config/output: Refactor handling of tiered configs

Output configuration can be applied to a particular output in three
ways: As a wildcard, by connector name and by identifier. This in turn
means that three different configurations must be handled at any given
time.

In the current model, this is managed by merging new configuration into
every other matching configuration. At the same time, an additional
synthetic configuration is made which matchehes both identifier and name
at the same time, further complicating logic.

Instead, manage and store each configuration independently and merge
them in order when retrieving configuration for an output. When changes
are made to a less specific configuration, clear these fields from more
specific configurations to allow the change to take effect regardless of
precedence.

Fixes: swaywm#8048

Author: kennylevinsen

include/sway/config.h

@@ -692,7 +692,7 @@ bool apply_output_configs(struct matched_output_config *configs, size_t configs_
 
 void apply_all_output_configs(void);
 
-struct output_config *store_output_config(struct output_config *oc);
+void store_output_config(struct output_config *oc);
 
 struct output_config *find_output_config(struct sway_output *output);
 

sway/config/output.c

@@ -79,6 +79,71 @@ struct output_config *new_output_config(const char *name) {
 	return oc;
 }
 
+// supersede_output_config clears all fields in dst that were set in src
+static void supersede_output_config(struct output_config *dst, struct output_config *src) {
+	if (src->enabled != -1) {
+		dst->enabled = -1;
+	}
+	if (src->width != -1) {
+		dst->width = -1;
+	}
+	if (src->height != -1) {
+		dst->height = -1;
+	}
+	if (src->x != -1) {
+		dst->x = -1;
+	}
+	if (src->y != -1) {
+		dst->y = -1;
+	}
+	if (src->scale != -1) {
+		dst->scale = -1;
+	}
+	if (src->scale_filter != SCALE_FILTER_DEFAULT) {
+		dst->scale_filter = SCALE_FILTER_DEFAULT;
+	}
+	if (src->subpixel != WL_OUTPUT_SUBPIXEL_UNKNOWN) {
+		dst->subpixel = WL_OUTPUT_SUBPIXEL_UNKNOWN;
+	}
+	if (src->refresh_rate != -1) {
+		dst->refresh_rate = -1;
+	}
+	if (src->custom_mode != -1) {
+		dst->custom_mode = -1;
+	}
+	if (src->drm_mode.type != (uint32_t) -1) {
+		dst->drm_mode.type = -1;
+	}
+	if (src->transform != -1) {
+		dst->transform = -1;
+	}
+	if (src->max_render_time != -1) {
+		dst->max_render_time = -1;
+	}
+	if (src->adaptive_sync != -1) {
+		dst->adaptive_sync = -1;
+	}
+	if (src->render_bit_depth != RENDER_BIT_DEPTH_DEFAULT) {
+		dst->render_bit_depth = RENDER_BIT_DEPTH_DEFAULT;
+	}
+	if (src->background) {
+		free(dst->background);
+		dst->background = NULL;
+	}
+	if (src->background_option) {
+		free(dst->background_option);
+		dst->background_option = NULL;
+	}
+	if (src->background_fallback) {
+		free(dst->background_fallback);
+		dst->background_fallback = NULL;
+	}
+	if (src->power != -1) {
+		dst->power = -1;
+	}
+}
+
+// merge_output_config sets all fields in dst that were set in src
 static void merge_output_config(struct output_config *dst, struct output_config *src) {
 	if (src->enabled != -1) {
 		dst->enabled = src->enabled;
@@ -142,94 +207,49 @@ static void merge_output_config(struct output_config *dst, struct output_config
 	}
 }
 
-static void merge_wildcard_on_all(struct output_config *wildcard) {
-	for (int i = 0; i < config->output_configs->length; i++) {
-		struct output_config *oc = config->output_configs->items[i];
-		if (strcmp(wildcard->name, oc->name) != 0) {
-			sway_log(SWAY_DEBUG, "Merging output * config on %s", oc->name);
-			merge_output_config(oc, wildcard);
-		}
-	}
-}
+// store_output_config stores a new output config. An output may be matched by
+// three different config types, in order of precedence: Identifier, name and
+// wildcard. When storing a config type of lower precedence, assume that the
+// user wants the config to take immediate effect by clearing the same values
+// from higher presedence configuration.
+void store_output_config(struct output_config *oc) {
 
-static void merge_id_on_name(struct output_config *oc) {
-	struct sway_output *output = all_output_by_name_or_id(oc->name);
-	if (output == NULL) {
-		return;
-	}
-
-	const char *name = output->wlr_output->name;
+	// Find the output that this configuration will apply to.
 	char id[128];
-	output_get_identifier(id, sizeof(id), output);
-
-	char *id_on_name = format_str("%s on %s", id, name);
-	if (!id_on_name) {
-		return;
+	bool merged = false, is_name = false;
+	bool wildcard = strcmp(oc->name, "*") == 0;
+	struct sway_output *output = wildcard ? NULL : output_by_name_or_id(oc->name);
+	if (output) {
+		output_get_identifier(id, sizeof(id), output);
+		is_name = strcmp(oc->name, output->wlr_output->name) == 0;
+	} else if (!wildcard) {
+		// There is no config by this name, just add it in
+		goto done;
 	}
 
