LoadLibrary : crash in release mode [closed] - c++

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I use the function LoadLibrary from the Windows API to load dynamically a DLL (compiled in release mode). Then I call an imported function my_function
When my exe is compiled in:
DEBUG mode: no issue
RELEASE mode w/ debug info: no issue
RELEASE mode w/out debug info: it crashes after LoadLibrary call, when I call the imported function my_function
Here's a code sample:
MyClass.cpp:
#include "myclass.h"
typedef int (__stdcall *f_my_function)(char*, int*);
MyClass::MyClass()
{
mDllHandler = NULL;
}
bool MyClass::loadLibrary()
{
qCritical() << "Loading library";
mDllHandler = LoadLibrary(L"my.dll");
qCritical() << "Library loaded";
if (!mDllHandler) {
qCritical() << "Error : could not load my.dll";
return false;
}
return true;
}
bool MyClass::freeLibrary()
{
if(!mDllHandler) {
qCritical() << "Error : DLL handler is null";
return false;
}
if(!FreeLibrary(mDllHandler)) {
qCritical() << "Error : could not unload my.dll";
return false;
}
mDllHandler = NULL;
return true;
}
bool MyClass::myFunction(const& QString str)
{
if(!mDllHandler) {
qCritical() << "Error : DLL handler is null";
return false;
}
f_my_function my_function = (f_my_function)GetProcAddress(mDllHandler, "my_function");
if (!my_function) {
qCritical() << "Error : Could not resolve the function my_function";
return false;
}
int size = str.size();
char* string = str.toLatin1().data();
int error = my_function(string, &size);
qDebug() << "my_function : Error code is " << error;
return !error;
}
MyClass.h:
#ifndef MYCLASS_H
#define MYCLASS_H
#include <QString>
class MyClass
{
public:
MyClass();
bool loadLibrary();
bool freeLibrary();
bool myFunction(const QString& str = "");
private:
HINSTANCE mDllHandler;
};
#endif // MYCLASS_H
main.cpp
#include <QCoreApplication>
#include <QDebug>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
MyClass myClass;
myClass.loadLibrary();
myClass.myFunction();
myClass.freeLibrary();
return a.exec();
}
I really have no idea why it crashes here.
EDIT : Here I don't have access to the source code of my.dll.

Answer 1

Well the crash (which eventually did not occur always at LoadLibrary call, but sometimes later in the code) was due to a wrong declaration of the imported functions.
In MyClass.cpp :
Wrong declaration:
typedef int (__stdcall *f_my_function)(char*, int*);
Correct declaration:
typedef int (*f_my_function)(char*, int*);
Indeed I wrongly declared f_my_function with __stdcall