shithub: choc

--- a/src/p_enemy.c

+++ b/src/p_enemy.c

@@ -1258,14 +1258,17 @@

 void A_Fire (mobj_t* actor)

     mobj_t*	dest;

+    mobj_t*     target;

     unsigned	an;

     dest = actor->tracer;

     if (!dest)

 	return;

+    target = P_SubstNullMobj(actor->target);

     // don't move it if the vile lost sight

-    if (!P_CheckSight (actor->target, dest) )

+    if (!P_CheckSight (target, dest) )

 	return;

     an = dest->angle >> ANGLETOFINESHIFT;

@@ -1359,14 +1362,17 @@

 void A_FatAttack1 (mobj_t* actor)

     mobj_t*	mo;

+    mobj_t*     target;

     int		an;

     A_FaceTarget (actor);

     // Change direction  to ...

     actor->angle += FATSPREAD;

-    P_SpawnMissile (actor, actor->target, MT_FATSHOT);

+    target = P_SubstNullMobj(actor->target);

+    P_SpawnMissile (actor, target, MT_FATSHOT);

-    mo = P_SpawnMissile (actor, actor->target, MT_FATSHOT);

+    mo = P_SpawnMissile (actor, target, MT_FATSHOT);

     mo->angle += FATSPREAD;

     an = mo->angle >> ANGLETOFINESHIFT;

     mo->momx = FixedMul (mo->info->speed, finecosine[an]);

@@ -1376,14 +1382,16 @@

 void A_FatAttack2 (mobj_t* actor)

     mobj_t*	mo;

+    mobj_t*     target;

     int		an;

     A_FaceTarget (actor);

     // Now here choose opposite deviation.

     actor->angle -= FATSPREAD;

-    P_SpawnMissile (actor, actor->target, MT_FATSHOT);

+    target = P_SubstNullMobj(actor->target);

+    P_SpawnMissile (actor, target, MT_FATSHOT);

-    mo = P_SpawnMissile (actor, actor->target, MT_FATSHOT);

+    mo = P_SpawnMissile (actor, target, MT_FATSHOT);

     mo->angle -= FATSPREAD*2;

     an = mo->angle >> ANGLETOFINESHIFT;

     mo->momx = FixedMul (mo->info->speed, finecosine[an]);

@@ -1393,17 +1401,20 @@

 void A_FatAttack3 (mobj_t*	actor)

     mobj_t*	mo;

+    mobj_t*     target;

     int		an;

     A_FaceTarget (actor);

+    target = P_SubstNullMobj(actor->target);

-    mo = P_SpawnMissile (actor, actor->target, MT_FATSHOT);

+    mo = P_SpawnMissile (actor, target, MT_FATSHOT);

     mo->angle -= FATSPREAD/2;

     an = mo->angle >> ANGLETOFINESHIFT;

     mo->momx = FixedMul (mo->info->speed, finecosine[an]);

     mo->momy = FixedMul (mo->info->speed, finesine[an]);

-    mo = P_SpawnMissile (actor, actor->target, MT_FATSHOT);

+    mo = P_SpawnMissile (actor, target, MT_FATSHOT);

     mo->angle += FATSPREAD/2;

     an = mo->angle >> ANGLETOFINESHIFT;

     mo->momx = FixedMul (mo->info->speed, finecosine[an]);

@@ -1598,7 +1609,11 @@

//

 void A_Explode (mobj_t* thingy)

-    P_RadiusAttack ( thingy, thingy->target, 128 );

+    mobj_t *target;

+    target = P_SubstNullMobj(thingy->target);

+    P_RadiusAttack(thingy, target, 128);

@@ -1823,7 +1838,7 @@

 mobj_t*		braintargets[32];

 int		numbraintargets;

-int		braintargeton;

+int		braintargeton = 0;

 void A_BrainAwake (mobj_t* mo)

@@ -1959,7 +1974,7 @@

     if (--mo->reactiontime)

 	return;	// still flying

-    targ = mo->target;

+    targ = P_SubstNullMobj(mo->target);

     // First spawn teleport fog.

     fog = P_SpawnMobj (targ->x, targ->y, targ->z, MT_SPAWNFIRE);

--- a/src/p_local.h

+++ b/src/p_local.h

@@ -119,6 +119,7 @@

   mobjtype_t	type );

 void 	P_RemoveMobj (mobj_t* th);

+mobj_t* P_SubstNullMobj (mobj_t* th);

 boolean	P_SetMobjState (mobj_t* mobj, statenum_t state);

 void 	P_MobjThinker (mobj_t* mobj);

--- a/src/p_mobj.c

+++ b/src/p_mobj.c

@@ -922,7 +922,29 @@

 	P_ExplodeMissile (th);

+// Certain functions assume that a mobj_t pointer is non-NULL,

+// causing a crash in some situations where it is NULL.  Vanilla

+// Doom did not crash because of the lack of proper memory

+// protection. This function substitutes NULL pointers for

+// pointers to a dummy mobj, to avoid a crash.

+mobj_t *P_SubstNullMobj(mobj_t *mobj)

+{

+    if (mobj == NULL)

+    {

+        static mobj_t dummy_mobj;

+        dummy_mobj.x = 0;

+        dummy_mobj.y = 0;

+        dummy_mobj.z = 0;

+        dummy_mobj.flags = 0;

+        mobj = &dummy_mobj;

+    }

+    return mobj;

+}

//

 // P_SpawnMissile

//

@@ -935,32 +957,7 @@

     mobj_t*	th;

     angle_t	an;

     int		dist;

-    fixed_t     dest_x, dest_y, dest_z, dest_flags;

-    // fraggle: This prevents against *crashes* when dest == NULL.

-    // For example, when loading a game saved when a mancubus was

-    // in the middle of firing, mancubus->target == NULL.  SpawnMissile

-    // then gets called with dest == NULL.

-    //

-    // However, this is not the *correct* behavior.  At the moment,

-    // the missile is aimed at 0,0,0.  In reality, monsters seem to aim

-    // somewhere else.

-    if (dest)

-    {

-        dest_x = dest->x;

-        dest_y = dest->y;

-        dest_z = dest->z;

-        dest_flags = dest->flags;

-    }

-    else

-    {

-        dest_x = 0;

-        dest_y = 0;

-        dest_z = 0;

-        dest_flags = 0;

-    }

     th = P_SpawnMobj (source->x,

 		      source->y,

 		      source->z + 4*8*FRACUNIT, type);

@@ -969,10 +966,10 @@

 	S_StartSound (th, th->info->seesound);

     th->target = source;	// where it came from

-    an = R_PointToAngle2 (source->x, source->y, dest_x, dest_y);

+    an = R_PointToAngle2 (source->x, source->y, dest->x, dest->y);

     // fuzzy player

-    if (dest_flags & MF_SHADOW)

+    if (dest->flags & MF_SHADOW)

 	an += (P_Random()-P_Random())<<20;

     th->angle = an;

@@ -980,13 +977,13 @@

     th->momx = FixedMul (th->info->speed, finecosine[an]);

     th->momy = FixedMul (th->info->speed, finesine[an]);

-    dist = P_AproxDistance (dest_x - source->x, dest_y - source->y);

+    dist = P_AproxDistance (dest->x - source->x, dest->y - source->y);

     dist = dist / th->info->speed;

     if (dist < 1)

 	dist = 1;

-    th->momz = (dest_z - source->z) / dist;

+    th->momz = (dest->z - source->z) / dist;

     P_CheckMissileSpawn (th);

     return th;