-	int i = list_seq_find(config->output_configs, output_name_cmp, id_on_name);
-	if (i >= 0) {
-		sway_log(SWAY_DEBUG, "Merging on top of existing id on name config");
-		merge_output_config(config->output_configs->items[i], oc);
-	} else {
-		// If both a name and identifier config, exist generate an id on name
-		int ni = list_seq_find(config->output_configs, output_name_cmp, name);
-		int ii = list_seq_find(config->output_configs, output_name_cmp, id);
-		if ((ni >= 0 && ii >= 0) || (ni >= 0 && strcmp(oc->name, id) == 0)
-				|| (ii >= 0 && strcmp(oc->name, name) == 0)) {
-			struct output_config *ion_oc = new_output_config(id_on_name);
-			if (ni >= 0) {
-				merge_output_config(ion_oc, config->output_configs->items[ni]);
-			}
-			if (ii >= 0) {
-				merge_output_config(ion_oc, config->output_configs->items[ii]);
-			}
-			merge_output_config(ion_oc, oc);
-			list_add(config->output_configs, ion_oc);
-			sway_log(SWAY_DEBUG, "Generated id on name output config \"%s\""
-				" (enabled: %d) (%dx%d@%fHz position %d,%d scale %f "
-				"transform %d) (bg %s %s) (power %d) (max render time: %d)",
-				ion_oc->name, ion_oc->enabled, ion_oc->width, ion_oc->height,
-				ion_oc->refresh_rate, ion_oc->x, ion_oc->y, ion_oc->scale,
-				ion_oc->transform, ion_oc->background,
-				ion_oc->background_option, ion_oc->power,
-				ion_oc->max_render_time);
+	// If the configuration matches the output by name, merge with existing
+	// name configuration and clear identifier configuration. If the
+	// configuration matches the output by identifier, merge with existing
+	// identifier configuration.
+	for (int i = 0; i < config->output_configs->length; i++) {
+		struct output_config *old = config->output_configs->items[i];
+		if (strcmp(old->name, oc->name) == 0) {
+			merge_output_config(old, oc);
+			merged = true;
+			continue;
 		}
-	}
-	free(id_on_name);
-}
+		bool matches_identifier = output && strcmp(old->name, id) == 0;
 
-struct output_config *store_output_config(struct output_config *oc) {
-	bool wildcard = strcmp(oc->name, "*") == 0;
-	if (wildcard) {
-		merge_wildcard_on_all(oc);
-	} else {
-		merge_id_on_name(oc);
+		if (wildcard || (is_name && matches_identifier)) {
+			supersede_output_config(old, oc);
+		}
 	}
 
-	int i = list_seq_find(config->output_configs, output_name_cmp, oc->name);
-	if (i >= 0) {
-		sway_log(SWAY_DEBUG, "Merging on top of existing output config");
-		struct output_config *current = config->output_configs->items[i];
-		merge_output_config(current, oc);
-		free_output_config(oc);
-		oc = current;
-	} else if (!wildcard) {
-		sway_log(SWAY_DEBUG, "Adding non-wildcard output config");
-		i = list_seq_find(config->output_configs, output_name_cmp, "*");
-		if (i >= 0) {
-			sway_log(SWAY_DEBUG, "Merging on top of output * config");
-			struct output_config *current = new_output_config(oc->name);
-			merge_output_config(current, config->output_configs->items[i]);
-			merge_output_config(current, oc);
-			free_output_config(oc);
-			oc = current;
-		}
+done:
+	if (!merged) {
 		list_add(config->output_configs, oc);
 	} else {
-		// New wildcard config. Just add it
-		sway_log(SWAY_DEBUG, "Adding output * config");
-		list_add(config->output_configs, oc);
+		free_output_config(oc);
 	}
 
 	sway_log(SWAY_DEBUG, "Config stored for output %s (enabled: %d) (%dx%d@%fHz "
@@ -239,8 +259,6 @@ struct output_config *store_output_config(struct output_config *oc) {
 		oc->x, oc->y, oc->scale, sway_wl_output_subpixel_to_string(oc->subpixel),
 		oc->transform, oc->background, oc->background_option, oc->power,
 		oc->max_render_time);
-
-	return oc;
 }
 
 static void set_mode(struct wlr_output *output, struct wlr_output_state *pending,
@@ -587,96 +605,49 @@ static void default_output_config(struct output_config *oc,
 	oc->max_render_time = 0;
 }
 
