Re: [RFC PATCH 0/5] net: socket bind to file descriptor introduced

"H. Peter Anvin" [off-list ref] writes:

On 08/15/2012 12:49 PM, Eric W. Biederman wrote:

quoted

There is also the trick of getting a shorter directory name using
/proc/self/fd if you are threaded and can't change the directory.

The obvious choices at this point are
- Teach bind and connect and af_unix sockets to take longer AF_UNIX
  socket path names.

- introduce sockaddr_fd that can be applied to AF_UNIX sockets,
  and teach unix_bind and unix_connect how to deal with a second type of sockaddr.
  struct sockaddr_fd { short fd_family; short pad; int fd; };

- introduce sockaddr_unix_at that takes a directory file descriptor
  as well as a unix path, and teach unix_bind and unix_connect to deal with a
  second sockaddr type.
  struct sockaddr_unix_at { short family; short pad; int dfd; char path[102]; }
  AF_UNIX_AT

I don't know what the implications of for breaking connect up into 3
system calls and changing the semantics are and I would really rather
not have to think about it.

But it certainly does not look to me like you introduce new systems
calls to do what you want.

How would you distinguish the new sockaddr types from the traditional
one?  New AF_?

Yeah.  AF_FD or AF_UNIX_AT is what I was thinking.  The way the code
falls out that should be compartively simple to implement.

recvmsg etc would give you sockaddr_un sockets when they come from the
kernel.

Eric