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fix #K1963 - warning after placing worm tail

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Report described this as a panic triggered by the sanity_check
option, but that's because it was running under the fuzzer, which
escalates any impossible() to panic(), rather than because nethack
panicked.

I couldn't find anything wrong--which doesn't mean that there
isn't something wrong--with place_worm_tail_randomly() and
random_dir().  They use xchar for map coordinates which should be
fine as long as no negative values are generated and I couldn't
discover any such.  The suggested fix of changing xchar to int
might indicate a compiler bug (although the odds of that are low).
The bogus coordinate of -15000 in the report suggests that
 typedef short int schar;
(which changes xchar too) is being used in the configuration but
I don't recall having any problems attributable to that.

This switches from xchar to int as a side-effect of replacing the
offending code entirely.  The new code might produce an 'ny' of -1
before goodpos() rejects it, so xchar would be inappropriate now.
The old code is commented out via #if 0 _after_ changing it from
xchar to int.

This also adds an extra sanity_check for worm tails, unrelated to
the current bug.  I'm not aware of any instance where it fails.
EXTRA_SANITY_CHECKS needs to be defined for it to do anything.
This commit is contained in:
PatR
2020-09-08 03:03:03 -07:00
parent f20a6bb491
commit a48b4aa8ba
4 changed files with 82 additions and 19 deletions
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4
doc/fixes37.0
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@@ -1,4 +1,4 @@
NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.298 $ $NHDT-Date: 1599434249 2020/09/06 23:17:29 $
NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.299 $ $NHDT-Date: 1599559379 2020/09/08 10:02:59 $
General Fixes and Modified Features
-----------------------------------
@@ -328,6 +328,8 @@ the fix to make worm visibility checks work as intended forced the coordinates
using 'O' to try to change 'symset' was a no-op; 'roguesymset' worked
change default for lit attribute in special level des.terrain directives to
'unchanged' instead of 'unlit'
replace worm tail placement code that reportedly led to a sanity_check warning
[no actual code problem found; might be compiler bug for 'xchar']
curses: 'msg_window' option wasn't functional for curses unless the binary
also included tty support

3
include/extern.h
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@@ -1,4 +1,4 @@
/* NetHack 3.7 extern.h $NHDT-Date: 1597069374 2020/08/10 14:22:54 $ $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.855 $ */
/* NetHack 3.7 extern.h $NHDT-Date: 1599559379 2020/09/08 10:02:59 $ $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.856 $ */
/* Copyright (c) Steve Creps, 1988. */
/* NetHack may be freely redistributed. See license for details. */
@@ -3078,6 +3078,7 @@ E void FDECL(save_worm, (NHFILE *));
E void FDECL(rest_worm, (NHFILE *));
E void FDECL(place_wsegs, (struct monst *, struct monst *));
E void FDECL(sanity_check_worm, (struct monst *));
E void NDECL(wormno_sanity_check);
E void FDECL(remove_worm, (struct monst *));
E void FDECL(place_worm_tail_randomly, (struct monst *, XCHAR_P, XCHAR_P));
E int FDECL(size_wseg, (struct monst *));

6
src/mon.c
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@@ -1,4 +1,4 @@
/* NetHack 3.7 mon.c $NHDT-Date: 1599330921 2020/09/05 18:35:21 $ $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.345 $ */
/* NetHack 3.7 mon.c $NHDT-Date: 1599559379 2020/09/08 10:02:59 $ $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.346 $ */
/* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
/*-Copyright (c) Derek S. Ray, 2015. */
/* NetHack may be freely redistributed. See license for details. */
@@ -150,6 +150,8 @@ mon_sanity_check()
for (mtmp = g.migrating_mons; mtmp; mtmp = mtmp->nmon) {
sanity_check_single_mon(mtmp, FALSE, "migr");
}
wormno_sanity_check(); /* test for bogus worm tail */
}
/* Would monster be OK with poison gas? */
@@ -1820,7 +1822,7 @@ struct monst *mtmp, *mtmp2;
if (mtmp != u.usteed) /* don't place steed onto the map */
place_monster(mtmp2, mtmp2->mx, mtmp2->my);
if (mtmp2->wormno) /* update level.monsters[wseg->wx][wseg->wy] */
place_wsegs(mtmp2, NULL); /* locations to mtmp2 not mtmp. */
place_wsegs(mtmp2, mtmp); /* locations to mtmp2 not mtmp. */
if (emits_light(mtmp2->data)) {
/* since this is so rare, we don't have any `mon_move_light_source' */
new_light_source(mtmp2->mx, mtmp2->my, emits_light(mtmp2->data),

