Concatenating two binary files

[nbkhwjm]

This function is called as a response to a slot/signal from a SEND button.. The apps comes up , but throws the errors... and now an additonal one...

QObject: Cannot create children for a parent that is in a different thread.
QObject: Cannot create children for a parent that is in a different thread.
*** glibc detected *** double free or corruption (!prev): 0x08b8ad00 ***
*** Process aborted ***

QObject: Cannot create children for a parent that is in a different thread.
QObject: Cannot create children for a parent that is in a different thread.
*** glibc detected *** double free or corruption (!prev): 0x08b8ad00 ***
*** Process aborted ***

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here is the full function...

void Window::sendFile()
 {
 
	cancelButton->setEnabled(true);
	sendButton->setEnabled(false);
	quitButton->setEnabled(false);
	browseButton->setEnabled(false);
	protocolComboBox->setEnabled(false);
	directoryComboBox->setEnabled(false);
	printerComboBox->setEnabled(false);
 
// The Two Files are here.
	QString ticketName = ticketComboBox->currentText(); 
	QFile *ticket = new QFile(ticketName, ftp);
	ticket->open(QIODevice::ReadOnly);
	QFileInfo ti( ticketName );
 
	QString fileName = directoryComboBox->currentText(); 
	QFile *file = new QFile(fileName, ftp);
	file->open(QIODevice::ReadOnly);
	QFileInfo fi( fileName );
 
// now put the two files together.
	QFile outPrn("out.prn");
 
//first write the ticket
      qint64 totalSize = ticket->size();
      qint64 chunkSize = 2048;
 
      char *readBuffer = new char[chunkSize];
      while ( totalSize )
      {
           if( chunkSize > totalSize )
              chunkSize = totalSize;
           qint64 actuallyRead = ticket->read( readBuffer, chunkSize );
 
          if( actuallyRead > 0 )
               outPrn.write( readBuffer, actuallyRead );
          else
              break;
          totalSize -= actuallyRead;
 
          delete[] readBuffer;
	 outPrn.flush();
      } 
 
      qint64 ptotalSize = file->size();
      qint64 pchunkSize = 2048;
 
      char *preadBuffer = new char[pchunkSize];
      while ( ptotalSize )
      {
           if( pchunkSize > ptotalSize )
              pchunkSize = ptotalSize;
           qint64 pactuallyRead = file->read( preadBuffer, pchunkSize );
 
          if( pactuallyRead > 0 )
               outPrn.write( preadBuffer, pactuallyRead );
          else
              break;
          ptotalSize -= pactuallyRead;
         delete[] preadBuffer;
	 outPrn.flush();
      } 
 
 
 
 
	ftp = new QFtp(this);
 
	connect(ftp, SIGNAL(stateChanged(int)), 
	     this, SLOT(ftp_stateChanged(int)));
 
	connect(ftp, SIGNAL(commandFinished(int, bool)),
             this, SLOT(ftpCommandFinished(int, bool)));
 
 
// FTP the final File to the printer here.
 
}

void Window::sendFile()
 {

	cancelButton->setEnabled(true);
	sendButton->setEnabled(false);
	quitButton->setEnabled(false);
	browseButton->setEnabled(false);
	protocolComboBox->setEnabled(false);
	directoryComboBox->setEnabled(false);
	printerComboBox->setEnabled(false);

// The Two Files are here.
	QString ticketName = ticketComboBox->currentText(); 
	QFile *ticket = new QFile(ticketName, ftp);
	ticket->open(QIODevice::ReadOnly);
	QFileInfo ti( ticketName );

	QString fileName = directoryComboBox->currentText(); 
	QFile *file = new QFile(fileName, ftp);
	file->open(QIODevice::ReadOnly);
	QFileInfo fi( fileName );

// now put the two files together.
	QFile outPrn("out.prn");

//first write the ticket
      qint64 totalSize = ticket->size();
      qint64 chunkSize = 2048;
 
      char *readBuffer = new char[chunkSize];
      while ( totalSize )
      {
           if( chunkSize > totalSize )
              chunkSize = totalSize;
           qint64 actuallyRead = ticket->read( readBuffer, chunkSize );

          if( actuallyRead > 0 )
               outPrn.write( readBuffer, actuallyRead );
          else
              break;
          totalSize -= actuallyRead;

          delete[] readBuffer;
	 outPrn.flush();
      } 

      qint64 ptotalSize = file->size();
      qint64 pchunkSize = 2048;
 
      char *preadBuffer = new char[pchunkSize];
      while ( ptotalSize )
      {
           if( pchunkSize > ptotalSize )
              pchunkSize = ptotalSize;
           qint64 pactuallyRead = file->read( preadBuffer, pchunkSize );

          if( pactuallyRead > 0 )
               outPrn.write( preadBuffer, pactuallyRead );
          else
              break;
          ptotalSize -= pactuallyRead;
         delete[] preadBuffer;
	 outPrn.flush();
      } 




	ftp = new QFtp(this);

	connect(ftp, SIGNAL(stateChanged(int)), 
	     this, SLOT(ftp_stateChanged(int)));

	connect(ftp, SIGNAL(commandFinished(int, bool)),
             this, SLOT(ftpCommandFinished(int, bool)));


// FTP the final File to the printer here.

