Codechange: Use std::vector for NewGRF station platform layouts.

This avoids the need to custom memory management and additional members.

This also resolves use-after-free if modifying copied layouts, so presumably nobody has ever done that.

(cherry picked from commit bd1a20f6ee)

src/newgrf.cpp

@@ -222,6 +222,19 @@ protected:
 public:
 	ByteReader(byte *data, byte *end) : data(data), end(end) { }
 
+	inline byte *ReadBytes(size_t size)
+	{
+		if (data + size >= end) {
+			/* Put data at the end, as would happen if every byte had been individually read. */
+			data = end;
+			throw OTTDByteReaderSignal();
+		}
+
+		byte *ret = data;
+		data += size;
+		return ret;
+	}
+
 	inline byte ReadByte()
 	{
 		if (data < end) return *(data)++;
@@ -1918,7 +1931,7 @@ static ChangeInfoResult StationChangeInfo(uint stid, int numinfo, int prop, cons
 				StationSpec **spec = &_cur.grffile->stations[stid + i];
 
 				/* Property 0x08 is special; it is where the station is allocated */
-				if (*spec == nullptr) *spec = CallocT<StationSpec>(1);
+				if (*spec == nullptr) *spec = new StationSpec();
 
 				/* Swap classid because we read it in BE meaning WAYP or DFLT */
 				uint32 classid = buf->ReadDWord();
@@ -2001,54 +2014,17 @@ static ChangeInfoResult StationChangeInfo(uint stid, int numinfo, int prop, cons
 				break;
 
 			case 0x0E: // Define custom layout
-				ClrBit(statspec->internal_flags, SSIF_COPIED_LAYOUTS);
-
 				while (buf->HasData()) {
 					byte length = buf->ReadByte();
 					byte number = buf->ReadByte();
-					StationLayout layout;
-					uint l, p;
 
 					if (length == 0 || number == 0) break;
 
-					if (length > statspec->lengths) {
-						byte diff_length = length - statspec->lengths;
-						statspec->platforms = ReallocT(statspec->platforms, length);
-						memset(statspec->platforms + statspec->lengths, 0, diff_length);
-
-						statspec->layouts = ReallocT(statspec->layouts, length);
-						memset(statspec->layouts + statspec->lengths, 0, diff_length * sizeof(*statspec->layouts));
-
-						statspec->lengths = length;
-					}
-					l = length - 1; // index is zero-based
-
-					if (number > statspec->platforms[l]) {
-						statspec->layouts[l] = ReallocT(statspec->layouts[l], number);
-						/* We expect nullptr being 0 here, but C99 guarantees that. */
-						memset(statspec->layouts[l] + statspec->platforms[l], 0,
-						       (number - statspec->platforms[l]) * sizeof(**statspec->layouts));
+					if (statspec->layouts.size() < length) statspec->layouts.resize(length);
+					if (statspec->layouts[length - 1].size() < number) statspec->layouts[length - 1].resize(number);
 
-						statspec->platforms[l] = number;
-					}
-
-					p = 0;
-					layout = MallocT<byte>(length * number);
-					try {
-						for (l = 0; l < length; l++) {
-							for (p = 0; p < number; p++) {
-								layout[l * number + p] = buf->ReadByte();
-							}
-						}
-					} catch (...) {
-						free(layout);
-						throw;
-					}
-
-					l--;
-					p--;
-					free(statspec->layouts[l][p]);
-					statspec->layouts[l][p] = layout;
+					const byte *layout = buf->ReadBytes(length * number);
+					statspec->layouts[length - 1][number - 1].assign(layout, layout + length * number);
 				}
 				break;
 
@@ -2061,10 +2037,7 @@ static ChangeInfoResult StationChangeInfo(uint stid, int numinfo, int prop, cons
 					continue;
 				}
 
-				statspec->lengths   = srcstatspec->lengths;
-				statspec->platforms = srcstatspec->platforms;
-				statspec->layouts   = srcstatspec->layouts;
-				SetBit(statspec->internal_flags, SSIF_COPIED_LAYOUTS);
+				statspec->layouts = srcstatspec->layouts;
 				break;
 			}
 
@@ -9022,20 +8995,8 @@ static void ResetCustomStations()
 
 			delete[] statspec->renderdata;
 
-			/* Release platforms and layouts */
-			if (!HasBit(statspec->internal_flags, SSIF_COPIED_LAYOUTS)) {
-				for (uint l = 0; l < statspec->lengths; l++) {
-					for (uint p = 0; p < statspec->platforms[l]; p++) {
-						free(statspec->layouts[l][p]);
-					}
-					free(statspec->layouts[l]);
-				}
-				free(statspec->layouts);
-				free(statspec->platforms);
-			}
-
 			/* Release this station */
-			free(statspec);
+			delete statspec;
 		}
 
