I need to write a file uploader PPAPI plugin instead of using NPAPI in Chrome.
I extend the hello_nacl_cpp project in vs_addin example to test PPAPI and NaCl. The code is similar to this:
...
int32_t showSelectFileDialog() {
pp::CompletionCallbackWithOutput< std::vector<pp::FileRef> > cb =
factory_.NewCallbackWithOutput(&NaClProjectInstance::onFilesSelected);
int32_t ret = file_chooser_.Show(cb);
return ret;
}
void onFilesSelected(int32_t result,
const std::vector<pp::FileRef>& files) {
std::stringstream ss;
if (result == PP_OK) {
// ok
} else {
ss << "undo select file? error code: " << result;
PostMessage(pp::Var(ss.str()));
}
}
...
It's ok if I select PPAPI platform and debug above code. But on NaCl64 platform, the result is PP_ERROR_NO_USER_GESTURE(-41). How can I fix this?
/**
* This value indicates failure due to lack of a user gesture such as a
* mouse click or key input event. Examples of actions requiring a user
* gesture are showing the file chooser dialog and going into fullscreen
* mode.
*/
PP_ERROR_NO_USER_GESTURE = -41,
call showSelectFileDialog() in HandleInputEvent
Related
I have an input QString that has HTML 4 entities, like õ that I’d like to decode. But I can’t find any facilities in Qt to do so. Is there a way to do so in Qt? If possible I’d like to avoid QTextDocument so I don’t have to bring in QtGui.
The HTML 4 entities are listed in this link:
https://www.w3schools.com/charsets/ref_html_entities_4.asp
Out of curiosity, I have looked a bit around.
I found this SO: How can i convert entity character(Escape character) to HTML in QT?. However, it uses QTextDocument (which is part of GUI) what OP wants to prevent.
The doc. of QTextDocument::setHtml() doesn't mention anything specific whether something is used which could be accessed directly (and is even part of the Qt core). Hence, I had a look into source code. I started with QTextDocument::setHtml() on woboq.org and followed the bread crumbs.
Finally, I ended up in qtbase/src/gui/text/qtexthtmlparser.cpp:
QString QTextHtmlParser::parseEntity()
{
const int recover = pos;
int entityLen = 0;
QStringRef entity;
while (pos < len) {
QChar c = txt.at(pos++);
if (c.isSpace() || pos - recover > 9) {
goto error;
}
if (c == QLatin1Char(';'))
break;
++entityLen;
}
if (entityLen) {
entity = QStringRef(&txt, recover, entityLen);
QChar resolved = resolveEntity(entity);
if (!resolved.isNull())
return QString(resolved);
if (entityLen > 1 && entity.at(0) == QLatin1Char('#')) {
entity = entity.mid(1); // removing leading #
int base = 10;
bool ok = false;
if (entity.at(0).toLower() == QLatin1Char('x')) { // hex entity?
entity = entity.mid(1);
base = 16;
}
uint uc = entity.toUInt(&ok, base);
if (ok) {
if (uc >= 0x80 && uc < 0x80 + (sizeof(windowsLatin1ExtendedCharacters)/sizeof(windowsLatin1ExtendedCharacters[0])))
uc = windowsLatin1ExtendedCharacters[uc - 0x80];
QString str;
if (QChar::requiresSurrogates(uc)) {
str += QChar(QChar::highSurrogate(uc));
str += QChar(QChar::lowSurrogate(uc));
} else {
str = QChar(uc);
}
return str;
}
}
}
error:
pos = recover;
return QLatin1String("&");
}
A table of named entities can be found in the same source file:
static const struct QTextHtmlEntity { const char name[9]; quint16 code; } entities[]= {
{ "AElig", 0x00c6 },
{ "AMP", 38 },
...
{ "zwj", 0x200d },
{ "zwnj", 0x200c }
};
Q_STATIC_ASSERT(MAX_ENTITY == sizeof entities / sizeof *entities);
These are bad news for OP:
The API of the QTextHtmlParser is private:
//
// W A R N I N G
// -------------
//
// This file is not part of the Qt API. It exists purely as an
// implementation detail. This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
and it's part of Qt GUI.
If OP insists to prevent GUI dependencies, the only other chance I see is to duplicate the code (or just to re-implement it from scratch).
I'm new to QT and I'm trying to create an encrypted function.
