Object_LoadExtra add size check to vanilla function

Author: djevangelia

ASM/c/object.c

@@ -40,22 +40,33 @@ int16_t Object_LoadExtra(z64_game_t* play, int16_t objectId, uint8_t syncDma) {
         }
     }
 
-    if(slot != -1) {
+    if (slot != -1) {
         // Take the found slot
         z64_mem_obj_t* newEntry = &play->obj_ctxt.objects[slot];    // The new object
         z64_mem_obj_t* lastEntry = &play->obj_ctxt.objects[play->obj_ctxt.n_objects-1]; // Previous last added object
         RomFile* lastObjectFile = &gObjectTable[ABS(lastEntry->id)];    // Get previous object start pointer and size
         uint32_t lastSize = lastObjectFile->vromEnd - lastObjectFile->vromStart;
         newEntry->data = (void*)ALIGN16((uintptr_t)lastEntry->data + lastSize); // Gives pointer to start for the new object data
 
-        func_800982FC(&play->obj_ctxt, slot, objectId); // Set up data for adding the object to the slot on next update
-        play->obj_ctxt.n_objects++;
+        // Set up data for adding the object to the slot on next update or now
+        if (func_800982FC(&play->obj_ctxt, slot, objectId) != NULL) {
+            play->obj_ctxt.n_objects++;
 
-        if (syncDma) {
-            play->obj_ctxt.objects[slot].id = objectId;    // Uninvert the id because it will get loaded now
-            RomFile* objectFile = &gObjectTable[ABS(objectId)];    // Get object start pointer and size
-            uint32_t size = objectFile->vromEnd - objectFile->vromStart;
-            DmaMgr_RequestSync(newEntry->data, objectFile->vromStart, size);
+            if (syncDma) {
+                play->obj_ctxt.objects[slot].id = objectId;    // Uninvert the id because it will get loaded now
+                RomFile* objectFile = &gObjectTable[objectId];    // Get object start pointer and size
+                uint32_t size = objectFile->vromEnd - objectFile->vromStart;
+                DmaMgr_RequestSync(newEntry->data, objectFile->vromStart, size);
+            }
+
+        } else { // Loading new object would exceed object space
+            #ifdef DEBUG_MODE
+                char msg[256];
+                sprintf(msg, "Obj %d slot %d", objectId, slot);
+                Fault_AddHungupAndCrashImpl("Object_LoadExtra: No memory", msg);
+            #endif
+
+            return -1;  // Don't crash non-debug mode for now but this should not happen!
         }
     }
 

ASM/src/build.asm

@@ -135,6 +135,7 @@ RANDO_CONTEXT:
 .include "big_poe.asm"
 .include "player_ladder_cutscene.asm"
 .include "enbox_callloadobject.asm"
+.include "object_checkmaxobjectspace.asm"
 
 .align 0x10
 .importobj "../build/bundle.o"

ASM/src/hacks.asm

@@ -4163,3 +4163,4 @@ DemoEffect_DrawJewel_AfterHook:
 .include "hacks/sound.asm"
 .include "hacks/z_player.asm"
 .include "hacks/en_box.asm"
+.include "hacks/z_scene.asm"

ASM/src/hacks/z_scene.asm

@@ -0,0 +1,11 @@
+.headersize (0x80114dd0 - 0x00b8ad30)
+
+; Object load: Add check to ensure that new object to be loaded
+; fits within object context space, else return NULL
+; Replaces  addu    t1,t4,t0
+;           addiu   t1,t1,15
+;           and     v0,t1,at
+.org 0x8008178c     ; in func_800982FC
+    jal     Object_CheckMaxObjectSpace
+    addu    t1,t4,t0        ; displaced
+    lw      ra,12(sp)       ; ra is already saved by another hack, but not saved in vanilla func_800982FC

ASM/src/object_checkmaxobjectspace.asm

@@ -0,0 +1,10 @@
+Object_CheckMaxObjectSpace:
+    addiu   t1,t1,15        ; displaced
+    and     v0,t1,at        ; displaced
+    lw      t1,4(a0)        ; objectCtx space end
+    sltu    at,v0,t1        ; next object start pointer < space end?
+    beqzl   at,@@Return     ; if yes, return pointer (v0)
+    move    v0,zero         ; if not - memory full, return NULL, let caller deal with it
+@@Return:
+    jr      ra
+    nop