Invoke only one swaybg process

include/sway/config.h

@@ -474,11 +474,11 @@ void free_sway_binding(struct sway_binding *sb);
 
 struct sway_binding *sway_binding_dup(struct sway_binding *sb);
 
-void load_swaybars();
+void load_swaybars(void);
 
 void invoke_swaybar(struct bar_config *bar);
 
-void terminate_swaybg(pid_t pid);
+void load_swaybg(void);
 
 struct bar_config *default_bar_config(void);
 

include/sway/output.h

@@ -31,8 +31,6 @@ struct sway_output {
 
 	struct wl_list link;
 
-	pid_t bg_pid;
-
 	struct {
 		struct wl_signal destroy;
 	} events;

sway/commands/reload.c

@@ -11,6 +11,7 @@ struct cmd_results *cmd_reload(int argc, char **argv) {
 		return cmd_results_new(CMD_FAILURE, "reload", "Error(s) reloading config.");
 	}
 
+	load_swaybg();
 	load_swaybars();
 	arrange_and_commit(&root_container);
 	return cmd_results_new(CMD_SUCCESS, NULL, NULL);

sway/config/bar.c

@@ -225,7 +225,7 @@ static bool active_output(const char *name) {
 	return false;
 }
 
-void load_swaybars() {
+void load_swaybars(void) {
 	for (int i = 0; i < config->bars->length; ++i) {
 		struct bar_config *bar = config->bars->items[i];
 		bool apply = false;

sway/config/bg.c

@@ -0,0 +1,92 @@
+#define _POSIX_C_SOURCE 200809L
+#define _XOPEN_SOURCE 700
+#include <assert.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <strings.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include "sway/config.h"
+#include "stringop.h"
+#include "list.h"
+#include "log.h"
+
+static pid_t swaybg_pid = -1;
+
+static void terminate_swaybg(void) {
+	wlr_log(WLR_DEBUG, "Terminating swaybg %d", swaybg_pid);
+	int ret = kill(-swaybg_pid, SIGTERM);
+	if (ret != 0) {
+		wlr_log_errno(WLR_ERROR, "Unable to terminate swaybg %d", swaybg_pid);
+	} else {
+		waitpid(swaybg_pid, NULL, 0);
+	}
+	swaybg_pid = 0;
+}
+
+void load_swaybg(void) {
+	if (swaybg_pid >= 0) {
+		terminate_swaybg();
+	}
+
+	swaybg_pid = fork();
+	if (swaybg_pid < 0) {
+		wlr_log(WLR_ERROR, "Failed to fork()");
+		return;
+	} else if (swaybg_pid == 0) {
+		setsid();
+
+		const char *cmd = config->swaybg_command ?
+			config->swaybg_command : "swaybg";
+
+		size_t argv_cap = 2 + 4 * config->output_configs->length;
+		size_t argv_len = 0;
+		char *argv[argv_cap];
+		argv[argv_len++] = "swaybg";
+
+		for (int i = 0; i < config->output_configs->length; ++i) {
+			struct output_config *oc = config->output_configs->items[i];
+
+			if (oc->background_option) {
+				if (strcmp(oc->background_option, "solid_color") == 0) {
+					argv[argv_len++] = "--color";
+					argv[argv_len++] = oc->background;
+					continue;
+				}
+
+				argv[argv_len++] = "--scaling";
+				argv[argv_len++] = oc->background_option;
+			}
+
+			if (oc->background) {
+				char *arg;
+				if (strcmp(oc->name, "*") == 0) {
+					arg = oc->background;
+				} else {
+					arg = malloc(strlen(oc->name) + 1 +
+						strlen(oc->background) + 1);
+					strcpy(arg, oc->name);
+					strcat(arg, ":");
+					strcat(arg, oc->background);
+				}
+
+				argv[argv_len++] = "--image";
+				argv[argv_len++] = arg;
+			}
+		}
+
+		argv[argv_len++] = NULL;
+		assert(argv_len <= argv_cap);
+
+		execvp(cmd, argv);
+
+		wlr_log(WLR_ERROR, "Failed to exec swaybg");
+		exit(EXIT_FAILURE);
+	}
+
+	wlr_log(WLR_ERROR, "Spawned swaybg %d", swaybg_pid);
+}

sway/config/output.c

@@ -2,8 +2,6 @@
 #include <assert.h>
 #include <stdbool.h>
 #include <string.h>
-#include <signal.h>
-#include <sys/wait.h>
 #include <unistd.h>
 #include <wlr/types/wlr_output.h>
 #include <wlr/types/wlr_output_layout.h>
@@ -113,16 +111,6 @@ static void set_mode(struct wlr_output *output, int width, int height,
 	}
 }
 