Overall what you do in C / C ++ is:
Take pointer to function
make the function page rwx
Encrypt it (for the example I encrypt and decrypt in the same program)
Decrypt it and run it
A simple code in C will happen roughly like this:
void TestFunction()
{
printf("\nmsgbox test encrypted func\n");
}
// use this as a end label
void FunctionStub() { return; }
void XorBlock(DWORD dwStartAddress, DWORD dwSize)
{
char * addr = (char *)dwStartAddress;
for (int i = 0; i< dwSize; i++)
{
addr[i] ^= 0xff;
}
}
DWORD GetFuncSize(DWORD* Function, DWORD* StubFunction)
{
DWORD dwFunctionSize = 0, dwOldProtect;
DWORD *fnA = NULL, *fnB = NULL;
fnA = (DWORD *)Function;
fnB = (DWORD *)StubFunction;
dwFunctionSize = (fnB - fnA);
VirtualProtect(fnA, dwFunctionSize, PAGE_EXECUTE_READWRITE, &dwOldProtect); // make function page read write execute permission
return dwFunctionSize;
}
int main()
{
DWORD dwFuncSize = GetFuncSize((DWORD*)&TestFunction, (DWORD*)&FunctionStub);
printf("use func");
TestFunction();
XorBlock((DWORD)&TestFunction, dwFuncSize); // XOR encrypt the function
printf("after enc");
//TestFunction(); // If you try to run the encrypted function you will get Access Violation Exception.
XorBlock((DWORD)&TestFunction, dwFuncSize); // XOR decrypt the function
printf("after\n");
TestFunction(); // Fine here
getchar();
}
When I try to run such an example in QT I get a run time error.
Here is the code in QT:
void TestFunction()
{
QMessageBox::information(0, "Test", "msgbox test encrypted func");
}
void FunctionStub() { return; }
void XorBlock(DWORD dwStartAddress, DWORD dwSize)
{
char * addr = (char *)dwStartAddress;
for (int i = 0; i< dwSize; i++)
{
addr[i] ^= 0xff; // here i get seg. fault
}
}
DWORD GetFuncSize(DWORD* Function, DWORD* StubFunction)
{
DWORD dwFunctionSize = 0, dwOldProtect;
DWORD *fnA = NULL, *fnB = NULL;
fnA = (DWORD *)Function;
fnB = (DWORD *)StubFunction;
dwFunctionSize = (fnB - fnA);
VirtualProtect(fnA, dwFunctionSize, PAGE_EXECUTE_READWRITE, &dwOldProtect); // Need to modify our privileges to the memory
QMessageBox::information(0, "Test", "change func to read write execute ");
return dwFunctionSize;
}
void check_enc_function()
{
DWORD dwFuncSize = GetFuncSize((DWORD*)&TestFunction, (DWORD*)&FunctionStub);
QMessageBox::information(0, "Test", "use func");
TestFunction();
XorBlock((DWORD)&TestFunction, dwFuncSize); // XOR encrypt the function -> ### i get seg fault in here ###
QMessageBox::information(0, "Test", "after enc");
TestFunction(); // If you try to run the encrypted function you will get Access Violation Exception.
XorBlock((DWORD)&TestFunction, dwFuncSize); // XOR decrypt the function
QMessageBox::information(0, "Test", "after dec");
TestFunction(); // Fine here
getchar();
}
Why should this happen?
QT is supposed to behave like precision as standard C ++ ...
post Scriptum.
Interestingly in the same matter, what is the most legitimate way to keep an important function encrypted (the reason it is encrypted is DRM)?
Legitimately I mean that anti-viruses will not mistakenly mark me as a virus because I defend myself.
PS2
If I pass an encrypted function over the network (say, I will build a server client schema that the client asks for the function it needs to run from the server and the server sends it to it if it is approved) How can I arrange the symbols so that the function does not collapse?
PS3
How in QT can I turn off the DEP and ASLR defenses? (In my opinion so that I can execute PS 2. I have to cancel them)
Thanks
yoko
The example is undefined behaviour on my system.
The first and main issue in your code is:
void TestFunction() { /* ... */ }
void FunctionStub() { return; }
You assume that the compiler will put FunctionStub after TestFunction without any padding. I compiled your example and FunctionStub in my case was above TestFunction which resulted in a negative dwFunctionSize.
dwFunctionSize = (fnB - fnA);
TestFunction located at # 0xa11d90
FunctionStub located at # 0xa11b50
dwFunctionSize = -0x240
Also in XorBlock
addr[i] ^= 0xff;
Is doing nothing.
I assume you want to write in XorBlock to the memory location to XOR the entire TestFunction.
You could do something like this:
void XorBlock(DWORD dwStartAddress, DWORD dwSize)
{
DWORD dwEndAddress = dwStartAddress + dwSize;
for(DWORD i = dwStartAddress; i < dwEndAddress; i++) {
// ...
