c++ - 适用于 Chrome 的 NPAPI 插件无法通过 NP_Initialize

Question

我一直在尝试为使用 NPAPI 插件的 Chrome 编写扩展程序。我正在使用 mingw 来编译它。我最初努力让 Chrome 加载插件，但现在我遇到了不同的问题。

我已经设法让 Chrome 调用 NP_GetEntryPoints 和 NP_Initialize，但它在那之后立即崩溃。到目前为止，这是我的代码...

ma​​in.cpp :

#include <iostream>
#include <cstdlib>
#include <Windows.h>
#include <npapi.h>
#include <npfunctions.h>
#define Exported extern "C" __declspec(dllexport)

NPNetscapeFuncs NPNFuncs;

Exported NPError NP_Initialize(NPNetscapeFuncs* pFuncs) {

    if (pFuncs == NULL)
        return NPERR_INVALID_FUNCTABLE_ERROR;

    if (HIBYTE(pFuncs->version) > NP_VERSION_MAJOR)
        return NPERR_INCOMPATIBLE_VERSION_ERROR;

    if (pFuncs->size < sizeof(NPNetscapeFuncs))
        return NPERR_INVALID_FUNCTABLE_ERROR;

    // Save functions
    NPNFuncs.size             = pFuncs->size;
    NPNFuncs.version          = pFuncs->version;
    NPNFuncs.geturlnotify     = pFuncs->geturlnotify;
    NPNFuncs.geturl           = pFuncs->geturl;
    NPNFuncs.posturlnotify    = pFuncs->posturlnotify;
    NPNFuncs.posturl          = pFuncs->posturl;
    NPNFuncs.requestread      = pFuncs->requestread;
    NPNFuncs.newstream        = pFuncs->newstream;
    NPNFuncs.write            = pFuncs->write;
    NPNFuncs.destroystream    = pFuncs->destroystream;
    NPNFuncs.status           = pFuncs->status;
    NPNFuncs.uagent           = pFuncs->uagent;
    NPNFuncs.memalloc         = pFuncs->memalloc;
    NPNFuncs.memfree          = pFuncs->memfree;
    NPNFuncs.memflush         = pFuncs->memflush;
    NPNFuncs.reloadplugins    = pFuncs->reloadplugins;
    NPNFuncs.getJavaEnv       = pFuncs->getJavaEnv;
    NPNFuncs.getJavaPeer      = pFuncs->getJavaPeer;
    NPNFuncs.getvalue         = pFuncs->getvalue;
    NPNFuncs.setvalue         = pFuncs->setvalue;
    NPNFuncs.invalidaterect   = pFuncs->invalidaterect;
    NPNFuncs.invalidateregion = pFuncs->invalidateregion;
    NPNFuncs.forceredraw      = pFuncs->forceredraw;*/

    // Success
    MessageBoxA(0, "NP_Initialize", "Log", 0);
    return NPERR_NO_ERROR;

}

Exported void NP_Shutdown() {

    MessageBoxA(0, "NP_Shutdown", "Log", 0);

}

    /* Entry points */
    NPError NPP_New(NPMIMEType pluginType, NPP instance, uint16_t mode, int16_t argc, char* argn[], char* argv[], NPSavedData* savedData) {

        MessageBoxA(0, "NPP_New", "Log", 0);
        return NPERR_NO_ERROR;

    }

    NPError NPP_GetValue(NPP instance, NPPVariable variable, void *value) {

        MessageBoxA(0, "NPP_GetValue", "Log", 0);
        return NPERR_NO_ERROR;

    }

    /*** Omitted... All the other functions are here, with just a MessageBox call in them ***/

