state: support querying whether virtual modifiers are active

Previously it was not possible to query the status of virtual modifiers
with the following functions:
- `xkb_state_mod_index_is_active`
- `xkb_state_mod_indices_are_active`
- `xkb_state_mod_name_is_active`
- `xkb_state_mod_names_are_active`

Note that it may *overmatch* if some modifier mappings overlap. For
example, the default “us” PC layout maps both “Alt” and “Meta” to the
real modifier “Mod1”; thus “Mod1”, “Alt” and “Meta” modifiers will
return the same result with these functions.

changes/api/+query-virtual-modifiers-state.bugfix.md

@@ -0,0 +1,9 @@
+The following functions now allow to query also *virtual* modifiers, so they work
+with *any* modifiers (real *and* virtual):
+- `xkb_state_mod_index_is_active`
+- `xkb_state_mod_indices_are_active`
+- `xkb_state_mod_name_is_active`
+- `xkb_state_mod_names_are_active`
+
+Warning: they may overmatch in case there are overlappings virtual-to-real
+modifiers mappings.

include/xkbcommon/xkbcommon.h

@@ -1706,10 +1706,19 @@ xkb_state_serialize_layout(struct xkb_state *state,
 /**
  * Test whether a modifier is active in a given keyboard state by name.
  *
+ * @warning For [virtual modifiers], this function may *overmatch* in case
+ * there are virtual modifiers with overlapping mappings to [real modifiers].
+ *
  * @returns 1 if the modifier is active, 0 if it is not.  If the modifier
  * name does not exist in the keymap, returns -1.
  *
  * @memberof xkb_state
+ *
+ * @since 0.1.0: Works only with *real* modifiers
+ * @since 1.8.0: Works also with *virtual* modifiers
+ *
+ * [virtual modifiers]: @ref virtual-modifier-def
+ * [real modifiers]: @ref real-modifier-def
  */
 int
 xkb_state_mod_name_is_active(struct xkb_state *state, const char *name,
@@ -1719,6 +1728,9 @@ xkb_state_mod_name_is_active(struct xkb_state *state, const char *name,
  * Test whether a set of modifiers are active in a given keyboard state by
  * name.
  *
+ * @warning For [virtual modifiers], this function may *overmatch* in case
+ * there are virtual modifiers with overlapping mappings to [real modifiers].
+ *
  * @param state The keyboard state.
  * @param type  The component of the state against which to match the
  * given modifiers.
@@ -1731,6 +1743,12 @@ xkb_state_mod_name_is_active(struct xkb_state *state, const char *name,
  * the modifier names do not exist in the keymap, returns -1.
  *
  * @memberof xkb_state
+ *
+ * @since 0.1.0: Works only with *real* modifiers
+ * @since 1.8.0: Works also with *virtual* modifiers
+ *
+ * [virtual modifiers]: @ref virtual-modifier-def
+ * [real modifiers]: @ref real-modifier-def
  */
 int
 xkb_state_mod_names_are_active(struct xkb_state *state,
@@ -1741,10 +1759,19 @@ xkb_state_mod_names_are_active(struct xkb_state *state,
 /**
  * Test whether a modifier is active in a given keyboard state by index.
  *
+ * @warning For [virtual modifiers], this function may *overmatch* in case
+ * there are virtual modifiers with overlapping mappings to [real modifiers].
+ *
  * @returns 1 if the modifier is active, 0 if it is not.  If the modifier
  * index is invalid in the keymap, returns -1.
  *
  * @memberof xkb_state
+ *
+ * @since 0.1.0: Works only with *real* modifiers
+ * @since 1.8.0: Works also with *virtual* modifiers
+ *
+ * [virtual modifiers]: @ref virtual-modifier-def
+ * [real modifiers]: @ref real-modifier-def
  */
 int
 xkb_state_mod_index_is_active(struct xkb_state *state, xkb_mod_index_t idx,
@@ -1754,6 +1781,9 @@ xkb_state_mod_index_is_active(struct xkb_state *state, xkb_mod_index_t idx,
  * Test whether a set of modifiers are active in a given keyboard state by
  * index.
  *
+ * @warning For [virtual modifiers], this function may *overmatch* in case
+ * there are virtual modifiers with overlapping mappings to [real modifiers].
+ *
  * @param state The keyboard state.
  * @param type  The component of the state against which to match the
  * given modifiers.
@@ -1766,6 +1796,12 @@ xkb_state_mod_index_is_active(struct xkb_state *state, xkb_mod_index_t idx,
  * the modifier indices are invalid in the keymap, returns -1.
  *
  * @memberof xkb_state
+ *
+ * @since 0.1.0: Works only with *real* modifiers
+ * @since 1.8.0: Works also with *virtual* modifiers
+ *
+ * [virtual modifiers]: @ref virtual-modifier-def
+ * [real modifiers]: @ref real-modifier-def
  */
 int
 xkb_state_mod_indices_are_active(struct xkb_state *state,

src/keymap.h

@@ -104,10 +104,10 @@
 #define XKB_MAX_GROUPS 4
 
 /* Don't allow more modifiers than we can hold in xkb_mod_mask_t. */
-#define XKB_MAX_MODS ((xkb_mod_index_t) (sizeof(xkb_mod_mask_t) * 8))
+#define XKB_MAX_MODS ((xkb_mod_index_t) (sizeof(xkb_mod_mask_t) * CHAR_BIT))
 
