Hello, socketpair(2) says:
"The type and protocol argument values are described in socket(2)." But as best as I can tell, socketpair(2) only ever accepts a protocol of 0, no other value. Per POSIX, "Specifying a protocol of 0 causes socketpair() to use an unspecified default protocol appropriate for the requested socket type." which is _not_ actually protocol 0 (HOPOPT, RFC2460, per /etc/protocols). Is there any scenario whereby a non-0 protocol can be specified to socketpair(2)? As it reads right now, a user might expect to be able to call socketpair(PF_LOCAL, SOCK_STREAM, 6, sv) which will lead to EPROTONOSUPPORT. -Jan
