core: parse and use universal rules

Design is described in #1284.

Added a trivial test of universal rules

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

src/c2.c

@@ -44,6 +44,7 @@ typedef struct _c2_l c2_l_t;
 /// Pointer to a condition tree.
 typedef struct {
 	bool isbranch : 1;
+	bool istrue : 1;
 	union {
 		c2_b_t *b;
 		c2_l_t *l;
@@ -101,13 +102,11 @@ struct c2_property_value {
 };
 
 /// Initializer for c2_ptr_t.
-#define C2_PTR_INIT                                                                      \
-	{                                                                                \
-	    .isbranch = false,                                                           \
-	    .l = NULL,                                                                   \
-	}
-
-static const c2_ptr_t C2_PTR_NULL = C2_PTR_INIT;
+static const c2_ptr_t C2_PTR_INIT = {
+    .isbranch = false,
+    .istrue = false,
+    .l = NULL,
+};
 
 /// Operator of a branch element.
 typedef enum {
@@ -199,23 +198,20 @@ struct _c2_l {
 };
 
 /// Initializer for c2_l_t.
-#define C2_L_INIT                                                                        \
-	{                                                                                \
-	    .neg = false,                                                                \
-	    .op = C2_L_OEXISTS,                                                          \
-	    .match = C2_L_MEXACT,                                                        \
-	    .match_ignorecase = false,                                                   \
-	    .tgt = NULL,                                                                 \
-	    .tgtatom = 0,                                                                \
-	    .target_on_client = false,                                                   \
-	    .predef = C2_L_PUNDEFINED,                                                   \
-	    .index = 0,                                                                  \
-	    .ptntype = C2_L_PTUNDEFINED,                                                 \
-	    .ptnstr = NULL,                                                              \
-	    .ptnint = 0,                                                                 \
-	}
-
-static const c2_l_t leaf_def = C2_L_INIT;
+static const c2_l_t C2_L_INIT = {
+    .neg = false,
+    .op = C2_L_OEXISTS,
+    .match = C2_L_MEXACT,
+    .match_ignorecase = false,
+    .tgt = NULL,
+    .tgtatom = 0,
+    .target_on_client = false,
+    .predef = C2_L_PUNDEFINED,
+    .index = 0,
+    .ptntype = C2_L_PTUNDEFINED,
+    .ptnstr = NULL,
+    .ptnint = 0,
+};
 
 /// Linked list type of conditions.
 struct _c2_lptr {
@@ -299,7 +295,7 @@ static inline attr_unused bool c2_ptr_isempty(const c2_ptr_t p) {
  */
 static inline void c2_ptr_reset(c2_ptr_t *pp) {
 	if (pp) {
-		memcpy(pp, &C2_PTR_NULL, sizeof(c2_ptr_t));
+		*pp = C2_PTR_INIT;
 	}
 }
 
@@ -697,7 +693,7 @@ static int c2_parse_grp(const char *pattern, int offset, c2_ptr_t *presult, int
 			}
 			// Otherwise, combine the second and the incoming one
 			else {
-				eles[1] = c2h_comb_tree(ops[2], eles[1], C2_PTR_NULL);
+				eles[1] = c2h_comb_tree(ops[2], eles[1], C2_PTR_INIT);
 				assert(eles[1].isbranch);
 				pele = &eles[1].b->opr2;
 			}
@@ -811,7 +807,7 @@ static int c2_parse_target(const char *pattern, int offset, c2_ptr_t *presult) {
 	presult->l = cmalloc(c2_l_t);
 
 	c2_l_t *const pleaf = presult->l;
-	memcpy(pleaf, &leaf_def, sizeof(c2_l_t));
+	*pleaf = C2_L_INIT;
 
 	// Parse negation marks
 	while ('!' == pattern[offset]) {
@@ -1168,7 +1164,7 @@ static int c2_parse_legacy(const char *pattern, int offset, c2_ptr_t *presult) {
 	auto pleaf = cmalloc(c2_l_t);
 	presult->isbranch = false;
 	presult->l = pleaf;
-	memcpy(pleaf, &leaf_def, sizeof(c2_l_t));
+	*pleaf = C2_L_INIT;
 	pleaf->op = C2_L_OEQ;
 	pleaf->ptntype = C2_L_PTSTRING;
 
