segv when getting QFileInfo from subclassed QFileSystemModel

CybeX

Context:

I am creating a directory browser using a QTableView & a subclassed QFileSystemModel due to its already existing file browser functionality.

I am using 5 columns, first column [0] is 128px wide, the rest spaced out in widths respectively are 6, 9, 3, 2 all which I set in the class containing both the QTableWidget and QFileSystemModel.

 [0] Icon (default icon for folder or file, except in the case of an image where the image icon is loaded from cache)
 [1] File name
 [2] File location (relative to a specific directory)
 [3] Last date modified of the file
 [4] File size (formatted to human readable

Problem:

On implementing the QAbstractItemView::doubleClick (QTableView) to enter a directory and set the new root model index(i.e. browse into a set directory).

When double-clicking on a cell:

 // Connect on list widget cell click to browse into directory or open file
 connect(ui->customTableView, &QTableView::doubleClicked, this, [this](const QModelIndex & index) {
      QFileInfo fi = model->getFileInfo(index);
      QString newPath = fi.filePath();
      changeDirectory(newPath);
 });

I query the model for the fileInfo entry (created a get method due for testing due to fileInfo(const QModexIndex&) wasn't working).

 QFileInfo FileSystemModel::getFileInfo(const QModelIndex& index)
 {
     QFileInfo mfileInfo = QFileInfo(fileInfo(index));
     return mfileInfo;
 }

Inside of the model, I ask for the QFileInfo object using fileInfo(index) which then results in a segv on a sharedpointer.

See details below.

Debugger output

Locals		
	index	@0x32d3dfd0	QModelIndex &
		c	1	int
		i	853000288	quintptr
		m	@0x32d7a548	FileSystemModel
			[QFileSystemModel]	@0x32d7a548	QFileSystemModel
			[d]	@0x32d79b58	QFileSystemModelPrivate
			[parent]	0x0	QObject *
			[children]	<0 items>	
			[properties]	<at least 0 items>	
			[methods]	<0 items>	
			[extra]		
			COLUMN_DATE_MODIFIED	3	int
			COLUMN_FILENAME	1	int
			COLUMN_ICON	0	int
			COLUMN_LOCATION	2	int
			COLUMN_SIZE	4	int
			dataPath	"H:/debug/Root"	QString
			locale	@0x32d7a558	QLocale
			mimeDb	@0x32d7a550	QMimeDatabase
			staticMetaObject	@0x53a4c0	QMetaObject
		r	0	int
	mfileInfo	<not accessible>	QFileInfo
	this	0xbaadf00d	FileSystemModel*
Inspector		
Expressions		
Return Value		
Tooltip

Stack Trace Output

1   QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData>>::operator->                                                                                                                                                   qscopedpointer.h          118  0x207175ea 
2   qGetPtrHelper<QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData>>>                                                                                                                                                qglobal.h                 1055 0x207175ea 
3   QFileSystemModel::d_func                                                                                                                                                                                                      qfilesystemmodel.h        152  0x207175ea 
4   QFileSystemModel::fileInfo                                                                                                                                                                                                    qfilesystemmodel.cpp      169  0x207175ea 
5   FileSystemModel::getFileInfo                                                                                                                                                                                                  filesystemmodel.cpp       85   0x48ca6a   
6   ExplorerDialog::<lambda(const QModelIndex&)>::operator()(const QModelIndex &) const                                                                                                                                           ExplorerView.cpp          418  0x44e3e6   
7   QtPrivate::FunctorCall<QtPrivate::IndexesList<0>, QtPrivate::List<const QModelIndex&>, void, ExplorerDialog::setupListWidget()::<lambda(const QModelIndex&)>>::call(ExplorerDialog::<lambda(const QModelIndex&)> &, void * *) qobjectdefs_impl.h        146  0x45b0e9   
8   QtPrivate::Functor<ExplorerDialog::setupListWidget()::<lambda(const QModelIndex&)>, 1>::call<QtPrivate::List<QModelIndex const&>, void>(ExplorerDialog::<lambda(const QModelIndex&)> &, void *, void * *)                     qobjectdefs_impl.h        256  0x45aca1   
9   QtPrivate::QFunctorSlotObject<ExplorerDialog::setupListWidget()::<lambda(const QModelIndex&)>, 1, QtPrivate::List<const QModelIndex&>, void>::impl(int, QtPrivate::QSlotObjectBase *, QObject *, void * *, bool *)            qobjectdefs_impl.h        439  0x459f5b   
10  QtPrivate::QSlotObjectBase::call                                                                                                                                                                                              qobjectdefs_impl.h        394  0x65c8161  
11  QMetaObject::activate                                                                                                                                                                                                         qobject.cpp               3789 0x65c8161  
12  QMetaObject::activate                                                                                                                                                                                                         qobject.cpp               3660 0x65c851b  
13  QAbstractItemView::doubleClicked                                                                                                                                                                                              moc_qabstractitemview.cpp 661  0x207519a6 
14  QAbstractItemView::mouseDoubleClickEvent                                                                                                                                                                                      qabstractitemview.cpp     1964 0x2075dd0a 
//...

