Read.cpp

#include <iostream>
#include <fstream>
#include <pthread.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <mutex>
#include <string>
using namespace std;

// Define a structure for PCB
struct PCB {
    int processID; // Unique process identifier
    string fileName; // File to be read by the process
    int* sharedMemory; // Reference to shared memory for resource management
};

int *SharedData;
mutex mtx;

void* readFile(void* arg) {
    PCB* pcb = (PCB*)arg; // Cast the argument back to PCB type

    string fname = pcb->fileName;

    ifstream file(fname);
    if (file.is_open()) {
        string line;
        cout << "Contents of file \"" << fname << "\":" << endl;
        while (getline(file, line)) {
            mtx.lock();
            cout << line << endl;
            mtx.unlock();
        }
        file.close();
    } else {
        cout << "Failed to open file \"" << fname << "\" for reading or the file does not exist!" << endl;
    }

    pthread_exit(NULL);
}

int main() {
    int shmid = shmget((key_t)8749, sizeof(int), IPC_CREAT | 0666);
    if (shmid == -1) {
        perror("Failed!");
        return 1;
    }

    SharedData = (int*)shmat(shmid, NULL, 0);
    if (SharedData == (int*)(-1)) {
        perror("Failed!");
        return 1;
    }

    cout << "\n\tProcess Requirements:\n";
    cout << "Memory: 400MB\n";
    cout << "Hard Disk Space: 100MB\n";
    cout << "Number of Cores: 1" << endl;
    cout << "Available Memory: " << *SharedData << endl;

    if (*SharedData < 400) {
        cout << "\tInsufficient resources to create a new process." << endl;
        do {
            // Keep waiting until sufficient resources are available
        } while (*SharedData < 400);
    }
    cout << "Memory Allocation Done to This Process!" << endl;

    // Update available memory after memory allocation
    *SharedData -= 400;

    string fileName;
    cout << "Enter name of the file to read: ";
    getline(cin, fileName);

    // Create a PCB for the current process
    PCB currentProcess;
    currentProcess.processID = 1; // Assuming a unique process ID
    currentProcess.fileName = fileName;
    currentProcess.sharedMemory = SharedData; // Reference to shared memory

    pthread_t readThread;
    pthread_create(&readThread, NULL, readFile, (void*)&currentProcess);

    pthread_join(readThread, NULL);

    // Update available memory after reading the file
    *SharedData += 400;

    return 0;
}