How to check the available free space of a selected drive in Qt?

[vishnu]

I am using Qt5.6.2 in Windows 7. My Goal is to save a CustomDatafile to a selected drive (mostly a Pen drive or local drive or network drive).

So before saving the file I would like to check the available memory and write access of the selected path.

From this thread I came to know about QStorageInfo class. So I wrote the below function.

bool ImportExport::checkWriteAccessAndEnoughDriveSpace(const QString &path,QString &error)
{
   error = QString();
   int fileSizeMB = 100;//for testing purpose I am comparing with 100 MB. correct solution is to compare with size of the file.
   qDebug() << "path to QStorage: " <<path;
   QStorageInfo storage = QStorageInfo::QStorageInfo(path);
   //QStorageInfo storage = QStorageInfo::root();
   qDebug() << "export root path: " <<storage.rootPath();
   qDebug() << "volume name:" << storage.name();
   qDebug() << "fileSystemType:" << storage.fileSystemType();
   qDebug() << "size:" << storage.bytesTotal()/1000/1000 << "MB";
   qDebug() << "availableSize:" << storage.bytesAvailable()/1000/1000 << "MB";

   if (storage.isValid() && storage.isReady()) {
      if (!storage.isReadOnly()) {
         // check enough memory
         int MBavailable = storage.bytesAvailable()/1000/1000;
         if(MBavailable > fileSizeMB){
            return true;
         }else{
            error = tr("Not enough disk space, available disk space is only : ") + QString::number(MBavailable);
            return false;
         }
      }else{
         error = tr("No permission to write to current folder ");
         qDebug() << error; // how to set this message as toolTip on the fileDialog
         return false;
      }
   }else{
      error = tr("Selected drive validity: ")+ QString::number(storage.isValid()) +tr("or storage availability: ") +QString::number(storage.isReady());
      qDebug() << error; // how to set this message as toolTip
      return false;
   }
}

This is the debug output:

path to QStorage: "D:/Aluminium Demo DMU105mB.cba"
export root path: ""
volume name: ""
fileSystemType: ""
size: 0 MB
availableSize: 0 MB
"Selected drive validity: 0or storage availability: 0"
As you can see the QStorageInfo is always giving me 0 size, drive not ready. No matter what ever the drive i select the result is always the same. Can anybody point out the error? any solution for my problem? Thank you in advance.

Note: isValid() is always false. I am not able to understand why is it false even though the drive is present and i have the write access as well?

[aha_1980]

@vishnu said in How to check the available free space of a selected drive in Qt?:

I am using Qt5.6.2 in Windows 7. My Goal is to save a CustomDatafile to a selected drive (mostly a Pen drive or local drive or network drive).

So before saving the file I would like to check the available memory and write access of the selected path.

From this thread I came to know about QStorageInfo class. So I wrote the below function.

bool ImportExport::checkWriteAccessAndEnoughDriveSpace(const QString &path,QString &error)
{
   error = QString();
   int fileSizeMB = 100;//for testing purpose I am comparing with 100 MB. correct solution is to compare with size of the file.
   qDebug() << "path to QStorage: " <<path;
   QStorageInfo storage = QStorageInfo::QStorageInfo(path);
   //QStorageInfo storage = QStorageInfo::root();
   qDebug() << "export root path: " <<storage.rootPath();
   qDebug() << "volume name:" << storage.name();
   qDebug() << "fileSystemType:" << storage.fileSystemType();
   qDebug() << "size:" << storage.bytesTotal()/1000/1000 << "MB";
   qDebug() << "availableSize:" << storage.bytesAvailable()/1000/1000 << "MB";

   if (storage.isValid() && storage.isReady()) {
      if (!storage.isReadOnly()) {
         // check enough memory
         int MBavailable = storage.bytesAvailable()/1000/1000;
         if(MBavailable > fileSizeMB){
            return true;
         }else{
            error = tr("Not enough disk space, available disk space is only : ") + QString::number(MBavailable);
            return false;
         }
      }else{
         error = tr("No permission to write to current folder ");
         qDebug() << error; // how to set this message as toolTip on the fileDialog
         return false;
      }
   }else{
      error = tr("Selected drive validity: ")+ QString::number(storage.isValid()) +tr("or storage availability: ") +QString::number(storage.isReady());
      qDebug() << error; // how to set this message as toolTip
      return false;
   }
}

I have two ideas:

1. change the constructor to QStorageInfo storage(path);
2. try a filename without spaces

[mrjj]

@vishnu
Hi
as @aha_1980 talks about.
What are you giving it for path ?
I tried with my ramdrive

and it seemed to work fine with "e:"

[raven-worx]

@aha_1980 said in How to check the available free space of a selected drive in Qt?:

QStorageInfo storage = QStorageInfo::QStorageInfo(path);

i guess this is your issue. I am wondering that this even compiles?!?! o.O

[vishnu]

@raven-worx
you're correct.

I have changed the constructor. Now it works.