}
}
I can't see any Qt-specific in your example. Even if it's Qt function call it's just a call. So I guess you have undefined behaviour in both examples but only second one crashes.
I can't see any reason for compiler and linker to keep function order. For example GCC let you specify the code section for each function. So you can reorder it in executable without reordering in cpp.
I think you need some compiler specific things to make it work.
I'm trying to create and implement a DDE dll with Qt but as for now I'm being unable to properly connect to a service which I know to be working after testing it with Excel.
The dll connection function is as following:
UINT respTemp;
respTemp = DdeInitializeA(&pidInst, NULL, APPCLASS_STANDARD | APPCMD_CLIENTONLY, 0L);
//handle error messages here
//...
//![]
hszService = DdeCreateStringHandleA(pidInst, (LPCSTR)service.utf16(), CP_WINANSI); //service.toLatin1().toStdString().c_str()
hszTopic = DdeCreateStringHandleA(pidInst, (LPCSTR)topic.utf16(), CP_WINANSI); //topic.toLatin1().toStdString().c_str()
hConv = DdeConnect(pidInst, hszService, hszTopic, NULL);
DdeFreeStringHandle(pidInst, hszService);
DdeFreeStringHandle(pidInst, hszTopic);
if (!hConv)
{
UINT ddeLastError = DdeGetLastError(pidInst);
switch (ddeLastError)
{
case DMLERR_DLL_NOT_INITIALIZED: return DDEConn_DLLNotInitialized;
case DMLERR_INVALIDPARAMETER: return DDEConn_InvalidParameter;
case DMLERR_NO_CONV_ESTABLISHED: return DDEConn_NoConvEstablished;
default: return DDEConn_NoConnectionStablished;
}
}
connStatus = true;
return DDEConn_NoError;
The test function is as follows:
void MainWindow::on_start_clicked()
{
const QString application = "profitchart"; //=profitchart|COT!VALE5.ult
const QString topic = "COT";
const QString item = "VALE5.ult";
test = CommDDE::instance();
CommDDE::DDEConnectionErrorList resp = test->connect(application,topic);
if (resp == CommDDE::DDEConn_NoError)
{
qDebug() << "request RESULT: " << test->request(item);
}
else
qDebug() << "Can't connect to application" << resp;
}
Always when I try to connect I get error DMLERR_NO_CONV_ESTABLISHED after the call to DdeConnect. I couldn't find guidence on what to do when such error occurs. I don't know too much about the details of configuring such functions so I used the default configuration used by a working dll from which I got part of the raw material for this dll. Should I try a different configuration I'm not aware of? Remembering that the call is working on Excel.
It would seem I found the answer: the commented way of writting the service and topic names were the right ways of passing the parameters to DdeCreateStringHandleA and DdeCreateStringHandleA.
I've developed a video player based on Qt and QtGstreamer. It is used to play live streams (RTSP). I have to add the possibility for the user to take snapshots while he is playing a live stream without perturbing the video playback.
Here the graph of the pipeline I've made:
-->queue-->autovideosink
uridecodebin-->videoflip-->tee--|
| -->queue->videoconvert-->pngenc-->filesink
|
|->audioconvert-->autoaudiosink
I use the pad-added signal from uridecodebin to add and link dynamically my elements to the pipeline, function of the received caps.
void Player::onPadAdded(const QGst::PadPtr &pad)
{
QGst::CapsPtr caps = pad->currentCaps();
if (caps->toString().startsWith("video/x-raw")) {
qDebug("Received 'video/x-raw' caps");
handleNewVideoPad(pad);
}
else if (caps->toString().startsWith("audio/x-raw")) {
qDebug("Received 'audio/x-raw' caps");
if (!m_audioEnabled) {
qDebug("Audio is disabled in the player. Ignoring...");
return;
}
handleNewAudioPad(pad);
}
else {
qWarning("Unsuported caps, arborting ...!");
return;
}
}
[...]
