Give a script none for an object that no longer exists, instead of crashing

port/linux/README.md

@@ -1834,6 +1834,7 @@ Other changes:
 | `cache/cache_files.c` | When a map's tags load and unload, the port finds the bitmaps that the high-res HUD replaces (`game/hud_hires_tags.c`), adds the tags of the menus to the menus' map (`game/menu_tags.c`), and plays the mods' tags (`game/mods.c`). |
 | `cache/xbox_sound_cache.c`, `cache/xbox_texture_cache.c` | The samples of a mod's sound are copied from memory, and the pixels of a mod's bitmap read from its file and laid out for the hardware, at once (`game/mod_sounds.c`, `game/mod_bitmaps.c`); a mod's linear bitmap need not have rows of whole steps of the pitch. |
 | `hs/hs.c` | The console's `mods_reload`, `mods_enable` and `mods_list`, which a client may run too. |
+| `hs/hs_runtime.c`, `hs/object_lists.c`, `units/units.c`, `objects/scenery.c` | A script that holds an object or a list that no longer exists gets none, not a crash: a global, a function's result or an argument with a deleted object's index is none, and walking a list passes over the objects that are gone. `list_count` still counts them. |
 | `interface/ui_widget.c`, `interface/ui_widget_event_handler_functions.c`, `interface/ui_widget_game_data_input_functions.c` | The main menu is the PC version's from `port/assets/menus` (`display.menus`); the menus' widgets can call the port's functions (`game/menu_functions.c`) and send the PC version's custom activation event; the widgets' memory is 256 KB, not 16 KB; the main menu and Multiplayer clear co-op's controllers, so that a gamepad going back to controller 1 is not a controller unplugged; the lobby's split screen players leave alone, and one who quits in game is not joined to the next game (`interface/player_ui.c`). |
 | `interface/player_ui.c` | Fast setup opens the pregame screen through the port's menus (the lobby), as `interface/ui_widget.c` does. |
 | `game/game_engine.c`, `game/game_engine.h`, `game/game_engine_slayer.c`, `game/game.c`, `game/aim_assist.c`, `game/players.c`, `objects/damage.c`, `objects/objects.c`, `units/units.c`, `items/weapons.c`, `saved games/playlist_profile.c`, `saved games/saved_game_files.c` | OpenCE's gametypes (`game/game_modes.c`, "OpenCE gametypes"): the gametype's PC options carry a mode and Hardcore with their options; the built-in ones are written after the Xbox's default gametypes; Infection's and Gun Game's game engines are Slayer's with their rules; SWAT's headshots, Hardcore's motion sensor, aim assist and restore of the killer; Infection's zombies' skulls, grenades, powerups, seats and melee. |

source/hs/hs_runtime.c

@@ -486,6 +486,9 @@ static long hs_object_to_object_list(
 static boolean hs_object_type_can_cast(
 	short actual_type,
 	short desired_type);
+static long hs_value_still_exists(
+	short type,
+	long value);
 static char const *hs_thread_format(
 	long thread_index);
 static void hs_stack_pop(
@@ -1842,6 +1845,25 @@ boolean hs_can_cast(
 	}
 }
 
+/* port: an object or a list that a script holds can be gone when the script
+uses it. A global keeps a vehicle's index after the vehicle is deleted, and a
+list made for an argument is collected while a later argument's static script
+sleeps. Maps do this, and Halo PC plays them, but here datum_get gives NULL for
+it and the read through that crashes the game. Such a value is none, which is
+already how a script says no object: an object's name gives none when that
+object doesn't exist. */
+static long hs_value_still_exists(
+	short type,
+	long value)
+{
+	if (HS_TYPE_IS_OBJECT(type))
+		return object_try_and_get(value) ? value : NONE;
+	if (type==_hs_type_object_list)
+		return datum_try_and_get(object_list_header_data, value) ? value : NONE;
+
+	return value;
+}
+
 long hs_cast(
 	long thread_index,
 	short actual_type,
@@ -1851,6 +1873,13 @@ long hs_cast(
 	match_hs_assert("c:\\halo\\SOURCE\\hs\\hs_runtime.c", 0x5d8, thread_index,
 		hs_can_cast(actual_type, desired_type), "bad typecast.");
 
+	/* port: every global read and every function's or script's result comes
+	through here. Checked before the casts below, so no list is made of an
+	object that is gone */
+	value = hs_value_still_exists(
+		actual_type==_hs_passthrough ? desired_type : actual_type,
+		value);
+
 	if (actual_type!=desired_type &&
 		actual_type!=_hs_passthrough &&
 		!HS_TYPE_IS_OBJECT_NAME(desired_type))
@@ -3363,6 +3392,7 @@ static long *hs_arguments_evaluate(
 	long *values = hs_stack_allocate(thread_index, formal_parameter_count*sizeof(long));
 	short *argument_index = hs_stack_allocate(thread_index, sizeof(short));
 	long *expression_index = hs_stack_allocate(thread_index, sizeof(long));
+	short value_index;
 
