fix sign casting and over flows

Author: Critlist

src/hack.apply.c

@@ -77,7 +77,7 @@ static void use_camera(struct obj *obj) {
   struct monst *mtmp;
   (void)obj;
   if (!getdir(1)) { /* ask: in what direction? */
-    flags.move = multi = 0;
+    flags.move = (unsigned char)(multi = 0); /* MODERN: Cast for bit field assignment */
     return;
   }
   if (u.uswallow) {
@@ -212,7 +212,7 @@ static struct monst *bchit(int ddx, int ddy, int range, char sym) {
       break;
     }
     if (sym)
-      Tmp_at(bchx, bchy);
+      Tmp_at((schar)bchx, (schar)bchy); /* MODERN: Safe cast - coordinates bounded by map size */
   }
   if (sym)
     Tmp_at(-1, -1);

src/hack.do.c

@@ -188,19 +188,19 @@ void goto_level(int newlevel, boolean at_stairs) {
 
   if (at_stairs) {
     if (up) {
-      u.ux = xdnstair;
-      u.uy = ydnstair;
+      u.ux = (xchar)xdnstair; /* MODERN: Safe cast - map coords are 0-79, within xchar range */
+      u.uy = (xchar)ydnstair; /* MODERN: Safe cast - map coords are 0-21, within xchar range */
       if (!u.ux) {       /* entering a maze from below? */
-        u.ux = xupstair; /* this will confuse the player! */
-        u.uy = yupstair;
+        u.ux = (xchar)xupstair; /* this will confuse the player! */ /* MODERN: Safe cast */
+        u.uy = (xchar)yupstair; /* MODERN: Safe cast */
       }
       if (Punished && !Levitation) {
         pline("With great effort you climb the stairs.");
         placebc(1);
       }
     } else {
-      u.ux = xupstair;
-      u.uy = yupstair;
+      u.ux = (xchar)xupstair; /* MODERN: Safe cast - map coords within xchar range */
+      u.uy = (xchar)yupstair; /* MODERN: Safe cast - map coords within xchar range */
       if (inv_weight() + 5 > 0 || Punished) {
         pline("You fall down the stairs."); /* %% */
         losehp(rnd(3), "fall");

src/hack.eat.c

@@ -10,6 +10,7 @@
  */
 
 #include "hack.h"
+#include <limits.h> /* MODERN: For SCHAR_MAX to prevent stat overflow */
 #include <stdio.h>
 char POISONOUS[] = "ADKSVabhks";
 extern const char
@@ -95,8 +96,12 @@ int opentin(void) {
   } else {
     pline("It contains spinach - this makes you feel like Popeye!");
     lesshungry(600);
-    if (u.ustr < 118)
-      u.ustr += rnd(((u.ustr < 17) ? 19 : 118) - u.ustr);
+    if (u.ustr < 118) {
+      int new_str = u.ustr + rnd(((u.ustr < 17) ? 19 : 118) - u.ustr);
+      /* MODERN: Prevent strength overflow - cap at max schar value */
+      if (new_str > SCHAR_MAX) new_str = SCHAR_MAX;
+      u.ustr = (schar)new_str;
+    }
     if (u.ustr > u.ustrmax)
       u.ustrmax = u.ustr;
     flags.botl = 1;

src/hack.engrave.c

@@ -251,7 +251,7 @@ int doengrave(void) {
       otmp->spe = -3;
       nomovemsg = "You cannot engrave more.";
     } else {
-      otmp->spe -= len / 2;
+      otmp->spe -= (schar)(len / 2); /* MODERN: Safe cast - engraving length bounded */
       nomovemsg = "You finished engraving.";
     }
     multi = -len;

