VFSFile.cpp

#define _CRT_SECURE_NO_WARNINGS
#define MAXINODE 50
#define READ 1
#define WRITE 2
#define MAXFILESIZE 1024
#define REGULAR 1
#define SPECIAL 2
#define START 0
#define CURRENT 1
#define END 2

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<io.h>

typedef struct superblock
{
	int TotalInodes;
	int FreeInode;
}SUPERBLOCK, *PSUPERBLOCK;

typedef struct inode
{
	char FileName[50];
	int InodeNumber;
	int FileSize;
	int FileActualSize;
	int FileType;
	char *Buffer;
	int LinkCount;
	int ReferenceCount;
	int permission;
	struct inode *next;
}INODE,*PINODE,**PPINODE;

typedef struct filetable
{
	int readoffset;
	int writeoffset;
	int count;
	int mode;
	PINODE ptrinode;
}FILETABLE, *PFILETABLE;

typedef struct ufdt
{
	PFILETABLE ptrfiletable;
}UFDT;

UFDT UFDTArr[50];
SUPERBLOCK SUPERBLOCKobj;
PINODE head= NULL;

void man(char *name)
{
	if(name==NULL)return;
	if(_stricmp(name,"create")==0)
	{
		printf("Description : Used to create new regular file \n");
		printf("Usage : create File_name Permission");
	}
	else if(_stricmp(name,"read")==0)
	{
		printf("Description : Used to read data from regular file \n");
		printf("Usage : read File_name No_Of_Bytes_To_Read\n");
	}
	else if(_stricmp(name,"write")==0)
	{
		printf("Description : Used to write into regular file \n");
		printf("Usage : write File_name\n After this enter the data that we want to write\n");
	}
	else if(_stricmp(name,"ls")==0)
	{
		printf("Description : Used to list all information files \n");
		printf("Usage : ls\n");
	}
	else if(_stricmp(name,"stat")==0)
	{
		printf("Description : Used to display  information file \n");
		printf("Usage : stat File_name\n");
	}
	else if(_stricmp(name,"fstat")==0)
	{
		printf("Description : Used to display information file \n");
		printf("Usage : stat File_Descriptor\n");
	}
	else if(_stricmp(name,"truncate")==0)
	{
		printf("Description : Used to remove data from file \n");
		printf("Usage : truncate File_name\n");
	}
	else if(_stricmp(name,"open")==0)
	{
		printf("Description : Used to open existing file \n");
		printf("Usage : open File_name mode\n");
	}
	else if(_stricmp(name,"close")==0)
	{
		printf("Description : Used to close opened file \n");
		printf("Usage : close File_name \n");
	}
	else if(_stricmp(name,"closeall")==0)
	{
		printf("Description : Used to close all opened file \n");
		printf("Usage : closeall\n");
	}
	else if(_stricmp(name,"lseek")==0)
	{
		printf("Description : Used to change file offset \n");
		printf("Usage : lseek File_name ChnageInOffset StartPoint\n");
	}
	else if(_stricmp(name,"rm")==0)
	{
		printf("Description : Used to delete the file \n");
		printf("Usage : rm File_name\n");
	}
	else
	{
		printf("ERROR : No mannual entry available \n");
	}
}

void DisplayHelp()
{
	printf("ls: To list out all files\n");
	printf("clear: To clear console\n");
	printf("open: To open the file\n");
	printf("close: To close the file\n");
	printf("closeall: To close all opened files\n");
	printf("read: To read the contents from file\n");
	printf("write: To write contents into file\n");
	printf("exit: To terminate file system\n");
	printf("stat: To display information of file using name\n");
	printf("fstat: To display information of file using file descriptor\n");
	printf("truncate: To remove all data from file\n");
	printf("rm: To delete the file\n");
}

int GetFDFromName(char *name)
{
	int i=0;
	while(i<50)
	{
		if(UFDTArr[i].ptrfiletable!=NULL)
		{
			if(_stricmp((UFDTArr[i].ptrfiletable->ptrinode->FileName),name)==0)
				break;
		}
		i++;
	}
	if(i==50)
		return -1;
	else
		return i;
}