Image of crash

Full Code Example (mostly adapted from ::data() found here) :

Header file

#ifndef FILESYSTEMMODEL_H
#define FILESYSTEMMODEL_H

#include <QFileSystemModel>
#include <QMimeDatabase>
#include "libs/global.h"
#include "libs/imagecachehelper.h"

class FileSystemModel : public QFileSystemModel {
     Q_OBJECT
  public:
     FileSystemModel(QString dataPath);

     // QAbstractItemModel interface
  public:
     QMimeDatabase mimeDb;
     QVariant data(const QModelIndex& index, int role) const;
     QFileInfo getFileInfo(const QModelIndex& index);

  private:
     static const int COLUMN_ICON = 0;
     static const int COLUMN_FILENAME = 1;
     static const int COLUMN_LOCATION = 2;
     static const int COLUMN_DATE_MODIFIED = 3;
     static const int COLUMN_SIZE = 4;

     QString dataPath;
     QLocale locale;

     // QAbstractItemModel interface
  public:
     QVariant headerData(int section, Qt::Orientation orientation, int role) const;

     // QAbstractItemModel interface
  public:
     int columnCount(const QModelIndex& parent) const;
};

#endif // FILESYSTEMMODEL_H

and implementation

#include "filesystemmodel.h"

FileSystemModel::FileSystemModel(QString path): dataPath(path)
{
     dataPath = QString(path);
     setRootPath(dataPath);
     setFilter(QDir::Files | QDir::Filter::Dirs | QDir::Filter::NoDotAndDotDot);
     sort(COLUMN_FILENAME, Qt::SortOrder::AscendingOrder);
}

QVariant FileSystemModel::data(const QModelIndex& index, int role) const
{

//    Q_D(const QFileSystemModel);
     if (!index.isValid() || index.model() != this)
          return QVariant();

     switch (role) {
          case Qt::EditRole:
               break;
          case Qt::DisplayRole:
               switch (index.column()) {
                    case COLUMN_FILENAME:
                         return fileInfo(index).fileName();
                    case COLUMN_LOCATION: {
                         QFileInfo fi = fileInfo(index);
                         QString s = fi.filePath();
                         QString localReplace = s.replace(dataPath, "/Root");
                         return localReplace;
                    }
                    case COLUMN_DATE_MODIFIED:
                         return Global::dateToQString(fileInfo(index).lastModified());;
                    case COLUMN_SIZE: {
                         QFileInfo fi = fileInfo(index);
                         if (fi.isDir()) {
                              return QString("--");
                         }
                         else {
                              return locale.formattedDataSize(fi.size());
                         }
                    };
                    default:
                         return QVariant();
               }
               break;
          case FilePathRole:
               return filePath(index);
          case FileNameRole:
               return fileName(index);
          case Qt::DecorationRole:
               if (index.column() == COLUMN_ICON) {
                    QFileInfo fi = fileInfo(index);
                    if (fi.isFile()) {
                         QPixmap p = QPixmap(fi.filePath());
                         if (p.isNull()) {
                              return QFileSystemModel::iconProvider()->icon(fi);
                         }
                         p.scaled(ImageHelper::getCacheImageSize());
                         return QIcon(p);
                    }
                    else {
                         return QFileSystemModel::iconProvider()->icon(fi);
                    }
               }
               break;
          case Qt::TextAlignmentRole:
               switch (index.column()) {
                    case COLUMN_FILENAME:
                    case COLUMN_LOCATION:
                         return QVariant(Qt::AlignLeft | Qt::AlignVCenter);
                    case COLUMN_DATE_MODIFIED:
                         return QVariant(Qt::AlignCenter);
                    case COLUMN_SIZE:
                         return QVariant(Qt::AlignRight | Qt::AlignVCenter);
                    case COLUMN_ICON:
                    default:
                         return QVariant(Qt::AlignCenter);
               }
     }
     return QFileSystemModel::data(index, role);
}

QFileInfo FileSystemModel::getFileInfo(const QModelIndex& index)
{
     QFileInfo mfileInfo = QFileInfo(fileInfo(index));
     return mfileInfo;
}

QVariant FileSystemModel::headerData(int section, Qt::Orientation orientation, int role) const
{
     switch (role) {
          case Qt::DisplayRole:  {
               switch (section) {
                    case COLUMN_ICON: return tr("Preview");
                    case COLUMN_FILENAME: return tr("Name");
                    case COLUMN_LOCATION: return tr("Location");
                    case COLUMN_DATE_MODIFIED: return tr("Last Date Modified");
                    case COLUMN_SIZE: return tr("Size");
               }
               return QVariant();
          }
          case Qt::SizeHintRole:  {
               return 128;
          }
          case Qt::TextAlignmentRole:  {
               return QVariant(Qt::AlignLeft);
          }
     }

     return QVariant();
}

int FileSystemModel::columnCount(const QModelIndex& parent) const
{
     Q_UNUSED(parent)
     return 5;
}

Christian Ehrlicher

What's the benefit of FileSystemModel::getFileInfo()? I would guess your this pointer is a nullptr