How to determine how much free space on a drive in Qt? - c++

Question

I'm using Qt and want a platform-independent way of getting the available free disk space.
I know in Linux I can use statfs and in Windows I can use GetDiskFreeSpaceEx(). I know boost has a way, boost::filesystem::space(Path const & p).
But I don't want those. I'm in Qt and would like to do it in a Qt-friendly way.
I looked at QDir, QFile, QFileInfo -- nothing!

Answer 1

I know It's quite old topic but somebody can still find it useful.
Since QT 5.4 the QSystemStorageInfo is discontinued, instead there is a new class QStorageInfo that makes the whole task really simple and it's cross-platform.
QStorageInfo storage = QStorageInfo::root();
qDebug() << storage.rootPath();
if (storage.isReadOnly())
qDebug() << "isReadOnly:" << storage.isReadOnly();
qDebug() << "name:" << storage.name();
qDebug() << "fileSystemType:" << storage.fileSystemType();
qDebug() << "size:" << storage.bytesTotal()/1024/1024 << "MB";
qDebug() << "availableSize:" << storage.bytesAvailable()/1024/1024 << "MB";
Code has been copied from the example in QT 5.5 docs

Answer 2

The new QStorageInfo class, introduced in Qt 5.4, can do this (and more). It's part of the Qt Core module so no additional dependencies required.
#include <QStorageInfo>
#include <QDebug>
void printRootDriveInfo() {
QStorageInfo storage = QStorageInfo::root();
qDebug() << storage.rootPath();
if (storage.isReadOnly())
qDebug() << "isReadOnly:" << storage.isReadOnly();
qDebug() << "name:" << storage.name();
qDebug() << "filesystem type:" << storage.fileSystemType();
qDebug() << "size:" << storage.bytesTotal()/1024/1024 << "MB";
qDebug() << "free space:" << storage.bytesAvailable()/1024/1024 << "MB";
}

Answer 3

I wrote this back when I wrote the question (after voting on QTBUG-3780); I figure I'll save someone (or myself) from doing this from scratch.
This is for Qt 4.8.x.
#ifdef WIN32
/*
* getDiskFreeSpaceInGB
*
* Returns the amount of free drive space for the given drive in GB. The
* value is rounded to the nearest integer value.
*/
int getDiskFreeSpaceInGB( LPCWSTR drive )
{
ULARGE_INTEGER freeBytesToCaller;
freeBytesToCaller.QuadPart = 0L;
if( !GetDiskFreeSpaceEx( drive, &freeBytesToCaller, NULL, NULL ) )
{
qDebug() << "ERROR: Call to GetDiskFreeSpaceEx() failed.";
}
int freeSpace_gb = freeBytesToCaller.QuadPart / B_per_GB;
qDebug() << "Free drive space: " << freeSpace_gb << "GB";
return freeSpace_gb;
}
#endif
Usage:
// Check available hard drive space
#ifdef WIN32
// The L in front of the string does some WINAPI magic to convert
// a string literal into a Windows LPCWSTR beast.
if( getDiskFreeSpaceInGB( L"c:" ) < MinDriveSpace_GB )
{
errString = "ERROR: Less than the recommended amount of free space available!";
isReady = false;
}
#else
# pragma message( "WARNING: Hard drive space will not be checked at application start-up!" )
#endif

Answer 4

There is nothing in Qt at time of writing.
Consider commenting on or voting for QTBUG-3780.

Answer 5

I need to write to a mounted USB-Stick and I got the available size of memory with the following code:
QFile usbMemoryInfo;
QStringList usbMemoryLines;
QStringList usbMemoryColumns;
system("df /dev/sdb1 > /tmp/usb_usage.info");
usbMemoryInfo.setFileName( "/tmp/usb_usage.info" );
usbMemoryInfo.open(QIODevice::ReadOnly);
QTextStream readData(&usbMemoryInfo);
while (!readData.atEnd())
{
usbMemoryLines << readData.readLine();
}
usbMemoryInfo.close();
usbMemoryColumns = usbMemoryLines.at(1).split(QRegExp("\\s+"));
QString available_bytes = usbMemoryColumns.at(3);

Answer 6

I know that this question is already quite old by now, but I searched stackoverflow and found that nobody got solution for this, so I decided to post.
There is QSystemStorageInfo class in QtMobility, it provides cross-platform way to get info about logical drives. For example: logicalDrives() returns list of paths which you can use as parameters for other methods: availableDiskSpace(), totalDiskSpace() to get free and total drive's space, accordingly, in bytes.
Usage example:
QtMobility::QSystemStorageInfo sysStrgInfo;
QStringList drives = sysStrgInfo.logicalDrives();
foreach (QString drive, drives)
{
qDebug() << sysStrgInfo.availableDiskSpace(drive);
qDebug() << sysStrgInfo.totalDiskSpace(drive);
}
This example prints free and total space in bytes for all logical drives in OS. Don't forget to add QtMobility in Qt project file:
CONFIG += mobility
MOBILITY += systeminfo
I used these methods in a project I'm working on now and it worked for me. Hope it'll help someone!

Answer 7

this code`s working for me:
#ifdef _WIN32 //win
#include "windows.h"
#else //linux
#include <sys/stat.h>
#include <sys/statfs.h>
#endif
bool GetFreeTotalSpace(const QString& sDirPath, double& fTotal, double& fFree)
{
double fKB = 1024;
#ifdef _WIN32
QString sCurDir = QDir::current().absolutePath();
QDir::setCurrent(sDirPath);
ULARGE_INTEGER free,total;
bool bRes = ::GetDiskFreeSpaceExA( 0 , &free , &total , NULL );
if ( !bRes )
return false;
QDir::setCurrent( sCurDir );
fFree = static_cast<__int64>(free.QuadPart) / fKB;
fTotal = static_cast<__int64>(total.QuadPart) / fKB;
#else // Linux
struct stat stst;
struct statfs stfs;
if ( ::stat(sDirPath.toLocal8Bit(),&stst) == -1 )
return false;
if ( ::statfs(sDirPath.toLocal8Bit(),&stfs) == -1 )
return false;
fFree = stfs.f_bavail * ( stst.st_blksize / fKB );
fTotal = stfs.f_blocks * ( stst.st_blksize / fKB );
#endif // _WIN32
return true;
}