PINODE Get_Inode(char * name)
{
	PINODE temp=head;
	if(name==NULL)
	return NULL;
	while(temp!=NULL)
	{
		if(strcmp(name,temp->FileName)==0)
			break;
		temp=temp->next;
	}
	return temp;
}

void CreateDILB()
{
	int i=1;
	PINODE newn= NULL;
	PINODE temp= head;

	while(i<=MAXINODE)
	{
		newn= (PINODE)malloc(sizeof(INODE));
		newn->LinkCount=newn->ReferenceCount=0;
		newn->FileType=newn->FileSize=0;
		newn->Buffer= NULL;
		newn->next= NULL;
		newn->InodeNumber=i;
		if(temp==NULL)
		{
			head=newn;
			temp=head;
		}
		else
		{
			temp->next= newn;
			temp=temp->next;
		}
		i++;
	}
}

void InitialiseSuperBlock()
{
	int i=0;
	while(i<MAXINODE)
	{
		UFDTArr[i].ptrfiletable= NULL;
		i++;
	}

	SUPERBLOCKobj.TotalInodes= MAXINODE;
	SUPERBLOCKobj.FreeInode=MAXINODE;
}

int CreateFile(char *name, int permission)
{
	int i=0;
	PINODE temp=head;

	if((name== NULL)||(permission==0)||(permission>3))
		return -1;

	if(SUPERBLOCKobj.FreeInode==0)
		return -2;

	if(Get_Inode(name)!=NULL)
		return -3;

	(SUPERBLOCKobj.FreeInode)--;

	while(temp!=NULL)
	{
		if(temp->FileType==0)
			break;
		temp=temp->next;
	}

	while(i<50)
	{
		if(UFDTArr[i].ptrfiletable==NULL)
			break;
		i++;
	}

	UFDTArr[i].ptrfiletable=(PFILETABLE)malloc(sizeof(FILETABLE));
	if(UFDTArr[i].ptrfiletable==NULL)
		return -4;


	UFDTArr[i].ptrfiletable->count= 1;
	UFDTArr[i].ptrfiletable->mode= permission;
	UFDTArr[i].ptrfiletable->readoffset =0;
	UFDTArr[i].ptrfiletable->writeoffset =0;

	UFDTArr[i].ptrfiletable->ptrinode=temp;
	strcpy_s(UFDTArr[i].ptrfiletable->ptrinode->FileName,name);
	UFDTArr[i].ptrfiletable->ptrinode->FileType= REGULAR;
	UFDTArr[i].ptrfiletable->ptrinode->ReferenceCount =1;
	UFDTArr[i].ptrfiletable->ptrinode->LinkCount =1;
	UFDTArr[i].ptrfiletable->ptrinode->FileSize= MAXFILESIZE;
	UFDTArr[i].ptrfiletable->ptrinode->FileActualSize=0;
	UFDTArr[i].ptrfiletable->ptrinode->permission= permission;
	UFDTArr[i].ptrfiletable->ptrinode->Buffer=(char *)malloc(MAXFILESIZE);
	memset(UFDTArr[i].ptrfiletable->ptrinode->Buffer,0,1024);

	return i;
}

int rm_File(char *name)
{
	int fd=0;

	fd=GetFDFromName(name);
	if(fd==-1)
		return -1;

	(UFDTArr[fd].ptrfiletable->ptrinode->LinkCount)--;

	if(UFDTArr[fd].ptrfiletable->ptrinode->LinkCount==0)
	{
		UFDTArr[fd].ptrfiletable->ptrinode->FileType=0;
		free(UFDTArr[fd].ptrfiletable);
	}
	UFDTArr[fd].ptrfiletable= NULL;
	(SUPERBLOCKobj.FreeInode)++;
}


int ReadFile(int fd, char *arr, int isize)
{
	int read_size=0;

    if(UFDTArr[fd].ptrfiletable== NULL)
	return -1;

	if(UFDTArr[fd].ptrfiletable->mode!=READ && UFDTArr[fd].ptrfiletable->mode != READ+WRITE)
	return -2;

	if((UFDTArr[fd].ptrfiletable->ptrinode->permission!=READ)&&
		(UFDTArr[fd].ptrfiletable->ptrinode->permission!= READ+WRITE))
	return -2;

	if(UFDTArr[fd].ptrfiletable->readoffset == UFDTArr[fd].ptrfiletable->ptrinode->FileActualSize)
	return -3;

	if(UFDTArr[fd].ptrfiletable->ptrinode->FileType != REGULAR)
	return -4;

	read_size = (UFDTArr[fd].ptrfiletable->ptrinode->FileActualSize)- 
		(UFDTArr[fd].ptrfiletable->readoffset);
	if(read_size<isize)
	{
		strncpy( arr, 
			(UFDTArr[fd].ptrfiletable->ptrinode->Buffer)+(UFDTArr[fd].ptrfiletable->readoffset),
			read_size);

