new API

and code cleanup

.gitignore

@@ -0,0 +1,4 @@
+protocol/*.c
+protocol/*.h
+*.o
+riverguile

Makefile

@@ -7,13 +7,18 @@ MANDIR=$(DATADIR)/man
 
 CFLAGS=-g -Wall -Werror -Wextra -Wpedantic -Wno-unused-parameter $\
 	-Wno-overlength-strings -Wformat-security -Wformat -Wunused-result $\
+	-I protocol $\
 	$(shell pkg-config --cflags wayland-client) $\
 	$(shell guile-config compile)
 LIBS=-lrt $\
 	$(shell pkg-config --libs wayland-client) $\
 	$(shell guile-config link)
-OBJ=riverguile.o river-layout-v3.o
-GEN=river-layout-v3.c river-layout-v3.h
+OBJ=src/riverguile.o $\
+	src/call-layout-demand-handler.o $\
+	src/call-user-command-handler.o $\
+	src/load-script.o $\
+	protocol/river-layout-v3.o
+GEN=protocol/river-layout-v3.c protocol/river-layout-v3.h
 
 all: riverguile
 
@@ -31,7 +36,7 @@ $(OBJ): $(GEN)
 
 install: riverguile
 	install        -D riverguile         $(DESTDIR)$(BINDIR)/riverguile
-	install -m 644 -D riverguile.1       $(DESTDIR)$(MANDIR)/man1/riverguile.1
+	install -m 644 -D doc/riverguile.1   $(DESTDIR)$(MANDIR)/man1/riverguile.1
 
 uninstall:
 	$(RM) $(DESTDIR)$(BINDIR)/riverguile

doc/riverguile.1

@@ -0,0 +1,97 @@
+.TH RIVERGUILE 1 2023-11-25 "git.sr.ht/~leon_plickat/riverguile" "General Commands Manual"
+.
+.SH NAME
+.P
+riverguile \- scheme powered layout generator for river
+.
+.
+.SH SYNOPSIS
+.SY riverguile
+.YS
+.
+.
+.SH DESCRIPTION
+.P
+Layout generator for the
+.BR river (1)
+Wayland server which allows users to define layouts using guile scheme functions.
+.
+.P
+The layout namespace is \fBriverguile\fB.
+.
+.P
+Uppon launch, riverguile tries to eval a scheme script and checks the following
+paths for it in the given order:
+.IP  \(bu 2
+\fBlayout.scm\fR
+.IP  \(bu 2
+\fB$XDG_CONFIG_HOME/river/layout.scm\fR
+.IP  \(bu 2
+\fB$HOME/.config/river/layout.scm\fR
+.IP  \(bu 2
+\fB/etc/riverguile/layout.scm\fR
+.
+.P
+In the context of this script, a special procedure
+\fB(install-handler \fR\fIkey\fR \fIproc\fR\fB)\fR is available, which can be
+used to install handlers to certain events.
+The parameter \fIkey\fR is a symbol indicating for which event to install
+the procedure \fIproc\fR.
+.P
+The key \fBlayout-demand\fR installs a handler for layout demands, which must
+accept five required arguments, which are, in order: The amount of views in the
+layout (integer), the available width (integer), the available height (integer),
+the currently active tag set (integer representing a bitfield of size 32)
+and the global name of the output the layout is needed for (integer).
+The procedure must return a list containing exactly as many lists as there are
+views in the layout.
+Each of those sublists must contains exactly four numerical values, which are
+the x and y coordinates of the window as well as its width and height.
+Window positions and dimensions get applied to rivers window list top to bottom.
+Note that the numerical values do not need to be exact, riverguile takes care
+of rounding and casting for you.
+.P
+The key \fBuser-command\fR install a handler for user commands, which are the
+strings a user can send to layout generators.
+This handler procedure must accept three arguments, which are, in order:
+The command (string), the currently active tags (integer representing a
+bitfield of size 32) and the global name of the output (integer).
+This event can be used to change paramters of the layout.
+A new layout demand will be send right after this event.
+.
+.
+.SH EXAMPLE
+.P
+This is an example configuration, which installs a layout that simply assigns
+each window all usable space and a user command handler that tries to evaluate
+all send commands as scheme code.
+.
+.P
+.RS
+.EX
+(install-handler 'user-command (lambda (cmd tags output)
+                                 (eval-string cmd)))
+
+(install-handler 'layout-demand (lambda (view-count width height tags output)
+                                  (letrec ((iter (lambda (n)
+                                                   (if (eq? 0 n)
+                                                       '()
+                                                       (append (list (list 0 0 width height))
+                                                               (iter (1- n)))))))
+                                    (iter view-count))))
+.EE
+.RE
+.
+.
+.SH SEE ALSO
+.BR river (1),
+.BR riverctl (1),
+.BR rivertile (1),
+.BR guile (1)
+.
+.
+.SH AUTHOR
+.P
+.MT leonhenrik.plickat@stud.uni-goettingen.de
+Leon Henrik Plickat
+.ME

