2 files changed, 72 insertions, 1 deletions
diff --git a/acl.go b/acl.go
index f1f496e5..d176d813 100644
--- a/acl.go
+++ b/acl.go
@@ -1,6 +1,5 @@
 package main
 
-import "C"
 import (
 	"errors"
 	"fmt"
diff --git a/x11.go b/x11.go
new file mode 100644
index 00000000..d25155e3
--- /dev/null
+++ b/x11.go
@@ -0,0 +1,72 @@
+package main
+
+import "C"
+import (
+	"errors"
+	"unsafe"
+)
+
+//#include <stdlib.h>
+//#include <xcb/xcb.h>
+//#cgo linux LDFLAGS: -lxcb
+import "C"
+
+const (
+	xcbHostModeInsert = C.XCB_HOST_MODE_INSERT
+	xcbHostModeDelete = C.XCB_HOST_MODE_DELETE
+
+	xcbFamilyInternet          = C.XCB_FAMILY_INTERNET
+	xcbFamilyDecnet            = C.XCB_FAMILY_DECNET
+	xcbFamilyChaos             = C.XCB_FAMILY_CHAOS
+	xcbFamilyServerInterpreted = C.XCB_FAMILY_SERVER_INTERPRETED
+	xcbFamilyInternet6         = C.XCB_FAMILY_INTERNET_6
+)
+
+func changeHosts(mode, family C.uint8_t, address string) error {
+	var c *C.xcb_connection_t
+	c = C.xcb_connect(nil, nil)
+	defer C.xcb_disconnect(c)
+
+	if err := xcbHandleConnectionError(c); err != nil {
+		return err
+	}
+
+	addr := C.CString(address)
+	cookie := C.xcb_change_hosts_checked(c, mode, family, C.ushort(len(address)), (*C.uchar)(unsafe.Pointer(addr)))
+	C.free(unsafe.Pointer(addr))
+
+	if err := xcbHandleConnectionError(c); err != nil {
+		return err
+	}
+
+	e := C.xcb_request_check(c, cookie)
+	if e != nil {
+		defer C.free(unsafe.Pointer(e))
+		return errors.New("xcb_change_hosts() failed")
+	}
+
+	return nil
+}
+
+func xcbHandleConnectionError(c *C.xcb_connection_t) error {
+	if errno := C.xcb_connection_has_error(c); errno != 0 {
+		switch errno {
+		case C.XCB_CONN_ERROR:
+			return errors.New("connection error")
+		case C.XCB_CONN_CLOSED_EXT_NOTSUPPORTED:
+			return errors.New("extension not supported")
+		case C.XCB_CONN_CLOSED_MEM_INSUFFICIENT:
+			return errors.New("memory not available")
+		case C.XCB_CONN_CLOSED_REQ_LEN_EXCEED:
+			return errors.New("request length exceeded")
+		case C.XCB_CONN_CLOSED_PARSE_ERR:
+			return errors.New("invalid display string")
+		case C.XCB_CONN_CLOSED_INVALID_SCREEN:
+			return errors.New("server has no screen matching display")
+		default:
+			return errors.New("generic X11 failure")
+		}
+	} else {
+		return nil
+	}
+}