system/internal/xcb: refactor and clean up

This package still does not deserve to be out of internal, but at least it is less haunting now. I am still not handling the xcb error though, the struct is almost entirely undocumented and the implementation is unreadable. Not even going to try.

Signed-off-by: Ophestra <cat@gensokyo.uk>

system/internal/xcb/changehosts.go

@@ -1,21 +1,16 @@
-// Package xcb implements X11 ChangeHosts via libxcb.
 package xcb
 
-import (
-	"errors"
-)
+import "errors"
 
 var ErrChangeHosts = errors.New("xcb_change_hosts() failed")
 
 func ChangeHosts(mode HostMode, family Family, address string) error {
-	var conn *connection
-
-	if c, err := connect(); err != nil {
-		c.disconnect()
+	conn := new(connection)
+	if err := conn.connect(); err != nil {
+		conn.disconnect()
 		return err
 	} else {
-		defer c.disconnect()
-		conn = c
+		defer conn.disconnect()
 	}
 
 	return conn.changeHostsChecked(mode, family, address)

system/internal/xcb/xcb.go

@@ -1,3 +1,4 @@
+// Package xcb implements X11 ChangeHosts via libxcb.
 package xcb
 
 import (
@@ -11,22 +12,28 @@ import (
 #include <stdlib.h>
 #include <xcb/xcb.h>
 
-static int _go_xcb_change_hosts_checked(xcb_connection_t *c, uint8_t mode, uint8_t family, uint16_t address_len, const uint8_t *address) {
-	xcb_void_cookie_t cookie = xcb_change_hosts_checked(c, mode, family, address_len, address);
-	free((void *)address);
+static int hakurei_xcb_change_hosts_checked(xcb_connection_t *c,
+                                            uint8_t mode, uint8_t family,
+                                            uint16_t address_len, const uint8_t *address) {
+  int ret;
+  xcb_generic_error_t *e;
+  xcb_void_cookie_t cookie;
 
-	int errno = xcb_connection_has_error(c);
-	if (errno != 0)
-		return errno;
+  cookie = xcb_change_hosts_checked(c, mode, family, address_len, address);
+  free((void *)address);
 
-	xcb_generic_error_t *e = xcb_request_check(c, cookie);
-	if (e != NULL) {
-		// don't want to deal with xcb errors
-		free((void *)e);
-		return -1;
-	}
+  ret = xcb_connection_has_error(c);
+  if (ret != 0)
+    return ret;
 
-	return 0;
+  e = xcb_request_check(c, cookie);
+  if (e != NULL) {
+    // don't want to deal with xcb errors
+    free((void *)e);
+    ret = -1;
+  }
+
+  return ret;
 }
 */
 import "C"
@@ -48,49 +55,60 @@ type (
 )
 
 func (conn *connection) changeHostsChecked(mode HostMode, family Family, address string) error {
-	errno := C._go_xcb_change_hosts_checked(
+	ret := C.hakurei_xcb_change_hosts_checked(
 		conn.c,
 		C.uint8_t(mode),
 		C.uint8_t(family),
 		C.uint16_t(len(address)),
 		(*C.uint8_t)(unsafe.Pointer(C.CString(address))),
 	)
-	switch errno {
+	switch ret {
 	case 0:
 		return nil
 	case -1:
 		return ErrChangeHosts
 	default:
-		return &ConnectionError{errno}
+		return ConnectionError(ret)
 	}
 }
 
 type connection struct{ c *C.xcb_connection_t }
 
-func connect() (*connection, error) {
-	conn := newConnection(C.xcb_connect(nil, nil))
-	return conn, conn.hasError()
+func (conn *connection) connect() error {
+	conn.c = C.xcb_connect(nil, nil)
+	runtime.SetFinalizer(conn, (*connection).disconnect)
+	return conn.hasError()
 }
 
-func newConnection(c *C.xcb_connection_t) *connection {
-	conn := &connection{c}
-	runtime.SetFinalizer(conn, (*connection).disconnect)
-	return conn
+func (conn *connection) hasError() error {
+	ret := C.xcb_connection_has_error(conn.c)
+	if ret == 0 {
+		return nil
+	}
+	return ConnectionError(ret)
+}
+
+func (conn *connection) disconnect() {
+	C.xcb_disconnect(conn.c)
+
+	// no need for a finalizer anymore
+	runtime.SetFinalizer(conn, nil)
 }
 
 const (
-	ConnError                 = C.XCB_CONN_ERROR
-	ConnClosedExtNotSupported = C.XCB_CONN_CLOSED_EXT_NOTSUPPORTED
-	ConnClosedMemInsufficient = C.XCB_CONN_CLOSED_MEM_INSUFFICIENT
-	ConnClosedReqLenExceed    = C.XCB_CONN_CLOSED_REQ_LEN_EXCEED
-	ConnClosedParseErr        = C.XCB_CONN_CLOSED_PARSE_ERR
-	ConnClosedInvalidScreen   = C.XCB_CONN_CLOSED_INVALID_SCREEN
+	ConnError                 ConnectionError = C.XCB_CONN_ERROR
+	ConnClosedExtNotSupported ConnectionError = C.XCB_CONN_CLOSED_EXT_NOTSUPPORTED
+	ConnClosedMemInsufficient ConnectionError = C.XCB_CONN_CLOSED_MEM_INSUFFICIENT
+	ConnClosedReqLenExceed    ConnectionError = C.XCB_CONN_CLOSED_REQ_LEN_EXCEED
+	ConnClosedParseErr        ConnectionError = C.XCB_CONN_CLOSED_PARSE_ERR
+	ConnClosedInvalidScreen   ConnectionError = C.XCB_CONN_CLOSED_INVALID_SCREEN
 )
 
-type ConnectionError struct{ errno C.int }
+// ConnectionError represents an error returned by xcb_connection_has_error.
+type ConnectionError int
 
-func (ce *ConnectionError) Error() string {
-	switch ce.errno {
+func (ce ConnectionError) Error() string {
+	switch ce {
 	case ConnError:
 		return "connection error"
 	case ConnClosedExtNotSupported:
@@ -107,18 +125,3 @@ func (ce *ConnectionError) Error() string {
 		return "generic X11 failure"
 	}
 }
-
-func (conn *connection) hasError() error {
-	errno := C.xcb_connection_has_error(conn.c)
-	if errno == 0 {
-		return nil
-	}
-	return &ConnectionError{errno}
-}
-
-func (conn *connection) disconnect() {
-	C.xcb_disconnect(conn.c)
-
-	// no need for a finalizer anymore
-	runtime.SetFinalizer(conn, nil)
-}