Ensure font data is free'd before other finalizers

Fixes #583

kitty/fonts.c

@@ -1155,8 +1155,8 @@ finalize(void) {
     Py_CLEAR(prerender_function);
     Py_CLEAR(descriptor_for_idx);
     free_font_groups();
-    if (harfbuzz_buffer) hb_buffer_destroy(harfbuzz_buffer);
+    if (harfbuzz_buffer) { hb_buffer_destroy(harfbuzz_buffer); harfbuzz_buffer = NULL; }
-    free(group_state.groups);
+    free(group_state.groups); group_state.groups = NULL; group_state.groups_capacity = 0;
 }
 
 static PyObject*
@@ -1292,9 +1292,15 @@ create_test_font_group(PyObject *self UNUSED, PyObject *args) {
     return Py_BuildValue("II", fg->cell_width, fg->cell_height);
 }
 
+static PyObject*
+free_font_data(PyObject *self UNUSED, PyObject *args UNUSED) {
+    finalize();
+    Py_RETURN_NONE;
+}
 
 static PyMethodDef module_methods[] = {
     METHODB(set_font_data, METH_VARARGS),
+    METHODB(free_font_data, METH_NOARGS),
     METHODB(create_test_font_group, METH_VARARGS),
     METHODB(sprite_map_set_layout, METH_VARARGS),
     METHODB(test_sprite_position_for, METH_VARARGS),
@@ -1309,10 +1315,6 @@ static PyMethodDef module_methods[] = {
 
 bool
 init_fonts(PyObject *module) {
-    if (Py_AtExit(finalize) != 0) {
-        PyErr_SetString(PyExc_RuntimeError, "Failed to register the fonts module at exit handler");
-        return false;
-    }
     harfbuzz_buffer = hb_buffer_create();
     if (harfbuzz_buffer == NULL || !hb_buffer_allocation_successful(harfbuzz_buffer) || !hb_buffer_pre_allocate(harfbuzz_buffer, 2048)) { PyErr_NoMemory(); return false; }
     hb_buffer_set_cluster_level(harfbuzz_buffer, HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS);

kitty/main.py

@@ -15,8 +15,8 @@ from .constants import (
     appname, config_dir, glfw_path, is_macos, is_wayland, logo_data_file
 )
 from .fast_data_types import (
-    create_os_window, glfw_init, glfw_terminate, set_default_window_icon,
+    create_os_window, free_font_data, glfw_init, glfw_terminate,
-    set_options
+    set_default_window_icon, set_options
 )
 from .fonts.box_drawing import set_scale
 from .fonts.render import set_font_family
@@ -38,10 +38,7 @@ def init_graphics():
     return glfw_module
 
 
-def run_app(opts, args):
+def _run_app(opts, args):
-    set_scale(opts.box_drawing_scale)
-    set_options(opts, is_wayland, args.debug_gl, args.debug_font_fallback)
-    set_font_family(opts)
     with cached_values_for(run_app.cached_values_name) as cached_values:
         with startup_notification_handler(extra_callback=run_app.first_window_callback) as pre_show_callback:
             window_id = create_os_window(
@@ -60,6 +57,16 @@ def run_app(opts, args):
             boss.destroy()
 
 
+def run_app(opts, args):
+    set_scale(opts.box_drawing_scale)
+    set_options(opts, is_wayland, args.debug_gl, args.debug_font_fallback)
+    set_font_family(opts)
+    try:
+        _run_app(opts, args)
+    finally:
+        free_font_data()  # must free font data before glfw/freetype/fontconfig/opengl etc are finalized
+
+
 run_app.cached_values_name = 'main'
 run_app.first_window_callback = lambda window_handle: None
 run_app.initial_window_size_func = initial_window_size_func