new API

and code cleanup

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

@@ -0,0 +1,424 @@
+#include <ctype.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <assert.h>
+#include <setjmp.h>
+#include <wayland-client.h>
+#include <libguile.h>
+
+#ifdef __linux__
+#include <features.h>
+#ifdef __GLIBC__
+#include<execinfo.h>
+#endif
+#endif
+
+#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;
+
+jmp_buf skip_main_loop;
+
+struct wl_display *wl_display = NULL;
+struct wl_registry *wl_registry = NULL;
+struct wl_callback *sync_callback = NULL;
+struct river_layout_manager_v3 *layout_manager = NULL;
+
+struct wl_list outputs;
+
+/* 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.
+ */
+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 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);
+		fputs("INFO: This error is not fatal.\n", stderr);
+		return;
+	}
+
+	// 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);
+	ret = EXIT_FAILURE;
+	loop = false;
+}
+
+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,
+	.user_command_tags = layout_handle_user_command_tags,
+};
+
+static void output_configure (struct Output *output)
+{
+	if ( layout_manager == NULL )
+		return;
+	if (output->configured)
+		return;
+
+	output->layout = river_layout_manager_v3_get_layout(
+		layout_manager, output->wl_output, "riverguile"
+	);
+	river_layout_v3_add_listener(output->layout, &layout_listener, output);
+	output->configured = true;
+}
+
+static struct Output *output_create (struct wl_output *wl_output)
+{
+	struct Output *output = calloc(1, sizeof(struct Output));
+	if ( output == NULL )
+	{
+		fprintf(stderr, "ERROR: calloc: %s\n", strerror(errno));
+		return NULL;
+	}
+
+	output->wl_output = wl_output;
+	output_configure(output);
+	return output;
+}
+
+static void output_destroy (struct Output *output)
+{
+	if ( output->layout != NULL )
+		river_layout_v3_destroy(output->layout);
+	assert(output->wl_output != NULL);
+	wl_output_destroy(output->wl_output);
+	free(output);
+}
+
+static void registry_handle_global (void *data, struct wl_registry *registry,
+		uint32_t name, const char *interface, uint32_t version)
+{
+	if ( strcmp(interface, river_layout_manager_v3_interface.name) == 0 )
+	{
+		layout_manager = wl_registry_bind(
+			registry, name, &river_layout_manager_v3_interface, 2
+		);
+	}
+	else if ( strcmp(interface, wl_output_interface.name) == 0 )
+	{
+		struct wl_output *wl_output = wl_registry_bind(
+			registry, name, &wl_output_interface, 1
+		);
+		struct Output *output = output_create(wl_output);
+		if ( output == NULL )
+		{
+			wl_output_destroy(wl_output);
+			ret = EXIT_FAILURE;
+			loop = false;
+			return;
+		}
+		wl_list_insert(&outputs, &output->link);
+	}
+}
+
+static void registry_handle_global_remove (void *data, struct wl_registry *registry,
+		uint32_t name)
+{
+	struct Output *output, *tmp;
+	wl_list_for_each_safe(output, tmp, &outputs, link)
+	{
+		if ( output->name != name )
+			continue;
+		wl_list_remove(&output->link);
+		output_destroy(output);
+		return;
+	}
+}
+
+static const struct wl_registry_listener registry_listener = {
+	.global        = registry_handle_global,
+	.global_remove = registry_handle_global_remove,
+};
+
+static void sync_handle_done (void *data, struct wl_callback *wl_callback, uint32_t other_data)
+{
+	wl_callback_destroy(wl_callback);
+	sync_callback = NULL;
+
+	if ( layout_manager == NULL )
+	{
+		fputs("ERROR: Wayland server  does not support river-layout-v3.\n", stderr);
+		ret = EXIT_FAILURE;
+		loop = false;
+		return;
+	}
+
+	/* If outputs were registered before the river_layout_manager is
+	 * available, they won't have a river_layout, so we need to create
+	 * those here.
+	 */
+	struct Output *output;
+	wl_list_for_each(output, &outputs, link)
+		output_configure(output);
+}
+
+static const struct wl_callback_listener sync_callback_listener = {
+	.done = sync_handle_done,
+};
+
+static void handle_interrupt (int signum)
+{
+	fputs("Killed 💀\n", stderr);
+	loop = false;
+	longjmp(skip_main_loop, 1);
+}
+
+/**
+ * Intercept error signals (like SIGSEGV and SIGFPE) so that we can try to
+ * print a fancy error message and a backtracke before letting the system kill us.
+ */
+static void handle_error (int signum)
+{
+	const char *msg =
+		"\n"
+		"┌──────────────────────────────────────────┐\n"
+		"│                                          │\n"
+		"│         riverguile has crashed.          │\n"
+		"│                                          │\n"
+		"│   This is most likely a bug, so please   │\n"
+		"│     report this to the mailing list.     │\n"
+		"│                                          │\n"
+		"│  ~leon_plickat/public-inbox@lists.sr.ht  │\n"
