Source: unixsock.go in package net


package net

import (
	"context"
	"os"
	"sync"
	"syscall"
	"time"
)

BUG(mikio): On JS and Plan 9, methods and functions related to UnixConn and UnixListener are not implemented.

BUG(mikio): On Windows, methods and functions related to UnixConn and UnixListener don't work for "unixgram" and "unixpacket".

UnixAddr represents the address of a Unix domain socket end point.

type UnixAddr struct {
	Name string
	Net  string
}

Network returns the address's network name, "unix", "unixgram" or "unixpacket".

func (a *UnixAddr) Network() string {
	return a.Net
}

func (a *UnixAddr) String() string {
	if a == nil {
		return "<nil>"
	}
	return a.Name
}

func (a *UnixAddr) isWildcard() bool {
	return a == nil || a.Name == ""
}

func (a *UnixAddr) opAddr() Addr {
	if a == nil {
		return nil
	}
	return a
}

ResolveUnixAddr returns an address of Unix domain socket end point. The network must be a Unix network name. See func Dial for a description of the network and address parameters.

func ResolveUnixAddr(network, address string) (*UnixAddr, error) {
	switch network {
	case "unix", "unixgram", "unixpacket":
		return &UnixAddr{Name: address, Net: network}, nil
	default:
		return nil, UnknownNetworkError(network)
	}
}

UnixConn is an implementation of the Conn interface for connections to Unix domain sockets.

type UnixConn struct {
	conn
}

SyscallConn returns a raw network connection. This implements the syscall.Conn interface.

func (c *UnixConn) SyscallConn() (syscall.RawConn, error) {
	if !c.ok() {
		return nil, syscall.EINVAL
	}
	return newRawConn(c.fd)
}

CloseRead shuts down the reading side of the Unix domain connection. Most callers should just use Close.

func (c *UnixConn) CloseRead() error {
	if !c.ok() {
		return syscall.EINVAL
	}
	if err := c.fd.closeRead(); err != nil {
		return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	return nil
}

CloseWrite shuts down the writing side of the Unix domain connection. Most callers should just use Close.

func (c *UnixConn) CloseWrite() error {
	if !c.ok() {
		return syscall.EINVAL
	}
	if err := c.fd.closeWrite(); err != nil {
		return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	return nil
}

ReadFromUnix acts like ReadFrom but returns a UnixAddr.

func (c *UnixConn) ReadFromUnix(b []byte) (int, *UnixAddr, error) {
	if !c.ok() {
		return 0, nil, syscall.EINVAL
	}
	n, addr, err := c.readFrom(b)
	if err != nil {
		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	return n, addr, err
}

ReadFrom implements the PacketConn ReadFrom method.

func (c *UnixConn) ReadFrom(b []byte) (int, Addr, error) {
	if !c.ok() {
		return 0, nil, syscall.EINVAL
	}
	n, addr, err := c.readFrom(b)
	if err != nil {
		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	if addr == nil {
		return n, nil, err
	}
	return n, addr, err
}

ReadMsgUnix reads a message from c, copying the payload into b and the associated out-of-band data into oob. It returns the number of bytes copied into b, the number of bytes copied into oob, the flags that were set on the message and the source address of the message. Note that if len(b) == 0 and len(oob) > 0, this function will still read (and discard) 1 byte from the connection.

func (c *UnixConn) ReadMsgUnix(b, oob []byte) (n, oobn, flags int, addr *UnixAddr, err error) {
	if !c.ok() {
		return 0, 0, 0, nil, syscall.EINVAL
	}
	n, oobn, flags, addr, err = c.readMsg(b, oob)
	if err != nil {
		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	return
}

WriteToUnix acts like WriteTo but takes a UnixAddr.

func (c *UnixConn) WriteToUnix(b []byte, addr *UnixAddr) (int, error) {
	if !c.ok() {
		return 0, syscall.EINVAL
	}
	n, err := c.writeTo(b, addr)
	if err != nil {
		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
	}
	return n, err
}

WriteTo implements the PacketConn WriteTo method.

func (c *UnixConn) WriteTo(b []byte, addr Addr) (int, error) {
	if !c.ok() {
		return 0, syscall.EINVAL
	}
	a, ok := addr.(*UnixAddr)
	if !ok {
		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr, Err: syscall.EINVAL}
	}
	n, err := c.writeTo(b, a)
	if err != nil {
		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: a.opAddr(), Err: err}
	}
	return n, err
}

WriteMsgUnix writes a message to addr via c, copying the payload from b and the associated out-of-band data from oob. It returns the number of payload and out-of-band bytes written. Note that if len(b) == 0 and len(oob) > 0, this function will still write 1 byte to the connection.