riverguile.1

@@ -1,62 +0,0 @@
-.TH RIVERGUILE 1 2023-11-25 "git.sr.ht/~leon_plickat/riverguile" "General Commands Manual"
-.
-.SH NAME
-.P
-riverguile \- scheme powered layout generator for river
-.
-.
-.SH SYNOPSIS
-.SY riverguile
-.YS
-.
-.
-.SH DESCRIPTION
-.P
-Layout generator for the
-.BR river (1)
-Wayland server which allows users to define layouts using guile scheme functions.
-.
-.P
-The layout namespace is `riverguile`.
-.
-.P
-Uppon launch, riverguile tries to eval a scheme script and checks the following
-paths for it in the given order:
-.IP  \(bu 2
-\fBlayout.scm\fR
-.IP  \(bu 2
-\fB$XDG_CONFIG_HOME/river/layout.scm\fR
-.IP  \(bu 2
-\fB$HOME/.config/river/layout.scm\fR
-.IP  \(bu 2
-\fB/etc/riverguile/layout.scm\fR
-.
-.P
-This script must contain the definition of a function
-\fB(layout-demand-handler view-count usable-width usable-height)\fR and may
-contain any other code the user desires.
-The function must return a list containing exactly as many lists as \fBview-count\fR.
-Each of those sublists must contains exactly four numerical values, which are
-the x and y coordinates of the window as well as its width and height.
-Window positions and dimensions get applied to rivers window list top to bottom.
-.
-.P
-Note that the numerical values do not need to be exact, riverguile takes care
-of rounding and casting for you.
-.
-.P
-If you send riverguile a layout-command, it will try to eval it as scheme code.
-.
-.
-.SH SEE ALSO
-.BR river (1),
-.BR riverctl (1),
-.BR rivertile (1),
-.BR guile (1)
-.
-.
-.SH AUTHOR
-.P
-.MT leonhenrik.plickat@stud.uni-goettingen.de
-Leon Henrik Plickat
-.ME

