net: Plan 9: open data file and set remote-addr properly

The data file should be opened when a Conn is first
established, rather than waiting for the first Read or
Write.

Upon Close, we now make sure to try to close both, the
ctl as well as data files and set both to nil, even in
the face of errors, instead of returning early.

The Accept call was not setting the remote address
of the connection properly. Now, we read the correct
file.

Make functions that establish Conn use newTCPConn
or newUDPConn.

R=rsc, rminnich, ality, dave
CC=golang-dev
https://golang.org/cl/7228068

src/pkg/net/fd_plan9.go

@@ -29,22 +29,16 @@ func dialTimeout(net, addr string, timeout time.Duration) (Conn, error) {
 	return dialTimeoutRace(net, addr, timeout)
 }
 
-func newFD(proto, name string, ctl *os.File, laddr, raddr Addr) *netFD {
-	return &netFD{proto, name, "/net/" + proto + "/" + name, ctl, nil, laddr, raddr}
+func newFD(proto, name string, ctl, data *os.File, laddr, raddr Addr) *netFD {
+	return &netFD{proto, name, "/net/" + proto + "/" + name, ctl, data, laddr, raddr}
 }
 
 func (fd *netFD) ok() bool { return fd != nil && fd.ctl != nil }
 
 func (fd *netFD) Read(b []byte) (n int, err error) {
-	if !fd.ok() {
+	if !fd.ok() || fd.data == nil {
 		return 0, syscall.EINVAL
 	}
-	if fd.data == nil {
-		fd.data, err = os.OpenFile(fd.dir+"/data", os.O_RDWR, 0)
-		if err != nil {
-			return 0, err
-		}
-	}
 	n, err = fd.data.Read(b)
 	if fd.proto == "udp" && err == io.EOF {
 		n = 0
@@ -54,15 +48,9 @@ func (fd *netFD) Read(b []byte) (n int, err error) {
 }
 
 func (fd *netFD) Write(b []byte) (n int, err error) {
-	if !fd.ok() {
+	if !fd.ok() || fd.data == nil {
 		return 0, syscall.EINVAL
 	}
-	if fd.data == nil {
-		fd.data, err = os.OpenFile(fd.dir+"/data", os.O_RDWR, 0)
-		if err != nil {
-			return 0, err
-		}
-	}
 	return fd.data.Write(b)
 }
 
@@ -85,11 +73,10 @@ func (fd *netFD) Close() error {
 		return syscall.EINVAL
 	}
 	err := fd.ctl.Close()
-	if err != nil {
-		return err
-	}
 	if fd.data != nil {
-		err = fd.data.Close()
+		if err1 := fd.data.Close(); err1 != nil && err == nil {
+			err = err1
+		}
 	}
 	fd.ctl = nil
 	fd.data = nil

src/pkg/net/ipsock_plan9.go

@@ -114,17 +114,24 @@ func dialPlan9(net string, laddr, raddr Addr) (*netFD, error) {
 		f.Close()
 		return nil, err
 	}
+	data, err := os.OpenFile("/net/"+proto+"/"+name+"/data", os.O_RDWR, 0)
+	if err != nil {
+		f.Close()
+		return nil, err
+	}
 	laddr, err = readPlan9Addr(proto, "/net/"+proto+"/"+name+"/local")
 	if err != nil {
+		data.Close()
 		f.Close()
 		return nil, err
 	}
 	raddr, err = readPlan9Addr(proto, "/net/"+proto+"/"+name+"/remote")
 	if err != nil {
+		data.Close()
 		f.Close()
 		return nil, err
 	}
-	return newFD(proto, name, f, laddr, raddr), nil
+	return newFD(proto, name, f, data, laddr, raddr), nil
 }
 
 func listenPlan9(net string, laddr Addr) (*netFD, error) {
@@ -142,11 +149,11 @@ func listenPlan9(net string, laddr Addr) (*netFD, error) {
 		f.Close()
 		return nil, err
 	}
-	return &netFD{proto: proto, name: name, dir: "/net/" + proto + "/" + name, ctl: f, laddr: laddr}, nil
+	return newFD(proto, name, f, nil, laddr, nil), nil
 }
 
