QTextStream readLine() problem

[walito]

Hi guys..
I have some problems reading a file.
always I run the program, this crash in the same position of file.
I used gdb to debug and I had this error:

#0 0x00002aaaabd4c40b in memcpy () from /lib64/libc.so.6
#1 0x00002aaaaaf9c172 in QString::append (this=0x639260, str=@0x7fff529efe10) at /usr/include/bits/string3.h:52
#2 0x00002aaaaafe4277 in QTextStreamPrivate::fillReadBuffer (this=0x6391d0, maxBytes=-1) at ../../src/corelib/tools/qstring.h:255
#3 0x00002aaaaafe4f25 in QTextStreamPrivate::scan (this=0x6391d0, ptr=0x7fff529f3f08, length=0x7fff529f3f1c, maxlen=0, delimiter=QTextStreamPrivate::EndOfLine) at io/qtextstream.cpp:696
#4 0x00002aaaaafe5a81 in QTextStream::readLine (this=<value optimized out>, maxlen=0) at io/qtextstream.cpp:1584
#5 0x0000000000401ed2 in main (argc=2, argv=0x7fff529f41b8) at main.cpp:53


the problem, I think is in.readLine() but I don't know why.

Could you help me?

if(sql_file.open(QIODevice::ReadOnly | QIODevice::Text))
{
	QTextStream in(&sql_file);
	QString line;
	int pos = 0;
 
	do {
		line = in.readLine();   <------- problem here
		qDebug() << "pos: " << pos << " length: " << line.length();
 
		++pos;
		//process_line(line);
	} while (!line.isNull());						
 
	sql_file.close();
}

if(sql_file.open(QIODevice::ReadOnly | QIODevice::Text))
{
	QTextStream in(&sql_file);
	QString line;
	int pos = 0;

	do {
		line = in.readLine();   <------- problem here
		qDebug() << "pos: " << pos << " length: " << line.length();

		++pos;
		//process_line(line);
	} while (!line.isNull());						
	
	sql_file.close();
}

To copy to clipboard, switch view to plain text mode 

Thanks in advance

[high_flyer]

What do you do with pos? Do you use it to seek in the file?
Can you show more code responsible for reading and navigating in file?

[walito]

yes, of course.
The "pos" var is only to see something and always crash in the same position.

QCoreApplication a(argc, argv);
 
QStringList args = QCoreApplication::arguments();
 
QRegExp rxArgPath("^--sql_path=(.*)");
 
for (int i = 1; i < args.size(); ++i)
{
	//qDebug() << args.at(i);
 
	if(rxArgPath.indexIn(args.at(i), 0) == 0)
	{
		if(!rxArgPath.cap(1).isEmpty())
		{
			QFile sql_file(rxArgPath.cap(1));
 
			if(sql_file.exists())
			{
				if(sql_file.open(QIODevice::ReadOnly | QIODevice::Text))
				{
					qDebug() << "reading file " << rxArgPath.cap(1);
 
					QTextStream in(&sql_file);
					QString line;
					int pos = 0;
 
					do {
						line = in.readLine();
						qDebug() << "pos: " << pos << " length: " << line.length();
 
						++pos;
					} while (!line.isNull());						
 
					sql_file.close();
				}
			}
			else
			{
				qWarning() << "Er: the file " << rxArgPath.cap(1) << "not exists";
			}
		}
		else
		{
			qWarning() << "Er: Add the path --sql_path";
		}
	}
}
 
return a.exec();

QCoreApplication a(argc, argv);

QStringList args = QCoreApplication::arguments();

QRegExp rxArgPath("^--sql_path=(.*)");

for (int i = 1; i < args.size(); ++i)
{
	//qDebug() << args.at(i);

	if(rxArgPath.indexIn(args.at(i), 0) == 0)
	{
		if(!rxArgPath.cap(1).isEmpty())
		{
			QFile sql_file(rxArgPath.cap(1));

			if(sql_file.exists())
			{
				if(sql_file.open(QIODevice::ReadOnly | QIODevice::Text))
				{
					qDebug() << "reading file " << rxArgPath.cap(1);
					
					QTextStream in(&sql_file);
					QString line;
					int pos = 0;

					do {
						line = in.readLine();
						qDebug() << "pos: " << pos << " length: " << line.length();

						++pos;
					} while (!line.isNull());						
					
					sql_file.close();
				}
			}
			else
			{
				qWarning() << "Er: the file " << rxArgPath.cap(1) << "not exists";
			}
		}
		else
		{
			qWarning() << "Er: Add the path --sql_path";
		}
	}
}

return a.exec();

To copy to clipboard, switch view to plain text mode 

thanks in advance

[high_flyer]

Ahh... this all thing is in your main...
I think that working with QIODevice needs a running event loop (but I am not sure).
Put this in to a class, and run this code after the event loop is running, that will be a good idea even if its not the problem.
Maybe some one else can confirm if this is the problem though.

EDIT:
[re-edit] I take back what I said here.