Qt application crashing when using ODBC driver (macOS)

[br4in]

My Qt application is crashing when i use ODBC driver to connect to Oracle database. The issue is a stack overflow. My code is

#include "mainwindow.h"
#include <QApplication>
#include <QSqlDatabase>
#include <QDebug>
#include <QSqlError>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);

QSqlDatabase db= QSqlDatabase::addDatabase("QODBC3");
db.setUserName("SYS");
db.setPassword("oracle");
 if (!db.open()) {
    qDebug() << db.lastError().text();
 } 
 else 
 {
    qDebug("success");
 }
 MainWindow w;
 w.show();
 db.close();
 return a.exec();

}

The error that appears :

I'm sure that there's no problem with the code , because i've tried it on a windows machine. Also i did build the ODBC driver with qmake.

I'm new to Qt , i'm probably doing something wrong.

Thank you.

[SGaist]

Hi and welcome to devnet,

What version of Qt are you using ? With which version of Xcode ?

Also, what did you use to build the plugin ?

[br4in]

Hello ,

I'm using Qt 5.7.0 with Xcode 8.0 (on macOS Sierra)
By the way i used the same code on another mac running OS X Yosemite (with Xcode 7.0) and the same problem occurs.

I used unixODBC to build the plugin , i followed this tutorial from qt website.

Thank you in advance ^^

[SGaist]

After a quick check, I'd recommend trying with iODBC.

There seems to be a bug with unixODBC and unicode that results in stack corruption. If you have to use unixODBC, I can show you a patch for the Qt odbc driver to workaround that bug.

[br4in]

Hello ,
yes i would prefer a workaround for the bug
because when i tried to rebuild with iODBC , i got :

"PROJECT ERROR : cannot load qmodule.pri"

Ty

[SGaist]

How are you trying to build the driver ?

[br4in]

EDIT : i have to resolve the qmodule.pri error , even if i will workaround the bug ,
because i have to rebuild with unixODBC due to an reinstallation of QT

[SGaist]

Again, how are you trying to build the driver and what exact error are you having ?

[br4in]

Here's how i did :

I launch a terminal , and i type
cd ~/Qt/5.7/Src/qtbase/src/plugins/sqldrivers/odbc

then i type
qmake "INCLUDEPATH+=/usr/local/unixODBC/include" "LIBS+=-L/usr/local/unixODBC/lib -lodbc" //Here's where the problem appears

then i run a simple "make"

it worked to first time , but when i tried to build the iODBC driver , it gives me the error. i that's why i reinstalled the whole Qt (but doesn't resolved a thing)

[SGaist]

what do you get if you call which qmake ?

To be sure to use the right one, you should use the full path to the binary.

[br4in]

Thank you so much ,
it turns out that my terminal is using another qmake , it worked when i used the full path.

so i builded the iODBC driver with this command line :
/Users/br4in/Qt5.6.2/5.6/clang_64/bin/qmake "INCLUDEPATH+=/usr/local/iODBC/include" "LIBS+=-L/usr/local/iODBC/lib -liodbc"

it gave no errors , but the app is still crashing when i use the ODBC driver.

it seems like an issue with QODBC , can you give me the tutorial to workaround the bug ?

[SGaist]

Just apply the patch you can find here and rebuild the driver.

[br4in]

I applied the patch , rebuilded the driver and my code.
but the issue isn't fixed yet :(

[hskoglund]

Hi, it might be something with Oracle's .dylib for ODBC, which .dylib/client do you use?

Qt's libqsqlodbc.dylib works fine for me, but I use it for MS SQLServer together with FreeTDS (libtdsodbc.so). Also in my Qt 5.7 libqsqlodbc.dylib was included so I didn't had to build it myself.

Edit: looked at the crash screen above, it indeed seems that the crash is where @SGaist 's patch should help. You could try to patch again, but this time just comment out the whole function, something like this:

static QString qWarnODBCHandle(int handleType, SQLHANDLE handle, int *nativeCode = 0)
{
    return "";
}

That function just returns an additional diagnostic error message, so it's not really needed :-)

[br4in]

Hey , I commented the whole function as you said , except the two above lines :
QString result;
return result; (because if i type return " " , i will get a constructor error)
then i rebuilded the driver and started a new project with the same code.

the problem wasn't resolved . Maybe my libqsqlodbc.dylib is executing a different qsql_odbc.cpp file ?