 func (l *netFD) netFD() *netFD {
-	return newFD(l.proto, l.name, l.ctl, l.laddr, nil)
+	return newFD(l.proto, l.name, l.ctl, l.data, l.laddr, l.raddr)
 }
 
 func (l *netFD) acceptPlan9() (*netFD, error) {
@@ -161,15 +168,16 @@ func (l *netFD) acceptPlan9() (*netFD, error) {
 		return nil, err
 	}
 	name := string(buf[:n])
-	laddr, err := readPlan9Addr(l.proto, l.dir+"/local")
+	data, err := os.OpenFile("/net/"+l.proto+"/"+name+"/data", os.O_RDWR, 0)
 	if err != nil {
 		f.Close()
 		return nil, err
 	}
-	raddr, err := readPlan9Addr(l.proto, l.dir+"/remote")
+	raddr, err := readPlan9Addr(l.proto, "/net/"+l.proto+"/"+name+"/remote")
 	if err != nil {
+		data.Close()
 		f.Close()
 		return nil, err
 	}
-	return newFD(l.proto, name, f, laddr, raddr), nil
+	return newFD(l.proto, name, f, data, l.laddr, raddr), nil
 }

src/pkg/net/tcpsock_plan9.go

@@ -98,7 +98,7 @@ func dialTCP(net string, laddr, raddr *TCPAddr, deadline time.Time) (*TCPConn, e
 	if err != nil {
 		return nil, err
 	}
-	return &TCPConn{conn{fd}}, nil
+	return newTCPConn(fd), nil
 }
 
 // TCPListener is a TCP network listener.  Clients should typically

src/pkg/net/udpsock_plan9.go

@@ -19,6 +19,10 @@ type UDPConn struct {
 	conn
 }
 
+func newUDPConn(fd *netFD) *UDPConn {
+	return &UDPConn{conn{fd}}
+}
+
 // ReadFromUDP reads a UDP packet from c, copying the payload into b.
 // It returns the number of bytes copied into b and the return address
 // that was on the packet.
@@ -27,15 +31,9 @@ type UDPConn struct {
 // Timeout() == true after a fixed time limit; see SetDeadline and
 // SetReadDeadline.
 func (c *UDPConn) ReadFromUDP(b []byte) (n int, addr *UDPAddr, err error) {
-	if !c.ok() {
+	if !c.ok() || c.fd.data == nil {
 		return 0, nil, syscall.EINVAL
 	}
-	if c.fd.data == nil {
-		c.fd.data, err = os.OpenFile(c.fd.dir+"/data", os.O_RDWR, 0)
-		if err != nil {
-			return 0, nil, err
-		}
-	}
 	buf := make([]byte, udpHeaderSize+len(b))
 	m, err := c.fd.data.Read(buf)
 	if err != nil {
@@ -76,16 +74,9 @@ func (c *UDPConn) ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *UDPAddr,
 // SetWriteDeadline.  On packet-oriented connections, write timeouts
 // are rare.
 func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (int, error) {
-	if !c.ok() {
+	if !c.ok() || c.fd.data == nil {
 		return 0, syscall.EINVAL
 	}
-	if c.fd.data == nil {
-		f, err := os.OpenFile(c.fd.dir+"/data", os.O_RDWR, 0)
-		if err != nil {
-			return 0, err
-		}
-		c.fd.data = f
-	}
 	h := new(udpHeader)
 	h.raddr = addr.IP.To16()
 	h.laddr = c.fd.laddr.(*UDPAddr).IP.To16()
@@ -141,7 +132,7 @@ func dialUDP(net string, laddr, raddr *UDPAddr, deadline time.Time) (*UDPConn, e
 	if err != nil {
 		return nil, err
 	}
-	return &UDPConn{conn{fd}}, nil
+	return newUDPConn(fd), nil
 }
 
 const udpHeaderSize = 16*3 + 2*2
@@ -193,7 +184,11 @@ func ListenUDP(net string, laddr *UDPAddr) (*UDPConn, error) {
 	if err != nil {
 		return nil, err
 	}
-	return &UDPConn{conn{l.netFD()}}, nil
+	l.data, err = os.OpenFile(l.dir+"/data", os.O_RDWR, 0)
+	if err != nil {
+		return nil, err
+	}
+	return newUDPConn(l.netFD()), nil
 }
 
 // ListenMulticastUDP listens for incoming multicast UDP packets