wm/win: fix handling of windows with multiple window types

ICCCM states a window can have multiple types, which we didn't handle.

Fixing this also includes a slight change to the dbus interface, I hope
that doesn't break too many people.

Also this is pretty unfixable for `wintypes`, and we are moving to
universal rules anyway, so I didn't bother.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

CHANGELOG.md

@@ -36,6 +36,7 @@
 * Type and format specifiers are no longer used in rules. These specifiers are what you put after the colon (':') in rules, e.g. the `:32c` in `"_GTK_FRAME_EXTENTS@:32c"`. Now this information is ignored and the property is matched regardless of format or type.
 * `backend` is now a required option. picom will not start if one is not specified explicitly.
 * New predefined target for conditions: `group_focused`. This target indicate whether the focused window is in the same window group as the window being matched.
+* Meaning of `window_type` in conditions changed slightly, now it supports windows with multiple types. (However the behavior of `wintypes` remains unchanged.)
 
 ## Deprecated features
 

man/picom.1.adoc

@@ -414,7 +414,7 @@ Supported predefined targets are: :::
 	Whether the window bounding shape only has rounded corners, and is otherwise rectangular. This implies <<c2-bounding-shaped>>. Requires <<detect-rounded-corners>>. This has no relation to <<corner-radius>>.
 
   `window_type`::::
-	Window type, as defined by _pass:[_]NET_WM_WINDOW_TYPE_. Name only, e.g. _normal_ means _pass:[_]NET_WM_WINDOW_TYPE_NORMAL_.
+	Window type, as defined by _pass:[_]NET_WM_WINDOW_TYPE_. Name only, e.g. _normal_ means _pass:[_]NET_WM_WINDOW_TYPE_NORMAL_. Because a window can have multiple types, testing for equality succeeds if any of the window's types match.
 
   `name`::::
 	Name of the window. This is either _pass:[_]NET_WM_NAME_ or _pass:[_]WM_NAME_.
@@ -538,7 +538,7 @@ When `@include` directive is used in the config file, picom will first search fo
 
 picom uses general libconfig configuration file format. A sample configuration file is available as `picom.sample.conf` in the source tree. Most of command line switches can be used as options in configuration file as well. For example, *--vsync* option documented above can be set in the configuration file using `vsync = `. Command line options will always overwrite the settings in the configuration file.
 
-Window-type-specific settings allow you to set window-specific options based on the window type. These settings are exposed only in configuration file. Using this is discouraged, see the xref:_window_rules[*WINDOW RULES*] section for the recommended way to set window-specific options. The format of this option is as follows:
+Window-type-specific settings allow you to set window-specific options based on the window type. These settings are exposed only in configuration file. The format of this option is as follows:
 
 [#wintypes]
 ------------
@@ -548,6 +548,10 @@ wintypes:
 };
 ------------
 
+WARNING: Using this is highly discouraged, see the xref:_window_rules[*WINDOW RULES*] section for the recommended way to set window-specific options.
+
+IMPORTANT: According to the window manager specification, a window can have multiple types. But due to the limitation of how _wintypes_ was implemented, if a window has multiple types, then for the purpose of applying `wintypes` options, one of the window types will be chosen at random. Again, you are recommended to use xref:_window_rules[*WINDOW RULES*] instead.
+
 _WINDOW_TYPE_ is one of the 15 window types defined in EWMH standard: "unknown", "desktop", "dock", "toolbar", "menu", "utility", "splash", "dialog", "normal", "dropdown_menu", "popup_menu", "tooltip", "notification", "combo", and "dnd".
 
