Restart a program of child process in C++ linux - c++

Question

I have learned recently about processes and threads, and I am building a project where I need to run a program inside a child process.
The problem is that after the program in the child process exits I don't know how to restart and run the program again.
Here's a test which demonstrates what I am trying to do.
main.cpp file:
#include <iostream>
#include <unistd.h>
#include <sys/ptrace.h>
#include "handler.h"
int main(int argc, char** argv)
{
if (argc < 2)
{
std::cerr << "usage: program name" << std::endl;
return 1;
}
pid_t pid = fork();
if (pid == 0)
{
if (ptrace(PTRACE_TRACEME, 0, nullptr, nullptr) < 0)
std::cerr << "ptrace error" << std::endl;
else
execl(argv[1], argv[1], nullptr);
}
else if (pid >= 1)
{
Handler handler(std::string(argv[1]), pid);
handler.run();
}
}
handler.h file:
#include <stdio.h>
#include <unistd.h>
#include <string>
#include <sys/ptrace.h>
#include <sys/wait.h>
class Handler
{
private:
pid_t m_pid;
std::string m_name;
public:
Handler(const std::string& name, pid_t pid) : m_name(name), m_pid(pid)
{
}
void run()
{
std::string line;
while (true)
{
std::cout << "(command) ";
std::getline(std::cin, line);
if (line == "run")
{
int options = 0, status = 0;
ptrace(PTRACE_CONT, m_pid, nullptr, nullptr);
int pid = waitpid(m_pid, &status, options);
// trying to restart again the program
if (pid < 0)
{
m_pid = fork();
execl(m_name.c_str(), m_name.c_str(), nullptr);
}
}
}
}
};