File writing in pendrive

ashajg

Hi

I am writing data in a text file present in a pendrive. I am successful in writing the data but I want to handle a case if pendrive is removed during data transfer I want to notify or I want to do an error handling in such case. How can I do this

code:

QDir pathDir("/media/jBuild/USBSTORAGE");
if(pathDir.exists())
{
QFile file("/media/jBuild/USBSTORAGE/out.txt")
if(!file.open(QIODevice::WriteOnly | QIODevice::Text))return;
QTextStream out(&file);
out<<"...………………………………………………………………………………..";
} 
else
{
qDebug()<<"path doesnot exist!!";
}

mrjj

hi
well you can check
https://doc-snapshots.qt.io/qt5-5.12/qtextstream.html#status
for
QTextStream::WriteFailed

ashajg

Hi @mrjj

Thanks for help!!

But Even if I am removing pendrive I am getting status as 0. i.e it is indicating "The text stream is operating normally."

CODE:

QDir pathDir("/media/jBuild/USBSTORAGE");
if(pathDir.exists())
{
QFile file("/media/jBuild/USBSTORAGE/out.txt")
if(!file.open(QIODevice::WriteOnly | QIODevice::Text))return;
QTextStream out(&file);
for(int i=0;i<100;i++)
{
QThread::msleep(1000);
qDebug()<<"STATUS"<<out.status();
out<<"the Magic num is"<<49<<"\n";
}
} 
else
{
qDebug()<<"path doesnot exist!!";
}

mrjj

oh
so on linux it wont detect usb being removed :)
well you can use some of the write function of QFile. they return
the bytes written and maybe you can detect that way ifs not going well.

ashajg

@mrjj What kind of write function I should write ….I mean I am new to this concept. Can you please explain me?

mrjj

Hi
QFile has functions to write data also besides the <<
https://doc.qt.io/qt-5/qiodevice.html#write
that will return how many you wrote and -1 if error
check if it gives error if usb is removed.
it might not as linux is very odd with USB.

ashajg

@mrjj ok Thank you I will try this.