From f33d31693ed2ab7d2a29320181b6aba2c12f76d3 Mon Sep 17 00:00:00 2001 From: Craig Robbins Date: Thu, 7 Aug 2014 15:39:12 +1000 Subject: Fix seg fault if popping from empty stack (L-system trees) See: https://github.com/minetest/minetest/issues/1525 Background Wuzzy2: If you attempt to spawn a L-system tree with minetest.spawn_tree, you can make Minetest crash if it is attempted to pop an empty stack. ShadowNinja: This shouldn't cause a segmentation fault, but it should throw a Lua error Commit Description This commit throws a Lua error instead of causing a segmentation fault. The server will still "crash" but will include a Lua backtrace. L-Systems fix randomness Unless a random seed is provided (via Lua treedef) seed the PRNG with a different seed for each tree Resolves: https://github.com/minetest/minetest/issues/1469 Fix l-system crash when treedef random_level not set by Lua --- src/treegen.cpp | 27 +++++++++++++++++++++++---- 1 file changed, 23 insertions(+), 4 deletions(-) (limited to 'src/treegen.cpp') diff --git a/src/treegen.cpp b/src/treegen.cpp index 542bdf21c..bd4a2f2c9 100644 --- a/src/treegen.cpp +++ b/src/treegen.cpp @@ -118,14 +118,19 @@ void make_tree(ManualMapVoxelManipulator &vmanip, v3s16 p0, } // L-System tree LUA spawner -void spawn_ltree(ServerEnvironment *env, v3s16 p0, INodeDefManager *ndef, TreeDef tree_definition) +treegen::error spawn_ltree(ServerEnvironment *env, v3s16 p0, INodeDefManager *ndef, TreeDef tree_definition) { ServerMap *map = &env->getServerMap(); std::map modified_blocks; ManualMapVoxelManipulator vmanip(map); v3s16 tree_blockp = getNodeBlockPos(p0); + treegen::error e; + vmanip.initialEmerge(tree_blockp - v3s16(1,1,1), tree_blockp + v3s16(1,3,1)); - make_ltree (vmanip, p0, ndef, tree_definition); + e = make_ltree (vmanip, p0, ndef, tree_definition); + if (e != SUCCESS) + return e; + vmanip.blitBackAll(&modified_blocks); // update lighting @@ -142,15 +147,25 @@ void spawn_ltree(ServerEnvironment *env, v3s16 p0, INodeDefManager *ndef, TreeDe event.modified_blocks.insert(i->first); } map->dispatchEvent(&event); + return SUCCESS; } //L-System tree generator -void make_ltree(ManualMapVoxelManipulator &vmanip, v3s16 p0, INodeDefManager *ndef, +treegen::error make_ltree(ManualMapVoxelManipulator &vmanip, v3s16 p0, INodeDefManager *ndef, TreeDef tree_definition) { MapNode dirtnode(ndef->getId("mapgen_dirt")); + int seed; + if (tree_definition.explicit_seed) + { + seed = tree_definition.seed+14002; + } + else + { + seed = p0.X*2 + p0.Y*4 + p0.Z; // use the tree position to seed PRNG + } + PseudoRandom ps(seed); - PseudoRandom ps(tree_definition.seed+14002); // chance of inserting abcd rules double prop_a = 9; double prop_b = 8; @@ -354,6 +369,8 @@ void make_ltree(ManualMapVoxelManipulator &vmanip, v3s16 p0, INodeDefManager *nd stack_position.push(position); break; case ']': + if (stack_orientation.empty()) + return UNBALANCED_BRACKETS; rotation=stack_orientation.top(); stack_orientation.pop(); position=stack_position.top(); @@ -393,6 +410,8 @@ void make_ltree(ManualMapVoxelManipulator &vmanip, v3s16 p0, INodeDefManager *nd break; } } + + return SUCCESS; } void tree_node_placement(ManualMapVoxelManipulator &vmanip, v3f p0, -- cgit v1.2.3