Voxelmanip: Do not emerge or blit to blocks over map gen limit

Placing a structure that extends into mapblocks that extend past
map_gen_limit causes a crash. For example a sapling growing at the
world edge which adds leaves beyond the edge, or placing a structure
using the lua voxelmanip, or placing a schematic or l-system tree.

Do not run the 'load_if_inexistent' block of code if the mapblock
is over limit, this also marks the mapblock with the flag
VMANIP_BLOCK_DATA_INEXIST which later prevents blitting back those
mapblocks.

This fix therefore uses existing functionality by having the same
effect as the 'load_if_inexistent' bool being false.

diff --git a/src/map.cpp b/src/map.cpp
index ffba772620e6576a7f777b5066dff6a192f13323..a415bda9618111c109d5617194a98aca81451519 100644 (file)
--- a/src/map.cpp
+++ b/src/map.cpp
@@ -3161,7 +3161,7 @@ void MMVManip::initialEmerge(v3s16 blockpos_min, v3s16 blockpos_max,
                if(block_data_inexistent)
                {
 
-                       if (load_if_inexistent) {
+                       if (load_if_inexistent && !blockpos_over_limit(p)) {
                                ServerMap *svrmap = (ServerMap *)m_map;
                                block = svrmap->emergeBlock(p, false);
                                if (block == NULL)