C++ Boot serialization cause a segmentation fault - c++

Question

I have those two classes and I'm trying to deserialize them using boost
class WorldItem
{
private:
friend class boost::serialization::access;
template <class Archive>
void serialize(Archive &ar, const unsigned int version)
{
ar &foreground;
ar &background;
ar &breakLevel;
ar &breakTime;
ar &water;
ar &fire;
ar &glue;
ar &red;
ar &green;
ar &blue;
}
public:
int foreground = 0;
int background = 0;
int breakLevel = 0;
long long int breakTime = 0;
bool water = false;
bool fire = false;
bool glue = false;
bool red = false;
bool green = false;
bool blue = false;
};
class Worlds
{
private:
friend class boost::serialization::access;
template <class Archive>
void serialize(Archive &ar, const unsigned int version)
{
ar &width;
ar &height;
ar &name;
for (int i = 0; i < 100 * 60; i++)
{
ar &items[i];
}
ar &owner;
ar &weather;
ar &isPublic;
ar &isNuked;
}
public:
int width;
int height;
string name;
WorldItem *items;
string owner = "";
int weather = 0;
bool isPublic = false;
bool isNuked = false;
};
Here I'm creating a world in this way
Worlds generateWorld(string name, int width, int height)
{
Worlds world;
world.name = name;
world.width = width;
world.height = height;
world.items = new WorldItem[100 * 60];
}
and here im using this function to serialize the world
std::stringstream serialize_world(Worlds world)
{
std::stringstream str;
{
boost::archive::binary_oarchive oa(str);
oa << world;
}
return str;
}
So the serialize_world function is working without issues and i am inserting it value to mysql longblob.
But now when I'm trying to get the blob from MySql and deserialize it back by using this function
Worlds deserialize(std::string world)
{
Worlds wld;
std::istream *blobdata = WORLD_DATA(world);
{
boost::archive::binary_iarchive ia(*blobdata);
ia >> wld;
}
return wld;
}
I'm getting a Segmentation fault (core dumped) I don't know what's wrong.
Thanks.

Answer 1

Looks like you never return a value from generateWorld.
My compiler warns about this. Try enabling your compiler's diagnostics. I usually have -Wall -Wextra -pedantic enabled
Also in deserialize you never initialize items to anything. That is going to lead to UB.
This, too, could be diagnosed by most compilers (-fsanitize=address,undefined helps, although it makes compilation and runtime slow). There's also external tools like Valgrind that do these
Finally, I have no idea what is going on with blobdata, so I'm going to ignore that, but it too looks wrong.
Don't use raw new/delete
See also e.g. https://www.quora.com/Why-are-the-%E2%80%98new%E2%80%99-and-%E2%80%98delete%E2%80%99-keywords-considered-bad-in-modern-C++
Just use std::array then and be happy:
Live On Coliru
#include <boost/archive/binary_iarchive.hpp>
#include <boost/archive/binary_oarchive.hpp>
#include <boost/serialization/serialization.hpp>
#include <boost/serialization/array.hpp>
#include <array>
#include <iostream>
#include <sstream>
class WorldItem {
private:
friend class boost::serialization::access;
template <class Ar> void serialize(Ar& ar, unsigned) {
ar& foreground& background& breakLevel& breakTime& water& fire& glue&
red& green& blue;
}
public:
int foreground = 0;
int background = 0;
int breakLevel = 0;
long long int breakTime = 0;
bool water = false;
bool fire = false;
bool glue = false;
bool red = false;
bool green = false;
bool blue = false;
auto operator<=>(WorldItem const&) const = default;
};
class Worlds
{
private:
friend class boost::serialization::access;
template <class Ar> void serialize(Ar& ar, unsigned) {
ar& width& height& name& items& owner& weather& isPublic& isNuked;
}
public:
int width;
int height;
std::string name;
std::array<WorldItem, 100 * 60> items;
std::string owner = "";
int weather = 0;
bool isPublic = false;
bool isNuked = false;
auto operator<=>(Worlds const&) const = default;
};
//So here im creating a world in this way
Worlds generateWorld(std::string name, int width, int height) {
Worlds world;
world.name = name;
world.width = width;
world.height = height;
return world;
}
std::string serialize_world(Worlds const& world) {
std::stringstream str;
{
boost::archive::binary_oarchive oa(str);
oa << world;
}
return str.str();
}
Worlds deserialize(std::string world) {
Worlds wld;
std::istringstream blobdata(world);
{
boost::archive::binary_iarchive ia(blobdata);
ia >> wld;
}
return wld;
}
int main() {
Worlds w = generateWorld("test", 6, 6);
Worlds clone = deserialize(serialize_world(w));
std::cout << "Worlds equal? " << std::boolalpha << (w == clone) << "\n";
}
Prints
Worlds equal? true