On Thu, 12 May 2022 at 14:41, Simon Ser <contact@xxxxxxxxxxx> wrote: > > On Thursday, May 12th, 2022 at 12:37, Simon Ser <contact@xxxxxxxxxxx> wrote: > > > what would be a good way to share a FD to another > > process without allowing it to write to the underlying file? > > (I'm reminded that memfd + seals exist for this purpose. Still, I'd be > interested to know whether that O_RDONLY/O_RDWR behavior is intended, > because it's pretty surprising. The motivation for using O_RDONLY over > memfd seals is that it isn't Linux-specific.) Yes, this is intended. The /proc/$PID/fd/$FD file represents the inode pointed to by $FD. So the open flags for $FD are irrelevant when operating on the proc fd file. Thanks, Miklos
