7 files changed, 52 insertions, 14 deletions
diff --git a/src/mapgen/dungeongen.cpp b/src/mapgen/dungeongen.cpp
index acdb1a0f0..1d439abeb 100644
--- a/src/mapgen/dungeongen.cpp
+++ b/src/mapgen/dungeongen.cpp
@@ -71,7 +71,7 @@ DungeonGen::DungeonGen(const NodeDefManager *ndef,
 		dp.num_dungeons        = 1;
 		dp.notifytype          = GENNOTIFY_DUNGEON;
 
-		dp.np_alt_wall = 
+		dp.np_alt_wall =
 			NoiseParams(-0.4, 1.0, v3f(40.0, 40.0, 40.0), 32474, 6, 1.1, 2.0);
 	}
 }
diff --git a/src/mapgen/mapgen.cpp b/src/mapgen/mapgen.cpp
index d767bd264..99db50426 100644
--- a/src/mapgen/mapgen.cpp
+++ b/src/mapgen/mapgen.cpp
@@ -238,7 +238,8 @@ u32 Mapgen::getBlockSeed(v3s16 p, s32 seed)
 
 u32 Mapgen::getBlockSeed2(v3s16 p, s32 seed)
 {
-	u32 n = 1619 * p.X + 31337 * p.Y + 52591 * p.Z + 1013 * seed;
+	// Multiply by unsigned number to avoid signed overflow (UB)
+	u32 n = 1619U * p.X + 31337U * p.Y + 52591U * p.Z + 1013U * seed;
 	n = (n >> 13) ^ n;
 	return (n * (n * n * 60493 + 19990303) + 1376312589);
 }
@@ -452,9 +453,8 @@ void Mapgen::lightSpread(VoxelArea &a, std::queue<std::pair<v3s16, u8>> &queue,
 			!ndef->get(n).light_propagates)
 		return;
 
-	// Since this recursive function only terminates when there is no light from
-	// either bank left, we need to take the max of both banks into account for
-	// the case where spreading has stopped for one light bank but not the other.
+	// MYMAX still needed here because we only exit early if both banks have
+	// nothing to propagate anymore.
 	light = MYMAX(light_day, n.param1 & 0x0F) |
 			MYMAX(light_night, n.param1 & 0xF0);
 
@@ -469,12 +469,9 @@ void Mapgen::calcLighting(v3s16 nmin, v3s16 nmax, v3s16 full_nmin, v3s16 full_nm
 	bool propagate_shadow)
 {
 	ScopeProfiler sp(g_profiler, "EmergeThread: update lighting", SPT_AVG);
-	//TimeTaker t("updateLighting");
 
 	propagateSunlight(nmin, nmax, propagate_shadow);
 	spreadLight(full_nmin, full_nmax);
-
-	//printf("updateLighting: %dms\n", t.stop());
 }
 
 
@@ -1041,6 +1038,8 @@ void MapgenParams::readParams(const Settings *settings)
 	settings->getS16NoEx("chunksize", chunksize);
 	settings->getFlagStrNoEx("mg_flags", flags, flagdesc_mapgen);
 
+	chunksize = rangelim(chunksize, 1, 10);
+
 	delete bparams;
 	bparams = BiomeManager::createBiomeParams(BIOMEGEN_ORIGINAL);
 	if (bparams) {
diff --git a/src/mapgen/mapgen.h b/src/mapgen/mapgen.h
index 61db4f3b9..ef5de6029 100644
--- a/src/mapgen/mapgen.h
+++ b/src/mapgen/mapgen.h
@@ -190,12 +190,38 @@ public:
 
 	void updateLiquid(UniqueQueue<v3s16> *trans_liquid, v3s16 nmin, v3s16 nmax);
 
+	/**
+	 * Set light in entire area to fixed value.
+	 * @param light Light value (contains both banks)
+	 * @param nmin Area to operate on
+	 * @param nmax ^
+	 */
 	void setLighting(u8 light, v3s16 nmin, v3s16 nmax);
-	void lightSpread(VoxelArea &a, std::queue<std::pair<v3s16, u8>> &queue,
-		const v3s16 &p, u8 light);
+	/**
+	 * Run all lighting calculations.
+	 * @param nmin Area to spread sunlight in
+	 * @param nmax ^
+	 * @param full_nmin Area to recalculate light in
+	 * @param full_nmax ^
+	 * @param propagate_shadow see propagateSunlight()
+	 */
 	void calcLighting(v3s16 nmin, v3s16 nmax, v3s16 full_nmin, v3s16 full_nmax,
 		bool propagate_shadow = true);
+	/**
+	 * Spread sunlight from the area above downwards.
+	 * Note that affected nodes have their night bank cleared so you want to
+	 * run a light spread afterwards.
+	 * @param nmin Area to operate on
+	 * @param nmax ^
+	 * @param propagate_shadow Ignore obstructions above and spread sun anyway
+	 */
 	void propagateSunlight(v3s16 nmin, v3s16 nmax, bool propagate_shadow);
+	/**
+	 * Spread light in the given area.
+	 * Artificial light is taken from nodedef, sunlight must already be set.
+	 * @param nmin Area to operate on
+	 * @param nmax ^
+	 */
 	void spreadLight(const v3s16 &nmin, const v3s16 &nmax);
 