 		/* Free and reset the station data */

src/newgrf_station.h

@@ -112,17 +112,17 @@ enum StationRandomTrigger {
 };
 
 enum StationSpecIntlFlags {
-	SSIF_COPIED_LAYOUTS,      ///< Copied StationLayout **layouts.
-	SSIF_BRIDGE_HEIGHTS_SET,  ///< byte bridge_height[8] is set.
+	SSIF_BRIDGE_HEIGHTS_SET,            ///< byte bridge_height[8] is set.
 	SSIF_BRIDGE_DISALLOWED_PILLARS_SET, ///< byte bridge_disallowed_pillars[8] is set.
 };
 
-/* Station layout for given dimensions - it is a two-dimensional array
- * where index is computed as (x * platforms) + platform. */
-typedef byte *StationLayout;
-
 /** Station specification. */
 struct StationSpec {
+	StationSpec() : cls_id(STAT_CLASS_DFLT), name(0),
+		disallowed_platforms(0), disallowed_lengths(0), tiles(0),
+		renderdata(nullptr), cargo_threshold(0), cargo_triggers(0),
+		callback_mask(0), flags(0), pylons(0), wires(0), blocked(0),
+		animation({0, 0, 0, 0}), internal_flags(0) {}
 	/**
 	 * Properties related the the grf file.
 	 * NUM_CARGO real cargo plus three pseudo cargo sprite groups.
@@ -175,10 +175,17 @@ struct StationSpec {
 
 	AnimationInfo animation;
 
-	byte lengths;
-	byte *platforms;
-	StationLayout **layouts;
 	byte internal_flags; ///< Bitmask of internal spec flags (StationSpecIntlFlags)
+
+	/**
+	 * Custom platform layouts.
+	 * This is a 2D array containing an array of tiles.
+	 * 1st layer is platform lengths.
+	 * 2nd layer is tracks (width).
+	 * These can be sparsely populated, and the upper limit is not defined but
+	 * limited to 255.
+	 */
+	std::vector<std::vector<std::vector<byte>>> layouts;
 };
 
 /** Struct containing information relating to station classes. */

src/station_cmd.cpp

@@ -1222,13 +1222,13 @@ static inline byte *CreateMulti(byte *layout, int n, byte b)
  * @param plat_len  The length of the platforms.
  * @param statspec  The specification of the station to (possibly) get the layout from.
  */
-void GetStationLayout(byte *layout, int numtracks, int plat_len, const StationSpec *statspec)
+void GetStationLayout(byte *layout, uint numtracks, uint plat_len, const StationSpec *statspec)
 {
-	if (statspec != nullptr && statspec->lengths >= plat_len &&
-			statspec->platforms[plat_len - 1] >= numtracks &&
-			statspec->layouts[plat_len - 1][numtracks - 1]) {
+	if (statspec != nullptr && statspec->layouts.size() >= plat_len &&
+			statspec->layouts[plat_len - 1].size() >= numtracks &&
+			!statspec->layouts[plat_len - 1][numtracks - 1].empty()) {
 		/* Custom layout defined, follow it. */
-		memcpy(layout, statspec->layouts[plat_len - 1][numtracks - 1],
+		memcpy(layout, statspec->layouts[plat_len - 1][numtracks - 1].data(),
 			plat_len * numtracks);
 		return;
 	}
@@ -1237,9 +1237,9 @@ void GetStationLayout(byte *layout, int numtracks, int plat_len, const StationSp
 		CreateSingle(layout, numtracks);
 	} else {
 		if (numtracks & 1) layout = CreateSingle(layout, plat_len);
-		numtracks >>= 1;
+		int n = numtracks >> 1;
 
-		while (--numtracks >= 0) {
+		while (--n >= 0) {
 			layout = CreateMulti(layout, plat_len, 4);
 			layout = CreateMulti(layout, plat_len, 6);
 		}

src/waypoint_cmd.cpp

@@ -152,7 +152,7 @@ static CommandCost IsValidTileForWaypoint(TileIndex tile, Axis axis, StationID *
 	return CommandCost();
 }
 
-extern void GetStationLayout(byte *layout, int numtracks, int plat_len, const StationSpec *statspec);
+extern void GetStationLayout(byte *layout, uint numtracks, uint plat_len, const StationSpec *statspec);
 extern CommandCost FindJoiningWaypoint(StationID existing_station, StationID station_to_join, bool adjacent, TileArea ta, Waypoint **wp);
 extern CommandCost CanExpandRailStation(const BaseStation *st, TileArea &new_ta, Axis axis);
 extern CommandCost IsRailStationBridgeAboveOk(TileIndex tile, const StationSpec *statspec, byte layout);