SIGSEGV in fromStdString

ChrisW67

@Robert-M said in SIGSEGV in fromStdString:

The parentWindow parameter is being set to a MainWindow* in the creation of the dialog:

OtherOptionsDialog *options = new OtherOptionsDialog(this, this); // !!! this IS NOT nullptr

but the constructor parameter is an actual MainWindow:

OtherOptionsDialog::OtherOptionsDialog(QWidget *parent, MainWindow parentWindow) :
  QDialog(parent),
  ui(new Ui::OtherOptionsDialog),
  mainWindow(parentWindow) // !!! HERE INITIALISATION
{...

How is the pointer to initialise an actual MainWindow object?

MainWindow is a QObject. You cannot pass a QObject by value, i.e. copy a QObject, as you do in this constructor. Assuming it does something to make this happen, the mainWindow member variable of OtherOptionsDialog is, it seems, a MainWindow* which cannot be constructed from an actual MainWindow.

Either this is your code and it does not compile, or this is not your code.

Robert M.

@ChrisW67
I don't know why Qt forum did not display asterisk before parameter parentWindow.

OtherOptionsDialog::OtherOptionsDialog(QWidget *parent, MainWindow *parentWindow) :
    QDialog(parent),
    ui(new Ui::OtherOptionsDialog),
    mainWindow(parentWindow)
{

Christian Ehrlicher

@Robert-M said in SIGSEGV in fromStdString:

don't know why Qt forum did not display asterisk before parameter parentWindow.

Because you don't format your code properly - use the format tags provided by the forum software!

JonB

@Robert-M
As @Christian-Ehrlicher said, please use the forum's Code tags to enclose blocks of code you want others to look at.

If you want an answer please reduce your code to some kind of minimal example. Literally the majority of the code you show cannot be relevant to your issue: message boxes, regular expressions, validators, spinboxes, line edits, etc. etc. How are these required or implicated? If you reduce your code to a minimum then maybe either you will spot the problem yourself or someone else will.

Robert M.

@Robert-M
I tried to run the code in Linux.
I see:
terminate called after throwing an instance of 'std::bad_alloc'
what(): std::bad_alloc
Aborted (core dumped)

JonB

@Robert-M
Great. So what are you going to do to simplify to find out why? The code you have posted is on the one hand too large and on the other incomplete.

Let's take a "random" example of what could be going on in your code, for all we know:

char array1[4];
std::string extensions;
char array2[4];
...
memcpy(array1, "12345678", 8);
memcpy(array2, "12345678", 8);
...
qDebug() << mainwindow->extensions;

(I put in both above & below because not sure which direction stack/member layout grows.) It's an example. That's why you need to create and paste a minimal example of actual code going wrong....

Pl45m4

@Robert-M said in SIGSEGV in fromStdString:

OtherOptionsDialog::OtherOptionsDialog(QWidget *parent, MainWindow parentWindow) :
QDialog(parent),
ui(new Ui::OtherOptionsDialog),
mainWindow(parentWindow) // !!! HERE INITIALISATION
{
ui->setupUi(this);
setFixedSize(size());
ui->checkBox->setChecked(!mainWindow->no_check);
ui->checkBox_5->setChecked(mainWindow->allow_reflection);
ui->spinBox->setMinimum(::min_random_identifiers_length);
ui->spinBox->setMaximum(::default_random_identifiers_length * 3);
ui->spinBox->setValue(mainWindow->random_identifiers_length);
ui->lineEdit->setValidator(new QIntValidator(ui->lineEdit));
ui->lineEdit->setText(QString::fromStdString(std::to_string(mainWindow->max_line_len)));
QRegularExpression rx1("([a-zA-Z0-9_\-\+]+,)[a-zA-Z0-9_\-\+]+");
QValidator validator1 = new QRegularExpressionValidator(rx1, ui->lineEdit_2);
ui->lineEdit_2->setValidator(validator1);
Q_ASSERT(mainWindow != nullptr);
Q_ASSERT(mainWindow->extensions != std::string(""));
std::string e = mainWindow->extensions; //!!! SIGSEGV
QString qs = QString::fromStdString(e);
ui->lineEdit_2->setText(qs);
ui->checkBox_2->setChecked(mainWindow->obfpctl);
ui->checkBox_3->setChecked(mainWindow->obfpmdl);
ui->checkBox_6->setChecked(mainWindow->obfpvw);
ui->checkBox_4->setChecked(mainWindow->obfvvw);
ui->lineEdit_3->setText(QString::fromStdString(mainWindow->reserved));
QRegularExpression rx2(QString::fromStdString("(" + ::identifier + ",)(" + ::identifier + ")?"));
QValidator *validator2 = new QRegularExpressionValidator(rx2, ui->lineEdit_3);
ui->lineEdit_3->setValidator(validator2);
}

Instead of passing this twice to your OtherOptionsDialog as QWidget and QMainWindow to access some data, you should pass the data directly. You seem to read-only anyway.
I assume, obfpctl, obfpmdl, obfpvw and obfvvw are boolean and extensions is a string.
So change

OtherOptionsDialog::OtherOptionsDialog(QWidget *parent, MainWindow *parentWindow) :
    QDialog(parent),
    ui(new Ui::OtherOptionsDialog),
    mainWindow(parentWindow) // !!! HERE INITIALISATION

to something like

OtherOptionsDialog::OtherOptionsDialog(QWidget *parent, QVector<QVariant> &data) :
    QDialog(parent),
    ui(new Ui::OtherOptionsDialog)

and pass the data with c'tor


QVector<QVariant> data;
data.push_back(obfpctl);
data.push_back(obfpmdl);
data.push_back(obfpvw);
data.push_back(obfvvw);
data.push_back(QString::fromStdString(extensions);

OtherOptionsDialog *options = new OtherOptionsDialog(this, data);

Since it's a constant data structure, you know the order of your data and can access it with data.at(...) or data[...] in your dialog class.
It's weird to pass the whole mainWindow to an options dialog just to read some variables.
Maybe you want to re-think your whole design

Robert M.

@Pl45m4
According to your advice I defined struct other_options.
Program works fine, there's no SIGSEGV.
Problem solved.
Thanks.

Robert M.

@Robert-M
Using struct instead of QVector<QVariant> produced simpler and smaller code.
What is adventage of using QVector<QVariant> instead of struct?

jsulm

This post is deleted!

JonB

@Robert-M
A struct must contain a fixed number of named members with their own (quite possibly) different types.

A vector/array allows a dynamic number of elements each of which must be of the same type (even if that is QVariant, which itself allows values with different underlying types).

If your problem fits into the first case a struct is preferable, as seems to be the case here.

Robert M.

@jsulm
I use other_options itself, not QVector<other_options>.

Pl45m4

@Robert-M said in SIGSEGV in fromStdString:

other_options

If other_options is your struct with your data, you want to send to your dialog, it's fine. Nobody said it's not :)
The QVector would make it more variable