 	/* port: none on a stack overflow (hs_stack_overflow): as for arguments
 	still being evaluated, the caller returns on NULL */
@@ -3399,6 +3429,15 @@ static long *hs_arguments_evaluate(
 	match_hs_assert("c:\\halo\\SOURCE\\hs\\hs_runtime.c", 0x3d1, thread_index,
 		*expression_index==NONE, "corrupted syntax tree.");
 
+	/* port: an argument was checked when it was evaluated, and a later one's
+	static script may have slept since (hs_value_still_exists) */
+	for (value_index = 0; value_index<formal_parameter_count; value_index++)
+	{
+		values[value_index] = hs_value_still_exists(
+			formal_parameters[value_index],
+			values[value_index]);
+	}
+
 	return values;
 }
 

source/hs/object_lists.c

@@ -60,6 +60,7 @@ symbols in this file:
 #include "errors.h"
 #include "data.h"
 #include "reference_lists.h"
+#include "objects/objects.h"
 
 /* ---------- constants */
 
@@ -80,6 +81,8 @@ enum
 
 /* ---------- prototypes */
 
+static long object_list_skip_deleted(long object_index, long *reference_index);
+
 /* ---------- globals */
 
 struct data_array *object_list_header_data;
@@ -192,7 +195,10 @@ long object_list_get_next(
 	long object_list_index,
 	long *reference_index)
 {
-	return reference_list_get_next_datum_index(object_list_data, reference_index);
+	/* port: (object_list_skip_deleted) */
+	return object_list_skip_deleted(
+		reference_list_get_next_datum_index(object_list_data, reference_index),
+		reference_index);
 }
 
 void object_list_add_reference(
@@ -277,9 +283,25 @@ long object_list_get_first(
 	if (object_list_index != NONE)
 	{
 		object_list_get_first_internal(object_list_index, reference_index, index);
+		/* port: (object_list_skip_deleted) */
+		index = object_list_skip_deleted(index, reference_index);
 	}
 
 	return index;
 }
 
 /* ---------- private code */
+
+/* port: a list in a script's global outlives the objects it holds, and its
+entry for a deleted object still has that object's index. Whoever walks the list
+gets the objects that still exist (hs_value_still_exists says why). list_count
+still counts the entries, as it always has. */
+static long object_list_skip_deleted(
+	long object_index,
+	long *reference_index)
+{
+	while (object_index!=NONE && !object_try_and_get(object_index))
+		object_index = reference_list_get_next_datum_index(object_list_data, reference_index);
+
+	return object_index;
+}

source/objects/scenery.c

@@ -170,9 +170,10 @@ short scenery_get_animation_time(
 {
 	struct animation *animation;
 	struct animation_graph *animation_graph;
-	struct scenery_datum *scenery = scenery_get(object_index);
+	/* port: a script's scenery may be none (hs_value_still_exists) */
+	struct scenery_datum *scenery = scenery_try_and_get(object_index);
 
-	if (TEST_FLAG(scenery->flags, 0))
+	if (scenery && TEST_FLAG(scenery->flags, 0))
 	{
 		animation_graph = animation_graph_definition_get(
 			scenery->object.object.animation.animation_graph_index);

source/units/units.c

@@ -1053,19 +1053,23 @@ void units_dispose(
 void unit_kill(
 	long unit_index)
 {
-	struct unit_datum *unit = unit_get(unit_index);
+	/* port: a script's unit may be none (hs_value_still_exists) */
+	struct unit_datum *unit = unit_try_and_get(unit_index);
 
-	SET_FLAG(unit->object.damage_flags, _object_die_act_of_god_bit, TRUE);
+	if (unit)
+		SET_FLAG(unit->object.damage_flags, _object_die_act_of_god_bit, TRUE);
 
 	return;
 }
 
 void unit_kill_silent(
 	long unit_index)
 {
-	struct unit_datum *unit = unit_get(unit_index);
+	/* port: a script's unit may be none (hs_value_still_exists) */
+	struct unit_datum *unit = unit_try_and_get(unit_index);
 
-	SET_FLAG(unit->object.damage_flags, _object_die_act_of_god_silent_bit, TRUE);
+	if (unit)
+		SET_FLAG(unit->object.damage_flags, _object_die_act_of_god_silent_bit, TRUE);
 
 	return;
 }