Weird result with QSettings access error

Loic B.

Hello,

I do not understand the result of the QSettings::status() function in this case:

I have a system and user scope settings file. When I remove the rights to write in the system scope file, the next time I use the user scope settings, I get an QSettings::AccessError when I call the status function. However, when I open the user scope file, the value has been written even with the error status

On the opposite, if I remove the rights to write in the user scope file, I get errors only when trying to write in the user scope settings.

Why the status is always at AccessError when the system scope in not writable ?

Here is a minimal reproducible code:

#include <QSettings>
#include <QDebug>

void printStatus(const QSettings& settings)
{
    switch (settings.status()) {
    case QSettings::NoError:
        qInfo() << settings.scope() << "No error";
        break;
    case QSettings::AccessError:
        qInfo() << settings.scope() << "Access error";
        break;
    case QSettings::FormatError:
        qInfo() << settings.scope() << "Format error";
        break;
    default:
        break;
    }
}

void testSettings(QSettings::Scope scope, int value)
{
    QSettings settings { QSettings::IniFormat, scope, "TestQSettings", "TestQSettings" };
    settings.sync();
    printStatus(settings);

    settings.setValue("test", value);
    settings.sync();
    printStatus(settings);
}

int main(int argc, char *argv[])
{
    testSettings(QSettings::UserScope, 40);

    testSettings(QSettings::SystemScope, 40);

    testSettings(QSettings::UserScope, 42);

    testSettings(QSettings::SystemScope, 42);
}

And this is what I obtain when the system scope file only is not writable:

QSettings::UserScope No error
QSettings::UserScope No error
QSettings::SystemScope No error
QSettings::SystemScope Access error
QSettings::UserScope Access error
QSettings::UserScope Access error
QSettings::SystemScope Access error
QSettings::SystemScope Access error

My system settings:

Windows 10
MSVC 2019
Qt 5.15.2

Loic B.

I also reproduced this behavior with Qt 6.2.4

This bug seems to match with what I encountered but even by creating a new QSettings, the problem remains.

JonB

@Loic-B
Did you at least try calling QSettings::sync() after the first error, to see whether that clears it?

Loic B.

@JonB it does the same thing.

Loic B.

Is someone has been able to reproduce this behavior ?