#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

int main (int argc, const char ** argv, const char ** envp)
{
    int newfd = dup(1), outfd = dup(1);
    char fd_argv[4];
    snprintf(fd_argv, 4, "%d", newfd);
    char * const new_argv[] = { "./exec_victim", fd_argv, NULL };

    setenv("IN_EXECVE", "1", 1);

    int pid = vfork();
    if (pid == 0) {
        close(outfd);
        execv(new_argv[0], new_argv);
    }

    wait(NULL);

    FILE * out = fdopen(outfd, "a");
    if (!out) {
        printf("cannot open file descriptor\n");
        return -1;
    }

    fprintf(out, "Goodbye world!\n");
    return 0;
}