From a3f176c9dce83014ae53d20303deb8053b1074c3 Mon Sep 17 00:00:00 2001
From: PatR <rankin@nethack.org>
Date: Tue, 24 Sep 2024 13:59:28 -0700
Subject: [PATCH] probably fix #K4269 - sanity failure for u.mh \

being greater than u.mhmax

I think this will fix the situation where current HP as a monster
was greater than maximum HP as a monster, triggering a sanity_check
failure.  No promises though.

[poisoned() needs some missing Upolyd handling.]
---
 include/extern.h |  1 +
 src/attrib.c     | 59 +++++++++++++++++++++++++++++++++++-------------
 src/mcastu.c     | 10 +++-----
 3 files changed, 47 insertions(+), 23 deletions(-)

diff --git a/include/extern.h b/include/extern.h
index 2b675eb3b..357131d5c 100644
--- a/include/extern.h
+++ b/include/extern.h
@@ -203,6 +203,7 @@ extern void adjabil(int, int);
 extern int newhp(void);
 extern int minuhpmax(int);
 extern void setuhpmax(int);
+extern int adjuhploss(int, int);
 extern schar acurr(int);
 extern schar acurrstr(void);
 extern boolean extremeattr(int);
diff --git a/src/attrib.c b/src/attrib.c
index c9d3df950..78fd1d3ca 100644
--- a/src/attrib.c
+++ b/src/attrib.c
@@ -243,7 +243,7 @@ losestr(int num, const char *knam, schar k_format)
 
         if (Upolyd) {
             /* when still poly'd, reduce you-as-monst maxHP; never below 1 */
-            u.mhmax -= min(dmg, u.mhmax - 1);
+            setuhpmax(max(u.mhmax - dmg, 1)); /* acts as setmhmax() */
         } else if (!waspolyd) {
             /* not polymorphed now and didn't rehumanize when taking damage;
                reduce max HP, but not below uhpmin */
@@ -352,6 +352,11 @@ poisoned(
         kprefix = KILLED_BY;
     }
 
+    /*
+     * FIXME:
+     *  this operates on u.uhp[max] even when hero is polymorphed....
+     */
+
     i = !fatal ? 1 : rn2(fatal + (thrown_weapon ? 20 : 0));
     if (i == 0 && typ != A_CHA) {
         /* sometimes survivable instant kill */
@@ -366,13 +371,7 @@ poisoned(
                 newuhpmax = u.uhpmax - (loss / 2);
 
             setuhpmax(max(newuhpmax, minuhpmax(3)));
-            /* reduce pending loss if uhp has already been reduced due to
-               drop in uhpmax */
-            if (u.uhp < olduhp) {
-                loss -= (olduhp - u.uhp);
-                if (loss < 1)
-                    loss = 1;
-            }
+            loss = adjuhploss(loss, olduhp);
 
             losehp(loss, pkiller, kprefix); /* poison damage */
             if (adjattrib(A_CON, (typ != A_CON) ? -1 : -3, TRUE))
@@ -1146,18 +1145,46 @@ minuhpmax(int altmin)
     return max(u.ulevel, altmin);
 }
 
-/* update u.uhpmax and values of other things that depend upon it */
+/* update u.uhpmax or u.mhmax and values of other things that depend upon
+   whichever of them is relevant */
 void
 setuhpmax(int newmax)
 {
-    if (newmax != u.uhpmax) {
-        u.uhpmax = newmax;
-        if (u.uhpmax > u.uhppeak)
-            u.uhppeak = u.uhpmax;
-        disp.botl = TRUE;
+    if (!Upolyd) {
+        if (newmax != u.uhpmax) {
+            u.uhpmax = newmax;
+            if (u.uhpmax > u.uhppeak)
+                u.uhppeak = u.uhpmax;
+            disp.botl = TRUE;
+        }
+        if (u.uhp > u.uhpmax)
+            u.uhp = u.uhpmax, disp.botl = TRUE;
+    } else { /* Upolyd */
+        if (newmax != u.mhmax) {
+            u.mhmax = newmax;
+            disp.botl = TRUE;
+        }
+        if (u.mh > u.mhmax)
+            u.mh = u.mhmax, disp.botl = TRUE;
     }
-    if (u.uhp > u.uhpmax)
-        u.uhp = u.uhpmax, disp.botl = TRUE;
+}
+
+/* called after setuhpmax() when damage is pending;
+   if uhpmax (or mhmax) has been reduced, it might have caused uhp (or mh)
+   to be reduced too; if so, recalculate pending loss to account for that */
+int
+adjuhploss(
+    int loss, /* pending hp loss */
+    int olduhp) /* does double duty as oldmh when Upolyd */
+{
+    if (!Upolyd) {
+        if (u.uhp < olduhp)
+            loss -= (olduhp - u.uhp);
+    } else {
+        if (u.mh < olduhp)
+            loss -= (olduhp - u.mh);
+    }
+    return max(loss, 1);
 }
 
 /* return the current effective value of a specific characteristic
diff --git a/src/mcastu.c b/src/mcastu.c
index 0836fa87d..1eb8e5dfd 100644
--- a/src/mcastu.c
+++ b/src/mcastu.c
@@ -395,13 +395,9 @@ touch_of_death(struct monst *mtmp)
             newuhpmax = u.uhpmax - drain;
 
         setuhpmax(max(newuhpmax, minuhpmax(3)));
-        /* reduce pending loss if uhp has already been reduced due to
-           drop in uhpmax */
-        if (u.uhp < olduhp) {
-            dmg -= (olduhp - u.uhp);
-            if (dmg < 1)
-                dmg = 1;
-        }
+        dmg = adjuhploss(dmg, olduhp); /* reduce pending damage if uhp has
+                                        * already been reduced due to drop
+                                        * in uhpmax */
         losehp(dmg, kbuf, KILLED_BY);
     }
     svk.killer.name[0] = '\0'; /* not killed if we get here... */