEnv)) {
        jsj_UnexpectedJavaError(cx, jEnv, "Unable to access source field of a JSException");
        goto done;
    }
    if (linebuf_jstr)
        linebuf = (*jEnv)->GetStringUTFChars(jEnv, linebuf_jstr, 0);
    report.linebuf = linebuf;

    token_index = (*jEnv)->GetIntField(jEnv, java_exception, njJSException_lineno);
    report.tokenptr = linebuf + token_index;

    message_jstr = (*jEnv)->CallObjectMethod(jEnv, java_exception, jlThrowable_getMessage);
    if ((*jEnv)->ExceptionOccurred(jEnv)) {
        jsj_UnexpectedJavaError(cx, jEnv, "Unable to access message of a JSException");
        goto done;
    }
    if (message_jstr)
        message = (*jEnv)->GetStringUTFChars(jEnv, message_jstr, 0);

    js_ReportErrorAgain(cx, message, &report);

    success = JS_TRUE;

done:

    if (filename_jstr && filename)
        (*jEnv)->ReleaseStringUTFChars(jEnv, filename_jstr, filename);
    if (linebuf_jstr && linebuf)
        (*jEnv)->ReleaseStringUTFChars(jEnv, linebuf_jstr, linebuf);
    if (message_jstr && message)
        (*jEnv)->ReleaseStringUTFChars(jEnv, message_jstr, message);
    return success;
}



/*************** Utilities for calling JavaScript from Java *****************/

/*
 * This routine is called just prior to invoking any JS API function from
 * Java.  It performs a common set of chores, such as obtaining the LiveConnect
 * state for the invoking Java thread and determining the JSContext to be
 * used for this thread.
 *
 * Returns NULL on failure.
 */


JSJavaThreadState *
jsj_enter_js(JNIEnv *jEnv, void* applet_obj, jobject java_wrapper_obj,
             JSContext **cxp, JSObject **js_objp, JSErrorReporter *old_error_reporterp,
             void **pNSIPrincipaArray, int numPrincipals, void *pNSISecurityContext)
{
    JSContext *cx;
    char *err_msg;
    JSObject *js_obj;
    JSJavaThreadState *jsj_env;

    cx = NULL;
    err_msg = NULL;

    /* Invoke callback, presumably used to implement concurrency constraints */
    if (JSJ_callbacks && JSJ_callbacks->enter_js_from_java) {
#ifdef OJI
        if (!JSJ_callbacks->enter_js_from_java(jEnv, &err_msg, pNSIPrincipaArray, numPrincipals, pNSISecurityContext,applet_obj))
#else
        if (!JSJ_callbacks->enter_js_from_java(jEnv, &err_msg))
#endif
            goto entry_failure;
    }

    /* Check the JSObject pointer in the wrapper object. */
    if (js_objp) {

#ifdef PRESERVE_JSOBJECT_IDENTITY
#if JS_BYTES_PER_LONG == 8
        js_obj = (JSObject *)((*jEnv)->GetLongField(jEnv, java_wrapper_obj, njJSObject_long_internal));
#else
        js_obj = (JSObject *)((*jEnv)->GetIntField(jEnv, java_wrapper_obj, njJSObject_internal));
#endif
#else   /* !PRESERVE_JSOBJECT_IDENTITY */
        js_obj = jsj_UnwrapJSObjectWrapper(jEnv, java_wrapper_obj);
#endif  /* PRESERVE_JSOBJECT_IDENTITY */

        JS_ASSERT(js_obj);
        if (!js_obj)
            goto error;
        *js_objp = js_obj;
    }

    /* Get the per-thread state corresponding to the current Java thread */
    jsj_env = jsj_MapJavaThreadToJSJavaThreadState(jEnv, &err_msg);
    if (!jsj_env)
        goto error;

    /* Get the JSContext that we're supposed to use for this Java thread */
    cx = jsj_env->cx;
    if (!cx) {
        /* We called spontaneously into JS from Java, rather than from JS into
           Java and back into JS.  Invoke a callback to obtain/create a
           JSContext for us to use. */
        if (JSJ_callbacks && JSJ_callbacks->map_jsj_thread_to_js_context) {
#ifdef OJI
            cx = JSJ_callbacks->map_jsj_thread_to_js_context(jsj_env,
                                                             applet_obj,
                                                             jEnv, &err_msg);
#else
            cx = JSJ_callbacks->map_jsj_thread_to_js_context(jsj_env,
                                                             jEnv, &err_msg);
#endif
            if (!cx)
                goto error;
        } else {
            err_msg = JS_smprintf("Unable to find/create JavaScript execution "
                                  "context for JNI thread 0x%08x", jEnv);
            goto error;
        }
    }
    *cxp = cx;

    /*
     * Capture all JS error reports so that they can be thrown into the Java
     * caller as an instance of netscape.javascript.JSException.
     */
    *old_error_reporterp =
        JS_SetErrorReporter(cx, capture_js_error_reports_for_java);