src/call-layout-demand-handler.c

@@ -0,0 +1,83 @@
+#include <assert.h>
+#include <libguile.h>
+
+#include "river-layout-v3.h"
+
+#include "call-layout-demand-handler.h"
+
+extern SCM layout_demand_handler;
+
+static void *call_layout_demand_handler_inner (void *data)
+{
+	struct Call_layout_demand_handler_parameters *params = (struct Call_layout_demand_handler_parameters *)data;
+	return scm_call_5(
+		layout_demand_handler,
+		scm_from_uint32(params->view_count),
+		scm_from_uint32(params->width),
+		scm_from_uint32(params->height),
+		scm_from_uint32(params->tags),
+		scm_from_uint32(params->output->name)
+	);
+}
+
+void *call_layout_demand_handler (void *data)
+{
+	struct Call_layout_demand_handler_parameters *params = (struct Call_layout_demand_handler_parameters *)data;
+
+	assert(layout_demand_handler != NULL);
+	assert(scm_is_true(scm_procedure_p(layout_demand_handler)) == 1);
+
+	/* Continuation barrier causes stack unwind on exceptions (i.e. errors
+	 * in the user defined layout demand handler) to stop here. Otherwise
+	 * the entire stack created by scm_with_guile() would be unwound. This
+	 * makes responding to exceptions nicer.
+	 */
+	SCM call_result = scm_c_with_continuation_barrier(
+		call_layout_demand_handler_inner, data
+	);
+
+	if ( call_result == NULL )
+		return (void *)"ERROR: An exception occured while calling the layout demand handler.\n";
+
+	/* Check integrity of data before firing off any Wayland requests. */
+	if ( scm_is_false(scm_list_p(call_result)) == 1 )
+		return (void *)"ERROR: layout-demand-handler did not return a list.\n";
+	if ( params->view_count != scm_to_uint32(scm_length(call_result)) )
+		return (void *)"ERROR: Length of list returned by layout-demand-handler does not match view count.\n";
+	for (uint32_t i = 0; i < params->view_count; i++)
+	{
+		SCM elem = scm_list_ref(call_result, scm_from_uint32(i));
+		if ( scm_is_false(scm_list_p(elem)) == 1 )
+			return (void *)"ERROR: View dimensions list is not a list.\n";
+		if ( scm_to_uint32(scm_length(elem)) != 4 )
+			return (void *)"ERROR: View dimensions list length does not equal four (x, y, width, height).\n";
+		for (uint8_t j = 0; j < 4; j++)
+		{
+			SCM list_elem = scm_list_ref(elem, scm_from_int(j));
+			if ( scm_is_false(scm_number_p(list_elem)) == 1 )
+				return (void *)"ERROR: Encountered non-numerical view dimensions.\n";
+		}
+	}
+
+	for (uint32_t i = 0; i < params->view_count; i++)
+	{
+		SCM elem = scm_list_ref(call_result, scm_from_uint32(i));
+		uint32_t x = scm_to_uint32(scm_inexact_to_exact(
+			scm_round_number(scm_list_ref(elem, scm_from_int(0)))));
+		uint32_t y = scm_to_uint32(scm_inexact_to_exact(
+			scm_round_number(scm_list_ref(elem, scm_from_int(1)))));
+		uint32_t w = scm_to_uint32(scm_inexact_to_exact(
+			scm_round_number(scm_list_ref(elem, scm_from_int(2)))));
+		uint32_t h = scm_to_uint32(scm_inexact_to_exact(
+			scm_round_number(scm_list_ref(elem, scm_from_int(3)))));
+
+		river_layout_v3_push_view_dimensions(
+			params->output->layout,
+			x, y, w, h,
+			params->serial
+		);
+	}
+
+	return NULL;
+}
+

src/call-layout-demand-handler.h

@@ -0,0 +1,16 @@
+#ifndef RIVERGUILE_CALL_LAYOUT_DEMAND_HANDLER_H
+#define RIVERGUILE_CALL_LAYOUT_DEMAND_HANDLER_H
+
+#include <libguile.h>
+
+#include "types.h"
+
+struct Call_layout_demand_handler_parameters
+{
+	uint32_t view_count, width, height, serial, tags;
+	struct Output *output;
+};
+
+void *call_layout_demand_handler (void *data);
+
+#endif

