Re: [PATCH v2] fix start_command() bug when stdin is closed

>  int start_command(struct child_process *cmd)
>  {
>  	int need_in, need_out, need_err;
>  	int fdin[2], fdout[2], fderr[2];
>  
>  	/*
> +	 * Make sure that all file descriptors <= 2 are open, otherwise we
> +	 * mess them up when dup'ing pipes onto stdin/stdout/stderr.  Since
> +	 * we are at it, open a file descriptor on /dev/null to use it later.
> +	 */
> +	if (devnull_fd == -1)
> +	  {
> +	    devnull_fd = open("/dev/null", O_RDWR);
> +	    while (devnull_fd >= 0 && devnull_fd <= 2)
> +	      devnull_fd = dup(devnull_fd);
> +	    if (devnull_fd == -1)
> +	      die("opening /dev/null failed (%s)", strerror(errno));
> +	  }