[SGaist]

Did you install the driver ?

[SGaist]

Can you check again with 5.8 ?

[Mohammad Kanan]

Steps to activate/test QODBC on Mac OS ((Seirra) towards MSSQL or any other ODBC DB:

Symptom 1: Qt Creator Run (Debug): application crashes (program unexpectedly finished/crashed).
Symptom 2: Qt Creator with pre-built Qt packages (Qt installed with MaintenanceTool).

Symptom 3: freeTDS driver (libtdsodbc.so) is missing after installing freeTDS packages.

Symptom 4: Qt built/configured before installing unixODBC.

1. Download and install unixODBC (must be done before installing freeTDS)
   Go -- > (www.unixODBC.org) / (Drivers) / (unixODBC-2.3.4.tar.gz)
   unzip and untar the packages.
   (Make sure you have write permissions otherwise run below last command with sudo prefix)

./configure --prefix=/usr/local/unixODBC
make
sudo make istall

2. Download and install freeTDS:
   Go --> (http://www.freetds.org/) / ( Quick Links) / (Latest Versions) / (Stable Release)
   untar/unzip the package.

./configure --prefix=/usr/local/freeTDS --with-unixodbc=/usr/local/unixODBC/
make
sudo make install

Note:
--with-unixodbc will cause the driver (libtdsodbc.so) to be installed.

3. Unfortunately, possibly the ODBC plugin on Qt should be rebuilt:

Note: If you are using the prebuilt Qt libraries, you will need to download sources using MaintenanceTool ($QTDIR/MaintenanceTool.app)

• Tell qmake where to find the unixODBC header files and shared libraries (here it is assumed that unixODBC is installed in /usr/local/unixODBC) and run make:

cd $QTDIR/qtbase/src/plugins/sqldrivers/odbc

my case:

cd /usr/local/Qt/5.9.1/Src/qtbase/src/plugins/sqldrivers/odbc

qmake "INCLUDEPATH+=/usr/local/unixODBC/include" "LIBS+=-L/usr/local/unixODBC/lib -lodbc"
make

if that goes correctly: you will get complied QODBC new libs:

cd ../plugins/sqldrivers/

copy the new packages for example to :

/usr/local/Qt/5.9.1/clang_64/plugins/sqldrivers/

4. Configure /etc/local/unixODBC/etc/odbc.ini (you might need root permissions to mdify)
   (No need to configure freeTDS):

(which port ? which version -> Run /usr/local/freeTDS/bin/tsql -LH 192.168.x.x
Create/Modify entry in /usr/local/unixODBC/etc/odbc.ini

[MYDSN]

Driver = /usr/local/freeTDS/lib/libtdsodbc.0.so

Server = 192.168.x.x

Port = 51271

5. In Qt project:

QSqlDatabase mydb = QSqlDatabase::addDatabase("QODBC");

mydb.setDatabaseName("MYDSN")

mydb.setUserName("name on Database");

mydb.setPassword(" password on Database");
mydb.open()

(Luck && !alas) = true.

[julrich]

To make the plugin link against unixodbc, I had to replace -liodbc with -lodbc in the configure.json file in the sqldrivers directory before following the instructions in the documentation (done with Qt 5.12.3).

So the complete steps for me were:

$ brew install unixodbc
$ cd path/to/Qt/5.12.3/Src/qtbase/src/plugins/sqldrivers
$ sed -i -e 's/-liodbc/-lodbc/' configure.json
$ qmake -- ODBC_PREFIX=/usr/local/Cellar/unixodbc/2.3.7
$ make sub-odbc
$ cp plugins/sqldrivers/libqsqlodbc* path/to/Qt/5.12.3/plugins/sqldrivers

[oxycoder]

@julrich I have to login and thank you.
It works.