Function destroy_items

src/zap.c:5964–6097

target items of specified class in mon's inventory for possible destruction return total amount of damage inflicted, though this is unused if mon is the player */

   return total amount of damage inflicted, though this is unused if mon is
   the player */
int
destroy_items(
    struct monst *mon, /* monster whose invent is being subjected to
                        * destruction */
    int dmgtyp,        /* AD_**** - currently only cold, fire, elec */
    int dmg_in)        /* the amount of HP damage the attack dealt */
{
    struct obj *obj;
    int i, defer;
    int limit; /* max amount of item stacks destroyed, based on damage */
    struct {
        unsigned oid;
        struct obj *otmp;
        boolean deferred;
    } items_to_destroy[MAX_ITEMS_DESTROYED];
    int elig_stacks = 0; /* number of destroyable objects found so far */
    boolean u_carry = (mon == &gy.youmonst);
    /* this is a struct obj** because we might destroy the first item in it */
    struct obj **objchn = u_carry ? &gi.invent : &mon->minvent;
    int dmg_out = 0; /* damage caused by items getting destroyed */
    xint8 where = NOBJ_STATES;

    /* initialize items_to_destroy */
    for (i = 0; i < MAX_ITEMS_DESTROYED; ++i) {
        /* 0 should not be a valid o_id for anything */
        items_to_destroy[i].oid = 0;
        items_to_destroy[i].otmp = (struct obj *) 0;
        items_to_destroy[i].deferred = FALSE;
    }

    /* don't straight up destroy all items with an equal chance; limit it
       based on the amount of damage being dealt by the source of the item
       destruction */
    limit = dmg_in / DMG_DESTROY_SCALE;
    if (dmg_in % DMG_DESTROY_SCALE > rn2(DMG_DESTROY_SCALE)) {
        limit++; /* dmg = 9: 20% chance of limit=1, 80% of limit=2, etc */
    }
    if (limit > MAX_ITEMS_DESTROYED) {
        /* in case of incredibly high damage, prevent from overflowing
         * items_to_destroy */
        limit = MAX_ITEMS_DESTROYED;
    }
    if (limit < 1) {
        return 0; /* nothing destroyed */
    }

    /* Sometimes destroying an item can change inventory aside from
     * the item itself (cited case was a potion of unholy water; when
     * boiled, potionbreathe() caused hero to transform into were-beast
     * form and that resulted in dropping or destroying some worn armor).
     *
     * Unlike other uses of the object bypass mechanism, destroy_items()
     * can be called multiple times for the same event.  So we have to
     * explicitly clear it before each use and hope no other section of
     * code expects it to retain previous value.
     *
     * Destruction of a ring of levitation or form change which pushes
     * off levitation boots could drop hero onto a fire trap that