/*_____________________________________________________________________________
|                                                                              |
| File name: cftcd.c                                                           |
|                                                                              |
| Program name: Completely Fill The Current Directory                          |
|																			   |
| Version: 2.1     															   |
|                                                                              |
| Description: Fills the directory it's located in entriely with 1's, i.e.     |
| 0xFF. It does so effeciently by making as large of write as possible and     |
| halving the size each time. It also compensates for possible file size limits|
| by filling a file until the file system won't allow. Quits when writes are no|
| longer possible. Capable of continuing where it left off. Can be used to wipe|
| free space because it writes on all freespace. Then, the files can simply be |
| deleted. 0xFF is chosen becuase it does not show up as a displayable         |
| character. The files are .txt, so it looks like a giant empty notepad file.  |
| This is intentional to be possibly confusing.                                |
|                                                                              |
| Author: Thaddeus Joseph "T.J." Jancewicz <tjjancewicz a t gmail d o t com>   |
|																			   |
| Creation date: Tuesday 13 January 2009									   |
|                                                                              |
| Update date: Friday 24 August 2010: Realized fwrite() doesn't output         |
| that makes sense to compare to the write size.                               |
|____________________________________________________________________________*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>

// nope, we don't EVER need to return anything. ever.
void main(void)
{
    FILE *file = NULL; /* the following array sizes won't overflow unless you're
                    trying to fill NASA... and are running a 128-bit computer
                    AND rewrite this code for 128 bit ints */
    char file_name[30], number_to_append[26], nothing = 0xFF;
    
#ifdef LLONG_MAX
#define WRITE_SIZE_LIMIT ULLONG_MAX
/* these lines are here if we're running on a 64-bit computer. the hilarious 
part is that no system on Earth can even store 2^64-1 bytes. well, in 10 years*/
    unsigned long long file_number = 0, write_size, check_value = 0;
#else
#define WRITE_SIZE_LIMIT ULONG_MAX
    unsigned long file_number = 0, write_size, check_value = 0;
#endif

    for( ; ; file_number++ )
    {
           sprintf(number_to_append, "%u", file_number); /* itoa() can give
                                                         negatives */
           file_name[0] = 0; // blanks the string
           strcat( strcat( file_name, "blank"), strcat( number_to_append, ".txt") );
           
           if( !( file = fopen(file_name, "ab" ) ) )
           { // quit if we can't make anymore files
               return; // exit unforunately takes an argument. we return nothing
           }
           
           setbuf(file, NULL); // disable buffering for increased performance
           
           for( write_size = WRITE_SIZE_LIMIT ; ; )
           {
                  // check_value holds the bytes written for comparison
                  // also, don't change the 1. you'll read random bytes
                  
                  check_value = fwrite(&nothing, 1, write_size, file);
                  
                  if( !check_value )
                  { // we work backwards by exponents. byte by byte is SLOW
                      write_size /= 2;
                  }
                  if( !write_size || feof(file) )
                  { // go make another file if we hit the file size limit
                    /* some file systems work wierd, so we include ALL
                     of the above checks. the checks are
                     arranged performance stealing backwards. */
                       break;
                  }
           }
           
           fclose(file);
    } 
}