Also override GObject introspection called functions

Some functions that we need to override may also be called via GObject
introspection (e.g. when calling them from Python and other scripting
languages), so we need to make sure that also this method of calling
these functions causes our overrides to be called.

To this end, override the g_function_info_prep_invoker method to
replace the function pointers if necessary.

Makefile

@@ -1,6 +1,6 @@
 PKG_CONFIG ?= pkg-config
 CFLAGS ?= -O2 -g
-CFLAGS += $(shell ${PKG_CONFIG} --cflags gtk+-3.0) -pthread -Wall -fPIC
+CFLAGS += $(shell ${PKG_CONFIG} --cflags gtk+-3.0) $(shell ${PKG_CONFIG} --cflags gobject-introspection-1.0) -pthread -Wall -fPIC
 LDLIBS = -ldl
 
 libdir ?= /usr/lib

gtk3-nocsd.c

@@ -32,6 +32,8 @@
 #include <gtk/gtk.h>
 #include <gdk/gdk.h>
 
+#include <girffi.h>
+
 typedef void (*gtk_window_buildable_add_child_t) (GtkBuildable *buildable, GtkBuilder *builder, GObject *child, const gchar *type);
 typedef GObject* (*gtk_dialog_constructor_t) (GType type, guint n_construct_properties, GObjectConstructParam *construct_params);
 typedef char *(*gtk_check_version_t) (guint required_major, guint required_minor, guint required_micro);
@@ -42,6 +44,7 @@ enum {
     GDK_LIBRARY,
     GOBJECT_LIBRARY,
     GLIB_LIBRARY,
+    GIREPOSITORY_LIBRARY,
     NUM_LIBRARIES
 };
 
@@ -61,17 +64,23 @@ enum {
 #define GLIB_LIBRARY_SONAME "libglib-2.0.so"
 #endif
 
+#ifndef GIREPOSITORY_LIBRARY_SONAME
+#define GIREPOSITORY_LIBRARY_SONAME "libgirepository-1.0.so.1"
+#endif
+
 static const char *library_sonames[NUM_LIBRARIES] = {
     GTK_LIBRARY_SONAME,
     GDK_LIBRARY_SONAME,
     GOBJECT_LIBRARY_SONAME,
-    GLIB_LIBRARY_SONAME
+    GLIB_LIBRARY_SONAME,
+    GIREPOSITORY_LIBRARY_SONAME
 };
 
 static void * volatile library_handles[NUM_LIBRARIES] = {
     NULL,
     NULL,
     NULL,
+    NULL,
     NULL
 };
 
@@ -171,6 +180,7 @@ RUNTIME_IMPORT_FUNCTION(GOBJECT_LIBRARY, g_type_instance_get_private, gpointer,
 RUNTIME_IMPORT_FUNCTION(GOBJECT_LIBRARY, g_signal_connect_data, gulong, (gpointer instance, const gchar *detailed_signal, GCallback c_handler, gpointer data, GClosureNotify destroy_data, GConnectFlags connect_flags), (instance, detailed_signal, c_handler, data, destroy_data, connect_flags))
 RUNTIME_IMPORT_FUNCTION(GLIB_LIBRARY, g_getenv, gchar *, (const char *name), (name))
 RUNTIME_IMPORT_FUNCTION(GLIB_LIBRARY, g_logv, void, (const gchar *log_domain, GLogLevelFlags log_level, const gchar *format, va_list args), (log_domain, log_level, format, args))
+RUNTIME_IMPORT_FUNCTION(GIREPOSITORY_LIBRARY, g_function_info_prep_invoker, gboolean, (GIFunctionInfo *info, GIFunctionInvoker *invoker, GError **error), (info, invoker, error))
 
 /* All methods that we want to overwrite are named orig_, all methods
  * that we just want to call (either directly or indirectrly)
@@ -209,6 +219,7 @@ RUNTIME_IMPORT_FUNCTION(GLIB_LIBRARY, g_logv, void, (const gchar *log_domain, GL
 #define g_getenv                                         rtlookup_g_getenv
 #define g_logv                                           rtlookup_g_logv
 #define g_log                                            static_g_log
+#define orig_g_function_info_prep_invoker                rtlookup_g_function_info_prep_invoker
 
 /* Forwarding of varadic functions is tricky. */
 static void static_g_log(const gchar *log_domain, GLogLevelFlags log_level, const gchar *format, ...)
@@ -679,3 +690,24 @@ static gtk_window_private_info_t gtk_window_private_info ()
     }
     return info;
 }
+
+gboolean g_function_info_prep_invoker (GIFunctionInfo *info, GIFunctionInvoker *invoker, GError **error)
+{
+    static gpointer orig_set_titlebar = NULL, orig_set_show_close_button = NULL;
+    gboolean result;
+
+    if (!orig_set_titlebar)
+        orig_set_titlebar = (gpointer) find_orig_function (GTK_LIBRARY, "gtk_window_set_titlebar");
+    if (!orig_set_show_close_button)
+        orig_set_show_close_button = (gpointer) find_orig_function (GTK_LIBRARY, "gtk_header_bar_set_show_close_button");
+
+    result = orig_g_function_info_prep_invoker (info, invoker, error);
+    if (result) {
+        if (G_UNLIKELY (invoker->native_address == orig_set_titlebar))
+            invoker->native_address = gtk_window_set_titlebar;
+        if (G_UNLIKELY (invoker->native_address == orig_set_show_close_button))
+            invoker->native_address = gtk_header_bar_set_show_close_button;
+    }
+
+    return result;
+}