88
src/worm.c
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@@ -1,4 +1,4 @@
/* NetHack 3.7 worm.c $NHDT-Date: 1596841504 2020/08/07 23:05:04 $ $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.47 $ */
/* NetHack 3.7 worm.c $NHDT-Date: 1599559380 2020/09/08 10:03:00 $ $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.48 $ */
/* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
/*-Copyright (c) Robert Patrick Rankin, 2009. */
/* NetHack may be freely redistributed. See license for details. */
@@ -16,7 +16,9 @@ struct wseg {
static void FDECL(toss_wsegs, (struct wseg *, BOOLEAN_P));
static void FDECL(shrink_worm, (int));
static void FDECL(random_dir, (XCHAR_P, XCHAR_P, xchar *, xchar *));
#if 0
static void FDECL(random_dir, (int, int, int *, int *));
#endif
static struct wseg *FDECL(create_worm_tail, (int));
/* Description of long worm implementation.
@@ -680,6 +682,31 @@ struct monst *worm;
}
}
/* called from mon_sanity_check(mon.c) */
void
wormno_sanity_check()
{
#ifdef EXTRA_SANITY_CHECKS
struct wseg *seg;
int wh = 0, wt = 0;
/* checking tail management, not a particular monster; since wormno==0
means 'not a worm', wheads[0] and wtails[0] should always be empty;
note: if erroneously non-Null, tail segment count will include the
extra segment for the worm's head that isn't shown on the map */
for (seg = wheads[0]; seg; seg = seg->nseg)
++wh;
for (seg = wtails[0]; seg; seg = seg->nseg)
++wt;
if (wh || wt) {
impossible(
"phantom worm tail #0 [head=%s, %d segment%s; tail=%s, %d segment%s]",
fmt_ptr(wheads[0]), wh, plur(wh),
fmt_ptr(wtails[0]), wt, plur(wt));
}
#endif /* EXTRA_SANITY_CHECKS */
}
/*
* remove_worm()
*
@@ -721,7 +748,7 @@ xchar x, y;
int wnum = worm->wormno;
struct wseg *curr = wtails[wnum];
struct wseg *new_tail;
xchar ox = x, oy = y;
int ox = x, oy = y;
if (wnum && (!wtails[wnum] || !wheads[wnum])) {
impossible("place_worm_tail_randomly: wormno is set without a tail!");
@@ -729,10 +756,14 @@ xchar x, y;
}
if (wtails[wnum] == wheads[wnum]) {
/* single segment, co-located with worm so nothing to place */
if (curr->wx != worm->mx || curr->wy != worm->my)
if (curr->wx != worm->mx || curr->wy != worm->my) {
impossible(
"place_worm_tail_randomly: tail segement at <%d,%d>, worm at <%d,%d>",
curr->wx, curr->wy, worm->mx, worm->my);
if (m_at(curr->wx, curr->wy) == worm)
remove_monster(curr->wx, curr->wy);
curr->wx = worm->mx, curr->wy = worm->my;
}
return;
}
/* remove head segment from map in case we end up calling toss_wsegs();
@@ -747,30 +778,56 @@ xchar x, y;
new_tail->wy = y;
while (curr) {
xchar nx, ny;
int tryct = 0;
int nx = 0, ny = 0;
#if 0 /* old code */
int trycnt = 0;
/* pick a random direction from x, y and search for goodpos() */
/* pick a random direction from x, y and test for goodpos() */
do {
random_dir(ox, oy, &nx, &ny);
} while (!goodpos(nx, ny, worm, 0) && (tryct++ < 50));
} while (!goodpos(nx, ny, worm, 0) && ++tryct <= 50);
if (tryct < 50) {
if (tryct <= 50)
#else /* new code */
int i, j, k, dirs[8];
/* instead of picking a random direction up to 50 times, try each
of the eight directions at most once after shuffling their order */
for (i = 0; i < 8; ++i)
dirs[i] = i;
for (i = 8; i > 0; --i) {
j = rn2(i);
k = dirs[j];
dirs[j] = dirs[i - 1];
dirs[i - 1] = k;
}
for (i = 0; i < 8; ++i) {
nx = ox + xdir[dirs[i]];
ny = oy + ydir[dirs[i]];
if (goodpos(nx, ny, worm, 0)) /* includes an isok() check */
break;
}
if (i < 8)
#endif
{
place_worm_seg(worm, nx, ny);
curr->wx = ox = nx;
curr->wy = oy = ny;
curr->wx = (xchar) (ox = nx);
curr->wy = (xchar) (oy = ny);
wtails[wnum] = curr;
curr = curr->nseg;
wtails[wnum]->nseg = new_tail;
new_tail = wtails[wnum];
newsym(nx, ny);
} else { /* Oops. Truncate because there was */
toss_wsegs(curr, FALSE); /* no place for the rest of it */
} else {
/* Oops. Truncate because there is no place for rest of it. */
toss_wsegs(curr, FALSE);
curr = (struct wseg *) 0;
}
}
}
#if 0
/*
* Given a coordinate x, y.
* return in *nx, *ny, the coordinates of one of the <= 8 squares adjoining.
@@ -781,8 +838,8 @@ xchar x, y;
static
void
random_dir(x, y, nx, ny)
xchar x, y;
xchar *nx, *ny;
int x, y;
int *nx, *ny;
{
*nx = x + (x > 1 /* extreme left ? */
? (x < COLNO - 1 /* extreme right ? */
@@ -802,6 +859,7 @@ xchar *nx, *ny;
: -1) /* bottom, use -1 */
: 1); /* top, use +1 */
}
#endif
/* for size_monst(cmd.c) to support #stats */
int