Read block device /dev/cdrom

[realdarkman71]

Hi all,

how can I read a block device (/dev/cdrom)? This works for files:

QFile file("/home/chris/backup.img");

file.open(QFile::ReadOnly);

while (!file.atEnd()) {
    QByteArray data = file.read(2048);
    (...)
}

file.close();

...but the method with

QFile file("/dev/cdrom");

won't work! (/dev/cdrom is a symlink to /dev/sr0)

Any hints?

Thanks!
Chris

[kusumk]

Hi,

Can you see this example here.

The above link shows how to use QDataStream api for IO devices.

	QFile read("c://test.txt");
	read.open(QIODevice::ReadOnly);
	QDataStream in(&read);    // read the data serialized from the file
	QString str;
	in >> str;

The above might help you.

[realdarkman71]

Ok, thanks for the hint!

[gnuton]

QFile open works for block devices too.
No matters if /dev/cdrom is a symlink to sr0.

#include <QtCore/QCoreApplication>
#include <QFile>
#include <QDebug>

int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QFile file("/dev/cdrom");
file.open(QFile::ReadOnly);
qDebug() << "XXX" << file.readAll().size();

return a.exec();
}

The code you see above prints out
XXX 732909568

[realdarkman71]

Ah yes, it's a symlink! Thanks for the hint!

Another problem is, on windows

QFile dvd("D:");
     
if (dvd.open(QIODevice::ReadOnly)) {
    (...)
}

doesn't work ... dvd.open returns false!

[gnuton]

Of course it does, windows manages directories in a different way.
You have to use QDir to access to D:

BTW what's your target?

[realdarkman71]

I want to read all raw data from the dvd to calculate a md5 checksum and compare it with the md5 sum of the image ... to check, if burn process 100% successful!