}

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[marcel]

Why do you create the QFiles with that ftp object as parent?
Did you know that ftp is not created when you pass it as parent? This is one problem.

As for the crash, I already said, delete the read buffer when you're done with it completely, meaning after you finished copying the pdf file.

I'm sure you get the thread error because ftp has an invalid address when you create the QFiles.

Solution: don't pass the ftp object bas parent to the QFiles. Pass NULL.

Regards

[nbkhwjm]

I started with an application that would FTP one file to the printer. This worked great..

Then I needed to send two file... so I added a second, but it turned out that i needed to send both files as one...

so looks like i got it...

I appreciate the patience... the issue seems big until you see the problem...

any way this error doesnt seem to cause the app to fail...

QObject: Cannot create children for a parent that is in a different thread.

should i ignore or keep working though it?

[marcel]

any way this error doesnt seem to cause the app to fail...

QObject: Cannot create children for a parent that is in a different thread.

should i ignore or keep working though it?

I already told you...Pass NULL instead of ftp when you create the QFiles and you will not get this error.

You get this error because the ftp pointer has an invalid adress when you create the QFiles.
At least initialize the pointer to NULL at the beginning of the application.

Regards

[nbkhwjm]

Marcel,

I completely missed that point, got it....

Thank you very much!!

[nbkhwjm]

as a Noob to C++, I appreciate your assistance very much!!

[marcel]

You're welcome

[marcel]

This is what it should be:

// The Two Files are here.
QString ticketName = ticketComboBox->currentText();
QFile *ticket = new QFile(ticketName, NULL);
ticket->open(QIODevice::ReadOnly);
QFileInfo ti( ticketName );
 
QString fileName = directoryComboBox->currentText();
QFile *file = new QFile(fileName, NULL);
file->open(QIODevice::ReadOnly);
QFileInfo fi( fileName );
 
// now put the two files together.
QFile prnFile("out.prn");
if (!outPrn.open(QIODevice::WriteOnly))
    return;
 
//first write the ticket
 
qint64 totalSize = ticket->size();
qint64 chunkSize = 2048; //you can increase it and decrease it as you will
 
char *readBuffer = new char[chunkSize];
while ( totalSize )
{
    if( chunkSize > totalSize )
        chunkSize = totalSize;
    qint64 actuallyRead = ticket->read( readBuffer, chunkSize );
    if( actuallyRead > 0 )
        prnFile.write( readBuffer, actuallyRead );
    else
        break;
    totalSize -= actuallyRead;
}
 
//Now Write the PDF file
qint64 ptotalSize = file->size();
qint64 pchunkSize = 2048; //you can increase it and decrease it as you will
 
char *preadBuffer = new char[pchunkSize];
while ( ptotalSize )
{
    if( pchunkSize > ptotalSize )
        pchunkSize = ptotalSize;
    qint64 pactuallyRead = file->read( preadBuffer, pchunkSize );
 
    if( pactuallyRead > 0 )
        prnFile.write( preadBuffer, pactuallyRead );
    else
        break;
    ptotalSize -= pactuallyRead;
}
 
// And when you're done:
delete[] preadBuffer;
prnFile.flush();
delete ticket;
delete file;

// The Two Files are here.
QString ticketName = ticketComboBox->currentText();
QFile *ticket = new QFile(ticketName, NULL);
ticket->open(QIODevice::ReadOnly);
QFileInfo ti( ticketName );

QString fileName = directoryComboBox->currentText();
QFile *file = new QFile(fileName, NULL);
file->open(QIODevice::ReadOnly);
QFileInfo fi( fileName );

// now put the two files together.
QFile prnFile("out.prn");
if (!outPrn.open(QIODevice::WriteOnly))
    return;

//first write the ticket

qint64 totalSize = ticket->size();
qint64 chunkSize = 2048; //you can increase it and decrease it as you will

char *readBuffer = new char[chunkSize];
while ( totalSize )
{
    if( chunkSize > totalSize )
        chunkSize = totalSize;
    qint64 actuallyRead = ticket->read( readBuffer, chunkSize );
    if( actuallyRead > 0 )
        prnFile.write( readBuffer, actuallyRead );
    else
        break;
    totalSize -= actuallyRead;
}

//Now Write the PDF file
qint64 ptotalSize = file->size();
qint64 pchunkSize = 2048; //you can increase it and decrease it as you will

char *preadBuffer = new char[pchunkSize];
while ( ptotalSize )
{
    if( pchunkSize > ptotalSize )
        pchunkSize = ptotalSize;
    qint64 pactuallyRead = file->read( preadBuffer, pchunkSize );

    if( pactuallyRead > 0 )
        prnFile.write( preadBuffer, pactuallyRead );
    else
        break;
    ptotalSize -= pactuallyRead;
}

// And when you're done:
delete[] preadBuffer;
prnFile.flush();
delete ticket;
delete file;

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[nbkhwjm]

Marcel,

I got this to work, Ill compare my code to yours to see how far off I am.. Had all kinds of trouble with a SEG fault in the FTP function, seemed i had a qDebug that was tossing it all...

Thanks for the help...

this is actually getting easier... still painful, but easier...