src/call-user-command-handler.c

@@ -0,0 +1,38 @@
+#include <assert.h>
+#include <libguile.h>
+
+#include "types.h"
+#include "call-user-command-handler.h"
+
+extern SCM user_command_handler;
+
+static void *call_user_command_handler_inner (void *data)
+{
+	struct Call_user_command_parameters *params = (struct Call_user_command_parameters *)data;
+	return scm_call_3(
+		user_command_handler,
+		scm_from_utf8_string(params->cmd),
+		scm_from_uint32(params->output->user_command_tags),
+		scm_from_uint32(params->output->name)
+	);
+}
+
+void *call_user_command_handler (void *data)
+{
+	assert(user_command_handler != NULL);
+	assert(scm_is_true(scm_procedure_p(user_command_handler)) == 1);
+
+	/* Continuation barrier causes stack unwind on exceptions (i.e. errors
+	 * in the user defined user-command handler) to stop here. Otherwise
+	 * the entire stack created by scm_with_guile() would be unwound. This
+	 * makes responding to exceptions nicer.
+	 */
+	SCM call_result = scm_c_with_continuation_barrier(
+		call_user_command_handler_inner, data
+	);
+
+	if ( call_result == NULL )
+		return (void *)"ERROR: An exception occured while calling the user-command handler.\n";
+
+	return NULL;
+}

src/call-user-command-handler.h

@@ -0,0 +1,14 @@
+#ifndef RIVERGUILE_CALL_USER_COMMAND_HANDLER_H
+#define RIVERGUILE_CALL_USER_COMMAND_HANDLER_H
+
+#include "types.h"
+
+struct Call_user_command_parameters
+{
+	struct Output *output;
+	const char *cmd;
+};
+
+void *call_user_command_handler (void *data);
+
+#endif

src/load-script.c

@@ -0,0 +1,104 @@
+#include <assert.h>
+#include <stdio.h>
+#include <libguile.h>
+
+/**
+ * ISO C forbids casting a function pointer to a void pointer because on some
+ * architectures they have different sizes. However scm_c_define_gsubr() wants
+ * a function pointer as a void pointer, which trips -Wpedantic. Compiling C
+ * without pedantic errors is not a reasonable option in my opinion, so instead
+ * we'll have to resort to this hack.
+ */
+#define scm_c_define_gsubr_fix(NAME, REQ, OPT, RST, FN) \
+	{ const long int ptr = (long int)FN; scm_c_define_gsubr(NAME, REQ, OPT, RST, (void *)ptr); }
+
+extern SCM layout_demand_handler;
+extern SCM user_command_handler;
+
+static SCM install_handler (SCM key, SCM proc)
+{
+	if ( scm_is_false(scm_symbol_p(key)) == 1 )
+	{
+		scm_error_scm(
+			scm_from_utf8_symbol("wrong-type-arg"),
+			scm_from_utf8_string("install-handler"),
+			scm_from_utf8_string("First argument must be a symbol."),
+			SCM_BOOL_F,
+			scm_list_1(key)
+		);
+		return SCM_UNSPECIFIED;
+	}
+
+	// TODO check if the procedure has the right amount of arguments.
+	if ( scm_is_false(scm_procedure_p(proc)) == 1 )
+	{
+		scm_error_scm(
+			scm_from_utf8_symbol("wrong-type-arg"),
+			scm_from_utf8_string("install-handler"),
+			scm_from_utf8_string("Second argument must be a procedure."),
+			SCM_BOOL_F,
+			scm_list_1(proc)
+		);
+		return SCM_UNSPECIFIED;
+	}
+
+	if (scm_is_eq(scm_from_utf8_symbol("layout-demand"), key))
+		layout_demand_handler = proc;
+	else if (scm_is_eq(scm_from_utf8_symbol("user-command"), key))
+		user_command_handler = proc;
+	else
+	{
+		scm_error_scm(
+			// TODO should this be 'misc-error instead?
+			scm_from_utf8_symbol("out-of-range"),
+			scm_from_utf8_string("install-handler"),
+			scm_from_utf8_string("Unknown key: ~A"),
+			scm_list_1(key),
+			scm_list_1(key)
+		);
+		return SCM_UNSPECIFIED;
+	}
+
+	return SCM_BOOL_T;
+}
+
+static void *load_script_inner (void *data)
+{
+	const char *path = (char *)data;
+
+	/* scm_primitive_load_path() searches guiles load-path when encountering
+	 * a relative path. That should never happen here though.
+	 */
+	assert(path[0] == '/');
+
+	return scm_primitive_load_path(scm_from_utf8_string(path));
+}
+
+void *load_script (void *data)
+{
+	/* Note: All guile objects are garbage collected. */
+
+	scm_c_define_gsubr_fix("install-handler", 2, 0, 0, install_handler);
+
+	/* Continuation barrier causes stack unwind on exceptions to stop here.
+	 * Otherwise the entire stack created by scm_with_guile() would be
+	 * unwound. This makes responding to exceptions nicer.
+	 */
+	SCM call_result = scm_c_with_continuation_barrier(
+		load_script_inner, data
+	);
+
+	if ( call_result == NULL )
+		return (void *)"ERROR: Fatal error while loading layout script.\n";
+
+	if ( layout_demand_handler == NULL )
+		return (void *)"ERROR: No layout demand handler installed.\n";
+
+	/* Checked in the installer functions. */
+	assert(scm_is_true(scm_procedure_p(layout_demand_handler)) == 1);
+	if ( user_command_handler != NULL )
+		assert(scm_is_true(scm_procedure_p(user_command_handler)) == 1);
+
+	return NULL;
+}
+

