Fix covering of composited notifications (#204)

Use the XComposite extension to get the composite overlay window,
instead of just using the normal root window. This ensures that
composited windows are covered.

This time, we hide it behind a config option because it might break
things more than it fixes.

README.md

@@ -25,6 +25,7 @@ Requirements
 - libxcb-util
 - libpam-dev
 - libcairo-dev
+- libxcb-composite0
 - libxcb-xinerama
 - libxcb-randr
 - libev

configure.ac

@@ -90,7 +90,7 @@ AC_SEARCH_LIBS([iconv_open], [iconv], , [AC_MSG_FAILURE([cannot find the require
 
 dnl Each prefix corresponds to a source tarball which users might have
 dnl downloaded in a newer version and would like to overwrite.
-PKG_CHECK_MODULES([XCB], [xcb xcb-xkb xcb-xinerama xcb-randr])
+PKG_CHECK_MODULES([XCB], [xcb xcb-xkb xcb-xinerama xcb-randr xcb-composite])
 PKG_CHECK_MODULES([XCB_IMAGE], [xcb-image])
 PKG_CHECK_MODULES([XCB_UTIL], [xcb-event xcb-util xcb-atom])
 PKG_CHECK_MODULES([XCB_UTIL_XRM], [xcb-xrm])

i3lock.1

@@ -115,6 +115,11 @@ Lock the console to disable TTY switching (Linux only).
 Enables debug logging.
 Note, that this will log the password used for authentication to stdout.
 
+.TP
+.B \-o, \-\-use-composite-overlay
+Use the composite overlay window. For some compositors it might fix windows
+appearing on top of the lock screen, for other compositors it might break.
+
 .SH DPMS
 
 The \-d (\-\-dpms) option was removed from i3lock in version 2.8. There were

i3lock.c

@@ -87,6 +87,7 @@ extern auth_state_t auth_state;
 int failed_attempts = 0;
 bool show_failed_attempts = false;
 bool retry_verification = false;
+bool use_composite_overlay = false;
 
 static struct xkb_state *xkb_state;
 static struct xkb_context *xkb_context;
@@ -895,6 +896,7 @@ int main(int argc, char *argv[]) {
         {"inactivity-timeout", required_argument, NULL, 'I'},
         {"show-failed-attempts", no_argument, NULL, 'f'},
         {"lock-console", no_argument, NULL, 'l'},
+        {"use-composite-overlay", no_argument, NULL, 'o'},
         {NULL, no_argument, NULL, 0}};
 
     if ((pw = getpwuid(getuid())) == NULL)
@@ -967,9 +969,12 @@ int main(int argc, char *argv[]) {
                 errx(EXIT_FAILURE, "TTY switch locking is only supported on Linux.");
 #endif
                 break;
+            case 'o':
+                use_composite_overlay = true;
+                break;
             default:
                 errx(EXIT_FAILURE, "Syntax: i3lock [-v] [-n] [-b] [-d] [-c color] [-u] [-p win|default]"
-                                   " [-i image.png] [-t] [-e] [-I timeout] [-f] [-l]");
+                                   " [-i image.png] [-t] [-e] [-I timeout] [-f] [-l] [-o]");
         }
     }
 

travis/Dockerfile

@@ -19,7 +19,7 @@ RUN apt-get update && \
     build-essential clang git autoconf automake libxcb-randr0-dev pkg-config libpam0g-dev \
     libcairo2-dev libxcb1-dev libxcb-dpms0-dev libxcb-image0-dev libxcb-util0-dev \
     libxcb-xrm-dev libev-dev libxcb-xinerama0-dev libxcb-xkb-dev libxkbcommon-dev \
-    libxkbcommon-x11-dev && \
+    libxkbcommon-x11-dev libxcb-composite0-dev && \
     rm -rf /var/lib/apt/lists/*
 
 WORKDIR /usr/src

xcb.c

@@ -11,6 +11,7 @@
 #include <xcb/xcb_image.h>
 #include <xcb/xcb_atom.h>
 #include <xcb/xcb_aux.h>
+#include <xcb/composite.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdbool.h>
@@ -25,6 +26,7 @@
 #include "unlock_indicator.h"
 
 extern auth_state_t auth_state;
+extern bool use_composite_overlay;
 
 xcb_connection_t *conn;
 xcb_screen_t *screen;
@@ -107,6 +109,32 @@ xcb_window_t open_fullscreen_window(xcb_connection_t *conn, xcb_screen_t *scr, c
     uint32_t mask = 0;
     uint32_t values[3];
     xcb_window_t win = xcb_generate_id(conn);
+    xcb_window_t parent_win = scr->root;
+
+    /* Check whether the composite extension is available */
+
+    if (use_composite_overlay) {
+        const xcb_query_extension_reply_t *extension_query = NULL;
+        xcb_generic_error_t *error = NULL;
+        xcb_composite_get_overlay_window_cookie_t cookie;
+        xcb_composite_get_overlay_window_reply_t *composite_reply = NULL;
+
+        extension_query = xcb_get_extension_data(conn, &xcb_composite_id);
+        if (extension_query && extension_query->present) {
+            /* When composition is used, we need to use the composite overlay
+             * window instead of the normal root window to be able to cover
+             * composited windows */
+            cookie = xcb_composite_get_overlay_window(conn, scr->root);
+            composite_reply = xcb_composite_get_overlay_window_reply(conn, cookie, &error);
+
+            if (!error && composite_reply) {
+                parent_win = composite_reply->overlay_win;
+            }
+
+            free(composite_reply);
+            free(error);
+        }
+    }
 
     if (pixmap == XCB_NONE) {
         mask |= XCB_CW_BACK_PIXEL;
@@ -128,8 +156,8 @@ xcb_window_t open_fullscreen_window(xcb_connection_t *conn, xcb_screen_t *scr, c
 
     xcb_create_window(conn,
                       XCB_COPY_FROM_PARENT,
-                      win,       /* the window id */
-                      scr->root, /* parent == root */
+                      win, /* the window id */
+                      parent_win,
                       0, 0,
                       scr->width_in_pixels,
                       scr->height_in_pixels, /* dimensions */