syscall: consolidate, simplify socket options for Unix-like systems

Also exposes common socket option functions on Solaris.

Update #7174
Update #7175

LGTM=aram
R=golang-codereviews, aram
CC=golang-codereviews
https://golang.org/cl/107280044

src/pkg/syscall/syscall_bsd.go

@@ -309,48 +309,6 @@ func Getsockname(fd int) (sa Sockaddr, err error) {
 }
 
 //sysnb socketpair(domain int, typ int, proto int, fd *[2]int32) (err error)
-
-func GetsockoptByte(fd, level, opt int) (value byte, err error) {
-	var n byte
-	vallen := _Socklen(1)
-	err = getsockopt(fd, level, opt, unsafe.Pointer(&n), &vallen)
-	return n, err
-}
-
-func GetsockoptInet4Addr(fd, level, opt int) (value [4]byte, err error) {
-	vallen := _Socklen(4)
-	err = getsockopt(fd, level, opt, unsafe.Pointer(&value[0]), &vallen)
-	return value, err
-}
-
-func GetsockoptIPMreq(fd, level, opt int) (*IPMreq, error) {
-	var value IPMreq
-	vallen := _Socklen(SizeofIPMreq)
-	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
-	return &value, err
-}
-
-func GetsockoptIPv6Mreq(fd, level, opt int) (*IPv6Mreq, error) {
-	var value IPv6Mreq
-	vallen := _Socklen(SizeofIPv6Mreq)
-	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
-	return &value, err
-}
-
-func GetsockoptIPv6MTUInfo(fd, level, opt int) (*IPv6MTUInfo, error) {
-	var value IPv6MTUInfo
-	vallen := _Socklen(SizeofIPv6MTUInfo)
-	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
-	return &value, err
-}
-
-func GetsockoptICMPv6Filter(fd, level, opt int) (*ICMPv6Filter, error) {
-	var value ICMPv6Filter
-	vallen := _Socklen(SizeofICMPv6Filter)
-	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
-	return &value, err
-}
-
 //sys   recvfrom(fd int, p []byte, flags int, from *RawSockaddrAny, fromlen *_Socklen) (n int, err error)
 //sys   sendto(s int, buf []byte, flags int, to unsafe.Pointer, addrlen _Socklen) (err error)
 //sys	recvmsg(s int, msg *Msghdr, flags int) (n int, err error)

src/pkg/syscall/syscall_linux.go

@@ -440,19 +440,6 @@ func Getsockname(fd int) (sa Sockaddr, err error) {
 	return anyToSockaddr(&rsa)
 }
 
-func GetsockoptInet4Addr(fd, level, opt int) (value [4]byte, err error) {
-	vallen := _Socklen(4)
-	err = getsockopt(fd, level, opt, unsafe.Pointer(&value[0]), &vallen)
-	return value, err
-}
-
-func GetsockoptIPMreq(fd, level, opt int) (*IPMreq, error) {
-	var value IPMreq
-	vallen := _Socklen(SizeofIPMreq)
-	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
-	return &value, err
-}
-
 func GetsockoptIPMreqn(fd, level, opt int) (*IPMreqn, error) {
 	var value IPMreqn
 	vallen := _Socklen(SizeofIPMreqn)
@@ -460,27 +447,6 @@ func GetsockoptIPMreqn(fd, level, opt int) (*IPMreqn, error) {
 	return &value, err
 }
 
-func GetsockoptIPv6Mreq(fd, level, opt int) (*IPv6Mreq, error) {
-	var value IPv6Mreq
-	vallen := _Socklen(SizeofIPv6Mreq)
-	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
-	return &value, err
-}
-
-func GetsockoptIPv6MTUInfo(fd, level, opt int) (*IPv6MTUInfo, error) {
-	var value IPv6MTUInfo
-	vallen := _Socklen(SizeofIPv6MTUInfo)
-	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
-	return &value, err
-}
-
-func GetsockoptICMPv6Filter(fd, level, opt int) (*ICMPv6Filter, error) {
-	var value ICMPv6Filter
-	vallen := _Socklen(SizeofICMPv6Filter)
-	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
-	return &value, err
-}
-
 func GetsockoptUcred(fd, level, opt int) (*Ucred, error) {
 	var value Ucred
 	vallen := _Socklen(SizeofUcred)

src/pkg/syscall/syscall_unix.go

@@ -207,13 +207,6 @@ func Getpeername(fd int) (sa Sockaddr, err error) {
 	return anyToSockaddr(&rsa)
 }
 
-func GetsockoptInt(fd, level, opt int) (value int, err error) {
-	var n int32
-	vallen := _Socklen(4)
-	err = getsockopt(fd, level, opt, unsafe.Pointer(&n), &vallen)
-	return int(n), err
-}
-
 func Recvfrom(fd int, p []byte, flags int) (n int, from Sockaddr, err error) {
 	var rsa RawSockaddrAny
 	var len _Socklen = SizeofSockaddrAny
@@ -234,24 +227,73 @@ func Sendto(fd int, p []byte, flags int, to Sockaddr) (err error) {
 	return sendto(fd, p, flags, ptr, n)
 }
 
