diskmanager.cpp

#include <iostream>
#include <cstring>
#include <string>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <unistd.h>
#include "diskutils.hpp"

void create_disk(key_t key) {
    int shmid = shmget(key, DISK_SIZE, IPC_CREAT | 0666);
    if (shmid < 0) { 
        perror("Error: shmget failed"); 
        exit(1); 
    }

    unsigned char* VD = (unsigned char*)shmat(shmid, NULL, 0);
    if (VD == (unsigned char*)-1) { 
        perror("Error: shmat failed"); 
        exit(1); 
    }

    memset(VD, 0, DISK_SIZE);

    // Block 0 – Superblock
    unsigned int nblocks      = TOTAL_BLOCKS;
    unsigned int nfreeblocks  = TOTAL_BLOCKS - 266;
    unsigned int root_block   = ROOT_DIR_BLOCK;

    memcpy(VD + (SUPERBLOCK * BLOCK_SIZE),     &nblocks,     4);
    memcpy(VD + (SUPERBLOCK * BLOCK_SIZE) + 4, &nfreeblocks, 4);
    memcpy(VD + (SUPERBLOCK * BLOCK_SIZE) + 8, &root_block,  4);

    // Bitmap (Blocks 1-8): mark blocks 0-265 as allocated
    unsigned int bitmap_offset = BITMAP_START * BLOCK_SIZE;
    for (int i = 0; i <= 265; i++) {
        int byte_idx = i / 8;
        int bit_idx  = i % 8;
        VD[bitmap_offset + byte_idx] |= (1 << bit_idx);
    }

    // Root directory (Block 265)
    metadata dot    = {'d', ".", 2, ROOT_DIR_BLOCK};
    metadata dotdot = {'d', "..", 0, ROOT_DIR_BLOCK};

    // Zero-pad the name fields properly
    memset(dot.name,    0, 23); 
    dot.name[0]    = '.';
    memset(dotdot.name, 0, 23); 
    dotdot.name[0] = '.'; 
    dotdot.name[1] = '.';

    unsigned int root_offset = ROOT_DIR_BLOCK * BLOCK_SIZE;
    memcpy(VD + root_offset, &dot, sizeof(metadata));
    memcpy(VD + root_offset + sizeof(metadata), &dotdot, sizeof(metadata));

    std::cout << "+++ Virtual Disk Created and Formatted successfully.\n";
    std::cout << "+++ Number of blocks: "      << nblocks     << "\n";
    std::cout << "+++ Number of free blocks: " << nfreeblocks << "\n";
    std::cout << "+++ First block of root directory: " << root_block << "\n";

    shmdt(VD);
}

void remove_disk(key_t key) {
    int shmid = shmget(key, DISK_SIZE, 0666);
    if (shmid < 0) {
        perror("Error: shmget failed (disk might not exist)");
        exit(1);
    }
    if (shmctl(shmid, IPC_RMID, NULL) == -1) {
        perror("Error: shmctl IPC_RMID failed");
        exit(1);
    }
    std::cout << "+++ Virtual Disk Removed successfully.\n";
}

int main(int argc, char* argv[]) {
    if (argc != 2) {
        std::cerr << "Usage: " << argv[0] << " [-create | -remove]\n";
        return 1;
    }

    key_t key = ftok(".", 'D');
    if (key == -1) { 
        perror("Error: ftok failed"); 
        return 1; 
    }

    std::string mode(argv[1]);
    if(mode == "-create") 
        create_disk(key);
    else if (mode == "-remove") 
        remove_disk(key);
    else {
        std::cerr << "***Error: Unknown mode. Use -create or -remove.\n";
        return 1;
    }
    return 0;
}