		UFDTArr[fd].ptrfiletable->readoffset=UFDTArr[fd].ptrfiletable->readoffset+read_size;
	}
	else
	{
		strncpy( arr,
				 (UFDTArr[fd].ptrfiletable->ptrinode->Buffer) + (UFDTArr[fd].ptrfiletable->readoffset),
				 isize);
		(UFDTArr[fd].ptrfiletable->readoffset)=(UFDTArr[fd].ptrfiletable->readoffset)+isize;
	}

	return read_size;
}

int WriteFile(int fd, char *arr, int isize)
{
	if(((UFDTArr[fd].ptrfiletable->mode)!=WRITE) &&
		((UFDTArr[fd].ptrfiletable->mode)!=READ+WRITE))
		return -1;
	if(((UFDTArr[fd].ptrfiletable->ptrinode->permission)!=WRITE)&&
		((UFDTArr[fd].ptrfiletable->ptrinode->permission)!=READ+WRITE))
		return-1;

	if((UFDTArr[fd].ptrfiletable->writeoffset)==MAXFILESIZE)
		return -2;

	if((UFDTArr[fd].ptrfiletable->ptrinode->FileType)!=REGULAR)
		return -3;

	strncpy((UFDTArr[fd].ptrfiletable->ptrinode->Buffer)+(UFDTArr[fd].ptrfiletable->writeoffset),arr,isize);

	(UFDTArr[fd].ptrfiletable->writeoffset)=(UFDTArr[fd].ptrfiletable->writeoffset) +isize;

	(UFDTArr[fd].ptrfiletable->ptrinode->FileActualSize)=(UFDTArr[fd].ptrfiletable->ptrinode->FileActualSize)
		+isize;
	return isize;
}

int OpenFile(char *name, int mode)
{
	int i=0;
	PINODE temp= NULL;
	 if(name == NULL || mode <=0)
		 return -1;

	 temp= Get_Inode(name);
	 if(temp==NULL)
		 return -2;

	 if(temp->permission < mode)
		 return -3;

	 while(i<50)
	 {
		 if(UFDTArr[i].ptrfiletable== NULL)
			 break;
		 i++;
	 }

	 UFDTArr[i].ptrfiletable=(PFILETABLE)malloc(sizeof(FILETABLE));
	 if(UFDTArr[i].ptrfiletable= NULL)
		 return -1;
	 UFDTArr[i].ptrfiletable->count=1;
	 UFDTArr[i].ptrfiletable->mode= mode;

	 if(mode==READ + WRITE)
	 {
		 UFDTArr[i].ptrfiletable->readoffset=0;
		 UFDTArr[i].ptrfiletable->writeoffset=0;
	 }
	 else if(mode==READ)
	 {
		 UFDTArr[i].ptrfiletable->readoffset=0;
	 }
	 else if(mode==WRITE)
	 {
		 UFDTArr[i].ptrfiletable->writeoffset=0;
	 }
	 UFDTArr[i].ptrfiletable->ptrinode=temp;
	 (UFDTArr[i].ptrfiletable->ptrinode->ReferenceCount)++;

	 return i;
}

void CloseFileByfd(int fd)
{
	UFDTArr[fd].ptrfiletable->readoffset=0;
	UFDTArr[fd].ptrfiletable->writeoffset=0;
	(UFDTArr[fd].ptrfiletable->ptrinode->ReferenceCount)--;
}

int CloseFileByName(char *name)
{
	int i=0;

	i= GetFDFromName(name);
	if(i==-1)
		return -1;

	UFDTArr[i].ptrfiletable->readoffset=0;
	UFDTArr[i].ptrfiletable->writeoffset=0;

