Write.cpp

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

int *SharedData;
mutex mtx; // Define a mutex object

void* createFile(void* filename) {
    string fname = *((string*)filename);

    mtx.lock(); // Lock the mutex before accessing shared resources

    // Check if the file exists
    ifstream checkFile(fname);
    if (checkFile) {
        cout << "File \"" << fname << "\" already exists!" << endl;
        checkFile.close();

        // Open the existing file for appending
        ofstream writeFile(fname, ios::app);
        if (writeFile) {
            // Write data to the file
            string data;
            cout << "Write the Data You Want to Write in File:" << endl;
            getline(cin, data);
            writeFile << data << endl;
            cout << "Data written to file \"" << fname << "\"!" << endl;
            writeFile.close();
        } else {
            cout << "Failed to open file \"" << fname << "\" for writing!" << endl;
        }
    } else {
        // Create a new file if it doesn't exist
        ofstream file(fname);
        file.close();
        cout << "File \"" << fname << "\" created successfully!" << endl;
        ofstream writeFile(fname, ios::app);
        if (writeFile) {
            // Write data to the file
            string data;
            cout << "Write the Data You Want to Write in File:" << endl;
            getline(cin, data);
            writeFile << data << endl;
            cout << "Data written to file \"" << fname << "\"!" << endl;
            writeFile.close();
        } else {
            cout << "Failed to open file \"" << fname << "\" for writing!" << endl;
        }
    }

    mtx.unlock(); // Unlock the mutex after accessing shared resources

    pthread_exit(NULL);
}
    
int main() {

    // Create or get the shared memory segment
    int shmid = shmget((key_t)8749, sizeof(int), IPC_CREAT | 0666);
    if (shmid == -1) {
        perror("Failed!");
        return 1;
    }

    // Attach the shared memory segment
    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;

    // Get the file name from the user
    string fileName;
    cout << "Enter name of the file: ";
    getline(cin, fileName);

    // Create a thread to handle file creation and writing
    pthread_t thread;
    pthread_create(&thread, NULL, createFile, (void*)&fileName);

    // Wait for the thread to complete
    pthread_join(thread, NULL);

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

    return 0;
}