Reversing Some C++ Io Operations

In general decompilers are not friendly with c++ let's analyse a simple program to get familiar with it.
Let's implement a simple code that loads a file into a vector and then save the vector with following functions:

• err
• load
• save
• main

Lets identify the typical way in C++ to print to stdout with the operator "<<"

The basic_ostream is initialized writing the word "error" to the cout, and then the operator<< again to add the endl.

The Main function simply calls  "vec = load(filename)"  but the compiler modified it and passed the vector pointer as a parámeter. Then it bulds and prints "loaded  " << size << " users".
And finally saves the vector to /tmp/pwd and print "saved".
Most of the mess is basically the operator "<<" to concat and print values.
Also note that the vectors and strings are automatically deallocated when exit the function.

And here is the code:

Let's take a look to the load function, which iterates the ifs.getline() and push to the vector.
First of all there is a mess on the function definition, __return_storage_ptr is the vector.
the ifstream object ifs is initialized as a basic_ifstream and then operator! checks if it wasn't possible to open the file and in that case calls err()
We see the memset and a loop, getline read a cstr like line from the file, and then is converted to a string before pushing it to the vector. lVar1 is the stack canary value.

In this situations dont obfuscate with the vector pointer vec initialization at the begining, in this case the logic is quite clear.

The function save is a bit more tricky, but it's no more than a vector iteration and ofs writing.
Looping a simple "for (auto s : *vec)" in the decompiler is quite dense, but we can see clearly two write, the second write DAT_0010400b is a "\n"

As we see, save implememtation is quite straightforward.

Related posts

1. Hacker Tools For Windows
2. Hack Tools For Mac
3. Hacker Tools Apk
4. Game Hacking
5. Hacking Tools Software
6. Hacker Tools Apk
7. Install Pentest Tools Ubuntu
8. Hacking Tools Pc
9. New Hacker Tools
10. Pentest Tools Framework
11. Pentest Tools Bluekeep
12. New Hacker Tools
13. New Hacker Tools
14. Game Hacking
15. Kik Hack Tools
16. Pentest Tools Port Scanner
17. Hacking App
18. Hackers Toolbox
19. New Hack Tools
20. Hacking Tools Hardware
21. Hacking Tools 2020
22. Pentest Tools Subdomain
23. Hacker Tools Linux
24. Pentest Tools Apk
25. Hackrf Tools
26. Hacker Tools Free