gnu_ostream_with_cloexec1.cpp - example to show how to create a std::ostream where the fd has |O_CLOEXEC| set
Posted by Anonymous on Tue 15th Oct 2024 10:48
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/*
 * gnu_ostream_with_cloexec1.cpp - example to show
 * how to create a std::ostream where the fd has
 * |O_CLOEXEC| set
 *
 * Works on:
 * - Debian Bullseye with gcc version 10.2.1
 * - Debian Bullseye with Debian clang version 11.0.1-2
 * - Cygwin 3.5.4 with gcc version 12.4.0
 *
 * Written by Roland Mainz <roland.mainz@nrubsig.org>
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <iostream>
#include <fstream>
#include <ext/stdio_filebuf.h>

int main(int ac, char *av[])
{
        int fd = open("hello.txt", O_WRONLY|O_CREAT|O_CLOEXEC, 0666);
        if (fd < 0) {
                std::cerr << "Error opening file" << std::endl;
                return EXIT_FAILURE;
        }

        __gnu_cxx::stdio_filebuf<char> fbuf(fd, std::ios_base::out);
        std::ostream os(&fbuf);
        os << "Hello fd cookie monster!" << std::endl;

        /* This will close |fd|, too! */
        fbuf.close();

        return EXIT_SUCCESS;
}