 Following per window-type options are available: ::

src/c2.c

@@ -1712,14 +1712,22 @@ c2_match_once_leaf_string(struct atom *atoms, const struct win *w, const c2_l_t
 	// A predefined target
 	const char *predef_target = NULL;
 	if (leaf->predef != C2_L_PUNDEFINED) {
+		if (leaf->predef == C2_L_PWINDOWTYPE) {
+			for (unsigned i = 0; i < NUM_WINTYPES; i++) {
+				if (w->window_types & (1 << i) &&
+				    c2_string_op(leaf, WINTYPES[i].name)) {
+					return true;
+				}
+			}
+			return false;
+		}
+
 		switch (leaf->predef) {
-		case C2_L_PWINDOWTYPE:
-			predef_target = WINTYPES[w->window_type].name;
-			break;
 		case C2_L_PNAME: predef_target = w->name; break;
 		case C2_L_PCLASSG: predef_target = w->class_general; break;
 		case C2_L_PCLASSI: predef_target = w->class_instance; break;
 		case C2_L_PROLE: predef_target = w->role; break;
+		case C2_L_PWINDOWTYPE:
 		default: unreachable();
 		}
 		if (!predef_target) {

src/compiler.h

@@ -118,6 +118,10 @@
 # define __has_include(x) 0
 #endif
 
+#ifndef __has_builtin
+# define __has_builtin(x) 0
+#endif
+
 #if !defined(__STDC_NO_THREADS__) && __has_include(<threads.h>)
 # include <threads.h>
 #elif __STDC_VERSION__ >= 201112L
@@ -137,3 +141,19 @@ typedef unsigned int uint;
 static inline int attr_const popcntul(unsigned long a) {
 	return __builtin_popcountl(a);
 }
+
+/// Get the index of the lowest bit set in a number. The result is undefined if
+/// `a` is 0.
+static inline int attr_const index_of_lowest_one(unsigned a) {
+#if __has_builtin(__builtin_ctz)
+	return __builtin_ctz(a);
+#else
+	auto lowbit = (a & -a);
+	int r = (lowbit & 0xAAAAAAAA) != 0;
+	r |= ((lowbit & 0xCCCCCCCC) != 0) << 1;
+	r |= ((lowbit & 0xF0F0F0F0) != 0) << 2;
+	r |= ((lowbit & 0xFF00FF00) != 0) << 3;
+	r |= ((lowbit & 0xFFFF0000) != 0) << 4;
+	return r;
+#endif
+}

src/dbus.c

@@ -605,13 +605,33 @@ cdbus_process_window_property_get(session_t *ps, DBusMessage *msg, cdbus_window_
 
 	append(Mapped, bool_variant, w->state == WSTATE_MAPPED);
 	append(Id, wid_variant, win_id(w));
-	append(Type, string_variant, WINTYPES[w->window_type].name);
 	append(RawFocused, bool_variant,
 	       w->a.map_state == XCB_MAP_STATE_VIEWABLE && w->is_focused);
 	append(ClientWin, wid_variant, win_client_id(w, /*fallback_to_self=*/true));
 	append(Leader, wid_variant, wm_ref_win_id(wm_ref_leader(w->tree_ref)));
 	append_win_property(Name, name, string_variant);
 