@@ -1853,6 +1849,8 @@ static bool c2_match_once(struct c2_state *state, const struct win *w, const c2_
 
 		log_debug("(%#010x): branch: result = %d, pattern = %s", win_id(w),
 		          result, c2_condition_to_str2(cond));
+	} else if (cond.istrue) {
+		return true;
 	} else {
 		// A leaf
 		const c2_l_t *pleaf = cond.l;
@@ -1876,6 +1874,12 @@ static bool c2_match_once(struct c2_state *state, const struct win *w, const c2_
 	return result;
 }
 
+c2_lptr_t *c2_new_true(void) {
+	auto ret = ccalloc(1, c2_lptr_t);
+	ret->ptr = (c2_ptr_t){.istrue = true};
+	return ret;
+}
+
 /**
  * Match a window against a condition linked list.
  *
@@ -1932,6 +1936,12 @@ void *c2_list_get_data(const c2_lptr_t *condlist) {
 	return condlist->data;
 }
 
+void *c2_list_set_data(c2_lptr_t *condlist, void *data) {
+	void *old = condlist->data;
+	condlist->data = data;
+	return old;
+}
+
 struct c2_state *c2_state_new(struct atom *atoms) {
 	auto ret = ccalloc(1, struct c2_state);
 	ret->atoms = atoms;
@@ -2182,3 +2192,9 @@ bool c2_state_is_property_tracked(struct c2_state *state, xcb_atom_t property) {
 	HASH_FIND(hh, state->tracked_properties, &key, sizeof(key), p);
 	return p != NULL;
 }
+
+void c2_condlist_insert(c2_lptr_t **pcondlst, c2_lptr_t *pnew) {
+	c2_lptr_t *pcur = *pcondlst;
+	pnew->next = pcur;
+	*pcondlst = pnew;
+}

src/c2.h

@@ -60,9 +60,14 @@ typedef bool (*c2_list_foreach_cb_t)(const c2_lptr_t *cond, void *data);
 bool c2_list_foreach(const c2_lptr_t *list, c2_list_foreach_cb_t cb, void *data);
 /// Return user data stored in a condition.
 void *c2_list_get_data(const c2_lptr_t *condlist);
+/// Set user data stored in a condition. Return the old user data.
+void *c2_list_set_data(c2_lptr_t *condlist, void *data);
 /// Convert a c2_lptr_t to string. The returned string is only valid until the
 /// next call to this function, and should not be freed.
 const char *c2_lptr_to_str(const c2_lptr_t *);
+void c2_condlist_insert(c2_lptr_t **pcondlst, c2_lptr_t *pnew);
+/// Create a new condition list with a single condition that is always true.
+c2_lptr_t *c2_new_true(void);
 
 /**
  * Destroy a condition list.

src/config.c

@@ -717,7 +717,9 @@ bool parse_config(options_t *opt, const char *config_file) {
 
 	    .track_leader = false,
 
-	    .rounded_corners_blacklist = NULL
+	    .rounded_corners_blacklist = NULL,
+
+	    .rules = NULL,
 	};
 	// clang-format on
 

src/config.h

@@ -8,6 +8,7 @@
 /// Common functions and definitions for configuration parsing
 /// Used for command line arguments and config files
 
+#include <stdalign.h>
 #include <stdbool.h>
 #include <stddef.h>
 #include <string.h>
@@ -166,6 +167,9 @@ struct window_maybe_options {
 	enum tristate unredir_ignore;
 };
 
+// Make sure `window_options` has no implicit padding.
+#pragma GCC diagnostic push
+#pragma GCC diagnostic error "-Wpadded"
 /// Like `window_maybe_options`, but all fields are guaranteed to be set.
 struct window_options {
 	double opacity;
@@ -181,17 +185,15 @@ struct window_options {
 	bool paint;
 	bool unredir_ignore;
 
-	char padding[2];
+	char padding[4];
 };
+#pragma GCC diagnostic pop
 
 static inline bool
 win_options_eq(const struct window_options *a, const struct window_options *b) {
 	return memcmp(a, b, offsetof(struct window_options, padding)) == 0;
 }
 
-static_assert(offsetof(struct window_options, padding) == 36, "window_options has "
-                                                              "implicit padding");
-
 extern struct shader_info null_shader;
 
 /// Structure representing all options.
@@ -399,6 +401,8 @@ typedef struct options {
 	struct win_script animations[ANIMATION_TRIGGER_LAST + 1];
 	/// Array of all the scripts used in `animations`. This is a dynarr.
 	struct script **all_scripts;
+
+	c2_lptr_t *rules;
 } options_t;
 
 extern const char *const BACKEND_STRS[NUM_BKEND + 1];

src/config_libconfig.c

@@ -529,6 +529,82 @@ void generate_fading_config(struct options *opt) {
 	dynarr_extend_from(opt->all_scripts, scripts, number_of_scripts);
 }
 
