On 08/11/2012 03:09 AM, H. Peter Anvin wrote:On 08/10/2012 12:28 PM, Alan Cox wrote:I vote for this (openat + O_WHATEVER on a unix socket) as well. It willExplicitly for Linux yes - this is not generally true of the AF_UNIXYes, but let's worry about what the Linux behavior should be.
socket domain and even the permissions aspect isn't guaranteed to be
supported on some BSD environments !
The name is however just a proxy for the socket itself. You don't even
get a device node in the usual sense or the same inode in the file system
space.
No, but it is looked up the same way any other inode is (the difference
between FIFOs and sockets is that sockets have separate connections,
which is also why open() on sockets would be nice.)
However, there is a fundamental difference between AF_UNIX sockets and
open(), and that is how the pathname is delivered. It thus would make
more sense to provide the openat()-like information in struct
sockaddr_un, but that may be very hard to do in a sensible way. In that
sense it perhaps would be cleaner to be able to do an open[at]() on the
socket node with O_PATH (perhaps there should be an O_SOCKET option,
even?) and pass the resulting file descriptor to bind() or connect().
help us in checkpoint-restore, making handling of overmounted/unlinked
sockets much cleaner.
-hpaThanks,
Pavel