void Player::handleNewVideoPad(QGst::PadPtr pad)
{
m_player->videoTeeVideoSrcPad = m_player->videoTee->getRequestPad("src_%u");
// Add video elements
m_player->pipeline->add(m_player->videoFlip);
m_player->pipeline->add(m_player->videoTee);
m_player->pipeline->add(m_player->videoQueue);
m_player->pipeline->add(m_player->videoSink);
// Add snap elements
m_player->pipeline->add(m_player->snapQueue);
m_player->pipeline->add(m_player->snapConverter);
m_player->pipeline->add(m_player->snapEncoder);
m_player->pipeline->add(m_player->snapSink);
// Link video elements
m_player->videoFlip->link(m_player->videoTee);
m_player->videoQueue->link(m_player->videoSink);
// Link snap elements
m_player->snapQueue->link(m_player->snapConverter);
m_player->snapConverter->link(m_player->snapEncoder);
m_player->snapEncoder->link(m_player->snapSink);
// Lock snap elements
m_player->snapQueue->setStateLocked(true);
m_player->snapConverter->setStateLocked(true);
m_player->snapEncoder->setStateLocked(true);
m_player->snapSink->setStateLocked(true);
m_player->videoFlip->setState(QGst::StatePlaying);
m_player->videoTee->setState(QGst::StatePlaying);
m_player->videoQueue->setState(QGst::StatePlaying);
m_player->videoSink->setState(QGst::StatePlaying);
// Link pads
m_player->videoTeeVideoSrcPad->link(m_player->videoQueue->getStaticPad("sink"));
pad->link(m_player->videoSinkPad);
m_player->videoLinked = true;
}
The method to take a snapshot:
void Player::takeSnapshot()
{
QDateTime dateTime = QDateTime::currentDateTime();
QString snapLocation = QString("/%1/snap_%2.png").arg(m_snapDir).arg(dateTime.toString(Qt::ISODate));
m_player->inSnapshotCaputre = true;
if (m_player->videoTeeSnapSrcPad) {
m_player->videoTee->releaseRequestPad(m_player->videoTeeSnapSrcPad);
m_player->videoTeeSnapSrcPad.clear();
}
m_player->videoTeeSnapSrcPad = m_player->videoTee->getRequestPad("src_%u");
// Stop the snapshot branch
m_player->snapQueue->setState(QGst::StateNull);
m_player->snapConverter->setState(QGst::StateNull);
m_player->snapEncoder->setState(QGst::StateNull);
m_player->snapSink->setState(QGst::StateNull);
// Link Tee src pad to snap queue sink pad
m_player->videoTeeSnapSrcPad->link(m_player->snapQueue->getStaticPad("sink"));
// Set the snapshot location property
m_player->snapSink->setProperty("location", snapLocation);
// Unlock snapshot branch
m_player->snapQueue->setStateLocked(false);
m_player->snapConverter->setStateLocked(false);
m_player->snapEncoder->setStateLocked(false);
m_player->snapSink->setStateLocked(false);
m_player->videoTeeSnapSrcPad->setActive(true);
// Synch snapshot branch state with parent
m_player->snapQueue->syncStateWithParent();
m_player->snapConverter->syncStateWithParent();
m_player->snapEncoder->syncStateWithParent();
m_player->snapSink->syncStateWithParent();
}
The bus message callback:
void Player::onBusMessage(const QGst::MessagePtr & message)
{
QGst::ElementPtr source = message->source().staticCast<QGst::Element>();
switch (message->type()) {
case QGst::MessageEos: { //End of stream. We reached the end of the file.
qDebug("Message End Off Stream");
if (m_player->inSnapshotCaputre) {
blockSignals(true);
pause();
play();
blockSignals(false);
m_player->inSnapshotCaputre = false;
}
else {
m_eos = true;
stop();
}
break;
}
[...]
}
The problem is:
When I set the snapshot property to true of the pngenc element, I receive the EOS event which stop my pipeline, so I need to restart it, which freeze the video playback for about half a second, which in not acceptable in my case.
When I set the snapshot property to false of the pngenc element, I have no pipeline perturbations, but my png file keeps growing until I call again the Player::takeSnapshot() method.
Where am I wrong ? Is there a better way to do it ?
I've tried unsuccessfully creating a QGst::Bin element for my snapshot branch. What about pad probe ?
Thanks by advance
You can take the last-sample property on any sink, e.g. your video sink. This contains a GstSample, which has a buffer with the very latest video frame in it. You can take that as a snapshot, and e.g. with gst_video_convert_sample() or the async variant of it, convert it to a PNG/JPG/whatever.
See https://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer-libs/html/GstBaseSink.html#GstBaseSink--last-sample and https://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-gstvideo.html#gst-video-convert-sample
Alternatively, you would have to shut down the filesink snapshot pipeline after the first frame. For example by having a pad probe to know when the first frame happened, and then injecting an EOS event to prevent further PNG frames to be appended to the same file.
Thanks to #sebastian-droge answer, I found the solution, using gst_video_convert_sample and the last-sample property of my video sink.