src/load-script.h

@@ -0,0 +1,6 @@
+#ifndef RIVERGUILE_LOAD_SCRIPT_H_INCLUDED
+#define RIVERGUILE_LOAD_SCRIPT_H_INCLUDED
+
+void *load_script (void *data);
+
+#endif

src/riverguile.c

@@ -8,7 +8,6 @@
 #include <errno.h>
 #include <assert.h>
 #include <setjmp.h>
-
 #include <wayland-client.h>
 #include <libguile.h>
 
@@ -21,6 +20,11 @@
 
 #include "river-layout-v3.h"
 
+#include "types.h"
+#include "call-layout-demand-handler.h"
+#include "call-user-command-handler.h"
+#include "load-script.h"
+
 bool loop = true;
 int ret = EXIT_SUCCESS;
 
@@ -33,119 +37,68 @@ struct river_layout_manager_v3 *layout_manager = NULL;
 
 struct wl_list outputs;
 
-struct Output
-{
-	struct wl_list link;
-	struct wl_output *wl_output;
-	struct river_layout_v3 *layout;
-	uint32_t name;
-	bool configured;
-};
-
-struct Layout_demand_parameters
-{
-	uint32_t view_count, width, height, serial;
-	struct Output *output;
-};
-
-static bool scm2uint(uint32_t *x, SCM s)
-{
-	if ( scm_is_false(scm_number_p(s)) == 1 )
-		return false;
-	*x = scm_to_uint32(scm_inexact_to_exact(scm_round_number(s)));
-	return true;
-}
-
-/**
- * Try to find a variable named 'name' and returns it, otherwise #f is returned.
+/* Handlers are initially NULL instead of SCM_EOL because I am not sure whether
+ * scm_null_p() is safe to use outside of a guile context and if yes, whether
+ * that is intended or will disappear in the future. Special care must be taken
+ * to never call any scm_* function on these while they are NULL.
  */
-static SCM scm_c_get_variable (const char *name)
-{
-	return scm_module_variable(
-		scm_current_module(),
-		scm_string_to_symbol(
-			scm_from_utf8_string(name)
-		)
-	);
-}
-
-static void *call_layout_demand_handler (void *data)
-{
-	struct Layout_demand_parameters *params = (struct Layout_demand_parameters *)data;
-
-	SCM layout_demand_handler = scm_c_get_variable("layout-demand-handler");
-	if ( scm_is_false(layout_demand_handler) == 1 )
-	{
-		ret = EXIT_FAILURE;
-		loop = false;
-		return (void *)"ERROR: layout-demand-handler no longer exists.\n";
-	}
-
-	SCM call_result = scm_call_3(
-		scm_variable_ref(layout_demand_handler),
-		scm_from_uint32(params->view_count),
-		scm_from_uint32(params->width),
-		scm_from_uint32(params->height)
-	);
-
-	if ( scm_is_false(scm_list_p(call_result)) == 1 )
-		return (void *)"ERROR: layout-demand-handler did not return a list.\n";
-	if ( params->view_count != scm_to_uint32(scm_length(call_result)) )
-		return (void *)"ERROR: Length of list returned by layout-demand-handler does not match view count.\n";
-
-	for (uint32_t i = 0; i < params->view_count; i++)
-	{
-		SCM elem = scm_list_ref(call_result, scm_from_uint32(i));
-
