fsInit.c

/**************************************************************
 * Class::  CSC-415-02 Spring 2024
 * Name::David Chang
 *       Yuiel Gebredngl
 *       Jiqing Liu
 *       Chia-Tung Liu
 * Student IDs::920460954
 *               922729168
 *               922056041
 *               923408847
 * GitHub-Name::JunN0tJune
 *               yuiela
 *               YTDY3867
 *               Mob1001
 * Group-Name::Alt+F4
 * Project:: Basic File System
 *
 * File:: fsInit.c
 *
 * Description:: Main driver for file system assignment.
 *
 * This file is where you will start and initialize your system
 *
 **************************************************************/
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <stdio.h>
#include <string.h>
#include <time.h>

#include "fsLow.h"
#include "mfs.h"
#include "VCB.h"
#include "FreeSpaceManager.h"
#include "Directory.h"

#define MAX_DIR_ENTRIES 128   // Adjust based on your system's needs
#define MAX_DIR_NAME_SIZE 255 // Adjust according to your definition


//We define our global variables here once, and they will be shared
//across the other files using globalVF
VCB_Block* VCBHolder = NULL;
FAT_Entry*  FATTable = NULL;

DIR_Entry* root_directory = NULL;

char* currentDirectory = NULL;
int initFileSystem(uint64_t numberOfBlocks, uint64_t blockSize) {
    printf("Initializing File System with %ld blocks with a block size of %ld\n", numberOfBlocks, blockSize);

    // Allocate space for VCB and attempt to read it from LBA 0
    VCBHolder = (VCB_Block*)malloc(blockSize);
    if (VCBHolder == NULL) {
        return -1; // Allocation failed
    }

    // Read the VCB from the disk
    LBAread(VCBHolder, 1, 0);

    // Check if the file system has been initialized by checking magic number
    if (VCBHolder->magic_number == MAGIC_NUMBER) {
        // Attempt to read the FAT table and root directory
        FATTable = readFATTable(VCBHolder->FAT_reference);
        root_directory = readRoot(VCBHolder->root_reference);
        
        if (FATTable == NULL || root_directory == NULL) {
            free(VCBHolder);
            VCBHolder=NULL;
            return -1; // Reading FAT or root directory failed
        }

        // Set the current directory to root
        currentDirectory = strdup("/");
        return 0; // Success, file system is initialized from disk
    } else {
        // No valid file system found, create a new one
        free(VCBHolder);
        VCBHolder=NULL;
        VCBHolder = createVCB(numberOfBlocks, blockSize);
        FATTable = initFATTable(numberOfBlocks);
        VCBHolder->root_reference = initDirectory(MAX_DIR_ENTRIES);
        VCBHolder->root_size = root_directory->size;

        // Write the new VCB back to the disk
        writeToLBA(VCBHolder, 1, 0);

        // Initialize current directory to root
        currentDirectory = strdup("/");
        return 0; // Success, new file system is formatted and initialized
    }
}


void exitFileSystem ()
{
	// main strucutres are freed 
	free(VCBHolder);
	VCBHolder = NULL;

	free(FATTable);
	FATTable = NULL;

	free(root_directory);
	root_directory = NULL;
	
	free(currentDirectory);
	currentDirectory = NULL;

	printf ("System exiting\n");
}