From ed08938ada65849e58592cf660c6222e074d6c3a Mon Sep 17 00:00:00 2001
From: Bart House <bart@barthouse.com>
Date: Sun, 23 Jun 2019 21:39:22 -0700
Subject: [PATCH] Fix dangling chain bug.

If a punished player picks up the iron ball, gets engulfed and
saves, then the saved game will have missed saving the dangling
chain since it was not on the floor or in the inventory.  Upon
restoring the saved game, the game will be in a bad state since
the ball will be worn but the chain will be missing.
---
 include/hack.h |  1 +
 src/restore.c  | 27 +++++++++++++++------------
 src/save.c     | 19 ++++++++++++-------
 3 files changed, 28 insertions(+), 19 deletions(-)

diff --git a/include/hack.h b/include/hack.h
index 0b8a780a4..5ba3bb9a0 100644
--- a/include/hack.h
+++ b/include/hack.h
@@ -436,6 +436,7 @@ enum bodypart_types {
 #define POTION_OCCUPANT_CHANCE(n) (13 + 2 * (n))
 #define WAND_BACKFIRE_CHANCE 100
 #define BALL_IN_MON (u.uswallow && uball && uball->where == OBJ_FREE)
+#define CHAIN_IN_MON (u.uswallow && uchain && uchain->where == OBJ_FREE)
 #define NODIAG(monnum) ((monnum) == PM_GRID_BUG)
 
 /* Flags to control menus */
diff --git a/src/restore.c b/src/restore.c
index 4f19ed878..010ef75c8 100644
--- a/src/restore.c
+++ b/src/restore.c
@@ -540,7 +540,8 @@ unsigned int *stuckid, *steedid;
     struct sysflag newgamesysflags;
 #endif
     struct context_info newgamecontext; /* all 0, but has some pointers */
-    struct obj *otmp, *tmp_bc;
+    struct obj *otmp;
+    struct obj *bc_obj;
     char timebuf[15];
     unsigned long uid;
     boolean defer_perm_invent;
@@ -643,17 +644,15 @@ unsigned int *stuckid, *steedid;
     restore_timers(fd, RANGE_GLOBAL, FALSE, 0L);
     restore_light_sources(fd);
     invent = restobjchn(fd, FALSE, FALSE);
-    /* tmp_bc only gets set here if the ball & chain were orphaned
-       because you were swallowed; otherwise they will be on the floor
-       or in your inventory */
-    tmp_bc = restobjchn(fd, FALSE, FALSE);
-    if (tmp_bc) {
-        for (otmp = tmp_bc; otmp; otmp = otmp->nobj) {
-            if (otmp->owornmask)
-                setworn(otmp, otmp->owornmask);
-        }
-        if (!uball || !uchain)
-            impossible("restgamestate: lost ball & chain");
+
+    /* restore dangling (not on floor or in inventory) ball and/or chain */
+    bc_obj = restobjchn(fd, FALSE, FALSE);
+    while(bc_obj) {
+        struct obj * nobj = bc_obj->nobj;
+        if (bc_obj->owornmask)
+            setworn(bc_obj, bc_obj->owornmask);
+        bc_obj->nobj = (struct obj *)0;
+        bc_obj = nobj;
     }
 
     migrating_objs = restobjchn(fd, FALSE, FALSE);
@@ -671,6 +670,10 @@ unsigned int *stuckid, *steedid;
     for (otmp = invent; otmp; otmp = otmp->nobj)
         if (otmp->owornmask)
             setworn(otmp, otmp->owornmask);
+
+    if ((uball && !uchain) || (uchain && !uball))
+        impossible("restgamestate: lost ball & chain");
+
     /* reset weapon so that player will get a reminder about "bashing"
        during next fight when bare-handed or wielding an unconventional
        item; for pick-axe, we aren't able to distinguish between having
diff --git a/src/save.c b/src/save.c
index 8bca5964a..e0af4b8d2 100644
--- a/src/save.c
+++ b/src/save.c
@@ -280,6 +280,7 @@ savegamestate(fd, mode)
 register int fd, mode;
 {
     unsigned long uid;
+    struct obj * bc_objs = (struct obj *)0;
 
 #ifdef MFLOPPY
     count_only = (mode & COUNT_SAVE);
@@ -307,14 +308,18 @@ register int fd, mode;
     save_light_sources(fd, mode, RANGE_GLOBAL);
 
     saveobjchn(fd, invent, mode);
-    if (BALL_IN_MON) {
-        /* prevent loss of ball & chain when swallowed */
-        uball->nobj = uchain;
-        uchain->nobj = (struct obj *) 0;
-        saveobjchn(fd, uball, mode);
-    } else {
-        saveobjchn(fd, (struct obj *) 0, mode);
+
+    /* save ball and chain if they are currently dangling free (i.e. not on
+       floor or in inventory) */
+    if (CHAIN_IN_MON) {
+        uchain->nobj = bc_objs;
+        bc_objs = uchain;
     }
+    if (BALL_IN_MON) {
+        uball->nobj = bc_objs;
+        bc_objs = uball;
+    }
+    saveobjchn(fd, bc_objs, mode);
 
     saveobjchn(fd, migrating_objs, mode);
     savemonchn(fd, migrating_mons, mode);