From f360dee4dde0c1846232cfb139a8d68425320779 Mon Sep 17 00:00:00 2001
From: Pasi Kallinen <paxed@alt.org>
Date: Sat, 18 Mar 2023 07:30:25 +0200
Subject: [PATCH] Engraving sanity checking

---
 include/extern.h |  1 +
 src/cmd.c        |  1 +
 src/engrave.c    | 28 ++++++++++++++++++++++++++++
 src/sp_lev.c     |  5 +++++
 4 files changed, 35 insertions(+)

diff --git a/include/extern.h b/include/extern.h
index 1443013c2..938adcb21 100644
--- a/include/extern.h
+++ b/include/extern.h
@@ -827,6 +827,7 @@ extern void del_engr_at(coordxy, coordxy);
 extern int freehand(void);
 extern int doengrave(void);
 extern void sanitize_engravings(void);
+extern void engraving_sanity_check(void);
 extern void save_engravings(NHFILE *);
 extern void rest_engravings(NHFILE *);
 extern void engr_stats(const char *, char *, long *, long *);
diff --git a/src/cmd.c b/src/cmd.c
index 08fdadde1..d979ea2f4 100644
--- a/src/cmd.c
+++ b/src/cmd.c
@@ -4247,6 +4247,7 @@ sanity_check(void)
     light_sources_sanity_check();
     bc_sanity_check();
     trap_sanity_check();
+    engraving_sanity_check();
 }
 
 /* qsort() comparison routine for use in list_migrating_mons() */
diff --git a/src/engrave.c b/src/engrave.c
index eac177b28..1033334c2 100644
--- a/src/engrave.c
+++ b/src/engrave.c
@@ -1376,6 +1376,34 @@ sanitize_engravings(void)
     }
 }
 
+void
+engraving_sanity_check(void)
+{
+    struct engr *ep;
+    schar typ;
+
+    if (head_engr && (Is_airlevel(&u.uz) || Is_waterlevel(&u.uz))) {
+        impossible("engraving sanity: on plane of air/water");
+        return;
+    }
+
+    for (ep = head_engr; ep; ep = ep->nxt_engr) {
+        coordxy x = ep->engr_x, y = ep->engr_y;
+
+        if (!isok(x, y)) {
+            impossible("engraving sanity: !isok <%i,%i>", x, y);
+            return;
+        }
+
+        typ = levl[x][y].typ;
+        if (typ == LAVAPOOL || typ == LAVAWALL || IS_POOL(typ)
+            || typ == AIR || !accessible(x, y)) {
+            impossible("engraving sanity: illegal surface (%i)", typ);
+            return;
+        }
+    }
+}
+
 void
 save_engravings(NHFILE *nhfp)
 {
diff --git a/src/sp_lev.c b/src/sp_lev.c
index 4a53eb4ac..0d26aa670 100644
--- a/src/sp_lev.c
+++ b/src/sp_lev.c
@@ -330,6 +330,7 @@ map_cleanup(void)
 {
     struct obj *otmp;
     struct trap *ttmp;
+    struct engr *etmp;
     coordxy x, y;
 
     for (x = 0; x < COLNO; x++)
@@ -347,6 +348,10 @@ map_cleanup(void)
                 if (((ttmp = t_at(x, y)) != 0)
                     && !undestroyable_trap(ttmp->ttyp))
                     deltrap(ttmp);
+
+                /* engravings? */
+                if ((etmp = engr_at(x, y)) != 0)
+                  del_engr(etmp);
             }
         }
 }