+static const struct {
+	const char *name;
+	ptrdiff_t offset;
+} all_window_options[] = {
+    {"fade", offsetof(struct window_maybe_options, fade)},
+    {"paint", offsetof(struct window_maybe_options, paint)},
+    {"shadow", offsetof(struct window_maybe_options, shadow)},
+    {"invert-color", offsetof(struct window_maybe_options, invert_color)},
+    {"blur-background", offsetof(struct window_maybe_options, blur_background)},
+    {"clip-shadow-above", offsetof(struct window_maybe_options, clip_shadow_above)},
+    {"transparent-clipping", offsetof(struct window_maybe_options, transparent_clipping)},
+};
+
+static c2_lptr_t *parse_rule(config_setting_t *setting) {
+	if (!config_setting_is_group(setting)) {
+		log_error("Invalid rule at line %d. It must be a group.",
+		          config_setting_source_line(setting));
+		return NULL;
+	}
+	int ival;
+	double fval;
+	const char *sval;
+	c2_lptr_t *rule = NULL;
+	if (config_setting_lookup_string(setting, "match", &sval)) {
+		rule = c2_parse(NULL, sval, NULL);
+		if (!rule) {
+			log_error("Failed to parse rule at line %d.",
+			          config_setting_source_line(setting));
+			return NULL;
+		}
+	} else {
+		// If no match condition is specified, it matches all windows
+		rule = c2_new_true();
+	}
+
+	auto wopts = cmalloc(struct window_maybe_options);
+	*wopts = (struct window_maybe_options){
+	    .opacity = NAN,
+	    .corner_radius = -1,
+	};
+	c2_list_set_data(rule, wopts);
+
+	for (size_t i = 0; i < ARR_SIZE(all_window_options); i++) {
+		if (config_setting_lookup_bool(setting, all_window_options[i].name, &ival)) {
+			void *ptr = (char *)wopts + all_window_options[i].offset;
+			*(enum tristate *)ptr = tri_from_bool(ival);
+		}
+	}
+	if (config_setting_lookup_float(setting, "opacity", &fval)) {
+		wopts->opacity = normalize_d(fval);
+	}
+	if (config_setting_lookup_float(setting, "dim", &fval)) {
+		wopts->dim = normalize_d(fval);
+	}
+	if (config_setting_lookup_int(setting, "corner-radius", &ival)) {
+		wopts->corner_radius = ival;
+	}
+	return rule;
+}
+
+static void parse_rules(config_setting_t *setting, c2_lptr_t **rules) {
+	if (!config_setting_is_list(setting)) {
+		log_error("Invalid value for \"rules\" at line %d. It must be a list.",
+		          config_setting_source_line(setting));
+		return;
+	}
+	const auto length = (unsigned int)config_setting_length(setting);
+	for (unsigned int i = 0; i < length; i++) {
+		auto sub = config_setting_get_elem(setting, i);
+		auto rule = parse_rule(sub);
+		if (rule != NULL) {
+			c2_condlist_insert(rules, rule);
+		}
+	}
+}
+
 static const char **
 resolve_include(config_t *cfg, const char *include_dir, const char *path, const char **err) {
 	char *result = locate_auxiliary_file("include", path, include_dir);
@@ -977,6 +1053,11 @@ bool parse_config_libconfig(options_t *opt, const char *config_file) {
 		parse_animations(opt->animations, animations, &opt->all_scripts);
 	}
 
+	config_setting_t *rules = config_lookup(&cfg, "rules");
+	if (rules) {
+		parse_rules(rules, &opt->rules);
+	}
+
 	opt->config_file_path = path;
 	path = NULL;
 	succeeded = true;

src/options.c

@@ -987,6 +987,7 @@ void options_destroy(struct options *options) {
 	c2_list_free(&options->corner_radius_rules, NULL);
 	c2_list_free(&options->window_shader_fg_rules, free);
 	c2_list_free(&options->transparent_clipping_blacklist, NULL);
+	c2_list_free(&options->rules, free);
 
 	free(options->config_file_path);
 	free(options->write_pid_path);

src/picom.c

@@ -1995,6 +1995,7 @@ static struct window_options win_options_from_config(const struct options *opts)
 	    .paint = true,
 	    .clip_shadow_above = false,
 	    .unredir_ignore = false,
+	    .opacity = 1,
 	};
 }