Bugfix: Correctly disable Xinerama, use TAILQ_HEAD_INITIALIZER where possible

src/mainx.c

@@ -47,7 +47,7 @@
 
 Display *xkbdpy;
 
-TAILQ_HEAD(bindings_head, Binding) bindings;
+TAILQ_HEAD(bindings_head, Binding) bindings = TAILQ_HEAD_INITIALIZER(bindings);
 xcb_event_handlers_t evenths;
 
 xcb_window_t root_win;
@@ -264,8 +264,6 @@ int main(int argc, char *argv[], char *env[]) {
         byChild = alloc_table();
         byParent = alloc_table();
 
-        TAILQ_INIT(&bindings);
-
         c = xcb_connect(NULL, &screens);
 
         /* TODO: this has to be more beautiful somewhen */

src/xinerama.c

@@ -22,10 +22,14 @@
 #include "util.h"
 #include "xinerama.h"
 
-/* This TAILQ of Rects stores the virtual screens, used for handling overlapping screens
+/* This TAILQ of i3Screens stores the virtual screens, used for handling overlapping screens
  * (xrandr --same-as) */
-struct screens_head virtual_screens;
+struct screens_head virtual_screens = TAILQ_HEAD_INITIALIZER(virtual_screens);
 
+/*
+ * Looks in virtual_screens for the i3Screen whose start coordinates are x, y
+ *
+ */
 i3Screen *get_screen_at(int x, int y) {
         i3Screen *screen;
         TAILQ_FOREACH(screen, &virtual_screens, screens)
@@ -35,6 +39,10 @@ i3Screen *get_screen_at(int x, int y) {
         return NULL;
 }
 
+/*
+ * Looks in virtual_screens for the i3Screen which contains coordinates x, y
+ *
+ */
 i3Screen *get_screen_containing(int x, int y) {
         i3Screen *screen;
         TAILQ_FOREACH(screen, &virtual_screens, screens)
@@ -45,6 +53,22 @@ i3Screen *get_screen_containing(int x, int y) {
         return NULL;
 }
 
+/*
+ * Fills virtual_screens with exactly one screen with width/height of the whole X server.
+ *
+ */
+static void disable_xinerama(xcb_connection_t *connection) {
+        xcb_screen_t *root_screen = xcb_setup_roots_iterator(xcb_get_setup(connection)).data;
+
+        i3Screen *s = calloc(sizeof(i3Screen), 1);
+
+        s->rect.x = 0;
+        s->rect.y = 0;
+        s->rect.width = root_screen->width_in_pixels;
+        s->rect.height = root_screen->height_in_pixels;
+
+        TAILQ_INSERT_TAIL(&virtual_screens, s, screens);
+}
 
 /*
  * We have just established a connection to the X server and need the initial Xinerama
@@ -58,11 +82,13 @@ void initialize_xinerama(xcb_connection_t *conn) {
 
         if (!xcb_get_extension_data(conn, &xcb_xinerama_id)->present) {
                 printf("Xinerama extension not found, disabling.\n");
+                disable_xinerama(conn);
                 return;
         }
 
         if (!xcb_xinerama_is_active_reply(conn, xcb_xinerama_is_active(conn), NULL)->state) {
                 printf("Xinerama is not active (in your X-Server), disabling.\n");
+                disable_xinerama(conn);
                 return;
         }
 
@@ -74,8 +100,6 @@ void initialize_xinerama(xcb_connection_t *conn) {
         screen_info = xcb_xinerama_query_screens_screen_info(reply);
         num_screens = xcb_xinerama_query_screens_screen_info_length(reply);
 
-        TAILQ_INIT(&virtual_screens);
-
         /* Just go through each workspace and associate as many screens as we can. */
         for (screen = 0; screen < num_screens; screen++) {
                 i3Screen *s = get_screen_at(screen_info[screen].x_org, screen_info[screen].y_org);
@@ -85,7 +109,7 @@ void initialize_xinerama(xcb_connection_t *conn) {
                         s->rect.width = min(s->rect.width, screen_info[screen].width);
                         s->rect.height = min(s->rect.height, screen_info[screen].height);
                 } else {
-                        s = calloc(sizeof(Screen), 1);
+                        s = calloc(sizeof(i3Screen), 1);
                         s->rect.x = screen_info[screen].x_org;
                         s->rect.y = screen_info[screen].y_org;
                         s->rect.width = screen_info[screen].width;