-func SetsockoptByte(fd, level, opt int, value byte) (err error) {
+func GetsockoptByte(fd, level, opt int) (byte, error) {
+	var v byte
+	l := _Socklen(1)
+	err := getsockopt(fd, level, opt, unsafe.Pointer(&v), &l)
+	return v, err
+}
+
+func GetsockoptInt(fd, level, opt int) (int, error) {
+	var v int32
+	l := _Socklen(4)
+	err := getsockopt(fd, level, opt, unsafe.Pointer(&v), &l)
+	return int(v), err
+}
+
+func GetsockoptInet4Addr(fd, level, opt int) ([4]byte, error) {
+	var v [4]byte
+	l := _Socklen(4)
+	err := getsockopt(fd, level, opt, unsafe.Pointer(&v[0]), &l)
+	return v, err
+}
+
+func GetsockoptIPMreq(fd, level, opt int) (*IPMreq, error) {
+	var v IPMreq
+	l := _Socklen(SizeofIPMreq)
+	err := getsockopt(fd, level, opt, unsafe.Pointer(&v), &l)
+	return &v, err
+}
+
+func GetsockoptIPv6Mreq(fd, level, opt int) (*IPv6Mreq, error) {
+	var v IPv6Mreq
+	l := _Socklen(SizeofIPv6Mreq)
+	err := getsockopt(fd, level, opt, unsafe.Pointer(&v), &l)
+	return &v, err
+}
+
+func GetsockoptIPv6MTUInfo(fd, level, opt int) (*IPv6MTUInfo, error) {
+	var v IPv6MTUInfo
+	l := _Socklen(SizeofIPv6MTUInfo)
+	err := getsockopt(fd, level, opt, unsafe.Pointer(&v), &l)
+	return &v, err
+}
+
+func GetsockoptICMPv6Filter(fd, level, opt int) (*ICMPv6Filter, error) {
+	var v ICMPv6Filter
+	l := _Socklen(SizeofICMPv6Filter)
+	err := getsockopt(fd, level, opt, unsafe.Pointer(&v), &l)
+	return &v, err
+}
+
+func SetsockoptByte(fd, level, opt int, value byte) error {
 	return setsockopt(fd, level, opt, unsafe.Pointer(&value), 1)
 }
 
-func SetsockoptInt(fd, level, opt int, value int) (err error) {
-	var n = int32(value)
+func SetsockoptInt(fd, level, opt int, value int) error {
+	n := int32(value)
 	return setsockopt(fd, level, opt, unsafe.Pointer(&n), 4)
 }
 
-func SetsockoptInet4Addr(fd, level, opt int, value [4]byte) (err error) {
+func SetsockoptInet4Addr(fd, level, opt int, value [4]byte) error {
 	return setsockopt(fd, level, opt, unsafe.Pointer(&value[0]), 4)
 }
 
-func SetsockoptIPMreq(fd, level, opt int, mreq *IPMreq) (err error) {
+func SetsockoptIPMreq(fd, level, opt int, mreq *IPMreq) error {
 	return setsockopt(fd, level, opt, unsafe.Pointer(mreq), SizeofIPMreq)
 }
 
-func SetsockoptIPv6Mreq(fd, level, opt int, mreq *IPv6Mreq) (err error) {
+func SetsockoptIPv6Mreq(fd, level, opt int, mreq *IPv6Mreq) error {
 	return setsockopt(fd, level, opt, unsafe.Pointer(mreq), SizeofIPv6Mreq)
 }
 
@@ -259,15 +301,15 @@ func SetsockoptICMPv6Filter(fd, level, opt int, filter *ICMPv6Filter) error {
 	return setsockopt(fd, level, opt, unsafe.Pointer(filter), SizeofICMPv6Filter)
 }
 
-func SetsockoptLinger(fd, level, opt int, l *Linger) (err error) {
+func SetsockoptLinger(fd, level, opt int, l *Linger) error {
 	return setsockopt(fd, level, opt, unsafe.Pointer(l), SizeofLinger)
 }
 
-func SetsockoptString(fd, level, opt int, s string) (err error) {
+func SetsockoptString(fd, level, opt int, s string) error {
 	return setsockopt(fd, level, opt, unsafe.Pointer(&[]byte(s)[0]), uintptr(len(s)))
 }
 
-func SetsockoptTimeval(fd, level, opt int, tv *Timeval) (err error) {
+func SetsockoptTimeval(fd, level, opt int, tv *Timeval) error {
 	return setsockopt(fd, level, opt, unsafe.Pointer(tv), unsafe.Sizeof(*tv))
 }