From b0ae758d7b1f7aff6d203c72ba79d79bb36d7557 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Miroslav=20=C5=A0ediv=C3=BD?= <sedivy.miro@gmail.com>
Date: Wed, 4 Nov 2020 00:09:52 +0100
Subject: [PATCH] refactor xorg race condition.

---
 internal/desktop/manager.go   |  8 ++++++-
 internal/desktop/xorg/xorg.c  | 39 +++++------------------------------
 internal/desktop/xorg/xorg.go | 20 +++++++++++++++---
 internal/desktop/xorg/xorg.h  | 13 +++---------
 4 files changed, 32 insertions(+), 48 deletions(-)

diff --git a/internal/desktop/manager.go b/internal/desktop/manager.go
index 3982ee86..aac9304b 100644
--- a/internal/desktop/manager.go
+++ b/internal/desktop/manager.go
@@ -3,6 +3,7 @@ package desktop
 import (
 	"time"
 
+	"github.com/kataras/go-events"
 	"github.com/rs/zerolog"
 	"github.com/rs/zerolog/log"
 
@@ -26,10 +27,15 @@ func New(display string) *DesktopManagerCtx {
 }
 
 func (manager *DesktopManagerCtx) Start() {
-	xorg.Display(manager.display)
+	if err := xorg.DisplayOpen(manager.display); err != nil {
+		manager.logger.Warn().Err(err).Msg("unable to open dispaly")
+	}
+
+	xorg.GetScreenConfigurations()
 
 	go func() {
 		defer func() {
+			xorg.DisplayClose()
 			manager.logger.Info().Msg("shutdown")
 		}()
 
diff --git a/internal/desktop/xorg/xorg.c b/internal/desktop/xorg/xorg.c
index ace9a1ff..f631fc5e 100644
--- a/internal/desktop/xorg/xorg.c
+++ b/internal/desktop/xorg/xorg.c
@@ -1,47 +1,18 @@
 #include "xorg.h"
 
 static Display *DISPLAY = NULL;
-static char *NAME = ":0.0";
-static int REGISTERED = 0;
-static int DIRTY = 0;
 
 Display *getXDisplay(void) {
-  /* Close the display if displayName has changed */
-  if (DIRTY) {
-    XDisplayClose();
-    DIRTY = 0;
-  }
-
-  if (DISPLAY == NULL) {
-    /* First try the user set displayName */
-    DISPLAY = XOpenDisplay(NAME);
-
-    /* Then try using environment variable DISPLAY */
-    if (DISPLAY == NULL) {
-      DISPLAY = XOpenDisplay(NULL);
-    }
-
-    if (DISPLAY == NULL) {
-      fputs("Could not open main display\n", stderr);
-    } else if (!REGISTERED) {
-      atexit(&XDisplayClose);
-      REGISTERED = 1;
-    }
-  }
-
   return DISPLAY;
 }
 
-void XDisplayClose(void) {
-  if (DISPLAY != NULL) {
-    XCloseDisplay(DISPLAY);
-    DISPLAY = NULL;
-  }
+int XDisplayOpen(char *name) {
+  DISPLAY = XOpenDisplay(name);
+  return DISPLAY == NULL;
 }
 
-void XDisplaySet(char *input) {
-  NAME = strdup(input);
-  DIRTY = 1;
+void XDisplayClose(void) {
+  XCloseDisplay(DISPLAY);
 }
 
 void XMove(int x, int y) {
diff --git a/internal/desktop/xorg/xorg.go b/internal/desktop/xorg/xorg.go
index 4063d352..09805d88 100644
--- a/internal/desktop/xorg/xorg.go
+++ b/internal/desktop/xorg/xorg.go
@@ -24,18 +24,32 @@ var debounce_button = make(map[int]time.Time)
 var debounce_key = make(map[uint64]time.Time)
 var mu = sync.Mutex{}
 
-func init() {
+func GetScreenConfigurations() {
 	C.XGetScreenConfigurations()
 }
 
-func Display(display string) {
+func DisplayOpen(display string) error {
 	mu.Lock()
 	defer mu.Unlock()
 
 	displayUnsafe := C.CString(display)
 	defer C.free(unsafe.Pointer(displayUnsafe))
 
-	C.XDisplaySet(displayUnsafe)
+	var err C.int
+	err = C.XDisplayOpen(displayUnsafe)
+
+	if int(err) == 1 {
+		return fmt.Errorf("Could not open display %s.", display)
+	}
+
+	return nil
+}
+
+func DisplayClose() {
+	mu.Lock()
+	defer mu.Unlock()
+	
+	C.XDisplayClose()
 }
 
 func Move(x, y int) {
diff --git a/internal/desktop/xorg/xorg.h b/internal/desktop/xorg/xorg.h
index 4a7b49a2..426769a0 100644
--- a/internal/desktop/xorg/xorg.h
+++ b/internal/desktop/xorg/xorg.h
@@ -9,18 +9,14 @@
 #include <X11/extensions/XTest.h>
 #include <stdint.h>
 #include <stdlib.h>
-#include <stdio.h> /* For fputs() */
-#include <string.h> /* For strdup() */
+#include <string.h>
 
 extern void goCreateScreenSize(int index, int width, int height, int mwidth, int mheight);
 extern void goSetScreenRates(int index, int rate_index, short rate);
 
-/* Returns the main display, closed either on exit or when closeMainDisplay()
-* is invoked. This removes a bit of the overhead of calling XOpenDisplay() &
-* XCloseDisplay() everytime the main display needs to be used.
-*
-* Note that this is almost certainly not thread safe. */
 Display *getXDisplay(void);
+int XDisplayOpen(char *input);
+void XDisplayClose(void);
 
 void XMove(int x, int y);
 void XScroll(int x, int y);
@@ -32,9 +28,6 @@ void XSetScreenConfiguration(int index, short rate);
 int XGetScreenSize();
 short XGetScreenRate();
 
-void XDisplayClose(void);
-void XDisplaySet(char *input);
-
 void SetKeyboardLayout(char *layout);
 void SetKeyboardModifiers(int num_lock, int caps_lock, int scroll_lock);