QTemporaryFile problems

[C167]

Hi, I try to write a blob to a file and then execute it. My code:
source:

ProgramLauncher::ProgramLauncher ( QObject *parent )
		: QObject ( parent )
{
	loader = new BinaryLoader ( );
	connect ( loader, SIGNAL ( dataLoaded ( int, QByteArray ) ), this, SLOT ( loaded ( int, QByteArray ) ) );
}
 
void ProgramLauncher::launch ( int id )
{
	qDebug() << id;
	loader->getData ( "bin_programs", id );
}
 
void ProgramLauncher::loaded ( int handle, QByteArray data )
{
	Q_UNUSED ( handle );
// 	QString path = QDir::tempPath() + "XXXXXX";
	QTemporaryFile *tmpFile = new QTemporaryFile ( QString ( "XXXXXX" ) );
	if ( !tmpFile->open ( ) )
	{
		return;
	}
	qDebug() << "tmpFile: " << tmpFile->fileName() << " opened";
	qint64 size = tmpFile->write ( data );
	if ( size != -1 )
	{
		qDebug() << "wrote " << size << " into the file";
		execute ( tmpFile );
	}
}
 
void ProgramLauncher::execute ( QTemporaryFile *file )
{
	QString path = QDir::tempPath() + "/" + file->fileName();
	qDebug() << "Launching filename " << path;
	qDebug() << QProcess::startDetached ( path );
}
ProgramLauncher::~ProgramLauncher()
{
}

ProgramLauncher::ProgramLauncher ( QObject *parent )
		: QObject ( parent )
{
	loader = new BinaryLoader ( );
	connect ( loader, SIGNAL ( dataLoaded ( int, QByteArray ) ), this, SLOT ( loaded ( int, QByteArray ) ) );
}

void ProgramLauncher::launch ( int id )
{
	qDebug() << id;
	loader->getData ( "bin_programs", id );
}

void ProgramLauncher::loaded ( int handle, QByteArray data )
{
	Q_UNUSED ( handle );
// 	QString path = QDir::tempPath() + "XXXXXX";
	QTemporaryFile *tmpFile = new QTemporaryFile ( QString ( "XXXXXX" ) );
	if ( !tmpFile->open ( ) )
	{
		return;
	}
	qDebug() << "tmpFile: " << tmpFile->fileName() << " opened";
	qint64 size = tmpFile->write ( data );
	if ( size != -1 )
	{
		qDebug() << "wrote " << size << " into the file";
		execute ( tmpFile );
	}
}

void ProgramLauncher::execute ( QTemporaryFile *file )
{
	QString path = QDir::tempPath() + "/" + file->fileName();
	qDebug() << "Launching filename " << path;
	qDebug() << QProcess::startDetached ( path );
}
ProgramLauncher::~ProgramLauncher()
{
}

To copy to clipboard, switch view to plain text mode 

header:

class ProgramLauncher : public QObject
{
		Q_OBJECT
	public:
		ProgramLauncher ( QObject *parent = 0 );
		~ProgramLauncher();
	public slots:
		void launch ( int id );
		void loaded ( int handle, QByteArray data );
	private:
		void execute ( QTemporaryFile *file );
		BinaryLoader *loader;
};

class ProgramLauncher : public QObject
{
		Q_OBJECT
	public:
		ProgramLauncher ( QObject *parent = 0 );
		~ProgramLauncher();
	public slots:
		void launch ( int id );
		void loaded ( int handle, QByteArray data );
	private:
		void execute ( QTemporaryFile *file );
		BinaryLoader *loader;
};

To copy to clipboard, switch view to plain text mode 

My problem is that it doesn't create the file where it should. According to the doc, it should be in QDir::tempPath(), but instead it is where the program was started. So, starting the binary fails cause my functions look into /tmp:

5
tmpFile:  "XN1408"  opened
wrote  24791336  into the file
Launching filename  "/tmp/XN1408"
false

5
tmpFile:  "XN1408"  opened
wrote  24791336  into the file
Launching filename  "/tmp/XN1408"
false

To copy to clipboard, switch view to plain text mode 

Why that?

The program is developed on linux, target platform will be windows where it should run from CD (so no write access).

And: I thought the file will be removed upon destruction of the object? it stays where it is, including content

C167

[mcosta]

From Qt documentation

QTemporaryFile::QTemporaryFile ( const QString & templateName )
Constructs a QTemporaryFile with a template filename of templateName. Upon opening the temporary file this will be used to create a unique filename. If the templateName does not contain XXXXXX it will automatically be appended and used as the dynamic portion of the filename.
If templateName is a relative path, the path will be relative to the current working directory. You can use QDir::tempPath() to construct templateName if you want use the system's temporary directory.

