shared-memory/src/SharedMemory.cpp

#include <cstdlib>
#include "SharedMemory.h"
#include <iostream>
#include <fstream>

key_t changedKey()
{
    std::ofstream keyFile;
    keyFile.open("key.log", std::ofstream::out | std::ofstream::trunc);
    keyFile.clear();
    int newKey;
    std::cout << "Type in a new Key for the Shared Memory Segment" << std::endl;
    std::cout << "new Key#";
    std::cin >> newKey;
    std::cout <<"New Key is -> " << newKey << std::endl;
    keyFile << newKey;
    keyFile.close();
    return key_t(newKey);
}

std::string getAnswerFromUser()
{
    std::cout <<"answer# ";
    std::string answer;
    std::cin >> answer;
    if(answer.compare("y") == 0 || answer.compare("n") == 0|| answer.compare("override") == 0) {
        return answer;
    } else {
        std::cout << "wrong input: pls answer with (y) for yes, (n) for no, or (override)\n";
        getAnswerFromUser();
    }
    return "-0";
}


void initSharedMemory(void) {
    if(impl.sharedMemoryKey != key_t(0)) {
        if (shmget(impl.sharedMemoryKey, Max_Memory_Size, IPC_CREAT | IPC_EXCL | 0666) < 0)
        {
            std::cout << "Shared Memory with Key: " << impl.sharedMemoryKey << " is already in use\n"
            <<"You can change the Key( type -> y or n ), or you can override the shared memory Segment(type -> override)\n";
            std::string answer = getAnswerFromUser();
            if(answer.compare("y") == 0)
            {
                impl.sharedMemoryKey = changedKey();
                std::cout << "new Try with Key:c " << impl.sharedMemoryKey << std::endl;
                initSharedMemory();
            } else if(answer.compare("n") == 0) {
                std::cout << "This will end shared memory" <<std::endl;
                exit(0);
            } else if(answer.compare("override") == 0) {
                deleteSharedMemory();
                initSharedMemory();
            }
        } else {
            std::cout << "Shared Memory is (Re-) allocated with Key: " << impl.sharedMemoryKey << std::endl;
        }
    } else {
        std::cerr <<"key -> " << impl.sharedMemoryKey << " is not allowed here " << std::endl;
        impl.sharedMemoryKey = changedKey();
        initSharedMemory();
    }
}

void deleteSharedMemory(int s)
{
    std::cerr << "programm ended with Code: " << s << std::endl;
    if (shmctl(shmget(impl.sharedMemoryKey, 0, 0), IPC_RMID, 0) < 0 )
    {
        std::cerr << "Failed to remove shared Memory, maybe not existing: try cmd: ipcs, then delete with ipcrm -m $memID " << std::endl;
    } else {
        std::cout << "shared Memory deleted" << std::endl;
    }
}

void deleteSharedMemory(void)
{
    if (shmctl(shmget(impl.sharedMemoryKey, 0, 0), IPC_RMID, 0) < 0 )
    {
        std::cerr << "Failed to remove shared Memory, maybe not existing: try cmd: ipcs " << std::endl;
    } else {
        std::cout << "shared Memory deleted" << std::endl;
    }
}