Write a program to simulate Indexed file allocation method.

 Write a program to simulate Indexed file allocation method. Assume disk with n number

of blocks. Give value of n as input. Write menu driver program with menu options as

mentioned above and implement each option.

#include<stdio.h>

#include<stdlib.h>

#include<string.h>

#define MAX 200

typedef struct dir

{

char fname[20];

int start,length;

struct dir *next;

}NODE;

NODE *first,*last;

int bit[MAX],n;

void init()

{

int i;

printf("Enter total no.of disk blocks:");

scanf("%d",&n);

for(i=0;i<n;i++)

{

bit[i] =rand()%2;

}

}

void show_bitvector()

{

int i;

for(i=0;i<n;i++)

{

printf("%d",bit[i]);

}

printf("\n");

}

void show_dir()

{

NODE *p;

printf("File\tStart\tLength\n");

p = first;

while(p!=NULL)

{

printf("%s\t%d\t%d\n",

p->fname,p->start,p->length);

p = p->next;

}

}

void create()

{

NODE *p;

char fname[20];

int nob,i=0,j=0,start;

printf("Enter file name:");

scanf("%s",fname);

printf("Enter no.of blocks:");

scanf("%d",&nob);

while(1)

{

while(i<n)

{

if(bit[i]==0) break;

i++;

}

if(i<n)

{

start = i;

j=1;

while(j<nob && i<n && bit[i]==0)

{

i++;j++;

}

if(j==nob)

{

p = (NODE*)malloc(sizeof(NODE));

strcpy(p->fname,fname);

p->start = start;

p->length = nob;

p->next = NULL;

if(first==NULL)

first=p;

else

last->next=p;

last=p;

for(j=0;j<nob;j++)

bit[j+start]=1;

printf("File %s created successfully.\n",fname);

return;

}

}

else

{

printf("Fail to create file %s\n",fname);

return;

}

}

}

void delete()

{

NODE *p,*q;

char fname[20];

int i;

printf("Enter file to be deleted:");

scanf("%s",fname);

p = q = first;

while(p!=NULL)

{

if(strcmp(p->fname,fname)==0)

break;

q = p;

p = p->next;

}

if(p==NULL)

{

printf("File %s not found.\n",fname);

return;

}

for(i=0;i<p->length;i++)

bit[p->start+i]=0;

if(p==first)

first = first->next;

else if(p==last)

{

last=q;

last->next=NULL;

}

else

{

q->next = p->next;

}

free(p);

printf("File %s deleted successfully.\n",fname);

}

void main()

{

int ch;

init();

while(1)

{

printf("1.Show bit vector\n");

printf("2.Create new file\n");

printf("3.Show directory\n");

printf("4.Delete file\n");

printf("5.Exit\n");

printf("Enter your choice (1-5):");

scanf("%d",&ch);

switch(ch)

{

case 1:

show_bitvector();

break;

case 2:

create();

break;

case 3:

show_dir();

break;

case 4:

delete();

break;

case 5:

exit(0);

}

}

}