The solution I've implemented is:
void Player::takeSnapshot()
{
QDateTime currentDate = QDateTime::currentDateTime();
QString location = QString("%1/snap_%2.png").arg(QDir::homePath()).arg(currentDate.toString(Qt::ISODate));
QImage snapShot;
QImage::Format snapFormat;
QGlib::Value val = m_videoSink->property("last-sample");
GstSample *videoSample = (GstSample *)g_value_get_boxed(val);
QGst::SamplePtr sample = QGst::SamplePtr::wrap(videoSample);
QGst::SamplePtr convertedSample;
QGst::BufferPtr buffer;
QGst::CapsPtr caps = sample->caps();
QGst::MapInfo mapInfo;
GError *err = NULL;
GstCaps * capsTo = NULL;
const QGst::StructurePtr structure = caps->internalStructure(0);
int width, height;
width = structure.data()->value("width").get<int>();
height = structure.data()->value("height").get<int>();
qDebug() << "Sample caps:" << structure.data()->toString();
/*
* { QImage::Format_RGBX8888, GST_VIDEO_FORMAT_RGBx },
* { QImage::Format_RGBA8888, GST_VIDEO_FORMAT_RGBA },
* { QImage::Format_RGB888 , GST_VIDEO_FORMAT_RGB },
* { QImage::Format_RGB16 , GST_VIDEO_FORMAT_RGB16 }
*/
snapFormat = QImage::Format_RGB888;
capsTo = gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, width,
"height", G_TYPE_INT, height,
NULL);
convertedSample = QGst::SamplePtr::wrap(gst_video_convert_sample(videoSample, capsTo, GST_SECOND, &err));
if (convertedSample.isNull()) {
qWarning() << "gst_video_convert_sample Failed:" << err->message;
}
else {
qDebug() << "Converted sample caps:" << convertedSample->caps()->toString();
buffer = convertedSample->buffer();
buffer->map(mapInfo, QGst::MapRead);
snapShot = QImage((const uchar *)mapInfo.data(),
width,
height,
snapFormat);
qDebug() << "Saving snap to" << location;
snapShot.save(location);
buffer->unmap(mapInfo);
}
val.clear();
sample.clear();
convertedSample.clear();
buffer.clear();
caps.clear();
g_clear_error(&err);
if (capsTo)
gst_caps_unref(capsTo);
}
I've create a simple test application, which implement this solution. The code is available on my Github
Using the twaindotnet library in C#, I'm wondering if there's a way to set the default datasource using the library.
As a feeble attempt, I've tried adding a SetDefault method to the DataSource class of twaindonet, like this
public static void SetDefault(Identity applicationId, IWindowsMessageHook messageHook, DataSource newDataSource)
{
var defaultSourceId = newDataSource.SourceId;
// Attempt to get information about the system default source
var result = Twain32Native.DsmIdentity(
applicationId,
IntPtr.Zero,
DataGroup.Control,
DataArgumentType.Identity,
Message.Set,
defaultSourceId);
if (result != TwainResult.Success)
{
var status = DataSourceManager.GetConditionCode(applicationId, null);
throw new TwainException("Error getting information about the default source: " + result, result, status);
}
}
which is called from the DataSourceManage class like this
public void SelectSource(DataSource dataSource)
{
DataSource.Dispose();
DataSource.SetDefault(ApplicationId, _messageHook, dataSource);
}
But when I try to use SetDefault, Twain32Native.DsmIdentity always results in Failure being returned.
I basically copied from SetDefault the setDefaultDataSource method from TWAIN sample Data Source and Application
pTW_IDENTITY TwainApp::setDefaultDataSource(unsigned int _index)
{
if(m_DSMState < 3)
{
cout << "You need to open the DSM first." << endl;
return NULL;
}
else if(m_DSMState > 3)
{
PrintCMDMessage("A source has already been opened, please close it first\n");
return NULL;
}
if(_index >= 0 && _index < m_DataSources.size())
{
m_pDataSource = &(m_DataSources[_index]);
// set the specific data source
TW_UINT16 twrc;
twrc = _DSM_Entry(
&m_MyInfo,
0,
DG_CONTROL,
DAT_IDENTITY,
MSG_SET,
(TW_MEMREF) m_pDataSource);
switch (twrc)
{
case TWRC_SUCCESS:
break;
case TWRC_FAILURE:
printError(0, "Failed to get the data source info!");
break;
}
}
else
{
return NULL;
}
return m_pDataSource;
}
Any help would be greatly appreciated.
The possible cause is that the version of your TWAIN DSM is too low. Only DSM 2.0 or above supports setting default TWAIN data source.