Dungeongen: Fix out-of-voxelmanip access segfault

My recent dungeon commit allowed stairs to be placed across the full
width of corridors, but some of the new node positions accessed were
missing checks for being within the voxelmanip, causing occasional
segfaults near dungeons with corridors wider than 1 node.

Add 'vm->m_area.contains(pos)' checks just before stair position
voxelmanip access. This allows an earlier check to be removed as it
is now redundant.

diff --git a/src/dungeongen.cpp b/src/dungeongen.cpp
index 5dc87f8b01e3e2b65714ea29db0e795405441145..b8ee2b92471cca5496511cf91841b1b4b8cd47df 100644 (file)
--- a/src/dungeongen.cpp
+++ b/src/dungeongen.cpp
@@ -415,8 +415,8 @@ void DungeonGen::makeCorridor(v3s16 doorplace, v3s16 doordir,
                if (partcount != 0)
                        p.Y += make_stairs;
 
-               if (vm->m_area.contains(p) && vm->m_area.contains(p + v3s16(0, 1, 0)) &&
-                               vm->m_area.contains(v3s16(p.X - dir.X, p.Y - 1, p.Z - dir.Z))) {
+               // Check segment of minimum size corridor is in voxelmanip
+               if (vm->m_area.contains(p) && vm->m_area.contains(p + v3s16(0, 1, 0))) {
                        if (make_stairs) {
                                makeFill(p + v3s16(-1, -1, -1),
                                        dp.holesize + v3s16(2, 3, 2),
@@ -444,11 +444,13 @@ void DungeonGen::makeCorridor(v3s16 doorplace, v3s16 doordir,
 
                                        for (u16 st = 0; st < stair_width; st++) {
                                                u32 vi = vm->m_area.index(ps.X - dir.X, ps.Y - 1, ps.Z - dir.Z);
-                                               if (vm->m_data[vi].getContent() == dp.c_wall)
+                                               if (vm->m_area.contains(ps + v3s16(-dir.X, -1, -dir.Z)) &&
+                                                               vm->m_data[vi].getContent() == dp.c_wall)
                                                        vm->m_data[vi] = MapNode(dp.c_stair, 0, facedir);
 
                                                vi = vm->m_area.index(ps.X, ps.Y, ps.Z);
-                                               if (vm->m_data[vi].getContent() == dp.c_wall)
+                                               if (vm->m_area.contains(ps) &&
+                                                               vm->m_data[vi].getContent() == dp.c_wall)
                                                        vm->m_data[vi] = MapNode(dp.c_stair, 0, facedir);
 
                                                ps += swv;