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saving vs ball&chain

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I started activating new program_state.saving and discovered that
saving of ball and chain could access freed memory.  The change
for the former and fix for the latter are mixed together here (but
easily distinguishable).

The saving flag inhibits status updating and perm_invent updating,
also map updating that goes through flush_screen().  That should
fix the exception triggered after an impossible warning was issued
during a save operation.  impossible() goes through pline() which
tries to bring the screen up to date before issuing a message.
During save, data for that update can be in an inconsistent state.

The code to save ball and/or chain when not on floor or in invent
(I think swallowed is the only expected case) was examining the
memory pointed to by uball and uchain even if saving the level had
just freed floor objects and saving invent had just freed carried
objects.  So for the usual cases, stale pointer values for uball
and uchain would be present and checking their obj->where field
was not reliable.
This commit is contained in:
PatR
2020-12-02 06:29:58 -08:00
parent 1360e63644
commit 4d6a140d34
7 changed files with 119 additions and 45 deletions
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22
src/worn.c
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@@ -1,4 +1,4 @@
/* NetHack 3.7 worn.c $NHDT-Date: 1596498231 2020/08/03 23:43:51 $ $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.67 $ */
/* NetHack 3.7 worn.c $NHDT-Date: 1606919259 2020/12/02 14:27:39 $ $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.70 $ */
/* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
/*-Copyright (c) Robert Patrick Rankin, 2013. */
/* NetHack may be freely redistributed. See license for details. */
@@ -131,7 +131,7 @@ register struct obj *obj;
is pending (via 'A' command for multiple items) */
cancel_doff(obj, wp->w_mask);
*(wp->w_obj) = 0;
*(wp->w_obj) = (struct obj *) 0;
p = objects[obj->otyp].oc_oprop;
u.uprops[p].extrinsic = u.uprops[p].extrinsic & ~wp->w_mask;
obj->owornmask &= ~wp->w_mask;
@@ -145,6 +145,24 @@ register struct obj *obj;
update_inventory();
}
/* called when saving with FREEING flag set has just discarded inventory */
void
allunworn()
{
const struct worn *wp;
u.twoweap = 0; /* uwep and uswapwep are going away */
/* remove stale pointers; called after the objects have been freed
(without first being unworn) while saving invent during game save;
note: uball and uchain might not be freed yet but we clear them
here anyway (savegamestate() and its callers deal with them) */
for (wp = worn; wp->w_mask; wp++) {
/* object is already gone so we don't/can't update is owornmask */
*(wp->w_obj) = (struct obj *) 0;
}
}
/* return item worn in slot indiciated by wornmask; needed by poly_obj() */
struct obj *
wearmask_to_obj(wornmask)