Re: [PATCH 1/3] Open device nodes with close-on-exec flag

[Lennart Poettering <mznyfn@0pointer.de>]

On Wed, 04.11.09 20:38, Rémi Denis-Courmont (remi@remlab.net) wrote:

>  static inline int snd_open_device(const char *filename, int fmode)
>  {
> -	int fd = open(filename, fmode);
> +	int fd;
> +
> +#ifdef O_CLOEXEC
> +	fd = open(filename, fmode|O_CLOEXEC);
>  	if (fd >= 0)
>  		return fd;
> +	if (errno == EINVAL)
> +#endif
> +	{
> +		fd = open(filename, fmode);
> +		if (fd >= 0) {
> +			fcntl(fd, F_SETFD, FD_CLOEXEC);
> +			return fd;
> +		}

That's actually not how things works. O_CLOEXEC is silently ignored by
old kernels. (The calls with SOCK_CLOEXEC fail with EINVAL while the
calls with O_CLOEXEC silently succeed) You need to set
FD_CLOEXEC unconditionally to cover all cases:

fd = open(fn, fmode
#ifdef O_CLOEXEC
          |O_CLOEXEC
#endif
);
fcntl(fd, F_SETFD, FD_CLOEXEC);


Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net
http://0pointer.net/lennart/           GnuPG 0x1A015CC4