(shp_nav_one_sector): When shp_interdict() removed the second ship in

a sector, interdiction loop followed dangling pointer and crashed.
Simplify & fix.
(mlist): Member done no longer used, remove.

diff --git a/include/ship.h b/include/ship.h
index 3a8d7086d749a7a2df1d54a3c18dec2e7289c9e2..e8f3e29e4c6a10b0afa3c119a561e1cd3f6ad670 100644 (file)
--- a/include/ship.h
+++ b/include/ship.h
@@ -191,7 +191,6 @@ struct mlist {
     struct mchrstr *mcp;       /* pointer to desc of ship */
     struct shpstr ship;                /* struct ship */
     double mobil;              /* how much mobility the ship has left */
-    int done;                  /* has this ship been interdicted yet? */
 };
 
 #define SHP_DEF(b, t) (t ? (b * (logx((double)t, (double)40.0) < 1.0 ? 1.0 : \

diff --git a/src/lib/subs/shpsub.c b/src/lib/subs/shpsub.c
index bc3207a0279ce74e4f804f8e662c392e730b707f..4b0533b1f8e68029b11cfdfa98959c7c3d847d9d 100644 (file)
--- a/src/lib/subs/shpsub.c
+++ b/src/lib/subs/shpsub.c
@@ -718,10 +718,9 @@ shp_interdict(struct emp_qelem *list, coord newx, coord newy, natid victim)
            stopping |=
                shp_damage(list,
                           unit_interdict(newx, newy, victim, "ships",
-                                         shp_easiest_target(list, 0,
-                                                            M_SUB),
-                                         MI_INTERDICT), 0, M_SUB, newx,
-                          newy);
+                                         shp_easiest_target(list, 0, M_SUB),
+                                         MI_INTERDICT),
+                          0, M_SUB, newx, newy);
            if (most_valuable_ship(list)) {
                stopping |=
                    shp_missile_interdiction(list, newx, newy, victim);
@@ -805,9 +804,8 @@ shp_nav_one_sector(struct emp_qelem *list, int dir, natid actor,
     struct sctstr sect;
     struct emp_qelem *qp;
     struct emp_qelem *next;
-    struct emp_qelem *nqp;
-    struct emp_qelem *nnext;
     struct mlist *mlp;
+    struct emp_qelem done;
     coord dx;
     coord dy;
     coord newx;
@@ -867,7 +865,6 @@ shp_nav_one_sector(struct emp_qelem *list, int dir, natid actor,
        }
        mlp->ship.shp_mobil = (int)mlp->mobil;
        putship(mlp->ship.shp_uid, &mlp->ship);
-       mlp->done = 0;          /* We haven't interdicted this ship yet */
 
        /* Now update the map for this ship */
        tech = techfact(mlp->ship.shp_tech, (double)mlp->mcp->m_vrnge);
@@ -887,26 +884,26 @@ shp_nav_one_sector(struct emp_qelem *list, int dir, natid actor,
     if (QEMPTY(list))
        return stopping;
 
-/* Ok, run through each ship and interdict each coordinate */
-    for (qp = list->q_back; qp != list; qp = next) {
-       next = qp->q_back;
-       mlp = (struct mlist *)qp;
-/* Has this ship been interdicted yet? */
-       if (mlp->done)
-           continue;
+    /* interdict ships sector by sector */
+    emp_initque(&done);
+    while (!QEMPTY(list)) {
+       mlp = (struct mlist *)list->q_back;
        newx = mlp->ship.shp_x;
        newy = mlp->ship.shp_y;
        stopping |= shp_interdict(list, newx, newy, actor);
-       if (QEMPTY(list))
-           return stopping;
-/* Now, set all ships in this coordinate to done */
-       for (nqp = list->q_back; nqp != list; nqp = nnext) {
-           nnext = nqp->q_back;
-           mlp = (struct mlist *)nqp;
-           if (mlp->ship.shp_x == newx && mlp->ship.shp_y == newy)
-               mlp->done = 1;
+       /* move survivors in this sector to done */
+       for (qp = list->q_back; qp != list; qp = next) {
+           next = qp->q_back;
+           mlp = (struct mlist *)qp;
+           if (mlp->ship.shp_x == newx && mlp->ship.shp_y == newy) {
+               emp_remque(qp);
+               emp_insque(qp, &done);
+           }
        }
     }
+    /* assign surviving ships back to list */
+    emp_insque(list, &done);
+    emp_remque(&done);
 
     return stopping;
 }