Spawn swaynag as a wayland client

This spawns swaynag as a wayland client similar to how swaybar and
swaybg are already done

common/util.c

@@ -1,5 +1,6 @@
 #define _POSIX_C_SOURCE 200809L
 #include <float.h>
+#include <fcntl.h>
 #include <math.h>
 #include <stdlib.h>
 #include <string.h>
@@ -75,3 +76,21 @@ const char *sway_wl_output_subpixel_to_string(enum wl_output_subpixel subpixel)
 	sway_assert(false, "Unknown value for wl_output_subpixel.");
 	return NULL;
 }
+
+bool set_cloexec(int fd, bool cloexec) {
+	int flags = fcntl(fd, F_GETFD);
+	if (flags == -1) {
+		sway_log_errno(SWAY_ERROR, "fcntl failed");
+		return false;
+	}
+	if (cloexec) {
+		flags = flags | FD_CLOEXEC;
+	} else {
+		flags = flags & ~FD_CLOEXEC;
+	}
+	if (fcntl(fd, F_SETFD, flags) == -1) {
+		sway_log_errno(SWAY_ERROR, "fcntl failed");
+		return false;
+	}
+	return true;
+}

include/sway/swaynag.h

@@ -1,9 +1,12 @@
 #ifndef _SWAY_SWAYNAG_H
 #define _SWAY_SWAYNAG_H
+#include <wayland-server-core.h>
 
 struct swaynag_instance {
+	struct wl_client *client;
+	struct wl_listener client_destroy;
+
 	const char *args;
-	pid_t pid;
 	int fd[2];
 	bool detailed;
 };
@@ -15,9 +18,6 @@ struct swaynag_instance {
 bool swaynag_spawn(const char *swaynag_command,
 		struct swaynag_instance *swaynag);
 
-// Kill the swaynag instance
-void swaynag_kill(struct swaynag_instance *swaynag);
-
 // Write a log message to swaynag->fd[1]. This will fail when swaynag->detailed
 // is false.
 void swaynag_log(const char *swaynag_command, struct swaynag_instance *swaynag,

include/util.h

@@ -32,4 +32,6 @@ float parse_float(const char *value);
 
 const char *sway_wl_output_subpixel_to_string(enum wl_output_subpixel subpixel);
 
+bool set_cloexec(int fd, bool cloexec);
+
 #endif

sway/config.c

@@ -175,15 +175,13 @@ static void set_color(float dest[static 4], uint32_t color) {
 
 static void config_defaults(struct sway_config *config) {
 	if (!(config->swaynag_command = strdup("swaynag"))) goto cleanup;
-	config->swaynag_config_errors = (struct swaynag_instance){
-		.args = "--type error "
+	config->swaynag_config_errors = (struct swaynag_instance){0};
+	config->swaynag_config_errors.args = "--type error "
 			"--message 'There are errors in your config file' "
 			"--detailed-message "
-			"--button 'Exit sway' 'swaymsg exit' "
-			"--button 'Reload sway' 'swaymsg reload'",
-		.pid = -1,
-		.detailed = true,
-	};
+			"--button-no-terminal 'Exit sway' 'swaymsg exit' "
+			"--button-no-terminal 'Reload sway' 'swaymsg reload'";
+	config->swaynag_config_errors.detailed = true;
 
 	if (!(config->symbols = create_list())) goto cleanup;
 	if (!(config->modes = create_list())) goto cleanup;
@@ -411,10 +409,9 @@ bool load_main_config(const char *file, bool is_active, bool validating) {
 		config->reloading = true;
 		config->active = true;
 
-		swaynag_kill(&old_config->swaynag_config_errors);
-		memcpy(&config->swaynag_config_errors,
-				&old_config->swaynag_config_errors,
-				sizeof(struct swaynag_instance));
+		if (old_config->swaynag_config_errors.client != NULL) {
+			wl_client_destroy(old_config->swaynag_config_errors.client);
+		}
 
 		input_manager_reset_all_inputs();
 	}
@@ -486,7 +483,7 @@ bool load_main_config(const char *file, bool is_active, bool validating) {
 		spawn_swaybg();
 
 		config->reloading = false;
-		if (config->swaynag_config_errors.pid > 0) {
+		if (config->swaynag_config_errors.client != NULL) {
 			swaynag_show(&config->swaynag_config_errors);
 		}
 

sway/config/output.c

@@ -1,6 +1,5 @@
 #define _POSIX_C_SOURCE 200809L
 #include <assert.h>
-#include <fcntl.h>
 #include <stdbool.h>
 #include <string.h>
 #include <sys/socket.h>
@@ -488,24 +487,6 @@ static void handle_swaybg_client_destroy(struct wl_listener *listener,
 	config->swaybg_client = NULL;
 }
 
