C++ memory leak while using std::string in child process - c++

Question

I'm having problem with this piece of code, valgrind detects memory leaks in std::basic_string and I don't know what am I doing wrong. The leak is only when std::string is used in child process. Could you please tell me, where the problem is? I've never used fork() in C++ before so I don't have much exprience.
#include <iostream>
#include <string>
#include <cerrno>
#include <cstdio>
#include <cstdlib>
#include <unistd.h>
#include <sys/wait.h>
int main(int argc, char *argv[])
{
pid_t childPid = fork();
if (childPid == -1)
{
perror("fork");
return EXIT_FAILURE;
}
else if (childPid == 0)
{
std::cout << "Child PID: " << getpid() << std::endl;
std::string str("something"); //valgrind detects mem leak here
_Exit(EXIT_SUCCESS);
}
else
{
//std::string str("something"); //but not here
}
waitpid(-1, 0, 0);
return EXIT_SUCCESS;
}

Answer 1

_Exit will not run any destructors or atexit functions, it simply ends immediately.
Obviously this punches a giant hole through RAII, so Don't Do That.
One way of implementing Don't Do That while maintaining the same exit strategy might be:
template <typename Func, typename... Args>
int wrap_cpp_code(Func&& func, Args&&.. args)
{
try
{
return std::forward<Func>(func)(std::forward<Args>(args)...);
}
catch (...)
{
return EXIT_FAILURE;
}
}
Which won't cough up an return value until all destructors under its scope are run, giving:
int child_main(int argc, char *argv[])
{
std::cout << "Child PID: " << getpid() << std::endl;
std::string str("something");
return EXIT_SUCCESS;
}
int main(int argc, char *argv[])
{
pid_t childPid = fork();
if (childPid == -1)
{
perror("fork");
return EXIT_FAILURE;
}
else if (childPid == 0)
{
int ret = wrap_cpp_code(child_main, argc, argv);
_Exit(ret);
}
else
{
/*
int ret = wrap_cpp_code(xyz, argc, argv);
*/
}
waitpid(-1, 0, 0);
return EXIT_SUCCESS;
}
But this still fails to account for atexit functions or global destructors. So still Avoid Doing That.