Initial QSfera import

Server/vendor/github.com/docker/go-connections/sockets/unix_socket.go

@@ -0,0 +1,84 @@
+/*
+Package sockets is a simple unix domain socket wrapper.
+
+# Usage
+
+For example:
+
+	import(
+		"fmt"
+		"net"
+		"os"
+		"github.com/docker/go-connections/sockets"
+	)
+
+	func main() {
+		l, err := sockets.NewUnixSocketWithOpts("/path/to/sockets",
+			sockets.WithChown(0,0),sockets.WithChmod(0660))
+		if err != nil {
+			panic(err)
+		}
+		echoStr := "hello"
+
+		go func() {
+			for {
+				conn, err := l.Accept()
+				if err != nil {
+					return
+				}
+				conn.Write([]byte(echoStr))
+				conn.Close()
+			}
+		}()
+
+		conn, err := net.Dial("unix", path)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		buf := make([]byte, 5)
+		if _, err := conn.Read(buf); err != nil {
+			panic(err)
+		} else if string(buf) != echoStr {
+			panic(fmt.Errorf("msg may lost"))
+		}
+	}
+*/
+package sockets
+
+import (
+	"net"
+	"os"
+	"syscall"
+)
+
+// SockOption sets up socket file's creating option
+type SockOption func(string) error
+
+// NewUnixSocketWithOpts creates a unix socket with the specified options.
+// By default, socket permissions are 0000 (i.e.: no access for anyone); pass
+// WithChmod() and WithChown() to set the desired ownership and permissions.
+//
+// This function temporarily changes the system's "umask" to 0777 to work around
+// a race condition between creating the socket and setting its permissions. While
+// this should only be for a short duration, it may affect other processes that
+// create files/directories during that period.
+func NewUnixSocketWithOpts(path string, opts ...SockOption) (net.Listener, error) {
+	if err := syscall.Unlink(path); err != nil && !os.IsNotExist(err) {
+		return nil, err
+	}
+
+	l, err := listenUnix(path)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, op := range opts {
+		if err := op(path); err != nil {
+			_ = l.Close()
+			return nil, err
+		}
+	}
+
+	return l, nil
+}