-static bool set_cloexec(int fd, bool cloexec) {
-	int flags = fcntl(fd, F_GETFD);
-	if (flags == -1) {
-		sway_log_errno(SWAY_ERROR, "fcntl failed");
-		return false;
-	}
-	if (cloexec) {
-		flags = flags | FD_CLOEXEC;
-	} else {
-		flags = flags & ~FD_CLOEXEC;
-	}
-	if (fcntl(fd, F_SETFD, flags) == -1) {
-		sway_log_errno(SWAY_ERROR, "fcntl failed");
-		return false;
-	}
-	return true;
-}
-
 static bool _spawn_swaybg(char **command) {
 	if (config->swaybg_client != NULL) {
 		wl_client_destroy(config->swaybg_client);

sway/main.c

@@ -391,7 +391,7 @@ int main(int argc, char **argv) {
 	load_swaybars();
 	run_deferred_commands();
 
-	if (config->swaynag_config_errors.pid > 0) {
+	if (config->swaynag_config_errors.client != NULL) {
 		swaynag_show(&config->swaynag_config_errors);
 	}
 

sway/swaynag.c

@@ -1,16 +1,32 @@
 #define _POSIX_C_SOURCE 200809L
-#include <fcntl.h>
 #include <signal.h>
 #include <stdbool.h>
 #include <stdlib.h>
 #include <stdio.h>
+#include <sys/socket.h>
 #include <sys/types.h>
+#include <sys/wait.h>
 #include <unistd.h>
 #include "log.h"
+#include "sway/server.h"
 #include "sway/swaynag.h"
+#include "util.h"
+
+static void handle_swaynag_client_destroy(struct wl_listener *listener,
+		void *data) {
+	struct swaynag_instance *swaynag =
+		wl_container_of(listener, swaynag, client_destroy);
+	wl_list_remove(&swaynag->client_destroy.link);
+	wl_list_init(&swaynag->client_destroy.link);
+	swaynag->client = NULL;
+}
 
 bool swaynag_spawn(const char *swaynag_command,
 		struct swaynag_instance *swaynag) {
+	if (swaynag->client != NULL) {
+		wl_client_destroy(swaynag->client);
+	}
+
 	if (!swaynag_command) {
 		return true;
 	}
@@ -20,44 +36,94 @@ bool swaynag_spawn(const char *swaynag_command,
 			sway_log(SWAY_ERROR, "Failed to create pipe for swaynag");
 			return false;
 		}
-		fcntl(swaynag->fd[1], F_SETFD, FD_CLOEXEC);
+		if (!set_cloexec(swaynag->fd[1], true)) {
+			goto failed;
+		}
 	}
 
-	pid_t pid;
-	if ((pid = fork()) == 0) {
-		if (swaynag->detailed) {
-			close(swaynag->fd[1]);
-			dup2(swaynag->fd[0], STDIN_FILENO);
-			close(swaynag->fd[0]);
-		}
+	int sockets[2];
+	if (socketpair(AF_UNIX, SOCK_STREAM, 0, sockets) != 0) {
+		sway_log_errno(SWAY_ERROR, "socketpair failed");
+		goto failed;
+	}
+	if (!set_cloexec(sockets[0], true) || !set_cloexec(sockets[1], true)) {
+		goto failed;
+	}
 
-		size_t length = strlen(swaynag_command) + strlen(swaynag->args) + 2;
-		char *cmd = malloc(length);
-		snprintf(cmd, length, "%s %s", swaynag_command, swaynag->args);
-		execl("/bin/sh", "/bin/sh", "-c", cmd, NULL);
-		_exit(0);
-	} else if (pid < 0) {
+	swaynag->client = wl_client_create(server.wl_display, sockets[0]);
+	if (swaynag->client == NULL) {
+		sway_log_errno(SWAY_ERROR, "wl_client_create failed");
+		goto failed;
+	}
+
+	swaynag->client_destroy.notify = handle_swaynag_client_destroy;
+	wl_client_add_destroy_listener(swaynag->client, &swaynag->client_destroy);
+
+	pid_t pid = fork();
+	if (pid < 0) {
 		sway_log(SWAY_ERROR, "Failed to create fork for swaynag");
-		if (swaynag->detailed) {
-			close(swaynag->fd[0]);
-			close(swaynag->fd[1]);
+		goto failed;
+	} else if (pid == 0) {
+		pid = fork();
+		if (pid < 0) {
+			sway_log_errno(SWAY_ERROR, "fork failed");
+			_exit(EXIT_FAILURE);
+		} else if (pid == 0) {
+			if (!set_cloexec(sockets[1], false)) {
+				_exit(EXIT_FAILURE);
+			}
+
+			if (swaynag->detailed) {
+				close(swaynag->fd[1]);
+				dup2(swaynag->fd[0], STDIN_FILENO);
+				close(swaynag->fd[0]);
+			}
+
+			char wayland_socket_str[16];
+			snprintf(wayland_socket_str, sizeof(wayland_socket_str),
+					"%d", sockets[1]);
+			setenv("WAYLAND_SOCKET", wayland_socket_str, true);
+
+			size_t length = strlen(swaynag_command) + strlen(swaynag->args) + 2;
+			char *cmd = malloc(length);
+			snprintf(cmd, length, "%s %s", swaynag_command, swaynag->args);
+			execl("/bin/sh", "/bin/sh", "-c", cmd, NULL);
+			sway_log_errno(SWAY_ERROR, "execl failed");
+			_exit(EXIT_FAILURE);
 		}
-		return false;
+		_exit(EXIT_SUCCESS);
 	}
 