#ifdef JSJ_THREADSAFE
    JS_BeginRequest(cx);
#endif

    return jsj_env;

error:
    /* Invoke callback, presumably used to implement concurrency constraints */
    if (JSJ_callbacks && JSJ_callbacks->exit_js)
        JSJ_callbacks->exit_js(jEnv, cx);

entry_failure:
    if (err_msg) {
        if (cx)
            JS_ReportError(cx, err_msg);
        else
            jsj_LogError(err_msg);
        free(err_msg);
    }

    return NULL;
}

/*
 * This utility function is called just prior to returning into Java from JS.
 */
JSBool
jsj_exit_js(JSContext *cx, JSJavaThreadState *jsj_env, JSErrorReporter original_reporter)
{
    JNIEnv *jEnv;

#ifdef JSJ_THREADSAFE
    JS_EndRequest(cx);
#endif

    /* Restore the JS error reporter */
    JS_SetErrorReporter(cx, original_reporter);

    jEnv = jsj_env->jEnv;

#ifdef DEBUG
    /* Any Java exceptions should have been noticed and reported already */
    if ((*jEnv)->ExceptionOccurred(jEnv)) {
        JS_ASSERT(0);
        jsj_LogError("Unhandled Java exception detected");
        return JS_FALSE;
    }
#endif

    /*
     * Convert reported JS errors to JSExceptions, unless the errors were
     * themselves the result of Java exceptions, in which case the original
     * Java exception is simply propagated.
     */
    throw_any_pending_js_error_as_a_java_exception(jsj_env);

    /* Invoke callback, presumably used to implement concurrency constraints */
    if (JSJ_callbacks && JSJ_callbacks->exit_js)
        JSJ_callbacks->exit_js(jEnv, cx);

    return JS_TRUE;
}


/* Get the JavaClassDescriptor that corresponds to java.lang.Object */
JavaClassDescriptor *
jsj_get_jlObject_descriptor(JSContext *cx, JNIEnv *jEnv)
{
    /* The JavaClassDescriptor for java.lang.Object */
    static JavaClassDescriptor *jlObject_descriptor = NULL;

    if (!jlObject_descriptor)
        jlObject_descriptor = jsj_GetJavaClassDescriptor(cx, jEnv, jlObject);
    return jlObject_descriptor;
}

/****************** Implementation of methods of JSObject *******************/

/*
 * Class:     netscape_javascript_JSObject
 * Method:    initClass
 * Signature: ()V
 */
JNIEXPORT void JNICALL
Java_netscape_javascript_JSObject_initClass(JNIEnv *jEnv, jclass java_class)
{
    jsj_init_js_obj_reflections_table();
}

/*
 * Class:     netscape_javascript_JSObject
 * Method:    getMember
 * Signature: (Ljava/lang/String;)Ljava/lang/Object;
 */
JNIEXPORT jobject JNICALL
Java_netscape_javascript_JSObject_getMember(JNIEnv *jEnv,
                                            jobject java_wrapper_obj,
                                            jstring property_name_jstr)
{
    JSContext *cx = NULL;
    JSObject *js_obj;
    jsval js_val;
    int dummy_cost;
    JSBool dummy_bool;
    const jchar *property_name_ucs2;
    jsize property_name_len;
    JSErrorReporter saved_reporter;
    jobject member;
    jboolean is_copy;
    JSJavaThreadState *jsj_env;
    
    jsj_env = jsj_enter_js(jEnv, NULL, java_wrapper_obj, &cx, &js_obj, &saved_reporter, NULL, 0, NULL);
    if (!jsj_env)
        return NULL;

    property_name_ucs2 = NULL;
    if (!property_name_jstr) {
        JS_ReportErrorNumber(cx, jsj_GetErrorMessage, NULL,
                             JSJMSG_NULL_MEMBER_NAME);
        member = NULL;
        goto done;
    }

    /* Get the Unicode string for the JS property name */
    property_name_ucs2 = (*jEnv)->GetStringChars(jEnv, property_name_jstr, &is_copy);
    if (!property_name_ucs2) {
        JS_ASSERT(0);
        goto done;
    }
    property_name_len = (*jEnv)->GetStringLength(jEnv, property_name_jstr);
    
    if (!JS_GetUCProperty(cx, js_obj, property_name_ucs2, property_name_len, &js_val))
        goto done;

    jsj_ConvertJSValueToJavaObject(cx, jEnv, js_val, 
                                   jsj_get_jlObject_descriptor(cx, jEnv),
                                   &dummy_cost, &member, &dummy_bool);

done:
    if (property_name_ucs2)
        (*jEnv)->ReleaseStringChars(jEnv, property_name_jstr, property_name_ucs2);
    if (!jsj_exit_js(cx, jsj_env, saved_reporter))
        return NULL;