Let us try this information to wipe the data of any file stored in 1.44Mb, 3 ½ inch floppy disk, with the help of root directory information. Assuming that the data in the floppy disk is not fragmented, the program given next wipes the data of specified file from its data area:
/* Program to wipe the data area of specified file in
floppy disk */
#include<stdio.h>
#include<dos.h>
///// Structure to read 32 bytes of File Entry in Root Directory \\\\\
struct root
{
unsigned char filename[8]; /* File name Entry of
8 Bytes */
unsigned char extension[3]; /* Extension of File of
3 Bytes */
unsigned char attribute; /* File Attribute Byte */
unsigned char reserved[10]; /* Reserved Bytes 10 */
unsigned int time; /* Time, 2 Bytes */
unsigned int date; /* Date, 2 Bytes */
unsigned int starting_cluster;/* Starting Cluster of File,
2 Bytes */
unsigned long file_size; /* File Size in Bytes,
4 Bytes */
};
/* Should be taken this to read all Root Directory
Entries */
//struct root entry[224];
/* Structure to read all 16 File entries in one Sector of Root Directory */
struct one_root_sector
{
struct root entry[16];
};
struct one_root_sector one;
void main()
{
int result, i, num_sectors,j;
char wipe_buf[512]; /* Data Buffer to be used to wipe
out the data Area of file */
clrscr();
result= absread(0x00, 1, 19, &one); /* Read Absolute Sector n19 (First Sector of Root Directory) */
if (result != 0)
{
perror("Error in Reading Sector, Press any key to
Exit...");
getch();
exit(1);
}
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