syscall: import upstream code for BSD sockets and sysctls

Import some missing upstream code for BSD sockets and sysctls and
adapt it for gccgo.

Updates golang/go#38538.

Change-Id: I3b08bf01b499b5be55ef79b4633f47ba266d0148
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/261137
Reviewed-by: Ian Lance Taylor <[email protected]>
Trust: Benny Siegert <[email protected]>

Author: benesch

libgo/go/syscall/route_bsd.go

@@ -18,7 +18,7 @@ var (
 
 // Round the length of a raw sockaddr up to align it properly.
 func rsaAlignOf(salen int) int {
-	salign := sizeofPtr
+	salign := int(sizeofPtr)
 	if darwin64Bit {
 		// Darwin kernels require 32-bit aligned access to
 		// routing facilities.

libgo/go/syscall/socket_bsd.go

@@ -13,6 +13,7 @@ import "unsafe"
 const SizeofSockaddrInet4 = 16
 const SizeofSockaddrInet6 = 28
 const SizeofSockaddrUnix = 110
+const SizeofSockaddrDatalink = 20
 
 type RawSockaddrInet4 struct {
 	Len    uint8
@@ -76,6 +77,46 @@ func (sa *RawSockaddrUnix) adjustAbstract(sl Socklen_t) Socklen_t {
 	return sl
 }
 
+type SockaddrDatalink struct {
+	Len    uint8
+	Family uint8
+	Index  uint16
+	Type   uint8
+	Nlen   uint8
+	Alen   uint8
+	Slen   uint8
+	Data   [12]int8
+	raw    RawSockaddrDatalink
+}
+
+func (sa *SockaddrDatalink) sockaddr() (*RawSockaddrAny, Socklen_t, error) {
+	if sa.Index == 0 {
+		return nil, 0, EINVAL
+	}
+	sa.raw.Len = sa.Len
+	sa.raw.Family = AF_LINK
+	sa.raw.Index = sa.Index
+	sa.raw.Type = sa.Type
+	sa.raw.Nlen = sa.Nlen
+	sa.raw.Alen = sa.Alen
+	sa.raw.Slen = sa.Slen
+	for i := 0; i < len(sa.raw.Data); i++ {
+		sa.raw.Data[i] = sa.Data[i]
+	}
+	return (*RawSockaddrAny)(unsafe.Pointer(&sa.raw)), SizeofSockaddrDatalink, nil
+}
+
+type RawSockaddrDatalink struct {
+	Len    uint8
+	Family uint8
+	Index  uint16
+	Type   uint8
+	Nlen   uint8
+	Alen   uint8
+	Slen   uint8
+	Data   [12]int8
+}
+
 type RawSockaddr struct {
 	Len    uint8
 	Family uint8

libgo/go/syscall/syscall_netbsd.go

@@ -17,3 +17,64 @@ func direntReclen(buf []byte) (uint64, bool) {
 func direntNamlen(buf []byte) (uint64, bool) {
 	return readInt(buf, unsafe.Offsetof(Dirent{}.Namlen), unsafe.Sizeof(Dirent{}.Namlen))
 }
+
+func sysctlNodes(mib []_C_int) (nodes []Sysctlnode, err error) {
+	var olen uintptr
+
+	// Get a list of all sysctl nodes below the given MIB by performing
+	// a sysctl for the given MIB with CTL_QUERY appended.
+	mib = append(mib, CTL_QUERY)
+	qnode := Sysctlnode{Flags: SYSCTL_VERS_1}
+	qp := (*byte)(unsafe.Pointer(&qnode))
+	sz := unsafe.Sizeof(qnode)
+	if err = sysctl(mib, nil, &olen, qp, sz); err != nil {
+		return nil, err
+	}
+
+	// Now that we know the size, get the actual nodes.
+	nodes = make([]Sysctlnode, olen/sz)
+	np := (*byte)(unsafe.Pointer(&nodes[0]))
+	if err = sysctl(mib, np, &olen, qp, sz); err != nil {
+		return nil, err
+	}
+
+	return nodes, nil
+}
+
+func nametomib(name string) (mib []_C_int, err error) {
+	// Split name into components.
+	var parts []string
+	last := 0
+	for i := 0; i < len(name); i++ {
+		if name[i] == '.' {
+			parts = append(parts, name[last:i])
+			last = i + 1
+		}
+	}
+	parts = append(parts, name[last:])
+
+	// Discover the nodes and construct the MIB OID.
+	for partno, part := range parts {
+		nodes, err := sysctlNodes(mib)
+		if err != nil {
+			return nil, err
+		}
+		for _, node := range nodes {
+			n := make([]byte, 0)
+			for i := range node.Name {
+				if node.Name[i] != 0 {
+					n = append(n, byte(node.Name[i]))
+				}
+			}
+			if string(n) == part {
+				mib = append(mib, _C_int(node.Num))
+				break
+			}
+		}
+		if len(mib) != partno+1 {
+			return nil, EINVAL
+		}
+	}
+
+	return mib, nil
+}