当我调用 NPN_GetValue 时,我的插件代码崩溃。基本上,我创建了一个可编写脚本的对象,它有一个“getDevice”方法,可以将设备数组返回给 JavaScript。下面是代码片段。
static bool mainNPObjectInvoke(NPObject *obj, NPIdentifier identifier, const NPVariant *args, uint32_t argCount, NPVariant *result)
{
printf("create main object");
MainNPObject *mainObject = (MainNPObject *)obj;
if (identifier == methodIdentifiers[METHOD_ID_GET_DEVICES])
{
NPObject *windowObj = NULL;
browser->getvalue(mainObject->npp, NPNVWindowNPObject, &windowObj);
// it crashed here
....
}
}
我用下面的方法创建了 MainNPObject 实例。
NPObject *createMainNPObject(NPP npp)
{
MainNPObject *object = (MainNPObject *)browser->createobject(npp, &mainNPClass);
object->npp = npp;
theMainObject = object;
return (NPObject *)object;
}
createMainNPObject 在我提供给浏览器的插件函数中被调用。
NPError NPP_GetValue(NPP instance, NPPVariable variable, void *value)
{
PluginObject *obj = instance->pdata;
switch (variable) {
case NPPVpluginCoreAnimationLayer:
if (!obj->rootLayer)
setupLayerHierarchy(obj);
*(CALayer **)value = obj->rootLayer;
return NPERR_NO_ERROR;
case NPPVpluginScriptableNPObject:
if (!obj->mainObject)
{
obj->mainObject = createMainNPObject(instance);
}
....
}
分配功能如下。
static NPObject *mainNPObjectAllocate(NPP npp, NPClass *class)
{
initializeIdentifiers();
MainNPObject *mainObject = malloc(sizeof(MainNPObject));
mainObject->deviceManager = [[DeviceManager alloc] init];
return (NPObject *)mainObject;
}
MainNPObject 的定义:
typedef struct
{
NPObject *npobject;
NPP npp;
DeviceManager *deviceManager;
} MainNPObject;
通过调试代码,发现系统在调用browser->getValue时抛出了EXC_BAD_ACCESS,看起来npp指针无效。
0x00007fff83f82dab <+0019> je 0x7fff83f82db9 <_ZN6WebKit14NetscapePlugin7fromNPPEP4_NPP+33>
0x00007fff83f82dad <+0021> incl 0x8(%rax)
有人可以帮我吗?
谢谢!