+	if (!strcmp("Type", target)) {
+		DBusMessageIter iter, sub;
+		dbus_message_iter_init_append(reply, &iter);
+		if (!dbus_message_iter_open_container(&iter, DBUS_TYPE_ARRAY, "s", &sub)) {
+			return DBUS_HANDLER_RESULT_NEED_MEMORY;
+		}
+		for (int i = 0; i < NUM_WINTYPES; i++) {
+			if ((w->window_types & (1 << i)) == 0) {
+				continue;
+			}
+			if (!dbus_message_iter_append_basic(&sub, DBUS_TYPE_STRING,
+			                                    &WINTYPES[i].name)) {
+				return DBUS_HANDLER_RESULT_NEED_MEMORY;
+			}
+		}
+		if (!dbus_message_iter_close_container(&iter, &sub)) {
+			return DBUS_HANDLER_RESULT_NEED_MEMORY;
+		}
+		return DBUS_HANDLER_RESULT_HANDLED;
+	}
+
 	if (!strcmp("Next", target)) {
 		cdbus_window_t next_id = 0;
 		auto below = wm_ref_below(cursor);
@@ -736,7 +756,7 @@ cdbus_process_win_get(session_t *ps, DBusMessage *msg, DBusMessage *reply, DBusE
 	append_win_property(mode, enum);
 	append_win_property(opacity, double);
 	append_win_property(ever_damaged, boolean);
-	append_win_property(window_type, enum);
+	append_win_property(window_types, enum);
 	append_win_property(name, string);
 	append_win_property(class_instance, string);
 	append_win_property(class_general, string);
@@ -1188,7 +1208,7 @@ static bool cdbus_process_window_introspect(DBusMessage *reply) {
 	    "    <property type='b' name='RawFocused' access='read'/>\n"
 	    "    <property type='b' name='Mapped' access='read'/>\n"
 	    "    <property type='s' name='Name' access='read'/>\n"
-	    "    <property type='s' name='Type' access='read'/>\n"
+	    "    <property type='as' name='Type' access='read'/>\n"
 	    "  </interface>\n"
 	    "</node>\n";
 	// clang-format on

src/inspect.c

@@ -280,8 +280,12 @@ int inspect_main(int argc, char **argv, const char *config_file) {
 	if (w->role != NULL) {
 		printf("    role = '%s'\n", w->role);
 	}
-	if (w->window_type != WINTYPE_UNKNOWN) {
+	if (w->window_types != 0) {
-		printf("    window_type = '%s'\n", WINTYPES[w->window_type].name);
+		for (int i = 0; i < NUM_WINTYPES; i++) {
+			if (w->window_types & (1 << i)) {
+				printf("    window_type = '%s'\n", WINTYPES[i].name);
+			}
+		}
 	}
 	printf("    %sfullscreen\n", w->is_fullscreen ? "" : "! ");
 	if (w->bounding_shaped) {

src/wm/win.c

@@ -105,7 +105,7 @@ static bool win_is_focused(session_t *ps, struct win *w) {
 	}
 	// Use wintype_focus, and treat WM windows and override-redirected
 	// windows specially
-	if (ps->o.wintype_option[w->window_type].focus ||
+	if (ps->o.wintype_option[index_of_lowest_one(w->window_types)].focus ||
 	    (ps->o.mark_wmwin_focused && is_wmwin) ||
 	    (ps->o.mark_ovredir_focused && wm_ref_client_of(w->tree_ref) == NULL && !is_wmwin) ||
 	    (w->a.map_state == XCB_MAP_STATE_VIEWABLE &&
@@ -655,24 +655,26 @@ static inline bool win_bounding_shaped(struct x_connection *c, xcb_window_t wid)
 	return bounding_shaped;
 }
 
-static wintype_t
+static uint32_t
-wid_get_prop_wintype(struct x_connection *c, struct atom *atoms, xcb_window_t wid) {
+wid_get_prop_window_types(struct x_connection *c, struct atom *atoms, xcb_window_t wid) {
 	winprop_t prop =
 	    x_get_prop(c, wid, atoms->a_NET_WM_WINDOW_TYPE, 32L, XCB_ATOM_ATOM, 32);
 
+	static_assert(NUM_WINTYPES <= 32, "too many window types");
+
+	uint32_t ret = 0;
 	for (unsigned i = 0; i < prop.nitems; ++i) {
 		for (wintype_t j = 1; j < NUM_WINTYPES; ++j) {
-			if (get_atom_with_nul(atoms, WINTYPES[j].atom, c->c) ==
+			if (get_atom_with_nul(atoms, WINTYPES[j].atom, c->c) == prop.atom[i]) {
-			    (xcb_atom_t)prop.p32[i]) {
+				ret |= (1 << j);
-				free_winprop(&prop);
+				break;
-				return j;
 			}
 		}
 	}
 
 	free_winprop(&prop);
 