 /* Don't allow more leds than we can hold in xkb_led_mask_t. */
-#define XKB_MAX_LEDS ((xkb_led_index_t) (sizeof(xkb_led_mask_t) * 8))
+#define XKB_MAX_LEDS ((xkb_led_index_t) (sizeof(xkb_led_mask_t) * CHAR_BIT))
 
 /* Special value to handle modMap None {…} */
 #define XKB_MOD_NONE 0xffffffffU

src/state.c

@@ -1265,6 +1265,17 @@ mod_mask_get_effective(struct xkb_keymap *keymap, xkb_mod_mask_t mods)
     return mask;
 }
 
+/* Get the mapping of a modifier */
+static inline xkb_mod_mask_t
+mod_mapping(struct xkb_mod *mod, xkb_mod_index_t idx)
+{
+    /*
+     * We cannot use `mod->mapping` directly, because it is
+     * not set for real modifiers.
+     */
+    return (mod->type & MOD_REAL) ? (1u << idx) : mod->mapping;
+}
+
 /**
  * Returns 1 if the given modifier is active with the specified type(s), 0 if
  * not, or -1 if the modifier is invalid.
@@ -1274,10 +1285,16 @@ xkb_state_mod_index_is_active(struct xkb_state *state,
                               xkb_mod_index_t idx,
                               enum xkb_state_component type)
 {
-    if (idx >= xkb_keymap_num_mods(state->keymap))
+    if (unlikely(idx >= xkb_keymap_num_mods(state->keymap)))
         return -1;
 
-    return !!(xkb_state_serialize_mods(state, type) & (1u << idx));
+    xkb_mod_mask_t mapping = mod_mapping(&state->keymap->mods.mods[idx], idx);
+    if (!mapping) {
+        /* Modifier not mapped */
+        return 0;
+    }
+    /* WARNING: this may overmatch for virtual modifiers */
+    return !!((xkb_state_serialize_mods(state, type) & mapping) == mapping);
 }
 
 /**
@@ -1321,17 +1338,22 @@ xkb_state_mod_indices_are_active(struct xkb_state *state,
         xkb_mod_index_t idx = va_arg(ap, xkb_mod_index_t);
         if (idx == XKB_MOD_INVALID)
             break;
-        if (idx >= num_mods) {
+        if (unlikely(idx >= num_mods)) {
             ret = -1;
             break;
         }
-        wanted |= (1u << idx);
+        wanted |= mod_mapping(&state->keymap->mods.mods[idx], idx);
     }
     va_end(ap);
 
     if (ret == -1)
         return ret;
 
+    if (!wanted) {
+        /* Modifiers not mapped */
+        return 0;
+    }
+
     return match_mod_masks(state, type, match, wanted);
 }
 
@@ -1376,13 +1398,18 @@ xkb_state_mod_names_are_active(struct xkb_state *state,
             ret = -1;
             break;
         }
-        wanted |= (1u << idx);
+        wanted |= mod_mapping(&state->keymap->mods.mods[idx], idx);
     }
     va_end(ap);
 
     if (ret == -1)
         return ret;
 
+    if (!wanted) {
+        /* Modifiers not mapped */
+        return 0;
+    }
+
     return match_mod_masks(state, type, match, wanted);
 }
 
@@ -1392,8 +1419,8 @@ xkb_state_mod_names_are_active(struct xkb_state *state,
  */
 XKB_EXPORT int
 xkb_state_layout_index_is_active(struct xkb_state *state,
-                                xkb_layout_index_t idx,
-                                enum xkb_state_component type)
+                                 xkb_layout_index_t idx,
+                                 enum xkb_state_component type)
 {
     int ret = 0;
 

test/data/rules/evdev

@@ -1157,6 +1157,8 @@
   lv5:lwin_switch_lock_cancel     =       +level5(lwin_switch_lock_cancel)
   lv5:rwin_switch_lock_cancel     =       +level5(rwin_switch_lock_cancel)
   parens:swap_brackets   =   +parens(swap_brackets)
+  overlapping_modifiers:super_hyper =     +overlapping_modifiers(super_hyper)
+  overlapping_modifiers:meta        =     +overlapping_modifiers(meta)
 
 
 ! option	=	compat

test/data/symbols/overlapping_modifiers

@@ -0,0 +1,15 @@
+partial modifier_keys
+xkb_symbols "super_hyper" {
+	key <MDSW> {
+		type[1] = "TWO_LEVEL",
+		symbols[1] = [ Super_L, Hyper_L ]
+	};
+	modifier_map Mod3 { <MDSW> };
+};
+xkb_symbols "meta" {
+	key <META> {
+		type[1] = "ONE_LEVEL",
+		symbols[1] = [ Meta_L ]
+	};
+	modifier_map Mod3 { <META> };
+};