PEACE

 1 #include <iostream>
 2 #include <fstream>
 3 #include <stdlib.h>
 4 
 5 using namespace std;
 6 
 7 int main ( int argc, char* argv[] ) {
 8     if ( argc != 4 ) {
 9         cout << "Usage: ft <File> <Off> <Data>" << endl;
10         return -1;
11     }
12     fstream file ( argv[1], ios::in | ios::out | ios::binary | ios::ate );
13     if ( file.is_open() ) {
14         long long fileSize = static_cast<long long> ( file.tellg() );
15         cout << "Size: " << fileSize << " bytes" << endl;
16         long int yPos = strtol ( argv[2], NULL, 16 );
17         long int yData = strtol ( argv[3], NULL, 16 );
18         unsigned char sData = static_cast<unsigned char> ( yData );
19         if ( yPos < 0 || yPos >= fileSize ) {
20             cout << "Overflow. [0 ~ " << fileSize - 1 << "]" << endl;
21             return -1;
22         }
23         std::ios_base::seekdir sPos = static_cast<std::ios_base::seekdir> ( yPos );
24         file.seekg ( sPos );
25         char cbit[8];
26         itoa ( file.get(), cbit, 16 );
27         cout << "Data: " << cbit << endl;
28         file.seekg ( sPos );
29         file << sData;
30         file.close();
31         cout << "Tampering successfully." << endl;
32         return 0;
33     } else {
34         cout << "Can not open file." << endl;
35         return -1;
36     }
37 }