-	return WINTYPE_UNKNOWN;
+	return ret;
 }
 
 // XXX should distinguish between frame has alpha and window body has alpha
@@ -745,12 +747,13 @@ static double win_calc_opacity_target(session_t *ps, const struct win *w, bool f
 		return 0;
 	}
 	// Try obeying opacity property and window type opacity firstly
+	auto window_type = index_of_lowest_one(w->window_types);
 	if (w->has_opacity_prop) {
 		opacity = ((double)w->opacity_prop) / OPAQUE;
 	} else if (!safe_isnan(w->options.opacity)) {
 		opacity = w->options.opacity;
-	} else if (!safe_isnan(ps->o.wintype_option[w->window_type].opacity)) {
+	} else if (!safe_isnan(ps->o.wintype_option[window_type].opacity)) {
-		opacity = ps->o.wintype_option[w->window_type].opacity;
+		opacity = ps->o.wintype_option[window_type].opacity;
 	} else {
 		// Respect active_opacity only when the window is physically
 		// focused
@@ -840,7 +843,7 @@ static void win_determine_shadow(session_t *ps, struct win *w) {
 	if (w->a.map_state != XCB_MAP_STATE_VIEWABLE) {
 		return;
 	}
-	if (!ps->o.wintype_option[w->window_type].shadow) {
+	if (!ps->o.wintype_option[index_of_lowest_one(w->window_types)].shadow) {
 		log_debug("Shadow disabled by wintypes");
 		w->options.shadow = TRI_FALSE;
 	} else if (c2_match(ps->c2_state, w, ps->o.shadow_blacklist, NULL)) {
@@ -887,8 +890,9 @@ bool win_update_prop_fullscreen(struct x_connection *c, const struct atom *atoms
 }
 
 static void win_determine_clip_shadow_above(session_t *ps, struct win *w) {
-	bool should_crop = (ps->o.wintype_option[w->window_type].clip_shadow_above ||
+	bool should_crop =
-	                    c2_match(ps->c2_state, w, ps->o.shadow_clip_list, NULL));
+	    (ps->o.wintype_option[index_of_lowest_one(w->window_types)].clip_shadow_above ||
+	     c2_match(ps->c2_state, w, ps->o.shadow_clip_list, NULL));
 	w->options.clip_shadow_above = should_crop ? TRI_TRUE : TRI_UNKNOWN;
 }
 
@@ -918,7 +922,7 @@ static void win_determine_blur_background(session_t *ps, struct win *w) {
 
 	bool blur_background_new = ps->o.blur_method != BLUR_METHOD_NONE;
 	if (blur_background_new) {
-		if (!ps->o.wintype_option[w->window_type].blur_background) {
+		if (!ps->o.wintype_option[index_of_lowest_one(w->window_types)].blur_background) {
 			log_debug("Blur background disabled by wintypes");
 			w->options.blur_background = TRI_FALSE;
 		} else if (c2_match(ps->c2_state, w, ps->o.blur_background_blacklist, NULL)) {
@@ -1029,8 +1033,10 @@ void win_on_factor_change(session_t *ps, struct win *w) {
 	// on the focused state of the window
 	win_update_is_fullscreen(ps, w);
 