 	virtual void makeChunk(BlockMakeData *data) {}
@@ -218,6 +244,18 @@ public:
 	static void setDefaultSettings(Settings *settings);
 
 private:
+	/**
+	 * Spread light to the node at the given position, add to queue if changed.
+	 * The given light value is diminished once.
+	 * @param a VoxelArea being operated on
+	 * @param queue Queue for later lightSpread() calls
+	 * @param p Node position
+	 * @param light Light value (contains both banks)
+	 *
+	 */
+	void lightSpread(VoxelArea &a, std::queue<std::pair<v3s16, u8>> &queue,
+		const v3s16 &p, u8 light);
+
 	// isLiquidHorizontallyFlowable() is a helper function for updateLiquid()
 	// that checks whether there are floodable nodes without liquid beneath
 	// the node at index vi.
diff --git a/src/mapgen/mapgen_flat.cpp b/src/mapgen/mapgen_flat.cpp
index 342455029..6b249ea1f 100644
--- a/src/mapgen/mapgen_flat.cpp
+++ b/src/mapgen/mapgen_flat.cpp
@@ -177,7 +177,7 @@ void MapgenFlatParams::setDefaultSettings(Settings *settings)
 int MapgenFlat::getSpawnLevelAtPoint(v2s16 p)
 {
 	s16 stone_level = ground_level;
-	float n_terrain = 
+	float n_terrain =
 		((spflags & MGFLAT_LAKES) || (spflags & MGFLAT_HILLS)) ?
 		NoisePerlin2D(&noise_terrain->np, p.X, p.Y, seed) :
 		0.0f;
diff --git a/src/mapgen/mapgen_fractal.cpp b/src/mapgen/mapgen_fractal.cpp
index fabb1b2b1..c9071cecf 100644
--- a/src/mapgen/mapgen_fractal.cpp
+++ b/src/mapgen/mapgen_fractal.cpp
@@ -131,6 +131,7 @@ void MapgenFractalParams::readParams(const Settings *settings)
 	settings->getNoiseParams("mgfractal_np_cave1",        np_cave1);
 	settings->getNoiseParams("mgfractal_np_cave2",        np_cave2);
 	settings->getNoiseParams("mgfractal_np_dungeons",     np_dungeons);
+	iterations = std::max<u16>(iterations, 1);
 }
 
 
diff --git a/src/mapgen/mg_biome.cpp b/src/mapgen/mg_biome.cpp
index f08cc190f..8b4c96cd5 100644
--- a/src/mapgen/mg_biome.cpp
+++ b/src/mapgen/mg_biome.cpp
@@ -273,7 +273,7 @@ Biome *BiomeGenOriginal::calcBiomeFromNoise(float heat, float humidity, v3s16 po
 			pos.Y - biome_closest_blend->max_pos.Y)
 		return biome_closest_blend;
 
-	return (biome_closest) ? biome_closest : (Biome *)m_bmgr->getRaw(BIOME_NONE);	
+	return (biome_closest) ? biome_closest : (Biome *)m_bmgr->getRaw(BIOME_NONE);
 }
 
 
diff --git a/src/mapgen/mg_ore.cpp b/src/mapgen/mg_ore.cpp
index 5814f433a..4f0c35548 100644
--- a/src/mapgen/mg_ore.cpp
+++ b/src/mapgen/mg_ore.cpp
@@ -498,8 +498,8 @@ void OreVein::generate(MMVManip *vm, int mapseed, u32 blockseed,
 		}
 
 		// randval ranges from -1..1
-		/* 
-			Note: can generate values slightly larger than 1 
+		/*
+			Note: can generate values slightly larger than 1
 			but this can't be changed as mapgen must be deterministic accross versions.
 		*/
 		float randval   = (float)pr.next() / float(pr.RANDOM_RANGE / 2) - 1.f;