On Thu, Oct 2, 2014 at 11:13 AM, Pádraig Brady [off-list ref] wrote:

On 10/02/2014 08:52 AM, Yann Droneaud wrote:

quoted

In order to not potentially break applications which were
requesting O_CLOEXEC on event file descriptors but which
actually need it to be not effective as the kernel currently
ignore the flag, so the file descriptor is inherited accross
exec regardless of O_CLOEXEC (please forgive me for the
wording), this patch introduces FAN_FD_CLOEXEC flag to
fanotify_init() so that application can request O_CLOEXEC
to be effective.
Newer application would use FAN_FD_CLOEXEC flag along
O_CLOEXEC to enable close on exec on newly created
file descriptor:

  fd = fanotify_init(FAN_CLOEXEC|FAN_NONBLOCK|FAN_FD_CLOEXEC,
                     O_RDONLY|O_LARGEFILE|O_CLOEXEC|O_NOATIME);

Ugh really?
IMHO there should be widespread or at least known breakage with
O_CLOEXEC before adding messiness like this.
It seems surprising to me that apps that would depend on
O_CLOEXEC being ineffective.

please reconsider this one.

Agreed. The number of applications for which there are silent (not
*yet* observed) breakages because O_CLOEXEC is not working as expected
is likely rather larger than the set of applications that randomly
specify O_CLOEXEC and then somehow get broken as a result.

Cheers,

Michael


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/