+		"│                                          │\n"
+		"└──────────────────────────────────────────┘\n"
+		"\n";
+	fputs(msg, stderr);
+
+	/* Set up the default handlers to deal with the rest. We do this before
+	 * attempting to get a backtrace, because sometimes that could also
+	 * cause a SEGFAULT and we don't want a funny signal loop to happen.
+	 */
+	signal(signum, SIG_DFL);
+
+#ifdef __linux__
+#ifdef __GLIBC__
+	fputs("Attempting to get backtrace:\n", stderr);
+	void *buffer[255];
+	const int calls = backtrace(buffer, sizeof(buffer) / sizeof(void *));
+	backtrace_symbols_fd(buffer, calls, fileno(stderr));
+	fputs("\n", stderr);
+#endif
+#endif
+
+	/* Easiest way of calling the default signal handler. */
+	kill(getpid(), signum);
+}
+
+
+static char *formatted_buffer (const char *fmt, ...)
+{
+	/* Determine length of formatted text. */
+	va_list args;
+	va_start(args, fmt);
+	/* +1 for NULL. */
+	unsigned long len = (unsigned long)vsnprintf(NULL, 0, fmt, args) + 1;
+	va_end(args);
+
+	char *buffer = calloc(1, len);
+	if ( buffer == NULL )
+	{
+		fprintf(stderr, "ERROR: calloc: %s\n", strerror(errno));
+		return NULL;
+	}
+
+	/* Finally write formatted text into buffer. */
+	va_start(args, fmt);
+	vsnprintf(buffer, len, fmt, args);
+	va_end(args);
+
+	return buffer;
+}
+
+static char *get_script_path (void)
+{
+	struct {
+		const char *fmt;
+		bool needs_env;
+		const char *env;
+	} paths[] = {
+		{ .fmt = "layout.scm",                       .needs_env = false, .env = NULL                      },
+		{ .fmt = "%s/riverguile/layout.scm",         .needs_env = true,  .env = getenv("XDG_CONFIG_HOME") },
+		{ .fmt = "%s/river/layout.scm",              .needs_env = true,  .env = getenv("XDG_CONFIG_HOME") },
+		{ .fmt = "%s/.config/riverguile/layout.scm", .needs_env = true,  .env = getenv("HOME")            },
+		{ .fmt = "%s/.config/river/layout.scm",      .needs_env = true,  .env = getenv("HOME")            },
+		{ .fmt = "/etc/riverguile/layout.scm",       .needs_env = false, .env = NULL                      }
+	};
+
+	char *path = NULL;
+	for (size_t i = 0; i < (sizeof(paths) / sizeof(paths[0])); i++)
+	{
+		if ( path != NULL )
+		{
+			free(path);
+			path = NULL;
+		}
+
+		/* Path needs env var, but it is not set. */
+		if ( paths[i].needs_env && paths[i].env == NULL )
+			continue;
+
+		path = formatted_buffer(paths[i].fmt, paths[i].env);
+		if ( path == NULL )
+			return NULL;
+
+		/* Does the path exist? */
+		if ( access(path, F_OK) != 0 )
+			continue;
+
+		/* Is it readable? */
+		if ( access(path, R_OK) != 0 )
+		{
+			fprintf(stderr, "ERROR: Script '%s' exists, but is not readable.\n", path);
+			free(path);
+			return NULL;
+		}
+
+		return path;
+	}
+
+	if ( path != NULL )
+		free(path);
+
+	fputs("ERROR: No layout script found.\n", stderr);
+	return NULL;
+}
+
+int main(int argc, char *argv[])
+{
+	signal(SIGSEGV, handle_error);
+	signal(SIGFPE, handle_error);
+	signal(SIGINT, handle_interrupt);
+	wl_list_init(&outputs);
+
+	// TODO use argv[1] if present
+	char *path = get_script_path();
+	if ( path == NULL )
+	{
+		ret = EXIT_FAILURE;
+		goto early_exit;
+	}
+
+	void *res = scm_with_guile(load_script, (void *)path);
+	if ( res != NULL )
+	{
+		fputs((char *)res, stderr);
+		ret = EXIT_FAILURE;
+		loop = false;
+		goto early_exit;
+	}
+
+	/* We query the display name here instead of letting wl_display_connect()
+	 * figure it out itself, because libwayland (for legacy reasons) falls
+	 * back to using "wayland-0" when $WAYLAND_DISPLAY is not set, which is
+	 * generally not desirable.
+	 */
+	const char *display_name = getenv("WAYLAND_DISPLAY");
+	if ( display_name == NULL )
+	{
+		fputs("ERROR: WAYLAND_DISPLAY is not set.\n", stderr);
+		ret = EXIT_FAILURE;
+		goto early_exit;
+	}
+
+	wl_display = wl_display_connect(display_name);
+	if ( wl_display == NULL )
+	{
+		fputs("ERROR: Can not connect to wayland display.\n", stderr);
+		ret = EXIT_FAILURE;
+		goto early_exit;
+	}
+
+	wl_registry = wl_display_get_registry(wl_display);
+	wl_registry_add_listener(wl_registry, &registry_listener, NULL);
+
+	sync_callback = wl_display_sync(wl_display);
+	wl_callback_add_listener(sync_callback, &sync_callback_listener, NULL);
+
+	if ( setjmp(skip_main_loop) == 0 )
+		while ( loop && wl_display_dispatch(wl_display) > 0 );
+
+	struct Output *output, *tmp;
+	wl_list_for_each_safe(output, tmp, &outputs, link)
+	{
+		wl_list_remove(&output->link);
+		output_destroy(output);
+	}
+
+	if ( sync_callback != NULL )
+		wl_callback_destroy(sync_callback);
+	if ( wl_registry != NULL )
+		wl_registry_destroy(wl_registry);
+	wl_display_disconnect(wl_display);
+
+early_exit:
+	if ( path != NULL )
+		free(path);
+
+	return ret;
+}
+

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