Checking is a drive is readable in Qt pops up a "no disk" error in Windows 7

Hawkeye64

Here is a snippet of code:

@
QStringList getAvailableDrives()
{
QStringList drives;
QFileInfoList fiList = QDir::drives();
bool firstRemovableDone = false;

QString path;
foreach( const QFileInfo& fi, fiList )
{
  path = fi.absoluteFilePath();

  if ( !fi.exists() )
  {
    continue;
  }

  if ( !QFile::exists( path ) )
  {
    continue;
  }

  if ( !fi.isReadable() )
  {
    continue;
  }
  // ...

@

The issue is I am in a corporate setting with network drives, mapped drives, whatever. The QDir::drives() is returning all my normal drives, but is also returning "R:/", "S:/", "T:/" and "X:/". I can't access these drives and have no idea where they are coming from. But, fi.exists(), QFile::exists() both say they agree. Then it falls down to fi.isReadable(). In the past (4.7, 4.8) this returned false. But, 5.1.1 is doing something different and Windows 7 is popping up a dialog that requires User input. I don't want this if I am checking if the drive is readable.

The dialog is like this:

There is no disk in the drive. Please insert a disk into drive \Device\Harddisk3\DR8.
[Cancel] [Try Again] [Continue]

This comes from line 791 of qfilesystemengine_win.cpp in the ::_waccess call:

@ // calculate user permissions
if (what & QFileSystemMetaData::UserReadPermission) {
if (::_waccess((wchar_t*)entry.nativeFilePath().utf16(), R_OK) == 0)
data.entryFlags |= QFileSystemMetaData::UserReadPermission;
data.knownFlagsMask |= QFileSystemMetaData::UserReadPermission;
}
@

So far, I have been able to work-around this by calling the following code before the fi.isReadable():
@
bool isValidDrive( const QString& path )
{
bool valid = true; // default

#ifdef Q_OS_WIN
LPCWSTR szHD = (LPCWSTR)path.utf16();
UCHAR szFileSys[255], szVolNameBuff[255];
DWORD dwSerial, dwMFL, dwSysFlags;
BOOL bSuccess;

bSuccess = ::GetVolumeInformationW(
  szHD,
  (LPWSTR)szVolNameBuff,
  255,
  &dwSerial,
  &dwMFL,
  &dwSysFlags,
  (LPWSTR)szFileSys,
  255
  );

valid = bSuccess;

if ( !bSuccess )
{
  qDebug() << "Error number " << ::GetLastError();
  return false;
}

#endif // Q_OS_WIN

return valid;

}
@

But I am looking for a more OS independent way of checking. Suggestions?