Code for evidence that errno was thread safe

multi_th_scandir.cpp

#include <string>
#include <iostream>
#include <thread>
#include <vector>
#include <dirent.h>
#include <cerrno>

struct ScanResult {
    int returnCode;
    int errnoCode;
};

ScanResult scandir(std::string path)
{
    struct dirent** dents = NULL;
    int n = scandir(path.c_str(), &dents, NULL, NULL);
    ScanResult result = {n, errno};
    return result;
}

void runner(std::string path, size_t iterations, int expectedReturnCode, int expectedErrnoCode)
{
    int allOk = true;
    for(size_t i = 0; i < iterations; i++)
    {
        ScanResult r = scandir(path);
        if ( r.returnCode != expectedReturnCode || r.errnoCode != expectedErrnoCode )
        {
            allOk = false;
            std::cout << "juston we have a problem: return code expected "
                << expectedReturnCode
                << " (found " << r.returnCode << ")"
                << " errno expected " << expectedErrnoCode
                << " (found " << r.errnoCode << ")"
                << std::endl;
        }
    }
    std::this_thread::sleep_for(std::chrono::milliseconds(25 + ( std::rand() % ( 63 - 25 + 1 ) )));
    if ( !allOk ) {
        std::cout << "Something goes wrong scan " << path << std::endl;
    } else {
        std::cout << "All ok from worker scanning " << path << std::endl;
    }
}

int main()
{
    std::string aValidDir = "fixture";
    std::string aNotValidDir = "fixture/empty_file";

    std::vector<std::thread*> threads;

    std::thread* t = new std::thread(runner, aValidDir, 1000*1000, 3, 0);
    std::thread* t2 = new std::thread(runner, aNotValidDir, 1000*1000, -1, ENOTDIR);
    threads.push_back(t);
    threads.push_back(t2);

    for(auto && t : threads) {
        t->join();
    }

    return 0;
}