(svn r20247) -Fix: when it is known the loading an old savegame is going to fail, bail out immediately (using an exception) instead of going on until e.g. the expected number of byte is read

src/saveload/oldloader.cpp

@@ -22,6 +22,8 @@
 #include "saveload_internal.h"
 #include "oldloader.h"
 
+#include <exception>
+
 static const int TTO_HEADER_SIZE = 41;
 static const int TTD_HEADER_SIZE = 49;
 
@@ -49,13 +51,14 @@ static byte ReadByteFromFile(LoadgameState *ls)
 	/* To avoid slow reads, we read BUFFER_SIZE of bytes per time
 	and just return a byte per time */
 	if (ls->buffer_cur >= ls->buffer_count) {
+
 		/* Read some new bytes from the file */
 		int count = (int)fread(ls->buffer, 1, BUFFER_SIZE, ls->file);
 
 		/* We tried to read, but there is nothing in the file anymore.. */
 		if (count == 0) {
 			DEBUG(oldloader, 0, "Read past end of file, loading failed");
-			ls->failed = true;
+			throw std::exception();
 		}
 
 		ls->buffer_count = count;
@@ -119,8 +122,6 @@ bool LoadChunk(LoadgameState *ls, void *base, const OldChunks *chunks)
 		if (chunk->type & OC_DEREFERENCE_POINTER) ptr = *(byte**)ptr;
 
 		for (uint i = 0; i < chunk->amount; i++) {
-			if (ls->failed) return false;
-
 			/* Handle simple types */
 			if (GetOldChunkType(chunk->type) != 0) {
 				switch (GetOldChunkType(chunk->type)) {
@@ -135,7 +136,7 @@ bool LoadChunk(LoadgameState *ls, void *base, const OldChunks *chunks)
 
 					case OC_ASSERT:
 						DEBUG(oldloader, 4, "Assert point: 0x%X / 0x%X", ls->total_read, chunk->offset + _bump_assert_value);
-						if (ls->total_read != chunk->offset + _bump_assert_value) ls->failed = true;
+						if (ls->total_read != chunk->offset + _bump_assert_value) throw std::exception();
 					default: break;
 				}
 			} else {
@@ -189,7 +190,6 @@ static void InitLoading(LoadgameState *ls)
 {
 	ls->chunk_size   = 0;
 	ls->total_read   = 0;
-	ls->failed       = false;
 
 	ls->decoding     = false;
 	ls->decode_char  = 0;
@@ -301,7 +301,14 @@ bool LoadOldSaveGame(const char *file)
 
 	_savegame_type = type;
 
-	if (proc == NULL || !proc(&ls)) {
+	bool game_loaded;
+	try {
+		game_loaded = proc != NULL && proc(&ls);
+	} catch (...) {
+		game_loaded = false;
+	}
+
+	if (!game_loaded) {
 		SetSaveLoadError(STR_GAME_SAVELOAD_ERROR_DATA_INTEGRITY_CHECK_FAILED);
 		fclose(ls.file);
 		return false;

src/saveload/oldloader.h

@@ -31,7 +31,6 @@ struct LoadgameState {
 	byte buffer[BUFFER_SIZE];
 
 	uint total_read;
-	bool failed;
 };
 
 /* OldChunk-Type */

src/saveload/oldloader_sl.cpp

@@ -1479,7 +1479,7 @@ static bool LoadOldMapPart1(LoadgameState *ls, int num)
 		}
 	}
 
-	return !ls->failed;
+	return true;
 }
 
 static bool LoadOldMapPart2(LoadgameState *ls, int num)
@@ -1493,7 +1493,7 @@ static bool LoadOldMapPart2(LoadgameState *ls, int num)
 		_m[i].m5 = ReadByte(ls);
 	}
 
-	return !ls->failed;
+	return true;
 }
 
 static bool LoadTTDPatchExtraChunks(LoadgameState *ls, int num)
@@ -1548,7 +1548,7 @@ static bool LoadTTDPatchExtraChunks(LoadgameState *ls, int num)
 		}
 	}
 
-	return !ls->failed;
+	return true;
 }
 
 extern TileIndex _cur_tileloop_tile;
@@ -1734,11 +1734,17 @@ bool LoadTTDMain(LoadgameState *ls)
 	SmallStackSafeStackAlloc<byte, OLD_MAP_SIZE * 2> map3;
 	_old_map3 = map3.data;
 	_old_vehicle_names = NULL;
+	try {
 		if (!LoadChunk(ls, NULL, main_chunk)) {
 			DEBUG(oldloader, 0, "Loading failed");
 			free(_old_vehicle_names);
 			return false;
 		}
+	} catch (...) {
+		free(_old_vehicle_names);
+		throw;
+	}
+
 	DEBUG(oldloader, 3, "Done, converting game data...");
 
 	FixTTDMapArray();