src/hack.fight.c

@@ -68,8 +68,8 @@ int hitmm(struct monst *magr, struct monst *mdef) {
             "You have a peculiarly sad feeling for a moment, then it passes.");
       monstone(mdef);
       hit = 2;
-    } else if ((mdef->mhp -= d(pa->damn, pa->damd)) < 1) {
-      magr->mhpmax += 1 + rn2(pd->mlevel + 1);
+    } else if ((mdef->mhp -= (schar)d(pa->damn, pa->damd)) < 1) { /* MODERN: Safe cast - damage capped by dice */
+      magr->mhpmax += (schar)(1 + rn2(pd->mlevel + 1)); /* MODERN: Safe cast - level-based increment */
       if (magr->mtame && magr->mhpmax > 8 * pa->mlevel) {
         if (pa == &li_dog)
           magr->data = pa = &dog;
@@ -245,14 +245,19 @@ boolean hmon(struct monst *mon, struct obj *obj,
   }
   if (tmp < 1)
     tmp = 1;
-  mon->mhp -= tmp;
+  mon->mhp -= (schar)tmp; /* MODERN: Safe cast - tmp bounded above by weapon damage */
   if (mon->mhp < 1) {
     killed(mon);
     return (FALSE);
   }
   if (mon->mtame && (!mon->mflee || mon->mfleetim)) {
     mon->mflee = 1; /* Rick Richardson */
-    mon->mfleetim += 10 * rnd(tmp);
+    int flee_add = 10 * rnd(tmp);
+    /* MODERN: Cap flee time to 7-bit field max (127) */
+    if (mon->mfleetim + flee_add > 127)
+      mon->mfleetim = 127;
+    else
+      mon->mfleetim += flee_add;
   }
 
   if (!hittxt) {

src/hack.h

@@ -76,7 +76,8 @@ typedef struct {
 
 extern void *alloc(unsigned lth);
 /* MODERN: CONST-CORRECTNESS: panic message is read-only */
-extern void panic(const char *str, ...);
+/* MODERN: noreturn attribute tells compiler panic() never returns */
+extern void panic(const char *str, ...) __attribute__((noreturn));
 
 /* Critical missing function prototypes */
 extern int carrying(int type);

src/hack.main.c

@@ -335,8 +335,8 @@ int main(int argc, char *argv[]) {
 
     (void)signal(SIGINT, done1);
     mklev();
-    u.ux = xupstair;
-    u.uy = yupstair;
+    u.ux = (xchar)xupstair; /* MODERN: Safe cast - map coords are 0-79, within xchar range */
+    u.uy = (xchar)yupstair; /* MODERN: Safe cast - map coords are 0-21, within xchar range */
     (void)inshop();
     setsee();
     flags.botlx = 1;

src/hack.mklev.c

@@ -206,7 +206,7 @@ int makerooms() {
     hix = lowx + dx;
     hiy = lowy + dy;
 
-    if (maker(lowx, dx, lowy, dy)) {
+    if (maker((schar)lowx, (schar)dx, (schar)lowy, (schar)dy)) { /* MODERN: Safe cast - room coordinates bounded by map */
       if (secret)
         return (1);
       addrs(lowx - 1, lowy - 1, hix + 1, hiy + 1);

src/hack.mkobj.c

@@ -88,9 +88,10 @@ int otyp;
     if (otmp->otyp == TIN)
       otmp->spe = rnd(...);
 #endif /* NOT_YET_IMPLEMENTED */
-       /* fallthrough */
+       /* FALLTHROUGH */
   case GEM_SYM:
     otmp->quan = rn2(6) ? 1 : 2;
+    /* FALLTHROUGH */
   case TOOL_SYM:
   case CHAIN_SYM:
   case BALL_SYM:

src/hack.potion.c

@@ -130,9 +130,12 @@ int dodrink(void) {
     pline("Wow do you feel strong!");
     if (u.ustr >= 118)
       break; /* > 118 is impossible */
-    if (u.ustr > 17)
-      u.ustr += rnd(118 - u.ustr);
-    else
+    if (u.ustr > 17) {
+      int new_str = u.ustr + rnd(118 - u.ustr);
+      /* MODERN: Prevent strength overflow - cap at max schar value */
+      if (new_str > 127) new_str = 127;
+      u.ustr = (schar)new_str;
+    } else
       u.ustr++;
     if (u.ustr > u.ustrmax)
       u.ustrmax = u.ustr;