-		if ( scm_is_false(scm_list_p(elem)) == 1 )
-			return (void *)"ERROR: View dimensions list is not a list.\n";
-		if ( scm_to_uint32(scm_length(elem)) != 4 )
-			return (void *)"ERROR: View dimensions list length does not equal four (x, y, width, height).\n";
-
-		uint32_t x, y, w, h;
-		if ( !scm2uint(&x, scm_list_ref(elem, scm_from_int(0)))
-			|| !scm2uint(&y, scm_list_ref(elem, scm_from_int(1)))
-			|| !scm2uint(&w, scm_list_ref(elem, scm_from_int(2)))
-			|| !scm2uint(&h, scm_list_ref(elem, scm_from_int(3))) )
-			return "ERROR: Encountered non-numerical view dimensions.\n";
-
-		river_layout_v3_push_view_dimensions(
-			params->output->layout,
-			x, y, w, h,
-			params->serial
-		);
-	}
-
-	return NULL;
-}
+SCM layout_demand_handler = NULL;
+SCM user_command_handler = NULL;
 
 static void layout_handle_layout_demand (void *data, struct river_layout_v3 *river_layout_v3,
 		uint32_t view_count, uint32_t width, uint32_t height, uint32_t tags, uint32_t serial)
 {
 	struct Output *output = (struct Output *)data;
 
-	struct Layout_demand_parameters params = {
+	struct Call_layout_demand_handler_parameters params = {
 		.view_count = view_count,
 		.width = width,
 		.height = height,
 		.serial = serial,
+		.tags = tags,
 		.output = output,
 	};
 
 	void *res = scm_with_guile(call_layout_demand_handler, (void *)&params);
-
 	if ( res != NULL )
 	{
 		fputs(res, stderr);
-		loop = false;
-		ret = EXIT_FAILURE;
+		fputs("INFO: This error is not fatal.\n", stderr);
 		return;
 	}
 
-	// TODO if 'layout-name' variable exists, use it.
+	// TODO allow setting layout name from user installed layout demand handler
 	river_layout_v3_commit(output->layout, "(🐦)", serial);
 }
 
+static void layout_handle_user_command (void *data,
+		struct river_layout_v3 *river_layout, const char *command)
+{
+	if ( user_command_handler == NULL )
+		return;
+
+	struct Output *output = (struct Output *)data;
+
+	struct Call_user_command_parameters params = {
+		.cmd = command,
+		.output = output,
+	};
+
+	void *res = scm_with_guile(call_user_command_handler, (void *)&params);
+	if ( res != NULL )
+	{
+		fputs(res, stderr);
+		fputs("INFO: This error is not fatal.\n", stderr);
+	}
+}
+
+static void layout_handle_user_command_tags (void *data,
+		struct river_layout_v3 *river_layout, uint32_t tags)
+{
+	struct Output *output = (struct Output *)data;
+	output->user_command_tags = tags;
+}
+
 static void layout_handle_namespace_in_use (void *data, struct river_layout_v3 *river_layout_v3)
 {
 	fputs("ERROR: Namespace already in use.\n", stderr);
@@ -153,22 +106,11 @@ static void layout_handle_namespace_in_use (void *data, struct river_layout_v3 *
 	loop = false;
 }
 
