net: add FileConn, FilePacketConn, FileListener

R=iant, rsc, brainman
CC=golang-dev
https://golang.org/cl/4306042

src/pkg/net/file.go

@@ -0,0 +1,115 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package net
+
+import (
+	"os"
+	"syscall"
+)
+
+func newFileFD(f *os.File) (*netFD, os.Error) {
+	fd, errno := syscall.Dup(f.Fd())
+	if errno != 0 {
+		return nil, os.NewSyscallError("dup", errno)
+	}
+
+	proto, errno := syscall.GetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_TYPE)
+	if errno != 0 {
+		return nil, os.NewSyscallError("getsockopt", errno)
+	}
+
+	toAddr := sockaddrToTCP
+	sa, _ := syscall.Getsockname(fd)
+	switch sa.(type) {
+	default:
+		closesocket(fd)
+		return nil, os.EINVAL
+	case *syscall.SockaddrInet4:
+		if proto == syscall.SOCK_DGRAM {
+			toAddr = sockaddrToUDP
+		} else if proto == syscall.SOCK_RAW {
+			toAddr = sockaddrToIP
+		}
+	case *syscall.SockaddrInet6:
+		if proto == syscall.SOCK_DGRAM {
+			toAddr = sockaddrToUDP
+		} else if proto == syscall.SOCK_RAW {
+			toAddr = sockaddrToIP
+		}
+	case *syscall.SockaddrUnix:
+		toAddr = sockaddrToUnix
+		if proto == syscall.SOCK_DGRAM {
+			toAddr = sockaddrToUnixgram
+		} else if proto == syscall.SOCK_SEQPACKET {
+			toAddr = sockaddrToUnixpacket
+		}
+	}
+	laddr := toAddr(sa)
+	sa, _ = syscall.Getpeername(fd)
+	raddr := toAddr(sa)
+
+	return newFD(fd, 0, proto, laddr.Network(), laddr, raddr)
+}
+
+// FileConn returns a copy of the network connection corresponding to
+// the open file f.  It is the caller's responsibility to close f when
+// finished.  Closing c does not affect f, and closing f does not
+// affect c.
+func FileConn(f *os.File) (c Conn, err os.Error) {
+	fd, err := newFileFD(f)
+	if err != nil {
+		return nil, err
+	}
+	switch fd.laddr.(type) {
+	case *TCPAddr:
+		return newTCPConn(fd), nil
+	case *UDPAddr:
+		return newUDPConn(fd), nil
+	case *UnixAddr:
+		return newUnixConn(fd), nil
+	case *IPAddr:
+		return newIPConn(fd), nil
+	}
+	fd.Close()
+	return nil, os.EINVAL
+}
+
+// FileListener returns a copy of the network listener corresponding
+// to the open file f.  It is the caller's responsibility to close l
+// when finished.  Closing c does not affect l, and closing l does not
+// affect c.
+func FileListener(f *os.File) (l Listener, err os.Error) {
+	fd, err := newFileFD(f)
+	if err != nil {
+		return nil, err
+	}
+	switch laddr := fd.laddr.(type) {
+	case *TCPAddr:
+		return &TCPListener{fd}, nil
+	case *UnixAddr:
+		return &UnixListener{fd, laddr.Name}, nil
+	}
+	fd.Close()
+	return nil, os.EINVAL
+}
+
+// FilePacketConn returns a copy of the packet network connection
+// corresponding to the open file f.  It is the caller's
+// responsibility to close f when finished.  Closing c does not affect
+// f, and closing f does not affect c.
+func FilePacketConn(f *os.File) (c PacketConn, err os.Error) {
+	fd, err := newFileFD(f)
+	if err != nil {
+		return nil, err
+	}
+	switch fd.laddr.(type) {
+	case *UDPAddr:
+		return newUDPConn(fd), nil
+	case *UnixAddr:
+		return newUnixConn(fd), nil
+	}
+	fd.Close()
+	return nil, os.EINVAL
+}