 	if (swaynag->detailed) {
-		close(swaynag->fd[0]);
+		if (close(swaynag->fd[0]) != 0) {
+			sway_log_errno(SWAY_ERROR, "close failed");
+			return false;
+		}
 	}
-	swaynag->pid = pid;
-	return true;
-}
 
+	if (close(sockets[1]) != 0) {
+		sway_log_errno(SWAY_ERROR, "close failed");
+		return false;
+	}
+
+	if (waitpid(pid, NULL, 0) < 0) {
+		sway_log_errno(SWAY_ERROR, "waitpid failed");
+		return false;
+	}
 
-void swaynag_kill(struct swaynag_instance *swaynag) {
-	if (swaynag->pid > 0) {
-		kill(swaynag->pid, SIGTERM);
-		swaynag->pid = -1;
+	return true;
+
+failed:
+	if (swaynag->detailed) {
+		if (close(swaynag->fd[0]) != 0) {
+			sway_log_errno(SWAY_ERROR, "close failed");
+			return false;
+		}
+		if (close(swaynag->fd[1]) != 0) {
+			sway_log_errno(SWAY_ERROR, "close failed");
+		}
 	}
+	return false;
 }
 
 void swaynag_log(const char *swaynag_command, struct swaynag_instance *swaynag,
@@ -71,7 +137,7 @@ void swaynag_log(const char *swaynag_command, struct swaynag_instance *swaynag,
 		return;
 	}
 
-	if (swaynag->pid <= 0 && !swaynag_spawn(swaynag_command, swaynag)) {
+	if (swaynag->client == NULL && !swaynag_spawn(swaynag_command, swaynag)) {
 		return;
 	}
 
@@ -96,7 +162,7 @@ void swaynag_log(const char *swaynag_command, struct swaynag_instance *swaynag,
 }
 
 void swaynag_show(struct swaynag_instance *swaynag) {
-	if (swaynag->detailed && swaynag->pid > 0) {
+	if (swaynag->detailed && swaynag->client != NULL) {
 		close(swaynag->fd[1]);
 	}
 }

swaynag/swaynag.c

@@ -45,17 +45,24 @@ static void swaynag_button_execute(struct swaynag *swaynag,
 		swaynag->details.visible = !swaynag->details.visible;
 		render_frame(swaynag);
 	} else {
-		if (fork() == 0) {
+		pid_t pid = fork();
+		if (pid < 0) {
+			sway_log_errno(SWAY_DEBUG, "Failed to fork");
+			return;
+		} else if (pid == 0) {
 			// Child process. Will be used to prevent zombie processes
-			setsid();
-			if (fork() == 0) {
+			pid = fork();
+			if (pid < 0) {
+				sway_log_errno(SWAY_DEBUG, "Failed to fork");
+				return;
+			} else if (pid == 0) {
 				// Child of the child. Will be reparented to the init process
 				char *terminal = getenv("TERMINAL");
 				if (button->terminal && terminal && strlen(terminal)) {
 					sway_log(SWAY_DEBUG, "Found $TERMINAL: %s", terminal);
 					if (!terminal_execute(terminal, button->action)) {
 						swaynag_destroy(swaynag);
-						exit(EXIT_FAILURE);
+						_exit(EXIT_FAILURE);
 					}
 				} else {
 					if (button->terminal) {
@@ -63,12 +70,16 @@ static void swaynag_button_execute(struct swaynag *swaynag,
 								"$TERMINAL not found. Running directly");
 					}
 					execl("/bin/sh", "/bin/sh", "-c", button->action, NULL);
+					sway_log_errno(SWAY_DEBUG, "execl failed");
+					_exit(EXIT_FAILURE);
 				}
 			}
-			exit(EXIT_SUCCESS);
+			_exit(EXIT_SUCCESS);
+		}
+		if (waitpid(pid, NULL, 0) < 0) {
+			sway_log_errno(SWAY_DEBUG, "waitpid failed");
 		}
 	}
-	wait(0);
 }
 
 static void layer_surface_configure(void *data,