-void terminate_swaybg(pid_t pid) {
-	int ret = kill(pid, SIGTERM);
-	if (ret != 0) {
-		wlr_log(WLR_ERROR, "Unable to terminate swaybg [pid: %d]", pid);
-	} else {
-		int status;
-		waitpid(pid, &status, 0);
-	}
-}
-
 void apply_output_config(struct output_config *oc, struct sway_container *output) {
 	assert(output->type == C_OUTPUT);
 
@@ -132,10 +120,6 @@ void apply_output_config(struct output_config *oc, struct sway_container *output
 
 	if (oc && oc->enabled == 0) {
 		struct sway_output *sway_output = output->sway_output;
-		if (output->sway_output->bg_pid != 0) {
-			terminate_swaybg(output->sway_output->bg_pid);
-			output->sway_output->bg_pid = 0;
-		}
 		container_destroy(output);
 		sway_output->swayc = NULL;
 		wlr_output_layout_remove(root_container.sway_root->output_layout,
@@ -165,58 +149,14 @@ void apply_output_config(struct output_config *oc, struct sway_container *output
 		wlr_output_layout_add_auto(output_layout, wlr_output);
 	}
 
-	if (!oc || !oc->background) {
-		// Look for a * config for background
-		int i = list_seq_find(config->output_configs, output_name_cmp, "*");
-		if (i >= 0) {
-			oc = config->output_configs->items[i];
-		} else {
-			oc = NULL;
-		}
-	}
-
-	int output_i;
-	for (output_i = 0; output_i < root_container.children->length; ++output_i) {
-		if (root_container.children->items[output_i] == output) {
-			break;
-		}
-	}
-
-	if (oc && oc->background) {
-		if (output->sway_output->bg_pid != 0) {
-			terminate_swaybg(output->sway_output->bg_pid);
-		}
-
-		wlr_log(WLR_DEBUG, "Setting background for output %d to %s",
-				output_i, oc->background);
-
-		size_t len = snprintf(NULL, 0, "%s %d %s %s",
-				config->swaybg_command ? config->swaybg_command : "swaybg",
-				output_i, oc->background, oc->background_option);
-		char *command = malloc(len + 1);
-		if (!command) {
-			wlr_log(WLR_DEBUG, "Unable to allocate swaybg command");
-			return;
-		}
-		snprintf(command, len + 1, "%s %d %s %s",
-				config->swaybg_command ? config->swaybg_command : "swaybg",
-				output_i, oc->background, oc->background_option);
-		wlr_log(WLR_DEBUG, "-> %s", command);
-
-		char *const cmd[] = { "sh", "-c", command, NULL };
-		output->sway_output->bg_pid = fork();
-		if (output->sway_output->bg_pid == 0) {
-			execvp(cmd[0], cmd);
-		}
-	}
 	if (oc && oc->dpms_state != DPMS_IGNORE) {
 		switch (oc->dpms_state) {
 		case DPMS_ON:
-			wlr_log(WLR_DEBUG, "Turning on screen");
+			wlr_log(WLR_DEBUG, "Turning on output %s", oc->name);
 			wlr_output_enable(wlr_output, true);
 			break;
 		case DPMS_OFF:
-			wlr_log(WLR_DEBUG, "Turning off screen");
+			wlr_log(WLR_DEBUG, "Turning off output %s", oc->name);
 			wlr_output_enable(wlr_output, false);
 			break;
 		case DPMS_IGNORE:

sway/meson.build

@@ -25,9 +25,10 @@ sway_sources = files(
 	'input/keyboard.c',
 
 	'config/bar.c',
+	'config/bg.c',
+	'config/input.c',
 	'config/output.c',
 	'config/seat.c',
-	'config/input.c',
 
 	'commands/assign.c',
 	'commands/bar.c',

sway/server.c

@@ -148,5 +148,6 @@ void server_run(struct sway_server *server) {
 		wlr_backend_destroy(server->backend);
 		return;
 	}
+	load_swaybg();
 	wl_display_run(server->wl_display);
 }