[PATCH] Fix for Coverity finding in tfork

[Jeremy Allison]

On Tue, Apr 25, 2017 at 05:53:23PM +0200, Ralph Böhme via samba-technical wrote:
> Hi!
> 
> Volker pointed me at a Coverity finding in tfork. Here's the (hopefully correct)
> patch.

Good catch ! LGTM. Pushed.

> Please review and push if happy. Thanks!
> 
> -slow

> From c2ab090a6eef84d24790d8c9c56d822a72ff8900 Mon Sep 17 00:00:00 2001
> From: Ralph Boehme <slow at samba.org>
> Date: Tue, 25 Apr 2017 17:47:57 +0200
> Subject: [PATCH] lib/util: fix a Coverity finding in tfork
> 
> If dup2() fails, fd is -1 and is later used in sys_write().
> 
> Signed-off-by: Ralph Boehme <slow at samba.org>
> ---
>  lib/util/tfork.c | 23 ++++++++++++++++++-----
>  1 file changed, 18 insertions(+), 5 deletions(-)
> 
> diff --git a/lib/util/tfork.c b/lib/util/tfork.c
> index 27b6cc0..37c00e6 100644
> --- a/lib/util/tfork.c
> +++ b/lib/util/tfork.c
> @@ -131,11 +131,24 @@ static pid_t level2_fork_and_wait(int child_ready_fd)
>  	 * We're going to stay around until child3 exits, so lets close all fds
>  	 * other then the pipe fd we may have inherited from the caller.
>  	 */
> -	fd = dup2(tfork_global->status_pipe[1], 0);
> -	if (fd == -1) {
> -		status = errno;
> -		kill(tfork_global->level3_pid, SIGKILL);
> -		wait = false;
> +	while (true) {
> +		fd = dup2(tfork_global->status_pipe[1], 0);
> +		if (fd == -1) {
> +			if (errno == EINTR) {
> +				continue;
> +			}
> +			status = errno;
> +
> +			kill(tfork_global->level3_pid, SIGKILL);
> +
> +			written = sys_write(tfork_global->status_pipe[1],
> +					    &status, sizeof(status));
> +			if (written != sizeof(status)) {
> +				abort();
> +			}
> +			_exit(0);
> +		}
> +		break;
>  	}
>  	closefrom(1);
>  
> -- 
> 2.9.3
>