Improve UnixSocketConfig field names and comments

Author: tomhjp

client.go

@@ -257,9 +257,10 @@ type UnixSocketConfig struct {
 	// not set, defaults to the directory chosen by os.MkdirTemp.
 	TempDir string
 
-	// The directory to create Unix sockets in. Internally managed by go-plugin
-	// and deleted when the plugin is killed.
-	directory string
+	// The directory to create Unix sockets in. Internally created and managed
+	// by go-plugin and deleted when the plugin is killed. Will be created
+	// inside TempDir if specified.
+	socketDir string
 }
 
 // ReattachConfig is used to configure a client to reattach to an
@@ -465,7 +466,7 @@ func (c *Client) Kill() {
 	c.l.Lock()
 	runner := c.runner
 	addr := c.address
-	hostSocketDir := c.unixSocketCfg.directory
+	hostSocketDir := c.unixSocketCfg.socketDir
 	c.l.Unlock()
 
 	// If there is no runner or ID, there is nothing to kill.
@@ -660,22 +661,22 @@ func (c *Client) Start() (addr net.Addr, err error) {
 	var runner runner.Runner
 	switch {
 	case c.config.RunnerFunc != nil:
-		c.unixSocketCfg.directory, err = os.MkdirTemp(c.unixSocketCfg.TempDir, "plugin-dir")
+		c.unixSocketCfg.socketDir, err = os.MkdirTemp(c.unixSocketCfg.TempDir, "plugin-dir")
 		if err != nil {
 			return nil, err
 		}
 		// os.MkdirTemp creates folders with 0o700, so if we have a group
 		// configured we need to make it group-writable.
 		if c.unixSocketCfg.Group != "" {
-			err = setGroupWritable(c.unixSocketCfg.directory, c.unixSocketCfg.Group, 0o770)
+			err = setGroupWritable(c.unixSocketCfg.socketDir, c.unixSocketCfg.Group, 0o770)
 			if err != nil {
 				return nil, err
 			}
 		}
-		cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%s", EnvUnixSocketDir, c.unixSocketCfg.directory))
-		c.logger.Trace("created temporary directory for unix sockets", "dir", c.unixSocketCfg.directory)
+		cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%s", EnvUnixSocketDir, c.unixSocketCfg.socketDir))
+		c.logger.Trace("created temporary directory for unix sockets", "dir", c.unixSocketCfg.socketDir)
 
-		runner, err = c.config.RunnerFunc(c.logger, cmd, c.unixSocketCfg.directory)
+		runner, err = c.config.RunnerFunc(c.logger, cmd, c.unixSocketCfg.socketDir)
 		if err != nil {
 			return nil, err
 		}

server.go

@@ -137,7 +137,7 @@ type ServeTestConfig struct {
 func unixSocketConfigFromEnv() UnixSocketConfig {
 	return UnixSocketConfig{
 		Group:     os.Getenv(EnvUnixSocketGroup),
-		directory: os.Getenv(EnvUnixSocketDir),
+		socketDir: os.Getenv(EnvUnixSocketDir),
 	}
 }
 
@@ -554,7 +554,7 @@ func serverListener_tcp() (net.Listener, error) {
 }
 
 func serverListener_unix(unixSocketCfg UnixSocketConfig) (net.Listener, error) {
-	tf, err := os.CreateTemp(unixSocketCfg.directory, "plugin")
+	tf, err := os.CreateTemp(unixSocketCfg.socketDir, "plugin")
 	if err != nil {
 		return nil, err
 	}