Purpose
This assignment should give you experience in using file descriptors, open(), close(), write(), stat() and chmod(), perror(), and command line arguments.
Program
Write a C++ program that will allow you to add messages to a file that has NO permissions for any user.
A Unix system has many files that have sensitive information in them. Permissions help keep these files secure. Some files can be publicly read, but can not be altered by a regular user (ex.: /etc/passwd). Other files can't be read at all by a regular user (ex.: /etc/shadow).
The program you develop should take a message given as a command line argument and append it to a file (also specified on the command line). The file should have no permissions, both before and after the message is appended. Of course, the file should be owned by you.
Your program should also have a -c option that will clear the file before the message is appended.
Algorithm
Useful Hints
Input
None, really. Just command line arguments.
Error Checking
If the log file cannot be opened, an appropriate error message should be printed and the program should exit. If the file has any permissions at all, the file should be rejected as insecure, and the program should exit.
Example Run
#include <iostream>
#include <fstream>
#include <sys/types.h>
#include <sys/stat.h>
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
using namespace std;
int main(int agrc,char*argv[])
{
struct stat sb;
if(agrc != 2){
cout << "invalind command line arguments "<<
endl;
return 0;
}
if (stat(argv[1], &sb) == -1) {
perror("stat");
exit(EXIT_FAILURE);
}
if((sb.st_mode & 777) != 0) {
cout<<"file has permission and its
invalid"<<endl;
}
//chmod(argv[1], S_IRWXU);
int status = chmod(argv[1], 0200);
if(status){
cout<<"permission sucessfull change"<<endl;
}
ofstream myfile;
myfile.open (argv[1], ios::out | ios::app);
myfile<<argv[2]<<endl;
status = chmod(argv[1], 0000);
if(status){
cout<<"permission sucessfull change p@ubuntu: /Desktop t
)1:34 PM P@ubuntu:/Desktops g++ nain.cpp P@ubuntu: /Desktops
./a.out sample.txt Hello file has permissio
0000"<<endl;
}
myfile.close();
cout << "thank you" << endl;
return 0;
}
Purpose This assignment should give you experience in using file descriptors, open(), close(), wr...
Hello, my name is Shady Slim. I understand you are going to help me figure out my gross income for the year... whatever that means. It's been a busy year and I'm a busy man, so let me give you the lowdown on my life and you can do your thing I was unemployed at the beginning of the year and got $2,000 in unemployment compensation. I later got a job as a manager for Roca Cola. I earned $57,500...