problem.c

problem.c

#include <sys/syscall.h>      /* Definition of SYS_* constants */
#include <unistd.h>
#include <errno.h>
#include <stdio.h>
#include <spawn.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>

#ifndef __NR_pidfd_open
   #define __NR_pidfd_open 434   /* System call # on most architectures */
#endif

extern char** environ;

static int pidfd_open(pid_t pid, unsigned int flags)
{
  return syscall(__NR_pidfd_open, pid, flags);
}

int main(int argc,char* argv[])
{
        char* command = "echo 3 > lala.txt";
        pid_t pid;
        int status = posix_spawn(&pid,"/bin/sh",NULL,NULL,argv,environ);
        printf("status: %i and %i\n",status,pid);
        int pidfd = pidfd_open(pid, 0);
        if (pidfd<0){
            printf("panic: %i\n",errno); 
            return 1;
        }
        printf("pidfd: %i\n",pidfd);
        write(pidfd,command,(strlen(command)+1));
        close(pidfd);
        system("ls");

    return 0;
}