Executing machine code in memory

Question

I\'m trying to figure out how to execute machine code stored in memory.

I have the following code:

#include 
#include          


        

Answer 1

You can dlopen() a file, look up the symbol "main" and call it with 0, 1, 2 or 3 arguments (all of type char*) via a cast to pointer-to-function-returning-int-taking-0,1,2,or3-char*

Answer 2

Executable files contain much more than just code. Header, code, data, more data, this stuff is separated and loaded into different areas of memory by the OS and its libraries. You can't load a program file into a single chunk of memory and expect to jump to it's first byte.

If you are trying to execute your own arbitrary code, you need to look into dynamic libraries because that is exactly what they're for.

Answer 3

Use the operating system for loading and executing programs.

On unix, the exec calls can do this.

Your snippet in the question could be rewritten:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int main(int argc, char* argv[])
{
    return execv(argv[1],argv+2);
}