	(UFDTArr[i].ptrfiletable->ptrinode->ReferenceCount)--;

	return 0;
}

void CloseAllFile()
{
	int i=0;
	while(i<50)
	{
		if(UFDTArr[i].ptrfiletable !=NULL)
		{
			UFDTArr[i].ptrfiletable->readoffset=0;
			UFDTArr[i].ptrfiletable->writeoffset=0;
			
			(UFDTArr[i].ptrfiletable->ptrinode->ReferenceCount)--;
		}
		i++;
	}
}

int LseekFile(int fd,int size, int from)
{
	if((fd<0)|| (from>0))
		return -1;
	if(UFDTArr[fd].ptrfiletable==NULL)
		return -1;

	if((UFDTArr[fd].ptrfiletable->mode==READ)||(UFDTArr[fd].ptrfiletable->mode==READ+WRITE))
	{
		
			if(from==CURRENT)
			{
				if(((UFDTArr[fd].ptrfiletable->readoffset)+ size)>
					(UFDTArr[fd].ptrfiletable->ptrinode->FileActualSize))
					return -1;
				if(((UFDTArr[fd].ptrfiletable->readoffset)+ size)<0)
					return -1;
				(UFDTArr[fd].ptrfiletable->readoffset)=(UFDTArr[fd].ptrfiletable->readoffset)+size;
			}
			else if(from== START)
			{
				if(size>(UFDTArr[fd].ptrfiletable->ptrinode->FileActualSize))
					return -1;
				if(size<0)
					return -1;
				(UFDTArr[fd].ptrfiletable->readoffset)=size;
			}
			else if(from== END)
			{
				if((UFDTArr[fd].ptrfiletable->ptrinode->FileActualSize)+size>MAXFILESIZE)
					return -1;
				if(((UFDTArr[fd].ptrfiletable->readoffset)+size)<0)
					return -1;
				(UFDTArr[fd].ptrfiletable->readoffset)=(UFDTArr[fd].ptrfiletable->ptrinode->FileActualSize)
					+size;
			}
	}

	else if(UFDTArr[fd].ptrfiletable->mode== WRITE)
	{
		if(from==CURRENT)
		{
			if(((UFDTArr[fd].ptrfiletable->writeoffset)+size)>MAXFILESIZE)
				return -1;
			if(((UFDTArr[fd].ptrfiletable->writeoffset)+size)<0)
				return -1;
			if(((UFDTArr[fd].ptrfiletable->writeoffset)+size)>
				(UFDTArr[fd].ptrfiletable->ptrinode->FileActualSize))
					(UFDTArr[fd].ptrfiletable->ptrinode->FileActualSize)=
					(UFDTArr[fd].ptrfiletable->writeoffset)+size;
			(UFDTArr[fd].ptrfiletable->writeoffset)=(UFDTArr[fd].ptrfiletable->writeoffset)+size;
		}
		else if(from== START)
		{
			if(size>MAXFILESIZE)
				return -1;
			if(size<0)
				return -1;
			if(size>(UFDTArr[fd].ptrfiletable->ptrinode->FileActualSize))
			(UFDTArr[fd].ptrfiletable->ptrinode->FileActualSize)=size;	
			(UFDTArr[fd].ptrfiletable->writeoffset)=size;
		}
		else if(from== END)
		{
			if((UFDTArr[fd].ptrfiletable->ptrinode->FileActualSize)+size>MAXFILESIZE)
					return -1;
			if(((UFDTArr[fd].ptrfiletable->writeoffset)+size)<0)
					return -1;
			(UFDTArr[fd].ptrfiletable->writeoffset)=(UFDTArr[fd].ptrfiletable->ptrinode->FileActualSize)
					+size;
		}
	}
}


void ls_file()
{
	PINODE temp=head;

	if(SUPERBLOCKobj.FreeInode==MAXINODE)
	{
		printf("Error: There are no files\n");
		return;
	}

	printf("\nFileName\t Inode number\t File size\t Link count\n");
	printf("-----------------------------------------------\n");
	while(temp!=NULL)
	{
		if(temp->FileType!=0)
		{
			printf("%s\t\t%d\t\t%d\t\t%d\n",
				temp->FileName,temp->InodeNumber,temp->FileActualSize,temp->LinkCount);
		}
		temp=temp->next;
	}
	printf("-----------------------------------------------\n");
}

