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Source file src/net/unixsock.go

Documentation: net

  // Copyright 2009 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 (
  	"context"
  	"os"
  	"sync"
  	"syscall"
  	"time"
  )
  
  // 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 parses addr as a Unix domain socket address.
  // The string net gives the network name, "unix", "unixgram" or
  // "unixpacket".
  func ResolveUnixAddr(net, addr string) (*UnixAddr, error) {
  	switch net {
  	case "unix", "unixgram", "unixpacket":
  		return &UnixAddr{Name: addr, Net: net}, nil
  	default:
  		return nil, UnknownNetworkError(net)
  	}
  }
  
  // UnixConn is an implementation of the Conn interface for connections
  // to Unix domain sockets.
  type UnixConn struct {
  	conn
  }
  
  // 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 reads a packet from c, copying the payload into b. It
  // returns the number of bytes copied into b and the source address of
  // the packet.
  //
  // ReadFromUnix can be made to time out and return an error with
  // Timeout() == true after a fixed time limit; see SetDeadline and
  // SetReadDeadline.
  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 packet 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 packet, and the source address of the packet.
  //
  // 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 writes a packet to addr via c, copying the payload from b.
  //
  // WriteToUnix can be made to time out and return an error with
  // Timeout() == true after a fixed time limit; see SetDeadline and
  // SetWriteDeadline. On packet-oriented connections, write timeouts
  // are rare.
  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 packet 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 connects to the remote address raddr on the network net,
  // which must be "unix", "unixgram" or "unixpacket".  If laddr is not
  // nil, it is used as the local address for the connection.
  func DialUnix(net string, laddr, raddr *UnixAddr) (*UnixConn, error) {
  	switch net {
  	case "unix", "unixgram", "unixpacket":
  	default:
  		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
  	}
  	c, err := dialUnix(context.Background(), net, laddr, raddr)
  	if err != nil {
  		return nil, &OpError{Op: "dial", Net: net, 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 }
  
  // 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.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, set to blocking
  // mode. 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 announces on the Unix domain socket laddr and returns a
  // Unix listener. The network net must be "unix" or "unixpacket".
  func ListenUnix(net string, laddr *UnixAddr) (*UnixListener, error) {
  	switch net {
  	case "unix", "unixpacket":
  	default:
  		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
  	}
  	if laddr == nil {
  		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: errMissingAddress}
  	}
  	ln, err := listenUnix(context.Background(), net, laddr)
  	if err != nil {
  		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: err}
  	}
  	return ln, nil
  }
  
  // ListenUnixgram listens for incoming Unix datagram packets addressed
  // to the local address laddr. The network net must be "unixgram".
  // The returned connection's ReadFrom and WriteTo methods can be used
  // to receive and send packets with per-packet addressing.
  func ListenUnixgram(net string, laddr *UnixAddr) (*UnixConn, error) {
  	switch net {
  	case "unixgram":
  	default:
  		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
  	}
  	if laddr == nil {
  		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: nil, Err: errMissingAddress}
  	}
  	c, err := listenUnixgram(context.Background(), net, laddr)
  	if err != nil {
  		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: err}
  	}
  	return c, nil
  }
  

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