Exported NPError NP_GetEntryPoints(NPPluginFuncs* pFuncs) {

    if (pFuncs == NULL)
        return NPERR_INVALID_FUNCTABLE_ERROR;

    if (pFuncs->size < sizeof(NPPluginFuncs))
        return NPERR_INVALID_FUNCTABLE_ERROR;

    pFuncs->size                = sizeof(NPPluginFuncs);
    pFuncs->version             = (NP_VERSION_MAJOR << 8) | NP_VERSION_MINOR;
    pFuncs->newp                = &NPP_New;
    pFuncs->destroy             = &NPP_Destroy;
    pFuncs->setwindow           = &NPP_SetWindow;
    pFuncs->newstream           = &NPP_NewStream;
    pFuncs->destroystream       = &NPP_DestroyStream;
    pFuncs->asfile              = &NPP_StreamAsFile;
    pFuncs->writeready          = &NPP_WriteReady;
    pFuncs->write               = &NPP_Write;
    pFuncs->print               = &NPP_Print;
    pFuncs->event               = &NPP_HandleEvent;
    pFuncs->urlnotify           = &NPP_URLNotify;
    pFuncs->getvalue            = &NPP_GetValue;
    pFuncs->setvalue            = &NPP_SetValue;
    pFuncs->javaClass           = NULL;
    pFuncs->gotfocus            = &NPP_GotFocus;
    pFuncs->lostfocus           = &NPP_LostFocus;
    pFuncs->urlredirectnotify   = &NPP_URLRedirectNotify;
    pFuncs->clearsitedata       = &NPP_ClearSiteData;
    pFuncs->getsiteswithdata    = &NPP_GetSitesWithData;

    MessageBoxA(0, "NP_GetEntryPoints", "Log", 0);
    return NPERR_NO_ERROR;

}

我为每个函数都添加了一个 MessageBox 调用，这样我就可以查看是否调用了正确的函数。当我运行我的测试页时，这是一个带有 <embed> 的空白页在其中标记，我收到一条消息说 NP_GetEntryPoints , 然后是一句话NP_Initialize ，然后 Chrome 弹出一个栏，说我的插件崩溃了。我认为问题出在我的 NP_GetEntryPoints 上，但我就是看不到它...有什么我做错了或忘记做的事吗？

我编译:

g++.exe -DWIN32 -D_WIN32 -D_WINDOWS -D_WIN32_WINNT=0x0600 -D_WIN32_IE=0x0600 -D_UNICODE -DUNICODE -static-libgcc -static-libstdc++ -c "main.cpp" -o main.o

和

windres.exe "resource.rc" "resource.o"

然后我链接到一个 .DLL 中:

g++.exe -Wl,--subsystem,windows -o "npplugin.dll" -s -shared main.o resource.o -lcomctl32 -lws2_32 -luxtheme -lgdi32 -lshell32 -lshlwapi

Answer 1

函数表之间的大小因浏览器和浏览器版本而异。

您根据硬编译的库 header 检查大小:

if (pFuncs->size < sizeof(NPNetscapeFuncs))
    return NPERR_INVALID_FUNCTABLE_ERROR;

这可能是问题所在。例如最新的(在编写 gecko xulrunner SDK 时包含一个 84 字节大小的结构:

typedef struct _NPPluginFuncs {
  uint16_t size;
  uint16_t version;
  NPP_NewProcPtr newp;
  NPP_DestroyProcPtr destroy;
  NPP_SetWindowProcPtr setwindow;
  NPP_NewStreamProcPtr newstream;
  NPP_DestroyStreamProcPtr destroystream;
  NPP_StreamAsFileProcPtr asfile;
  NPP_WriteReadyProcPtr writeready;
  NPP_WriteProcPtr write;
  NPP_PrintProcPtr print;
  NPP_HandleEventProcPtr event;
  NPP_URLNotifyProcPtr urlnotify;
  void* javaClass;
  NPP_GetValueProcPtr getvalue;
  NPP_SetValueProcPtr setvalue;
  NPP_GotFocusPtr gotfocus;
  NPP_LostFocusPtr lostfocus;
  NPP_URLRedirectNotifyPtr urlredirectnotify;
  NPP_ClearSiteDataPtr clearsitedata;
  NPP_GetSitesWithDataPtr getsiteswithdata;
  NPP_DidCompositePtr didComposite;
} NPPluginFuncs;

Chrome 发送一个 80 字节的结构。

所以我猜最后一个函数指针不在 chrome 使用的结构中。