Crashing on deleting QProcess

[rajesh]

why deleting QProcess is crashing?
see my code :

{
...
	m_pFindinFilesProcess = new QProcess(this);
 
	connect(m_pFindinFilesProcess, SIGNAL(finished(int)), this, SLOT(onFindFileSearchFinished()));
	connect(m_pFindinFilesProcess, SIGNAL(readyReadStandardOutput()), this, SLOT(onReadFindFileResult()));
 
	m_pFindinFilesProcess->start("grep", processParam);
}
 
void MainWindow::onFindFileSearchFinished()
{
	if(m_pFindinFilesProcess)
	{
		delete m_pFindinFilesProcess;      --> Crashing here
		m_pFindinFilesProcess = NULL;
	}
}

{
...
	m_pFindinFilesProcess = new QProcess(this);

	connect(m_pFindinFilesProcess, SIGNAL(finished(int)), this, SLOT(onFindFileSearchFinished()));
	connect(m_pFindinFilesProcess, SIGNAL(readyReadStandardOutput()), this, SLOT(onReadFindFileResult()));

	m_pFindinFilesProcess->start("grep", processParam);
}

void MainWindow::onFindFileSearchFinished()
{
	if(m_pFindinFilesProcess)
	{
		delete m_pFindinFilesProcess;      --> Crashing here
		m_pFindinFilesProcess = NULL;
	}
}

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[yogeshgokul]

You can (if not already) check that process is stopped successfully before deleting it.

if(process->state() == QProcess::NotRunning)
    delete process;

if(process->state() == QProcess::NotRunning)
    delete process;

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[arashadsaifi]

Hi Rajesh,

Solution:

m_pFindinFilesProcess->close();

if(m_pFindinFilesProcess)
{
delete m_pFindinFilesProcess;
m_pFindinFilesProcess = NULL;
}

Why:
There are 3 following state of process in Qt

QProcess::NotRunning 0 The process is not running.
QProcess::Starting 1 The process is starting, but the program has not yet been invoked.
QProcess::Running 2 The process is running and is ready for reading and writing.

and when QProcess exits, QProcess reenters the NotRunning state and emits finished().

but in this case buffers in QProcess are still intact and You can still read any data that the process may have written before it finished


in that case you can't delete the QProcess pointer.

before deleting QProcess pointer you need to clear the buffer by calling the

close() function.