Fix a couple of out-of-bounds accesses when roaming around with noclip.

- guard cansee() against negative sectnums (return 0 immediately), since
  it's often called with the player sectnum as one argument
- in resetpspritevars(), don't inset APLAYER sprite if sectnum < 0, which
  can happen if a map is started in void space accidentally (e.g. from
  the editor)
- two checks before accessing sector[] with a player sectnum

git-svn-id: https://svn.eduke32.com/eduke32@2342 1a8010ca-5511-0410-912e-c29ae57300e0

polymer/eduke32/build/src/engine.c

@@ -10822,6 +10822,10 @@ int32_t cansee(int32_t x1, int32_t y1, int32_t z1, int16_t sect1, int32_t x2, in
     int32_t cfz1[2], cfz2[2];  // both wrt dasectnum
     int16_t bn[2];
 
+    // invalid sectnums can happen, for example if the player is using noclip
+    if (sect1 < 0 || sect2 < 0)
+        return 0;
+
     Bmemset(&pendingvec, 0, sizeof(vec3_t));  // compiler-happy
 #endif
 

polymer/eduke32/source/actors.c

@@ -1041,18 +1041,21 @@ void A_MoveDummyPlayers(void)
 
     while (i >= 0)
     {
+        int32_t psectnum;
+
         nexti = nextspritestat[i];
 
         p = sprite[OW].yvel;
+        psectnum = g_player[p].ps->cursectnum;
 
-        if (g_player[p].ps->on_crane >= 0 || (g_player[p].ps->cursectnum >= 0 && sector[g_player[p].ps->cursectnum].lotag != 1) || sprite[g_player[p].ps->i].extra <= 0)
+        if (g_player[p].ps->on_crane >= 0 || (psectnum >= 0 && sector[psectnum].lotag != 1) || sprite[g_player[p].ps->i].extra <= 0)
         {
             g_player[p].ps->dummyplayersprite = -1;
             KILLIT(i);
         }
         else
         {
-            if (g_player[p].ps->on_ground && g_player[p].ps->on_warping_sector == 1 && sector[g_player[p].ps->cursectnum].lotag == 1)
+            if (g_player[p].ps->on_ground && g_player[p].ps->on_warping_sector == 1 && psectnum >= 0 && sector[psectnum].lotag == 1)
             {
                 CS = 257;
                 SZ = sector[SECT].ceilingz+(27<<8);
@@ -2833,7 +2836,6 @@ ACTOR_STATIC void G_MoveWeapons(void)
         }
         else
         {
-
             // here
             switch (DYNAMICTILEMAP(s->picnum))
             {

polymer/eduke32/source/premap.c

@@ -1581,8 +1581,11 @@ static void resetpspritevars(char g)
     uint8_t aimmode[MAXPLAYERS],autoaim[MAXPLAYERS],weaponswitch[MAXPLAYERS];
     DukeStatus_t tsbar[MAXPLAYERS];
 
-    A_InsertSprite(g_player[0].ps->cursectnum,g_player[0].ps->pos.x,g_player[0].ps->pos.y,g_player[0].ps->pos.z,
-                   APLAYER,0,0,0,g_player[0].ps->ang,0,0,0,10);
+    if (g_player[0].ps->cursectnum >= 0)  // < 0 may happen if we start a map in void space (e.g. testing it)
+    {
+        A_InsertSprite(g_player[0].ps->cursectnum,g_player[0].ps->pos.x,g_player[0].ps->pos.y,g_player[0].ps->pos.z,
+                       APLAYER,0,0,0,g_player[0].ps->ang,0,0,0,10);
+    }
 
     if (ud.recstat != 2)
         TRAVERSE_CONNECT(i)

polymer/eduke32/source/sector.c

@@ -3208,7 +3208,7 @@ void P_CheckSectors(int32_t snum)
             return;
 
         if (neartagsprite == -1 && neartagwall == -1)
-            if (sector[p->cursectnum].lotag == 2)
+            if (p->cursectnum >= 0 && sector[p->cursectnum].lotag == 2)
             {
                 oldz = A_CheckHitSprite(p->i,&neartagsprite);
                 if (oldz > 1280) neartagsprite = -1;