0

I am trying figure out a simple way to fill argv[1] with an extremely large string of input to see how much input my program can handle. Any ideas on the simplest way to do this?

Acorn
  • 24,970
  • 5
  • 40
  • 69
cLax
  • 93
  • 1
  • 7
  • This seems pointless, but you can look [here](https://stackoverflow.com/questions/5349718/how-can-i-repeat-a-character-in-bash) for suggetions on how to piece together a large value to pass to the program in the shell. – Blaze Sep 20 '19 at 13:34
  • `argv[1]`, in case you are designating the second parameter to the `main()` function, is operating system dependant. You have not specified neither the operating system, nor any sample code to be able to decide how to answer you. Voting to close. – Luis Colorado Sep 22 '19 at 13:53

2 Answers2

2

If you are calling your program from a shell, you typically take the advantage of that.

For instance, for POSIX, something like:

./program `printf '%*s' 500 | tr ' ' x`

(Taken from Creating string of repeated characters in shell script)

You can also create the string dynamically over a loop to test the program until it crashes, etc.

If you want a C solution (without spawning another process, e.g. using something like system or OS-specific APIs), I would suggest you rename your main() into a different function, and then write a new main() that calls the old one with an argv customized however you like:

int old_main(int argc, char *argv[]) { ... }

int main()
{
    int argc = 2;
    char *argv[2] = {
        "program",
        "xxxxxxxxxxxxxxxxxxxxxxx",
    };
    return old_main(argc, argv);
}
Acorn
  • 24,970
  • 5
  • 40
  • 69
2

If you're using a POSIX shell (Like Bash on Linux or similar) then you could use a simply Python script to "fill" an argument, and call it using the shell back-tick to execute commands "inline":

./your_program `python -c "print('A'*100)"`

The above will create a string of 100 A characters as the first argument to the program.

Some programmer dude
  • 400,186
  • 35
  • 402
  • 621