-static struct output_config *get_output_config(char *identifier,
-		struct sway_output *sway_output) {
+// find_output_config returns a merged output_config containing all stored
+// configuration that applies to the specified output.
+struct output_config *find_output_config(struct sway_output *sway_output) {
 	const char *name = sway_output->wlr_output->name;
+	struct output_config *oc = NULL;
 
-	struct output_config *oc_id_on_name = NULL;
-	struct output_config *oc_name = NULL;
-	struct output_config *oc_id = NULL;
-
-	char *id_on_name = format_str("%s on %s", identifier, name);
-	int i = list_seq_find(config->output_configs, output_name_cmp, id_on_name);
-	if (i >= 0) {
-		oc_id_on_name = config->output_configs->items[i];
-	} else {
-		i = list_seq_find(config->output_configs, output_name_cmp, name);
-		if (i >= 0) {
-			oc_name = config->output_configs->items[i];
-		}
-
-		i = list_seq_find(config->output_configs, output_name_cmp, identifier);
-		if (i >= 0) {
-			oc_id = config->output_configs->items[i];
-		}
-	}
-
-	struct output_config *result = new_output_config("temp");
+	struct output_config *result = new_output_config(name);
 	if (config->reloading) {
 		default_output_config(result, sway_output->wlr_output);
 	}
-	if (oc_id_on_name) {
-		// Already have an identifier on name config, use that
-		free(result->name);
-		result->name = strdup(id_on_name);
-		merge_output_config(result, oc_id_on_name);
-	} else if (oc_name && oc_id) {
-		// Generate a config named `<identifier> on <name>` which contains a
-		// merged copy of the identifier on name. This will make sure that both
-		// identifier and name configs are respected, with identifier getting
-		// priority
-		struct output_config *temp = new_output_config(id_on_name);
-		merge_output_config(temp, oc_name);
-		merge_output_config(temp, oc_id);
-		list_add(config->output_configs, temp);
-
-		free(result->name);
-		result->name = strdup(id_on_name);
-		merge_output_config(result, temp);
-
-		sway_log(SWAY_DEBUG, "Generated output config \"%s\" (enabled: %d)"
-			" (%dx%d@%fHz position %d,%d scale %f transform %d) (bg %s %s)"
-			" (power %d) (max render time: %d)", result->name, result->enabled,
-			result->width, result->height, result->refresh_rate,
-			result->x, result->y, result->scale, result->transform,
-			result->background, result->background_option, result->power,
-			result->max_render_time);
-	} else if (oc_name) {
-		// No identifier config, just return a copy of the name config
-		free(result->name);
-		result->name = strdup(name);
-		merge_output_config(result, oc_name);
-	} else if (oc_id) {
-		// No name config, just return a copy of the identifier config
-		free(result->name);
-		result->name = strdup(identifier);
-		merge_output_config(result, oc_id);
-	} else {
-		i = list_seq_find(config->output_configs, output_name_cmp, "*");
-		if (i >= 0) {
-			// No name or identifier config, but there is a wildcard config
-			free(result->name);
-			result->name = strdup("*");
-			merge_output_config(result, config->output_configs->items[i]);
-		} else if (!config->reloading) {
-			// No name, identifier, or wildcard config. Since we are not
-			// reloading with defaults, the output config will be empty, so
-			// just return NULL
-			free_output_config(result);
-			result = NULL;
-		}
+
+	char id[128];
+	output_get_identifier(id, sizeof(id), sway_output);
+
+	int i;
+	bool match = false;
+	if ((i = list_seq_find(config->output_configs, output_name_cmp, "*")) >= 0) {
+		match = true;
+		oc = config->output_configs->items[i];
+		merge_output_config(result, oc);
+	}
+	if ((i = list_seq_find(config->output_configs, output_name_cmp, name)) >= 0) {
+		match = true;
+		oc = config->output_configs->items[i];
+		merge_output_config(result, oc);
+	}
+	if ((i = list_seq_find(config->output_configs, output_name_cmp, id)) >= 0) {
+		match = true;
+		oc = config->output_configs->items[i];
+		merge_output_config(result, oc);
+	}
+
+	if (!match && !config->reloading) {
+		// No name, identifier, or wildcard config. Since we are not
+		// reloading with defaults, the output config will be empty, so
+		// just return NULL
+		free_output_config(result);
+		return NULL;
 	}
 
-	free(id_on_name);
 	return result;
 }
 
-struct output_config *find_output_config(struct sway_output *output) {
-	char id[128];
-	output_get_identifier(id, sizeof(id), output);
-	return get_output_config(id, output);
-}
-
 bool apply_output_configs(struct matched_output_config *configs, size_t configs_len) {
 	struct wlr_backend_output_state *states = calloc(configs_len, sizeof(*states));
 	if (!states) {