+	assert(w->window_types != 0);
 	if (ps->o.rules == NULL) {
 		bool focused = win_is_focused(ps, w);
+		auto window_type = index_of_lowest_one(w->window_types);
 		// Universal rules take precedence over wintype_option and
 		// other exclusion/inclusion lists. And it also supersedes
 		// some of the "override" options.
@@ -1056,7 +1062,7 @@ void win_on_factor_change(session_t *ps, struct win *w) {
 		}
 		if (w->a.map_state == XCB_MAP_STATE_VIEWABLE &&
 		    c2_match(ps->c2_state, w, ps->o.unredir_if_possible_blacklist, NULL)) {
-			if (ps->o.wintype_option[w->window_type].redir_ignore) {
+			if (ps->o.wintype_option[window_type].redir_ignore) {
 				w->options.unredir = WINDOW_UNREDIR_PASSIVE;
 			} else {
 				w->options.unredir = WINDOW_UNREDIR_TERMINATE;
@@ -1067,7 +1073,7 @@ void win_on_factor_change(session_t *ps, struct win *w) {
 			// look different after unredirecting. Instead we always follow
 			// the request.
 			w->options.unredir = WINDOW_UNREDIR_FORCED;
-		} else if (ps->o.wintype_option[w->window_type].redir_ignore) {
+		} else if (ps->o.wintype_option[window_type].redir_ignore) {
 			w->options.unredir = WINDOW_UNREDIR_WHEN_POSSIBLE;
 		}
 
@@ -1078,7 +1084,7 @@ void win_on_factor_change(session_t *ps, struct win *w) {
 			w->options.transparent_clipping = TRI_FALSE;
 		}
 		w->options.full_shadow =
-		    tri_from_bool(ps->o.wintype_option[w->window_type].full_shadow);
+		    tri_from_bool(ps->o.wintype_option[window_type].full_shadow);
 	} else {
 		struct win_update_rule_params params = {
 		    .w = w,
@@ -1136,27 +1142,27 @@ void win_on_win_size_change(struct win *w, int shadow_offset_x, int shadow_offse
  * Update window type.
  */
 bool win_update_wintype(struct x_connection *c, struct atom *atoms, struct win *w) {
-	const wintype_t wtype_old = w->window_type;
+	const uint32_t wtypes_old = w->window_types;
 	auto wid = win_client_id(w, /*fallback_to_self=*/true);
 
 	// Detect window type here
-	w->window_type = wid_get_prop_wintype(c, atoms, wid);
+	w->window_types = wid_get_prop_window_types(c, atoms, wid);
 
 	// Conform to EWMH standard, if _NET_WM_WINDOW_TYPE is not present, take
 	// override-redirect windows or windows without WM_TRANSIENT_FOR as
 	// _NET_WM_WINDOW_TYPE_NORMAL, otherwise as _NET_WM_WINDOW_TYPE_DIALOG.
-	if (WINTYPE_UNKNOWN == w->window_type) {
+	if (w->window_types == 0) {
 		if (w->a.override_redirect ||
 		    !wid_has_prop(c->c, wid, atoms->aWM_TRANSIENT_FOR)) {
-			w->window_type = WINTYPE_NORMAL;
+			w->window_types = (1 << WINTYPE_NORMAL);
 		} else {
-			w->window_type = WINTYPE_DIALOG;
+			w->window_types = (1 << WINTYPE_DIALOG);
 		}
 	}
 
-	log_debug("Window (%#010x) has type %s", win_id(w), WINTYPES[w->window_type].name);
+	log_debug("Window (%#010x) has type %#x", win_id(w), w->window_types);
 
-	return w->window_type != wtype_old;
+	return w->window_types != wtypes_old;
 }
 
 /**
@@ -1253,7 +1259,6 @@ struct win *win_maybe_allocate(session_t *ps, struct wm_ref *cursor,
 	                                 // change
 
 	    .mode = WMODE_TRANS,
-	    .window_type = WINTYPE_UNKNOWN,
 	    .opacity_prop = OPAQUE,
 	    .opacity_set = 1,
 	    .frame_extents = MARGIN_INIT,

src/wm/win.h

@@ -165,8 +165,9 @@ struct win {
 	bool in_openclose;
 
 	// Client window related members
-	/// Type of the window.
+	/// A bitflag of window types. According to ICCCM, a window can have more than one
-	wintype_t window_type;
+	/// type.
+	uint32_t window_types;
 
 	// Blacklist related members
 	/// Name of the window.