int fstat_file(int fd)
{
	PINODE temp=head;
	if(fd<0)
		return -1;
	if(UFDTArr[fd].ptrfiletable==NULL)
		return -2;
	temp=UFDTArr[fd].ptrfiletable->ptrinode;

	printf("\n--------Statistical information about file----------\n");
	printf("File name : %s\n",temp->FileName);
	printf("Inode Number : %d\n",temp->InodeNumber);
	printf("File size : %d\n",temp->FileSize);
	printf(" Actual File size : %d\n",temp->FileActualSize);
	printf("Link count : %d\n",temp->LinkCount);
	printf("Reference count : %d\n",temp->ReferenceCount);
	if(temp->permission == 1)
		printf("File permission : Read only\n");
	else if(temp->permission==2)
		printf("File permission : Write\n");
	else if(temp->permission==3)
		printf("File permission : Read & Write\n");
	printf("-----------------------------------\n\n");
	return 0;
}

int stat_file(char *name)
{
	PINODE temp= head;
	
	if(name == NULL)
		return -1;
	while(temp!=NULL)
	{
		if(strcmp(name,temp->FileName)==0)
			break;
		temp=temp->next;
	}

	if(temp==NULL)
		return -2;
	printf("\n--------Statistical information about file----------\n");
	printf("File name : %s\n",temp->FileName);
	printf("Inode Number : %d\n",temp->InodeNumber);
	printf("File size : %d\n",temp->FileSize);
	printf(" Actual File size : %d\n",temp->FileActualSize);
	printf("Link count : %d\n",temp->LinkCount);
	printf("Reference count : %d\n",temp->ReferenceCount);
	if(temp->permission == 1)
		printf("File permission : Read only\n");
	else if(temp->permission==2)
		printf("File permission : Write\n");
	else if(temp->permission==3)
		printf("File permission : Read & Write\n");
	printf("-----------------------------------\n\n");
	return 0;
}
int truncate_File(char *name)
{
	int fd= GetFDFromName(name);
	if(fd==-1)
		return -1;
	memset(UFDTArr[fd].ptrfiletable->ptrinode->Buffer,0,1024);
	UFDTArr[fd].ptrfiletable->readoffset=0;
	UFDTArr[fd].ptrfiletable->writeoffset;
	UFDTArr[fd].ptrfiletable->ptrinode->FileActualSize=0;
}



int main()
{
	char *ptr=NULL;
	int ret = 0, fd=0, count=0;
	char command[4][80],str[80],arr[1024];
		
	InitialiseSuperBlock();
	CreateDILB();


	while(1)
	{
		fflush(stdin);
		strcpy_s(str,"");


		printf("\n Marvellous VFS: >");
		fgets(str,80,stdin);

		count= sscanf(str,"%s%s%s%s",command[0],command[1],command[2],command[3]);

		if(count==1)
		{
			if(_stricmp(command[0],"ls")==0)
			{
				ls_file();
			}
			else if(_stricmp(command[0],"closeall")==0)
			{
				CloseAllFile();
				printf("All files closed successfully\n");
				continue;
			}
			else if(_stricmp(command[0],"clear")==0)
			{
				system("cls");
				continue;
			}
			else if(_stricmp(command[0],"help")==0)
			{
				DisplayHelp();
				continue;
			}
			else if(_stricmp(command[0],"exit")==0)
			{
				printf("Terminating the Marvellous Virtual File System\n");
				break;
			}
			else
			{
				printf("\nERROR: command not found!!!\n");
				continue;
			}
		}
		else if(count==2)
		{
			if(_stricmp(command[0],"stat")==0)
			{
				ret= stat_file(command[1]);
				if(ret==-1)
					printf("ERROR : Incorrect parameters\n");
				
				if(ret==-2)
					printf("ERROR : There is no such file\n");
				continue;
			}
			else if(_stricmp(command[0],"fstat")==0)
			{
				ret=fstat_file(atoi(command[1]));
				if(ret==-1)
					printf("ERROR : Incorrect parameters\n");
				
