/* Function to Delete the Temporary files automatically */
remove_temp_file()
{
int i=0;
for(i=0;i<=file_num;i++)
{
strcpy(filename,"TTPT");
itoa(i,temp,10);
strcat(filename,temp);
strcat(filename,file_extension);
remove(filename);
}
exit(1);
return 0;
}
Comments on logic and the coding of the program:
In this program basically we follow the following two steps to wipe the unallocated space of the disk:
- Create temporary data files automatically: First we create temporary files with unique names and having some data in them until the disk volume is full with these temporary data files. By doing this, all the unallocated data area of the logical drive is occupied by the data of the temporary files and all unallocated data is overwritten.
For doing this, I chose the names of temporary files in the TTPTxxxx.PTT format, which means, the first four characters of the temporary files are TTPT and the extension of the files is .PTT. It is done so to provide the temporary files the unique filenames.
I have set the maximum size of the single temporary file, equivalent to approximately 11,718 sectors data however you can define it according to you. I chose space character “ ” (ASCII character 32) to fill the data in temporary files. However random characters may also be used instead of space.
- Remove all temporary files: When the logical drive is full with temporary files, it indicates that all the unallocated data area is now overwritten. Now all the temporary files created by the program are removed automatically. And thus wiped out unallocated space is achieved.
In the coding of the program, the character array filename stores the file name to generate temporary files automatically, with different names.
The function write_to_temp(filename); fills the temporary file up to 11,718 sectors (because there is no occurrence of 10,000 sectors in specified group writing of buffer) equivalent data with help of data buffer dbuf of 40,000 bytes. 50 times data buffer is written at a time to speed up the writing.
The temporary files are created until the disk volume is full and file creation error occurs. The function remove_temp_file() removes all temporary file, created by the program.
In this way all the unallocated space is wiped out without harming the data of the disk volume.
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