[C167]

Oh, i see i misunderstood the last two sentences, i thought it would automatically go to /tmp if not set to anything else, sorry
It now generates the files below /tmp :-)

Okay, as this works, i still have the problem that it does not auto-delete the files after the destruction. I changed my code, it now looks like this:

ProgramLauncher::ProgramLauncher ( QObject *parent )
		: QObject ( parent )
{
	loader = new BinaryLoader ( );
	connect ( loader, SIGNAL ( dataLoaded ( int, QByteArray ) ), this, SLOT ( loaded ( int, QByteArray ) ) );
}
 
void ProgramLauncher::launch ( int id )
{
	qDebug() << id;
	loader->getData ( "bin_programs", id );
}
 
void ProgramLauncher::loaded ( int handle, QByteArray data )
{
	Q_UNUSED ( handle );
 
	tmpFile = new QTemporaryFile ( QString ( QDir::tempPath() + "/XXXXXX" ) );
	if ( !tmpFile->open ( ) )
	{
		return;
	}
	qDebug() << "tmpFile: " << tmpFile->fileName() << " opened";
	qint64 size = tmpFile->write ( data );
	if ( size != -1 )
	{
		qDebug() << "wrote " << size << " into the file";
		QString fname = tmpFile->fileName();
		qDebug() << tmpFile->autoRemove();
		tmpFile->close();
		qDebug() << QFile::copy ( fname, fname + "_bak" );
		qDebug() << QProcess::startDetached ( fname );
		delete tmpFile;
	}
}

ProgramLauncher::ProgramLauncher ( QObject *parent )
		: QObject ( parent )
{
	loader = new BinaryLoader ( );
	connect ( loader, SIGNAL ( dataLoaded ( int, QByteArray ) ), this, SLOT ( loaded ( int, QByteArray ) ) );
}

void ProgramLauncher::launch ( int id )
{
	qDebug() << id;
	loader->getData ( "bin_programs", id );
}

void ProgramLauncher::loaded ( int handle, QByteArray data )
{
	Q_UNUSED ( handle );

	tmpFile = new QTemporaryFile ( QString ( QDir::tempPath() + "/XXXXXX" ) );
	if ( !tmpFile->open ( ) )
	{
		return;
	}
	qDebug() << "tmpFile: " << tmpFile->fileName() << " opened";
	qint64 size = tmpFile->write ( data );
	if ( size != -1 )
	{
		qDebug() << "wrote " << size << " into the file";
		QString fname = tmpFile->fileName();
		qDebug() << tmpFile->autoRemove();
		tmpFile->close();
		qDebug() << QFile::copy ( fname, fname + "_bak" );
		qDebug() << QProcess::startDetached ( fname );
		delete tmpFile;
	}
}

To copy to clipboard, switch view to plain text mode 

And it does not launch the binaries although they are valid linux executables like xterm and konsole (just for testing)

[marcel]

You can't delete the file while the process is executing, that's why the delete doesn;t succeed.

[C167]

sorry for double-post, firefox is bit unstable here

Hm... but QProcess::startDetached returns false, and no window opens. Qt Documentation sais it gets executed like a daemon, so maybe i should just write a two-liner that touches a file...

[marcel]

Don't worry, I deleted it.
Starting detached means that the process won't be a child of your process, therefore you won't be able to monitor its events (like exit). Indeed it starts as a daemon, but that doesn;t mean you can delete the binary.

As for startDetached returning false, maybe you don;'t have the right permissions set on the temp file. See QFile::setPermissions.

[C167]

Thanks
Okay, i'm using this code now:

if ( size != -1 )
	{
		qDebug() << "wrote " << size << " into the file";
		QFile file ( tmpFile->fileName() );
		tmpFile->close();
		if ( file.open( QIODevice::ReadOnly ) && file.exists() )
		{
			qDebug() << file.fileName();
			file.setPermissions ( QFile::ReadOwner | QFile::WriteOwner | 
			QFile::ExeOwner | QFile::ExeUser | QFile::ExeGroup | QFile::ExeOther );
			qDebug() << QProcess::startDetached ( file.fileName() );
		}
	}

if ( size != -1 )
	{
		qDebug() << "wrote " << size << " into the file";
		QFile file ( tmpFile->fileName() );
		tmpFile->close();
		if ( file.open( QIODevice::ReadOnly ) && file.exists() )
		{
			qDebug() << file.fileName();
			file.setPermissions ( QFile::ReadOwner | QFile::WriteOwner | 
			QFile::ExeOwner | QFile::ExeUser | QFile::ExeGroup | QFile::ExeOther );
			qDebug() << QProcess::startDetached ( file.fileName() );
		}
	}

To copy to clipboard, switch view to plain text mode 

you see, i've set the permissions to execute for everyone, but it still gives a false
€dit: even if i close the file before launching. strange

[C167]

any ideas? on windows, its the same problem and the program must be finished by tomorrow (need some time to test it etc.)

[marcel]

why don't you manually check the temporary file? put a break point before startDetached and go where the temp file is. try to execute it in a terminal and see what happens.

[C167]

gdb tells me that the file i want to load does not exist, even if i use kdevelop to debug (which is not able to start the program)

[marcel]

probably the file already got deleted.
I meant trying to manually execute the temporary program. just open a console, go to the location where the temp file was created and try to open it.

I suggested the breakpoint before startDetached because that would prevent the file from being deleted.

[C167]

sorry, i meant the file where ther startDetached is, i cannot load the cpp file. I now simply make a QFile::copy to copy it to another filename

Hm... seems that i broke something in the database that contains the blobs, but older, not deleted version work, they start konsole, xterm or wine
€dit: oh wait, the konsole doesn't start, i get no output, but it is a valid binary according to file