-static void *exec_user_command (void *str)
-{
-	return (void *)scm_c_eval_string((char *)str);
-}
-
-static void layout_handle_user_command (void *data,
-		struct river_layout_v3 *river_layout_manager_v3,
-		const char *command)
-{
-	(void)scm_with_guile(exec_user_command, (void *)command);
-}
-
 static const struct river_layout_v3_listener layout_listener = {
-	.namespace_in_use = layout_handle_namespace_in_use,
-	.layout_demand    = layout_handle_layout_demand,
-	.user_command     = layout_handle_user_command,
+	.namespace_in_use  = layout_handle_namespace_in_use,
+	.layout_demand     = layout_handle_layout_demand,
+	.user_command      = layout_handle_user_command,
+	.user_command_tags = layout_handle_user_command_tags,
 };
 
 static void output_configure (struct Output *output)
@@ -214,7 +156,7 @@ static void registry_handle_global (void *data, struct wl_registry *registry,
 	if ( strcmp(interface, river_layout_manager_v3_interface.name) == 0 )
 	{
 		layout_manager = wl_registry_bind(
-			registry, name, &river_layout_manager_v3_interface, 1
+			registry, name, &river_layout_manager_v3_interface, 2
 		);
 	}
 	else if ( strcmp(interface, wl_output_interface.name) == 0 )
@@ -281,7 +223,7 @@ static const struct wl_callback_listener sync_callback_listener = {
 
 static void handle_interrupt (int signum)
 {
-	fputs("Killed.\n", stderr);
+	fputs("Killed 💀\n", stderr);
 	loop = false;
 	longjmp(skip_main_loop, 1);
 }
@@ -327,30 +269,6 @@ static void handle_error (int signum)
 	kill(getpid(), signum);
 }
 
-static void *load_script (void *data)
-{
-	/* Note: All guile objects are garbage collected. */
-
-	const char *path = (char *)data;
-
-	/* scm_primitive_load_path() searches guiles load-path when encountering
-	 * a relative path. That should never happen here though.
-	 */
-	assert(path[0] == '/');
-
-	scm_primitive_load_path(scm_from_utf8_string(path));
-
-	/* Check if the handler has been defined. */
-	SCM layout_demand_handler = scm_c_get_variable("layout-demand-handler");
-	if ( scm_is_false(layout_demand_handler) == 1 )
-	{
-		ret = EXIT_FAILURE;
-		loop = false;
-		return (void *)"ERROR: Script does not define layout-demand-handler.\n";
-	}
-
-	return NULL;
-}
 
 static char *formatted_buffer (const char *fmt, ...)
 {
@@ -437,6 +355,7 @@ int main(int argc, char *argv[])
 	signal(SIGINT, handle_interrupt);
 	wl_list_init(&outputs);
 
+	// TODO use argv[1] if present
 	char *path = get_script_path();
 	if ( path == NULL )
 	{
@@ -449,6 +368,7 @@ int main(int argc, char *argv[])
 	{
 		fputs((char *)res, stderr);
 		ret = EXIT_FAILURE;
+		loop = false;
 		goto early_exit;
 	}
 

src/types.h

@@ -0,0 +1,25 @@
+#ifndef RIVERGUILE_TYPES_H_INCLUDED
+#define RIVERGUILE_TYPES_H_INCLUDED
+
+#include <stdbool.h>
+#include <wayland-client.h>
+
+#include "river-layout-v3.h"
+
+struct Output
+{
+	struct wl_list link;
+	struct wl_output *wl_output;
+	struct river_layout_v3 *layout;
+	uint32_t name;
+	bool configured;
+
+	/* Tags for the next user command. Due to backwards compatability, the
+	 * layout protocol sends us the currently active tags for a user command
+	 * in a separate event before the actual user command. This event is
+	 * guaranteed to be received.
+	 */
+	uint32_t user_command_tags;
+};
+
+#endif