unix: unify Sendmsg prologues

Follow CL 361256 which did the same in package syscall.

Change-Id: Ifd22e515c220806f02400baded821ec583959d78
Reviewed-on: https://go-review.googlesource.com/c/sys/+/393274
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

unix/syscall_aix.go

@@ -221,12 +221,7 @@ func Recvmsg(fd int, p, oob []byte, flags int) (n, oobn int, recvflags int, from
 	return -1, -1, -1, sa, ENOSYS
 }
 
-func Sendmsg(fd int, p, oob []byte, to Sockaddr, flags int) (err error) {
+func sendmsgN(fd int, p, oob []byte, ptr unsafe.Pointer, salen _Socklen, flags int) (n int, err error) {
-	_, err = SendmsgN(fd, p, oob, to, flags)
-	return
-}
-
-func SendmsgN(fd int, p, oob []byte, to Sockaddr, flags int) (n int, err error) {
 	// SendmsgN not implemented on AIX
 	return -1, ENOSYS
 }

unix/syscall_bsd.go

@@ -361,20 +361,7 @@ func Recvmsg(fd int, p, oob []byte, flags int) (n, oobn int, recvflags int, from
 
 //sys	sendmsg(s int, msg *Msghdr, flags int) (n int, err error)
 
-func Sendmsg(fd int, p, oob []byte, to Sockaddr, flags int) (err error) {
+func sendmsgN(fd int, p, oob []byte, ptr unsafe.Pointer, salen _Socklen, flags int) (n int, err error) {
-	_, err = SendmsgN(fd, p, oob, to, flags)
-	return
-}
-
-func SendmsgN(fd int, p, oob []byte, to Sockaddr, flags int) (n int, err error) {
-	var ptr unsafe.Pointer
-	var salen _Socklen
-	if to != nil {
-		ptr, salen, err = to.sockaddr()
-		if err != nil {
-			return 0, err
-		}
-	}
 	var msg Msghdr
 	msg.Name = (*byte)(unsafe.Pointer(ptr))
 	msg.Namelen = uint32(salen)

unix/syscall_linux.go

@@ -1538,21 +1538,7 @@ func Recvmsg(fd int, p, oob []byte, flags int) (n, oobn int, recvflags int, from
 	return
 }
 
-func Sendmsg(fd int, p, oob []byte, to Sockaddr, flags int) (err error) {
+func sendmsgN(fd int, p, oob []byte, ptr unsafe.Pointer, salen _Socklen, flags int) (n int, err error) {
-	_, err = SendmsgN(fd, p, oob, to, flags)
-	return
-}
-
-func SendmsgN(fd int, p, oob []byte, to Sockaddr, flags int) (n int, err error) {
-	var ptr unsafe.Pointer
-	var salen _Socklen
-	if to != nil {
-		var err error
-		ptr, salen, err = to.sockaddr()
-		if err != nil {
-			return 0, err
-		}
-	}
 	var msg Msghdr
 	msg.Name = (*byte)(ptr)
 	msg.Namelen = uint32(salen)

unix/syscall_solaris.go

@@ -483,22 +483,9 @@ func Recvmsg(fd int, p, oob []byte, flags int) (n, oobn int, recvflags int, from
 	return
 }
 
-func Sendmsg(fd int, p, oob []byte, to Sockaddr, flags int) (err error) {
-	_, err = SendmsgN(fd, p, oob, to, flags)
-	return
-}
-
 //sys	sendmsg(s int, msg *Msghdr, flags int) (n int, err error) = libsocket.__xnet_sendmsg
 
-func SendmsgN(fd int, p, oob []byte, to Sockaddr, flags int) (n int, err error) {
+func sendmsgN(fd int, p, oob []byte, ptr unsafe.Pointer, salen _Socklen, flags int) (n int, err error) {
-	var ptr unsafe.Pointer
-	var salen _Socklen
-	if to != nil {
-		ptr, salen, err = to.sockaddr()
-		if err != nil {
-			return 0, err
-		}
-	}
 	var msg Msghdr
 	msg.Name = (*byte)(unsafe.Pointer(ptr))
 	msg.Namelen = uint32(salen)

unix/syscall_unix.go

@@ -337,6 +337,23 @@ func Recvfrom(fd int, p []byte, flags int) (n int, from Sockaddr, err error) {
 	return
 }
 
+func Sendmsg(fd int, p, oob []byte, to Sockaddr, flags int) (err error) {
+	_, err = SendmsgN(fd, p, oob, to, flags)
+	return
+}
+
+func SendmsgN(fd int, p, oob []byte, to Sockaddr, flags int) (n int, err error) {
+	var ptr unsafe.Pointer
+	var salen _Socklen
+	if to != nil {
+		ptr, salen, err = to.sockaddr()
+		if err != nil {
+			return 0, err
+		}
+	}
+	return sendmsgN(fd, p, oob, ptr, salen, flags)
+}
+
 func Send(s int, buf []byte, flags int) (err error) {
 	return sendto(s, buf, flags, nil, 0)
 }