				if(ret==-2)
					printf("ERROR : There is no such file\n");
				continue;
			}
			else if(_stricmp(command[0],"close")==0)
			{
				ret=CloseFileByName(command[1]);
				if(ret==-1)
					printf("ERROR : There is no such file\n");
				continue;
			}
			else if(_stricmp(command[0],"rm")==0)
			{
				ret=rm_File(command[1]);
				if(ret==-1)
					printf("ERROR : There is no such file\n");
				continue;
			}
			else if(_stricmp(command[0],"man")==0)
			{
				man(command[1]);
			}
			else if(_stricmp(command[0],"write")==0)
			{
				fd=GetFDFromName(command[1]);
				if(fd==-1)
				{
					printf("ERROR : Incorrect parameter\n");
					continue;
				}
			
				printf("Enter the data : \n");
				scanf("%[^\n]",arr);

				ret=strlen(arr);
				if(ret==0)
				{
					printf("ERROR : Incorrect parameter\n");
					continue;
				}
				ret=WriteFile(fd,arr,ret);
				if(ret==-1)
					printf("ERROR : Permission denied\n");
				if(ret==-2)
					printf("ERROR : There is no sufficient memory to write\n");
				if(ret==-3)
					printf("ERROR : It is not regular file\n");
			}
		else if(_stricmp(command[0],"truncate")==0)
			{
				ret=truncate_File(command[1]);
				if(ret==-1)
					printf("ERROR : Incorrect parameter\n");
				
			}
			else
			{
				printf("\nERROR : command not found!!!\n");
				continue;
			}
		}
		else if(count==3)
		{
			if(_stricmp(command[0],"create")==0)
			{
				ret=CreateFile(command[1],atoi(command[2]));
				if(ret>=0)
					printf("File is successfully created with the file descriptor : %d\n",ret);
				if(ret==-1)
					printf("ERROR : Incorrecr parameters\n");
				if(ret==-2)
					printf("ERROR : There is no inodes\n");
				if(ret==-3)
					printf("ERROR : File already exist\n");
				if(ret==-4)
					printf("ERROR : Memory allocation failure\n");
				continue;
			}
			else if(_stricmp(command[0],"open")==0)
			{
				ret=OpenFile(command[1],atoi(command[2]));

				if(ret>=0)
					printf("File is successfully opened with descriptor : %d\n",ret);
				if(ret==-1)
					printf("ERROR : Incorrect parameters\n");
				if(ret==-2)
					printf("ERROR : File not present\n");
				if(ret==-3)
					printf("ERROR : Permission denied\n");
				continue;
			}
			else if(_stricmp(command[0],"read")==0)
			{
				fd=GetFDFromName(command[1]);
				if(fd==-1)
				{
					printf("ERROR : Incorrecr parametrs\n");
					continue;
				}
				ptr=(char *)malloc(sizeof(atoi(command[2]))+1);
				if(ptr==NULL)
				{
					printf("ERROR : Memory allocation failure\n");
					continue;
				}
				ret= ReadFile(fd,ptr,atoi(command[2]));
				if(ret==-1)
					printf("ERROR : File not existing\n");
				if(ret==-2)
					printf("ERROR : Permission denied\n");
				if(ret==-3)
					printf("ERROR : Reached at end of file\n");
				if(ret==-4)
					printf("ERROR : It is not regular file\n");
				if(ret==0)
					printf("ERROR : File Empty\n");
				if(ret>0)
				{
					_write(2,ptr,ret);
				}
				continue;
			}
			else
			{
				printf("\nERROR : Command not found !!!\n");
				continue;
			}
		}
		else if(count==4)
		{
			if(_stricmp(command[0],"lseek")==0)
			{
				fd=GetFDFromName(command[1]);
				if(fd==-1)
				{
					printf("ERROR : Incorrecr parameter\n");
					continue;
				}
				ret= LseekFile(fd,atoi(command[2]),atoi(command[3]));
				if(ret==-1)
				{
					printf("ERROR : Unable to perform lseek\n");
				}
			}
			else
			{
				printf("\nERROR : Command not found !!!\n");
				continue;
			}
		}
		else
		{
			printf("\nERROR : Command not found !!!\n");
			continue;
		}
	}
	return 0;
}