new EPFNOSUPPORT errno

include/errno.h

@@ -110,6 +110,7 @@ extern int errno;		  /* place where the error numbers go */
 #define EOPNOTSUPP    (_SIGN 76)  /* Operation not supported */
 #define ENOTSUP       EOPNOTSUPP  /* Not supported */
 #define ENETDOWN      (_SIGN 77)  /* network is down */
+#define EPFNOSUPPORT  (_SIGN 78)  /* Protocol family not supported */
 
 /* The following are not POSIX errors, but they can still happen. 
  * All of these are generated by the kernel and relate to message passing.

lib/libc/ansi/errlist.c

@@ -85,6 +85,7 @@ const char *_sys_errlist[] = {
 	"Protocol not available",	/* ENOPROTOOPT */
 	"Operation not supported",	/* EOPNOTSUPP */
 	"Network is down",		/* ENETDOWN */
+	"Protocol family not supported", /* EPFNOSUPPORT */
 };
 
 const int _sys_nerr = sizeof(_sys_errlist) / sizeof(_sys_errlist[0]);

man/man2/intro.2

@@ -365,6 +365,8 @@ for example, trying to
 a connection on a datagram socket.
 .It Er 77 ENETDOWN Em "Network is down" .
 A socket operation encountered a dead network.
+.It Er 77 EPFNOSUPPORT Em "Protocol family not supported" .
+A socket operation specified an unsupported protocol family.
 .El
 .Sh DEFINITIONS
 .Bl -tag -width Ds