add exit handler

Makefile

@@ -18,6 +18,7 @@ OBJ=src/riverguile.o $\
 	src/call-layout-demand-handler.o $\
 	src/call-user-command-handler.o $\
 	src/call-idle-handler.o $\
+	src/call-exit-handler.o $\
 	src/load-script.o $\
 	protocol/river-layout-v3.o $\
 	protocol/ext-idle-notify-v1.o

doc/riverguile.1

@@ -78,6 +78,9 @@ of the system being idle is over.
 Multiple idle handlers can be installed.
 Note: All idle events relate to the first advetised seat.
 As of now, river only supports a single seat anyway.
+.P
+The key \fBexit\fR installs a handler which is called when riverguile exits.
+The procedure takes no arguments.
 .
 .
 .SH EXAMPLE

src/call-exit-handler.c

@@ -0,0 +1,29 @@
+#include <libguile.h>
+#include <assert.h>
+
+#include "riverguile.h"
+
+static void *call_exit_handler_inner (void *data)
+{
+	assert(data == NULL);
+	return scm_call_0(context.exit_handler);
+}
+
+void *call_exit_handler (void)
+{
+	assert(context.exit_handler != NULL);
+
+	/* Continuation barrier causes stack unwind on exceptions (i.e. errors
+	 * in the user defined exit 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_exit_handler_inner, NULL
+	);
+
+	if ( call_result == NULL )
+		return (void *)"ERROR: An exception occured while calling the exit handler.\n";
+
+	return NULL;
+}

src/call-exit-handler.h

@@ -0,0 +1,6 @@
+#ifndef RIVERGUILE_CALL_EXIT_HANDLER_H
+#define RIVERGUILE_CALL_EXIT_HANDLER_H
+
+void *call_exit_handler (void);
+
+#endif

src/call-idle-handler.c

@@ -21,7 +21,7 @@ static void *call_idle_handler_inner (void *data)
 void *call_idle_handler (void *data)
 {
 	/* Continuation barrier causes stack unwind on exceptions (i.e. errors
-	 * in the user defined ide handler) to stop here. Otherwise the entire
+	 * in the user defined idle handler) to stop here. Otherwise the entire
          * stack created by scm_with_guile() would be unwound. This makes
          * responding to exceptions nicer.
 	 */
@@ -30,7 +30,7 @@ void *call_idle_handler (void *data)
 	);
 
 	if ( call_result == NULL )
-		return (void *)"ERROR: An exception occured while calling the user-command handler.\n";
+		return (void *)"ERROR: An exception occured while calling the idle handler.\n";
 
 	return NULL;
 }

src/load-script.c

@@ -78,6 +78,8 @@ static SCM install_handler (SCM key, SCM proc)
 		context.layout_demand_handler = proc;
 	else if ( scm_is_eq(scm_from_utf8_symbol("user-command"), key) == 1)
 		context.user_command_handler = proc;
+	else if ( scm_is_eq(scm_from_utf8_symbol("exit"), key) == 1)
+		context.exit_handler = proc;
 	else if ( scm_is_true(scm_string_prefix_p(scm_from_utf8_string("idle:"), scm_symbol_to_string(key),
 		scm_from_int(0), scm_from_int(5),
 		scm_from_int(0), scm_string_length(scm_symbol_to_string(key)))) == 1 )

src/riverguile.c

@@ -22,6 +22,7 @@
 #include "ext-idle-notify-v1.h"
 
 #include "load-script.h"
+#include "call-exit-handler.h"
 #include "riverguile.h"
 #include "output.h"
 #include "seat.h"
@@ -346,6 +347,9 @@ int main(int argc, char *argv[])
 	if ( setjmp(skip_main_loop) == 0 )
 		while ( context.loop && wl_display_dispatch(context.wl_display) > 0 );
 
+	if ( context.exit_handler != NULL )
+		call_exit_handler();
+
 	struct Idle *idle, *tmp_i;
 	wl_list_for_each_safe(idle, tmp_i, &context.unconfigured_idles, link)
 	{

src/riverguile.h

@@ -11,6 +11,7 @@ struct Context
 {
 	SCM layout_demand_handler;
 	SCM user_command_handler;
+	SCM exit_handler;
 
 	bool loop;
 	int ret;