func (c *UnixConn) WriteMsgUnix(b, oob []byte, addr *UnixAddr) (n, oobn int, err error) {
	if !c.ok() {
		return 0, 0, syscall.EINVAL
	}
	n, oobn, err = c.writeMsg(b, oob, addr)
	if err != nil {
		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
	}
	return
}

func newUnixConn(fd *netFD) *UnixConn { return &UnixConn{conn{fd}} }

DialUnix acts like Dial for Unix networks. The network must be a Unix network name; see func Dial for details. If laddr is non-nil, it is used as the local address for the connection.

func DialUnix(network string, laddr, raddr *UnixAddr) (*UnixConn, error) {
	switch network {
	case "unix", "unixgram", "unixpacket":
	default:
		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(network)}
	}
	sd := &sysDialer{network: network, address: raddr.String()}
	c, err := sd.dialUnix(context.Background(), laddr, raddr)
	if err != nil {
		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
	}
	return c, nil
}

UnixListener is a Unix domain socket listener. Clients should typically use variables of type Listener instead of assuming Unix domain sockets.

type UnixListener struct {
	fd         *netFD
	path       string
	unlink     bool
	unlinkOnce sync.Once
}

func (ln *UnixListener) ok() bool { return ln != nil && ln.fd != nil }

SyscallConn returns a raw network connection. This implements the syscall.Conn interface. The returned RawConn only supports calling Control. Read and Write return an error.

func (l *UnixListener) SyscallConn() (syscall.RawConn, error) {
	if !l.ok() {
		return nil, syscall.EINVAL
	}
	return newRawListener(l.fd)
}

AcceptUnix accepts the next incoming call and returns the new connection.

func (l *UnixListener) AcceptUnix() (*UnixConn, error) {
	if !l.ok() {
		return nil, syscall.EINVAL
	}
	c, err := l.accept()
	if err != nil {
		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
	}
	return c, nil
}

Accept implements the Accept method in the Listener interface. Returned connections will be of type *UnixConn.

func (l *UnixListener) Accept() (Conn, error) {
	if !l.ok() {
		return nil, syscall.EINVAL
	}
	c, err := l.accept()
	if err != nil {
		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
	}
	return c, nil
}

Close stops listening on the Unix address. Already accepted connections are not closed.

func (l *UnixListener) Close() error {
	if !l.ok() {
		return syscall.EINVAL
	}
	if err := l.close(); err != nil {
		return &OpError{Op: "close", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
	}
	return nil
}

Addr returns the listener's network address. The Addr returned is shared by all invocations of Addr, so do not modify it.

func (l *UnixListener) Addr() Addr { return l.fd.laddr }

SetDeadline sets the deadline associated with the listener. A zero time value disables the deadline.

func (l *UnixListener) SetDeadline(t time.Time) error {
	if !l.ok() {
		return syscall.EINVAL
	}
	if err := l.fd.pfd.SetDeadline(t); err != nil {
		return &OpError{Op: "set", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
	}
	return nil
}

File returns a copy of the underlying os.File. It is the caller's responsibility to close f when finished. Closing l does not affect f, and closing f does not affect l. The returned os.File's file descriptor is different from the connection's. Attempting to change properties of the original using this duplicate may or may not have the desired effect.

func (l *UnixListener) File() (f *os.File, err error) {
	if !l.ok() {
		return nil, syscall.EINVAL
	}
	f, err = l.file()
	if err != nil {
		err = &OpError{Op: "file", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
	}
	return
}

ListenUnix acts like Listen for Unix networks. The network must be "unix" or "unixpacket".

func ListenUnix(network string, laddr *UnixAddr) (*UnixListener, error) {
	switch network {
	case "unix", "unixpacket":
	default:
		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(network)}
	}
	if laddr == nil {
		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: errMissingAddress}
	}
	sl := &sysListener{network: network, address: laddr.String()}
	ln, err := sl.listenUnix(context.Background(), laddr)
	if err != nil {
		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: err}
	}
	return ln, nil
}

ListenUnixgram acts like ListenPacket for Unix networks. The network must be "unixgram".

func ListenUnixgram(network string, laddr *UnixAddr) (*UnixConn, error) {
	switch network {
	case "unixgram":
	default:
		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(network)}
	}
	if laddr == nil {
		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: nil, Err: errMissingAddress}
	}
	sl := &sysListener{network: network, address: laddr.String()}
	c, err := sl.listenUnixgram(context.Background(), laddr)
	if err != nil {
		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: err}
	}
	return c, nil