How to write out all connected devices using Libparted on Linux Mint?

Question

I have been trying to print out all connected storage devices to my machine using C++ and libparted on Linux Mint 22 x86_64.

I have been tinkering with the ped_device_get_next() function, that should return the next device in the list provided by the ped_device_probe_all() function. I have trouble getting this to work, since the documentation on this library is pretty poor.

The most useful thing I've gotten to work is this simple chunk of code.

#include <cmakeconfig.h>
#include "mainheader.h"

int main()
{
    ped_device_probe_all();

    PedDevice *tempbed;
    int c = 0;
    do {
        tempbed = ped_device_get_next(NULL);
        std::cout<<c<<" "<<tempbed->model<<"\n";
        c++;
    } while(tempbed != NULL && c < 256); 

    return 0;
}

And all it does is print out the model of my SSD 256 times. Without the c variable acting as a safety mechanism, it does it forever (until the resources run out I guess).

It does not print out the model of my HDD anywhere.

I know that my code does exactly what the documentation says, prints out the first device x times, but I just cannot figure out how to make it print out the devices consecutively.

0 <model name>
1 <model name>
2 <model name>
3 <model name>
4 <model name>
etc.

Documentation of ped_device_get_next

Answer 1

You initially call ped_device_get_next(NULL); Then on subsequent calls, you pass the value it returned on the previous call. One way to do this would be something like this:

int main()
{
    ped_device_probe_all();

    PedDevice *tempbed = nullptr;
    int c = 0;

    while((tempbed = ped_device_get_next(tempbed))!= nullptr && c <255) {
        std::cout<<c<<" "<<tempbed->model<<"\n";
        c++;
    } 

    return 0;
}

...or you could wrap it up onto a class that imitates a container:

#include <parted/parted.h>


class devices {
public:
    class iterator {
        PedDevice *current = nullptr;
    public:
        iterator &operator++() {
            current = ped_device_get_next(current);
            return *this;
        }

        PedDevice &operator*() const { return *current; }

        bool operator!=(iterator const &other) const { 
            return current != other.current;
        }
    };
    
    devices() { ped_device_probe_all(); }
    iterator begin() {
        iterator i;
        return ++i;        
    }
    iterator end() { return iterator(); }
};

...then iterate over it like almost a other container:

int main()
{
    devices dev;

    for (auto const &d : dev) {
        std::cout << d.model << "\n";
    }
}

As an aside, note that on most systems, you'll have to run this as root for it to actually show anything.