Add exec_before and exec_after

Adds an option to execute some program before and after screencast (e.g.
for disabling notifications during a cast)

include/config.h

@@ -6,6 +6,8 @@
 struct config_screencast {
 	char *output_name;
 	double max_fps;
+	char *exec_before;
+	char *exec_after;
 };
 
 struct xdpw_config {

src/core/config.c

@@ -20,6 +20,8 @@ void finish_config(struct xdpw_config *config) {
 
 	// screencast
 	free(&config->screencast_conf.output_name);
+	free(&config->screencast_conf.exec_before);
+	free(&config->screencast_conf.exec_after);
 }
 
 static void getstring_from_conffile(dictionary *d,
@@ -79,6 +81,8 @@ static void config_parse_file(const char *configfile, struct xdpw_config *config
 	// screencast
 	getstring_from_conffile(d, "screencast:output_name", &config->screencast_conf.output_name, NULL);
 	getdouble_from_conffile(d, "screencast:max_fps", &config->screencast_conf.max_fps, 0);
+	getstring_from_conffile(d, "screencast:exec_before", &config->screencast_conf.exec_before, NULL);
+	getstring_from_conffile(d, "screencast:exec_after", &config->screencast_conf.exec_after, NULL);
 
 	iniparser_freedict(d);
 	logprint(DEBUG, "config: config file parsed");

src/screencast/screencast.c

@@ -18,8 +18,36 @@
 static const char object_path[] = "/org/freedesktop/portal/desktop";
 static const char interface_name[] = "org.freedesktop.impl.portal.ScreenCast";
 
+void exec_with_shell(char *command) {
+	pid_t pid = fork();
+	if (pid < 0) {
+		perror("fork");
+	} else if (pid == 0) {
+		char *const argv[] = {
+			"sh",
+			"-c",
+			command,
+			NULL,
+		};
+		execvp("sh", argv);
+
+		perror("execvp");
+		exit(127);
+	}
+}
+
 void xdpw_screencast_instance_init(struct xdpw_screencast_context *ctx,
 		struct xdpw_screencast_instance *cast, struct xdpw_wlr_output *out, bool with_cursor) {
+
+	// only run exec_before if there's no other instance running that already ran it
+	if (wl_list_empty(&ctx->screencast_instances)) {
+		char *exec_before = ctx->state->config->screencast_conf.exec_before;
+		if (exec_before) {
+			logprint(INFO, "xdpw: executing %s before screencast", exec_before);
+			exec_with_shell(exec_before);
+		}
+	}
+
 	cast->ctx = ctx;
 	cast->target_output = out;
 	cast->framerate = out->framerate;
@@ -34,6 +62,16 @@ void xdpw_screencast_instance_init(struct xdpw_screencast_context *ctx,
 void xdpw_screencast_instance_destroy(struct xdpw_screencast_instance *cast) {
 	assert(cast->refcount == 0); // Fails assert if called by screencast_finish
 	logprint(DEBUG, "xdpw: destroying cast instance");
+
+	// make sure this is the last running instance that is being destroyed
+	if (wl_list_length(&cast->link) == 1) {
+		char *exec_after = cast->ctx->state->config->screencast_conf.exec_after;
+		if (exec_after) {
+			logprint(INFO, "xdpw: executing %s after screencast", exec_after);
+			exec_with_shell(exec_after);
+		}
+	}
+
 	wl_list_remove(&cast->link);
 	xdpw_pwr_stream_destroy(cast);
 	free(cast);

xdg-desktop-portal-wlr.5.scd

@@ -25,6 +25,8 @@ The configuration files use the INI file format. Example:
 [screencast]
 output_name=HDMI-A-1
 max_fps=30
+exec_before=disable_notifications.sh
+exec_after=enable_notifications.sh
 ```
 
 # SCREENCAST OPTIONS
@@ -44,6 +46,12 @@ These options need to be placed under the **[screencast]** section.
 	This is useful to reduce CPU usage when capturing frames at the output's
 	refresh rate is unnecessary.
 
+**exec_before** = _command_
+	Execute _command_ before starting a screencast. The command will be executed within sh.
+
+**exec_after** = _command_
+	Execute _command_ after ending all screencasts. The command will be executed within sh.
+
 # SEE ALSO
 
 **pipewire**(1)